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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #30 dnia: Czerwiec 04, 2022, 05:22 »
Gravity Assist: Gardens at the Bottom of the Sea, with Laurie Barge (2)

A “chimney” structure, simulating minerals coming together at the bottom of the ocean, grows in the laboratory of astrobiologist Laurie Barge at NASA’s Jet Propulsion Laboratory, Pasadena, Credits: NASA/JPL-Caltech

Laurie Barge: No one really knows the answer to that because with the origin of life, you can look at it from two directions. You can look at it from top down, which is where you look at all life on Earth and you say, "What does it have in common? What was the last common ancestor like?" And you can get some information, and then you can go bottom up and say, "Based on what we know of early Earth geologically, what was possible." And then where does that take you? And ideally you want those two to meet up somewhere reasonable. And so, we don't actually know where the first life lived, there's theories that it could have been on land, underwater in a vent at a high temperature. And no one really knows the answer to that, honestly. So for origin of life chemistry, we have to test all kinds of different conditions and try to narrow it down. And then ideally, one of those, at least, will be similar to what we know about the earliest life.

Jim Green: So when you're in the laboratory and you're recreating a vent, what does that look like? Is that just a slit in the ground?

Laurie Barge: We make a little bottle that is the ocean. We make an ocean solution. And actually the nice thing about lab is you don't have to be limited to the ocean that Earth has today. You can make early Earth's ocean, you could make an early Mars guess at an ocean. So we make a little ocean, and then at the base of that, we inject, with a syringe, a little hydrothermal fluid. And if you slowly inject that, then those two fluids react and you can form mineral precipitates. And so, if you inject slowly and carefully, you can grow a little chimney in the lab, just like you see in vents in the field.

Laurie Barge: We make choices about how fast do we want the fluid to flow, how fast do we want the chimney to grow. And so, we control the situation more by having just one injection point at the bottom. So it really is a syringe needle that comes up the bottom, and then we control that injection. But if you make it different speeds or different forces, you can get all kinds of different effects on the chimney that you make.

Jim Green: Well, what are some of the processes then that are occurring besides the precipitation, as you say, there's a reduction, and what does that mean chemically?

Laurie Barge: Well, we have, let's say, if we inject organics into the hydrothermal fluids. So we pretend they're coming up from below from some water rock-chemistry, then those organics can react with the iron minerals in the chimneys, or even not just in a chimney, but around the chimney you have sediments and it's like this big chemical reactor or fluid is flowing through a porous pile of mineral with so much surface area and so much pore space, so you can really get a lot of reactions. So one thing that we look at is reduction using that iron to reduce organics into other molecules, and then also trying to form those building blocks of life, like amino acids.

Jim Green: Oh, wow. So you actually can form amino acids in these environments? Are there some specific conditions or temperature ranges that you're finding out are really critical to be able to do that?

Laurie Barge: We are finding that for amino acids specifically, it is good to have more minerals than less minerals. So it's nice to have a nice pile of sediments, or a really a big chimney rather than something small. And we find that it works a little bit better when you're at a more alkaline pH and when the temperature is medium high, like maybe 50 to 70 degrees, not too high. But a lot of times in lab, you find the "best condition" for a reaction, but that's not actually the condition that Earth had. And so, you have to say, "Well, what's the best condition?" But also, "What's the most realistic one?"
Jim Green: Well, you know, Mars, in its distant past, when Earth was a blue planet, Mars was a blue planet, around four billion years ago, it actually had a huge ocean. Two thirds of the Northern hemisphere was under water, but that water's gone. So can we, or should we roam around that ancient ocean floor of Mars looking for old hydrothermal vents? Would that be a good idea?

Laurie Barge: I think that'd be a great idea. I would like to see that. I would like to see some roving around looking for evidence of old vents, but also if you can get underground at all and look and see what's there. On Earth, we do this, we look for the oldest rocks and say, "What do they say about our ancient ocean?" So being able to do things like that for Mars and other planets would be amazing.

Jim Green: Well, if you could invent a spacecraft to find the type of life that we're talking about, which would be extremophile, living in extreme areas like high pressure vents and high temperature ocean world, what would it be like? And where would you go?

Laurie Barge: Well, I think there's so many places you could go. And I would personally want to see things like how we study Earth's ocean. So we have robots that go underwater and look at vents. And even on Earth, where it's the easiest possible scenario for a planet, because we're here, it's still really hard to explore the ocean. And there's a lot of work still to be done about understanding our sea floor. So, I would love it if we could ever get to the sea floor of another world that might have vents, even though I know that would take perhaps many missions or many years to actually characterize that environment. But if we could ever go to a vent with a robot and actually look at it and see, does it have life? Or could it support life? Or what does it even look like? I think that would be fascinating.

Jim Green: On Gravity Assist, we also get questions from our listeners, and one of them, I think you're going to be able to answer, and that is, "Do you expect evolutionary rules to be universal? Or would extraterrestrial life just follow its own rules?"

Laurie Barge: I would say, probably in general, some things are the same, like the fact that certain chemical elements are going to be better energy sources for life, or maybe the way that organic chemistry might have to work for mutation. But I think that also evolution is largely directed by the environment and the planet. And so, on another world or with another origin, you would also have to ask, "How is that planetary environment and the evolution of the planet affecting its life as well?'

Jim Green: Another listener wanted to know about the similarity of genetic material across all of Earth's life form, they appear to be the basis for a single origin of life. But could that similarity of genetic material also indicate that life can only form in one manner?

Laurie Barge: I think we don't know for sure how many origins of life there could have been. All we know is that all life on Earth has one common ancestor. But we don't know what happened before that. And so it is possible you had other origins that either fizzled out or something. But also, it's interesting because if you did have multiple origins, and if it was the case that life could only happen one way, then you might expect a tree of life that had more than one ancestor. And so that's something that we can look of when we see life on other planets as well.

Jim Green: Well, I found out that one of the things that you like to do through a National Science Foundation program is to work with summer students. What are some of the things that you do?

Laurie Barge: Yeah. It's actually a year-round program. Well, it was called Bridge to the Geosciences. And so we design modules for community college students to learn about different careers in geoscience or in STEM. And so we would go to different institutes and show them what are the types of jobs you could have as a geology major or as a science major, beyond just say, being a professor at universities. There's all kinds of really interesting things that one can do with that. So we try to give them a more broad view of what this looks like while they're still in school.

Jim Green: Well, Laurie, I always like to ask my guests to tell me what was the event, or person, place, or thing that happened that got them so excited that they became the scientist they are today. I call that event a gravity assist. So Laurie, what was your gravity assist?

Laurie Barge: Well, honestly, I would say it was the missions that went on during my childhood and also when I was in college. And so for me, I think the first time I thought I really decided I was going to work for NASA was when the Voyager mission passed Neptune. And I forgot what year this was, but I was in elementary school. And so, I remember seeing that on the news and thinking, "Wow, this is great. I should work for NASA." And at that time I had no idea what astrobiology was, or that I would end up liking geology or chemistry or any of this. But it was what put it on my radar.

Laurie Barge: And then when I was in grad school, the Mars Rovers, Spirit and Opportunity landed. And so, that was really fun too. And Cassini got to Saturn at that same time. So it was really fun to be studying my research as these missions were studying these planets. And so, I think the missions were very inspiring, and I think they have been for a lot of people in my cohort.

Jim Green: Well, thanks so much for joining us today and talking about a real passionate topic you have, the origin of life here on Earth. Because if we don't understand it, how it happened here, how can we possibly find it elsewhere? Thanks so much, Laurie.

Laurie Barge: Thank you.

Jim Green: Well, join me next time as we continue our journey to look for life beyond Earth. I'm Jim Green, and this is your Gravity Assist.

Lead producer: Elizabeth Landau

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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #31 dnia: Czerwiec 18, 2022, 07:52 »
Jak w obiegu zamkniętym?
All life takes in energy and creates waste products or, for lack of a better word, poops, and it is indeed often these waste products that turn into biosignatures or possible biosignatures of life. For example, we're breathing poop right now. We are breathing tree poop. Oxygen is tree poop. So oxygen, molecular oxygen, is a potential biosignature that we look for in extrasolar planets. So, absolutely, poop can be a biosignature.

Gravity Assist: Looking For Life in Ancient Lakes
Aug 14, 2020

Astrobiologist Kennda Lynch at her field site in Pilot Valley, Utah. Credits: Kennda Lynch

As the Perseverance Rover flies toward Jezero Crater on Mars, which once hosted water, astrobiologists are interested in places on Earth that are similar to the rover landing site. Kennda Lynch, scientist at the Lunar and Planetary Institute in Houston, Texas, has been doing fieldwork in an ancient lake location in Utah called the Pilot Valley Playa. In this episode she describes her recent discoveries and why she’s excited about Perseverance. She also explains how all life forms create waste products, even bacteria, that could leave tracers or “biosignatures” for scientists to detect. By looking at how microbes survive in extreme environments on Earth, scientists can explore the bigger question of how life could sustain itself on other planetary bodies like Mars and Jupiter’s moon Europa.

Credits: NASA

Jim Green: The Perseverance rover is on its way to Mars. In February, it will land in a fabulous area called Jezero crater. 

Jim Green: It's right there on that edge between the land and the ancient ocean.

Jim Green: What do we expect to find?

Kennda Lynch: There could've been a habitable environment in that watershed area that picked up some potential biosignatures and deposited into the delta and got preserved.

Jim Green:  Hi, I’m Jim Green, Chief Scientist at NASA, and this is Gravity Assist. On this season of Gravity Assist we’re looking for life beyond Earth.

Jim Green: I'm here with Dr. Kennda Lynch, and she is an astrobiologist and a geomicrobiologist studying life in extremes. She works at the Lunar and Planetary Institute in Houston, Texas. Welcome, Kennda, to Gravity Assist.

Kennda Lynch: Thank you. It's so great to be here.

Jim Green: Well, your current research really focuses on the studying of paleo-lake basins here on Earth, and so that makes you a perfect expert to be involved in the Perseverance rover since it's going to Jezero crater and land on an ancient lake basin, doesn't it?

Kennda Lynch: I would say it makes me one of several really good experts that are really excited at the fact that we're going to Jezero.

Jim Green: Well, let's first discuss what we know about the Earth's paleo-lake basins.

Kennda Lynch: Absolutely. What we know about Earth lake basins is a lot of our paleo-lake basins, these were ancient lakes that were, in a lot of cases, very, very big, very deep lakes. For example, Lake Bonneville, where my field site is, was an ancient lake of the Pleistocene era, and at some point, at one point, it was a thousand foot in depth. It was very big, very deep, actually freshwater lake. But, over time, because it was a closed basin lake and we had climate change, the lake started to dry out. It didn't have any outflow, so everything just evaporated.

Kennda Lynch: There's many of these across the world that we study. There's the Great Salt Lake here in Utah. Death Valley also has paleo-lakes in it. The Salar de Uyuni in Bolivia also has one. We have one in China. We have paleo-lakes in China in the Qaidam Basin. So all these big lakes dried into these amazing playa environments where we have all of these lake sediments, we sometimes have occasional very, very shallow lakes that can develop in these environments, but we have amazing microbial diversity that can be found in these lake basin sediments after the lake went away, and that's what I like to study.

Jim Green: Well, what exactly are you looking for when you get these sediments?

Kennda Lynch: We're looking at a couple of different things. Initially, we wanted to just try to understand what these ecosystems look like. There really hasn't been a lot of research, believe it or not, in these kind of systems because people didn't really understand that they could be very, very rich in life. So the first thing we do is we do a lot of heavy biology, so a lot of looking for DNA and trying to understand what we call the phylogeny. Who's there, how diverse they are, what does the ecosystem, what do the microbial communities look like? A lot of the first work that I did was understanding who's there and what they look like.

Kennda Lynch: Then the next thing we look for is how are they interacting with the environment, how are they interacting with the geochemistry, how are they living there, what are they eating, what are they breathing, how are they getting their energy, how are they interacting, all of these kinds of things. So we look for that, and we try to understand that.

Jim Green: Can you tell me about a particularly memorable experience you had out in the field?

Kennda Lynch: Oh, wow, there's so many. I'm going to give you two quick little ones. When we were at the center of the basin where there's an actual well that my colleagues had put in permanently, we found a little mouse hanging out in the well, just hanging out in the shade of the well, and he had somehow gotten onto the playa. But he was hanging out there during the heat of the day. Well, the next day, we came back to one of my boreholes that was about a mile away. That mouse was in my borehole using the borehole as shade. So he had, overnight, had gone that whole mile, mile and a half, and was using our borehole as a refuge for the day heat. It was very cute, and we got pictures of it.

Kennda Lynch: Then the second memorable experience was when we got our UTV stuck in some of the playa mud. That was a challenge.

NASA's Mars Perseverance rover will land in Jezero Crater, pictured here. The image was taken by instruments on NASA's Mars Reconnaissance Orbiter, which regularly takes images of potential landing sites for future missions. Credits: NASA/JPL-Caltech/ASU

Jim Green: You know, the first mission to find perchlorates on Mars was Phoenix, but even Curiosity has confirmed that there are perchlorates but not everywhere. What are perchlorates, and tell us a little bit about how are they important?

Kennda Lynch: 
So perchlorates are what we call chlorine oxyanions. It's a chlorine atom surrounded by four oxygen atoms, and it's a really, really, really big oxidizer very similar to oxygen, so it gives the same kind of energy release that oxygen does. In fact, here on Earth, we use perchlorates as part of solid rocket fuel because when you light it up, it really gives a lot of energy that helps our rockets take off. People experience perchlorates every day in things like firecrackers. But we also know that perchlorate occurs naturally on Earth and, of course, on Mars. On Mars, we see more perchlorate on Mars than we see anywhere on Earth, and so it's this incredible potential energy resource that life could use to generate energy and sustain an ecosystem.

Kennda Lynch:  The other reason, which is not as exciting, but perchlorates on Earth, they can be toxic to humans, so we want to understand perchlorates so that we can make sure that it doesn't affect our astronauts when we send them to Mars, so that we can mitigate the perchlorates and make sure that they don't make our astronauts sick when we send our first human mission to Mars.

Jim Green: This field site that you went to, the Pilot field site, where is it at, and why did you choose that?

Kennda Lynch: So Pilot Valley Basin is a part of the Great Salt Lake Desert, which basically encompasses most of northwestern Utah. Basically, once you get past Salt Lake City, the rest of it is the Great Salt Lake Desert, and Pilot Valley is a sub-basin of that desert that actually because of how it's nestled in between two mountain ranges is off on its own, it's all Jeep roads to get there, it's not that easy to get to. So there hasn't been a lot of anthropogenic input onto Pilot Valley, whereas other basins in the Great Salt Lake Desert, they do a lot of salt-mining, a lot of economic geology. Pilot Valley has been off on its own and pretty much left pristine.

Kennda Lynch: How I found this environment actually very much relates to the Phoenix mission and our discovery of perchlorate. I was working with Dr. Sam Kounaves, who was a Co-I on Phoenix at the time and is one of my long-term mentors and definitely a wonderful, wonderful scientist. I was working with him on his sensors, his wet chemistry sensors, and during the Phoenix mission, I was in grad school and he called me. He called me and I think he actually might've called me from JPL and said, "Kennda, do you know anything about perchlorate," and started me down this road about looking at perchlorate and microbes that can use perchlorate.

Kennda Lynch: The following summer, I was driving to Ames Research Center to start my Harriet Jenkins Predoctoral Fellowship summer portion. I was driving through Utah and looking at the Great Salt Lake Desert, and I had done all this research about perchlorate and where it lives in the Atacama, and I'm looking at the Great Salt Lake Desert and I'm like, "I wonder if there's perchlorate here. That would be kind of a neat environment to study." So I wrote a little mini-proposal to get the summer internship money the next summer from my school, and I went out and did a field expedition, and literally it changed my whole direction of my dissertation. It just keeps getting more and more interesting and more and more fun every time we go out there.

Jim Green: Well, there are other places in the solar system that we were thinking of looking for life, like Europa. Are you doing any research on Earth that relates to Europa?

Kennda Lynch:  Definitely some of the work that we're doing in my basin. One of my recent research papers that just came out last summer, where we basically documented our first discovery of perchlorate reducing microbes cohabitating in an area there was actually also naturally occurring perchlorate, something that's never been documented before. So, now, we have a relevant Earth analog ecosystem to learn about how perchlorate reducing microbes can live in what on Earth is an extreme environment but would be more of a normal environment on Mars or Europa, living in a brine or a salty environment in Mars and Europa.

Jim Green: I remember that once you did a talk called "All Life Poops." Does that mean that even bacteria has waste, and could we find traces of that in any of the samples that we bring back, whether it's from Mars or flying through the plume over Europa?

Kennda Lynch: Yep, indeed. All life takes in energy and creates waste products or, for lack of a better word, poops, and it is indeed often these waste products that turn into biosignatures or possible biosignatures of life. For example, we're breathing poop right now. We are breathing tree poop. Oxygen is tree poop. So oxygen, molecular oxygen, is a potential biosignature that we look for in extrasolar planets. So, absolutely, poop can be a biosignature.

Jim Green: Wow. You're absolutely right. I just never thought of it that way.

Kennda Lynch: I know. It's so funny. When I show kids, some of them go ... and try to hold their breath. They're like, "I don't want to breathe poop," and I'm like, "Don't have a choice."

Jim Green: You need that. You need that, okay?

Kennda Lynch: You need that poop.

Jim Green: That's what makes different types of life coexist together, and in fact, we need that oxygen production from our plants.

Kennda Lynch: Yep, absolutely.

Jim Green: Just as they need the CO2 production that we create.

Kennda Lynch: Yep.

Jim Green: So that's what creates a biosphere is that important relationship between the different species of life.

Kennda Lynch: Exactly.

Jim Green: So, Kennda, what about Perseverance is getting you really excited? When that lands in Jezero crater, what do you want it to do?

Kennda Lynch: I am so excited about what we call the bottomset deposits. These are these really, really fine deposits, really fine grains. They're usually mostly made up of clays and carbonates on Earth. They're really small particles that deposit in the lake basin and at the front of the delta that can make these great sediments where we can preserve organics and biosignatures. I am so excited for Perseverance to go and start taking a look at those particular deposits in the crater.

Kennda Lynch: We're going to have some of the best chances of finding preserved organics in those deposits because that's an environment on Earth where those kind of lake bed deposits or delta deposits, we know we get a lot of concentrated carbon that gets preserved and stabilized very well in those kind of deposits. So I'm really excited about the bottomsets.

Jim Green: It's right there on that edge between the land and the ancient ocean, and this river was dumping into that when this impact occurred and created this huge crater we now call Jezero.

Jim Green: Would you think we might be able to find some biomolecules if you've got complex carbon, a material that we're also finding? Is there a hope that we could do that?

Kennda Lynch: You know, I really do think so because what's really amazing about these bottomset deposits is that because of the lake environment and the fact that we have this delta, it could come from potentially different habitable environments within the Jezero crater area. It could've come from up in the watershed, and the watershed is that area where all the water that developed on Mars in that region flowed together into one big river or stream and deposited the water and the sediments that created the delta. There could've been a habitable environment in that watershed area that picked up some potential biosignatures and deposited into the delta and got preserved. It could've come from the lake itself.

Kennda Lynch: Or it could've been preserved from a transitional habitable zone like I study, this subsurface environment where there's groundwater moving through these sediments after the lake's gone, and there could've been a subsurface ecosystem that could've lived there for a time before water retreated even deeper into Mars, and there could've been life that could've left some potential biosignatures there. So we have three different potential habitable environments that could've left biosignatures in these deposits, so I'm so excited to see what we can find out when we get samples from there.

Jim Green: You bring up something I hadn't really thought about, but, indeed, with that lake over time being eroded away and then the atmosphere becomes very thin, that's going to draw groundwater out.

Kennda Lynch: Yeah, especially since we know now that groundwater was a significant part of the hydrology on Mars, that that's going to be a really important environment for us to start to try to understand. Again, I'm so excited to see what we're going to be able to find out.

Jim Green: Well, you've also been involved in education and diversity efforts in what we call science, technology, engineering, and mathematics or STEM as an acronym. Can you tell us a little bit about what your efforts are and what you've been doing in this area?

Kennda Lynch: I am a lifetime member of the Girl Scouts. I was my mom's first girl scout, and my mom worked on the professional staff, so I grew up in girl scouting and giving back and reaching out and educating. Yeah, I've just been doing it my whole life, all through college and undergrad. I have mentored so many students while working as a full-time engineer. I've done a lot of school presentations. And in grad school, I've mentored students and taught classes.

Kennda Lynch: Right now, I've got three students I'm mentoring, two directly at the LPI, one indirectly with a colleague who's asked me to mentor one of their students of color, and I'm very excited to be able to do that. I also do a lot of STEM outreach with our education and public engagement department here at the Lunar and Planetary Institute.

Kennda Lynch: I'm a Ford Fellow, so I interact with that community quite a lot and try to help with efforts to increase diversity, equity, and inclusion across the space sciences and just STEM in general

Jim Green: Well, I personally want to thank you for all that activity. I enjoy talking to the public and talking about the fabulous science that we do. You just can't stop me, and I'm just delighted that you're doing the same. Well, Kennda, I always like to ask my guests to tell me what was that person, place, or thing that happened that got them so excited, that enabled them to become the scientist they are today, and I call that a gravity assist. So, Kennda, what was your gravity assist?

Kennda Lynch: Well, there was so many people along the way, I can't recount them all, but what I will tell you is that my biggest gravity assist, the one that just makes me well up right now is that my first summer internship at Kennedy Space Center, I was a space life science training program participant. I won't give you a year, but it was way back when, when the shuttle was flying. It was my first entry into the space world that I'd always wanted to be a part of, and I got accepted into that program. The biggest gravity assist for me was seeing my first shuttle launch.

Kennda Lynch: They let us go out to this place called ... They let us go out and watch the shuttle launch at Kennedy, and I got to see one of the shuttle launches, and that first shuttle launch and watching that spacecraft go into the air and hearing the noise and watching the alligators jump out of the water because it was so noise for them was just so inspiring and just ... I couldn't believe that at 20 years old I was there, and I could be here and that I was a part of the space industry finally. So that was definitely one of my biggest gravity assists that kept me going.

Jim Green: Well, that was wonderful. Well, thanks so much for joining me today. I've really enjoyed our discussion.

Kennda Lynch: Me, too. Thank you so much for having me.

Jim Green: Well, join me next time as we continue our journey to look for life beyond Earth. I'm Jim Green, and this is your Gravity Assist.

Lead producer: Elizabeth Landau
Audio engineer: Manny Cooper
Last Updated: Aug 14, 2020
Editor: Gary Daines

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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #32 dnia: Lipiec 02, 2022, 04:16 »
Badanie podobnych gwiazd do Słońca na późniejszym etapie ewolucyjnym pozwala dokładniej określić przyszłe oddziaływanie Słońca na Ziemię.
Vladimir Airapetian: Recent observations of mature solar analogs, like our Sun today showed the generation of very strong flares a 100 times stronger that we observe today. That suggest that in the future we can observe a catastrophic event and we need to understand its impact on the whole system, on a system starting from magnetosphere to our civilization

Gravity Assist: Our Sun, Our Life, with Vladimir Airapetian
Aug 21, 2020

This artist’s rendering shows our Sun as it may have looked 4 billion years ago. Credits: NASA/GSFC/CIL

How well do you know the Sun? It hasn’t always looked the way it does today. Billions of years ago, the Sun was fainter but also more active, throwing out huge flares of radiation in powerful tantrums. This “young Sun” helped shape the evolution of life as we know it. By understanding what our Sun was like when life emerged on Earth, scientists can look to other stars in the galaxy and think about whether life could emerge on planets there, too. Vladimir Airapetian, scientist at NASA’s Goddard Space Flight Center, explains what researchers hope to find as they gaze beyond our solar system.

Jim Green: We know the light from the Sun is so important to us today.

Jim Green: What is really the evolution of our Sun and how it has affected life here on Earth?

Vladimir Airapetian: The lack of oxygen was one of the most important conditions to start biological molecules.

Jim Green:  Hi, I’m Jim Green, Chief Scientist at NASA, and this is Gravity Assist. On this season of Gravity Assist we’re looking for life beyond Earth.

Jim Green: I'm here with Dr. Vladimir Airapetian and he's an astrobiologist at the Goddard Space Flight Center. In addition to that, he's a full professor at American University. Vladimir has been analyzing solar storms and how they affect planets. So today we're going to talk about the effect of our Sun on life here on this planet, and what it tells us about possible life on other planets. Welcome Vladimir.

Vladimir Airapetian: Thank you. It's great to be here.

Jim Green: We think of the Sun as a constant, you know, constantly shining in the same way. But is that really true?

Vladimir Airapetian: Well, our Sun is a magnetic star. From time to time, large bundles of magnetic field emerge to the solar surface and form Sunspots, the regions of enhanced magnetic field that causes activity known as active regions. Strong magnetic field in these regions move due to the surface convection and at some point can generate magnetic tornadoes and hurricanes. That can generate flares by transforming magnetic energy into heat and kinetic energy through magnetic reconnection, or by snapping and reconnecting magnetic field lines.

Vladimir Airapetian: So field lines break and rejoin fast and expel billions of tons of materials, unleashed in a ejection called the coronal mass ejection. As this coronal mass ejections travel to Earth and other planets, they disturb their magnetic bubbles called magnetospheres and generate magnetic disturbances known as magnetic storms.

Jim Green: So this is really an exciting field for us. In fact, you can see the excitement that's going on in the Sun with these solar storms, so to speak, by looking at a variety of our satellite data that's online. So, uh, we know that the Earth and the Sun are about 4.6 billion years old. But what do we know about the young Sun and what was it like, how active was it?

Vladimir Airapetian: It was an extremely magnetically active star, rotating up to 10 times faster than it is today, producing large Sunspots which the size is 10% of its surface and generating large and frequent flares.

Vladimir Airapetian: We see super flares on young stars in abundance from Kepler mission. Recently we found a couple of super flares from Kappa-1 Ceti, a twin star of our Sun at the time when life started on Earth.

Jim Green: When you talk about super flares, how big are they? What are we really talking about?

Vladimir Airapetian: Well, the super flares can be as energetic as a 100 times more energetic than the largest solar flare ever observed on our Sun today, in current times.

Jim Green: So just how important was the young Sun to life here on Earth?

Vladimir Airapetian: Well, it was essential component in producing life because life needs three essential requirements. The first requirement is to have liquid water and the Sun was also the one important contributor to that because it produced greenhouse gases. The Sun was a faint star, it was magnetically active star. But with 30% fainter lens today.

Vladimir Airapetian: So the so called faint young Sun's paradox was in place, how to explain the liquid water under the young Sun, when it's supposed to be an icy ball. So therefore, we think that the Sun produced abundant nitrous oxide, one of the gases that help to heat it to the temperatures to allow liquid water. The second requirement is to have a chemistry and an atmosphere that can eventually be broken into those complex molecules.

Vladimir Airapetian: Those requirements are important in order to accumulate those molecules and make them mature to the complexity. Become more and more complex on the surface. So it's a complex process.

Jim Green: We know that early life started on Earth about 3.8 billion years ago, but the atmosphere at that time had little or no oxygen. What else is happening to that early Earth and the life that may have started here on Earth?

Vladimir Airapetian: That's an amazing question. The point is that the lack of oxygen was one of the most important conditions to start biological molecules. Because oxygen oxidizes the simple molecules and doesn't help to create complexity. Complex molecules need a little oxygen like carbon monoxide for instance, instead of carbon dioxide. So we say that the atmosphere was mildly reducing, meaning that it had some hydrogen, it had carbon dioxide, a little bit methane, nitrogen, that was the one essential component of life.

Vladimir Airapetian: That helped to create the major gases like hydrogen cyanide, the feedstock molecule of life, formaldehyde and other molecules outer with that should be present abundantly in the gas phase in the atmospheres. So the future observations, we need to look for those signatures. And then later on when the life started, when the chemistry became biology, that created methanogens. The simple organisms, as you correctly stated, that basically didn't need any oxygen. They absorb carbon dioxide and release methane. That's why they're called methanogens.

Jim Green: Well, it sounds like this breaking apart and recombination can generate some really poisonous gases. How does life come out of that?

Vladimir Airapetian: Hydrogen cyanide is a really poisonous gas. It's the matter of national security. Today, you cannot buy it in stores, but it turns out that this hydrogen cyanide, if you add up to the simple molecules, you create more and more complexity. The poison early in life becomes treasure of life today.

Jim Green: So how do we know so far back, that the Sun was really active? How do we tease that out?

Vladimir Airapetian: Oh, that's a fantastic question, and the point is that large flares produce coronal mass ejections that ignite solar energetic particles and those energetic particles penetrate into the atmosphere. They break molecules and they create the carbon 14 isotopes. So out of carbon uh oxygen and nitrogen, and this carbon 14 joins the oxygen, creates the carbon 14 uh carbon dioxide and absorbed by the trees. So we see traces in the tree rings.

Jim Green: Wow. That's interesting. We always knew that the tree rings where you see a ring every year that it lives and it grows. The thickness of that ring tells us a lot about that year's input, which is the Sunlight and these heavy particles that come streaming through our atmosphere.

Jim Green: So during a star's life, they are very active when they're young, what happens next?

Vladimir Airapetian: Oh, then they lose their steam because the Sun rotates slower, it produces much weaker magnetic field. So producers smaller flares, less frequently. Some becomes a mature star. Any mature system behaves a little bit quietly. So that's what we have today.

Jim Green: But even today, a quiet star, we know that our Sun has really put out some fantastic coronal mass ejections.

Vladimir Airapetian: Recent observations of mature solar analogs, like our Sun today showed the generation of very strong flares a 100 times stronger that we observe today. That suggest that in the future we can observe a catastrophic event and we need to understand its impact on the whole system, on a system starting from magnetosphere to our civilization, that can produce the large atmospheric currents, all the way producing the changes in a stratospheric ozone that will increase the radiation, the extreme UVB and UVC emission coming to the surface and actually affecting crops, affecting a lot of life forms on our planet. Because the effect can last up to a year or even longer.

Jim Green: Do you think we can find a young Earth in our local neighborhood of stars?

Vladimir Airapetian: Well that's amazing question and we're looking for, so I hope that, well we need to look through K2, that extended mission of Kepler that looked at the stellar young solar clusters. Unfortunately Kepler couldn't observe it because it was pretty small telescope and also, stellar vulnerability of those young stars mimics the planetary signatures too. So we need to work a little bit harder in order to uncover the signatures of exoplanets around young stars.

Jim Green: So this is really a fascinating topic. We really need to do looking at the Sun and how it is evolved and how our planets evolved and therefore match that with how life here evolved on Earth. Then go find places near our Sun, near our neighborhood of the galaxy where we expect a lot of planets to be created and find that object that is not just Earth size but Earth-like. So we have some exciting observations coming up.

Jim Green: We have a whole variety of stars in our galaxy. Are some better for creating solar systems and looking for life than others?

Vladimir Airapetian: The point is that first the planet needs to be in a habitable zone and the cool stars, smaller stars, they have much narrow habitable zones. The planet needs to be much, much closer. That means that they should be exposed to the huge fluxes of X-ray and extreme UV emission and the flare emission, that is bad for, too much of a good thing it's a bad thing.

Jim Green: We talk about habitable zone, but what does that really mean?

Vladimir Airapetian: Well, the habitable zone classically originally was introduced as a shell around a star, where so called Goldilocks zone, where the temperature is not too cold and not too hot. Allows the water to exist in liquid state. But then later we found that that's only one condition and then you need to have the zone not too close to the star, to make sure that the planet has a thick atmosphere. So therefore that's another factor to space weather important factor in addition to the classical habitable zone.

Jim Green: So small stars have problems of having the planets too close. Well, what about the really large stars?

Vladimir Airapetian: Oh, well, we're talking about the stars a little bit hotter than the so called M dwarfs and cold cold stars like K type star. So the stars are slightly cooler than our Sun probably a sweet spots for life. Because the planets in the habitable zones a little bit closer at the distance of might be a Mercury or between Mercury and Venus, but still, I mean, they exposed to a lot of radiation, which is a good thing, but still they can preserve their thick atmospheres, which is a big, big requirement.

Jim Green: What about the A and B stars, the really big and really hot stars?

Vladimir Airapetian: A and B stars, they're one of the worst cases for life because they produce so much emission. So the habitable zone should be located farther away where you don't see any materials. You need to have some material not to build a planet first and have essential chemistry for this planet to have life. So I would imagine that, they should have very, very little material to form planets in the first place.

Jim Green: So when we're out there looking for life at different stars, we have to really be choosy about what stars could actually support a solar system where life may exist?

Vladimir Airapetian: Absolutely. A star is the first clue for a life on an exoplanet. First, the existence of an exoplanet and then life and habitability.

Jim Green: Vladimir, I always like to ask my guests to tell me what was the event or the place or person or thing that really got them so excited that forced them to become the scientist they are today? I call that event a gravity assist. So Vladimir, what was your gravity assist?

Vladimir Airapetian: My gravity assist had in my childhood, three massive brains. I would say. The first one is the head of the Amateur Astronomy Club when I was 10 year old. I was infected with astronomy and Mars was one of the amazing planets that I was dreaming about to understand whether life is possible on Mars or was possible on Mars. So, as soon as I graduated from the university, the second person who made my life to turn around was [astrophysicist Viktor] Ambartsumian, who was the head of the Byurakan Observatory in Armenia. So I turned my attention to the young, to the young stars and eventually I realized at some point that the Sun is a star.

Vladimir Airapetian: So if I know the life of young stars, I can uncover the life of young Sun. The third person who made a big difference was Stirling Colgate that was Los Alamos National Laboratory who passed away a few years ago. So, those three people created this environment that made it impossible not to think about astrobiology.

Jim Green: That's great. Well, join me next time as we continue our journey to look for life beyond Earth. I'm Jim Green and this is your Gravity Assist.

Credits: Lead producer: Elizabeth Landau
Audio engineer: Manny Cooper
Last Updated: Aug 31, 2020
Editor: Gary Daines

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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #33 dnia: Lipiec 17, 2022, 09:59 »

Gravity Assist: Is Artificial Intelligence the Future of Life? With Susan Schneider
Sep 11, 2020

Antennas at NASA’s Deep Space Network complex in Goldstone, California. Credits: NASA/JPL-Caltech

If astrobiologists find life beyond Earth in the solar system, it will most likely be in the form of tiny organisms called microbes – nothing that would talk to us. But the galaxy is a big place; the universe even bigger. Somewhere out there, life may have evolved to become as smart, or even much smarter, than us. And the next step in that ladder may be “post-biological,” argues Susan Schneider, the Baruch S. Blumberg NASA/Library of Congress Chair in Astrobiology, Exploration, and Scientific Innovation. Advanced life may be entirely based on microchips and silicon, using the tools of artificial intelligence instead of brains. In this episode of “Gravity Assist,” learn about what life might be like in the future and how science fiction has influenced thinking around this topic. Bonus: Jim Green’s theory about the movie “2001: A Space Odyssey.”

Jim Green: In our search for life, particularly here in the solar system, we think we'll find microbial life first. But beyond that, intelligent life, well out into the galaxy, what are we going to find? What would it look like?

Susan Schneider: They may be so different from us that they're unrecognizable.

Jim Green:  Hi, I’m Jim Green, Chief Scientist at NASA, and this is Gravity Assist. On this season of Gravity Assist we’re looking for life beyond Earth.

Jim Green: I'm here with Dr. Susan Schneider and she is the NASA Blumberg Chair at the Library of Congress and the William Dietrich Chair, Distinguished Professor at Florida Atlantic University. So today we're going to talk about looking for life beyond Earth and what it might be like. Welcome, Susan to Gravity Assist.

Susan Schneider: Hi Jim, it's nice to meet you and be on your show.

Jim Green: Well, the NASA Astrobiology Chair at the Library of Congress is really a neat position. What are you working on?

Susan Schneider: Oh, so many things. I'm writing a book on the future of intelligence right now.

Susan Schneider: And I'm asking the question, what sort of system will have the greatest capacity to be the most intelligent system? So I'm worried just looking here on Earth about whether humans could keep up with AI.

Jim Green: So Susan, what is artificial intelligence?

Susan Schneider: So AI is all around us. It's there when you're doing a Google search, it's there when you're talking to Siri and it's getting smarter all the time. So you might think AI is like a robot, but that's only one type of artificial intelligence. I like to think of AI as any sort of intelligent algorithm.

Jim Green: So what do you think artificial intelligence has to do in the search for life?

Susan Schneider: Well, we might use our AIs to make predictions, for example. So we might find information about exoplanets from our computers. But what I focus on is a little different. I actually focus on the possibility that life forms out there, should there be any that survived their technological maturity, may actually develop their own artificial intelligences. And I argued in a recent book called “Artificial You” that the greatest sorts of intelligences, whether they be on, in Earth's future or out somewhere on other planets, would be artificial intelligences.

Susan Schneider: I actually think that we could augment the brain to become far more intelligent than we are right now. And I also think that artificial intelligence could eventually out-think us.

Susan Schneider: Look at the speed of processing that has gone for over the last decade, we've seen immense improvements in computational speed. And then just think about the possibility that you could have in principle, a general intelligence that is instantiated in something the size of a planet. That is to say you could have a computronium the size of a planet that has access to the entire internet. I think that that in principle could just blow us away.

Susan Schneider is the Baruch S. Blumberg NASA/Library of Congress Chair in Astrobiology, Exploration, and Scientific Innovation. Credits: Susan Schneider

Jim Green: Well, you know, NASA you know, is always looking forward to push that envelope of more intelligence in our spacecraft. When I think about the 60s, we had some really tough times getting our circuitries to work and run instruments. And then as we got in the 70s, we had some initial computers. But each and every generation of computers were updating our systems. We would love to be able to have complete artificial intelligence in our rovers on Mars to avoid things, get to places, drill this place. And so moving in that direction is a natural thing for NASA to do. And should we be considering doing that here on Earth too, in terms of being able to have these machines access the internet, get access to information, allow us huge amounts of resources that can help us in our life?

Susan Schneider: Well, when you were saying that about what NASA would like, I was thinking, well, haven’t you all seen [the science fiction film] “2001: [A Space Odyssey]” ? Hal was iconic! And here on Earth, there's something called the control problem.

Susan Schneider: So people like Bill Gates, Elon Musk, Nick Bostrom, the list is really, really long. The late Stephen Hawking, were all very, very worried about how to control artificial intelligence that reaches a human level and then surpasses us, becoming what they call “super intelligent,” which is by definition, a hypothetical form of intelligence, which out-thinks humans in every dimension, social reasoning, mathematical skills and more.

Susan Schneider: And so until we get a handle on the control problem, I think we have to bear in mind that if we use too general of AIs, too sophisticated AIs, we have to make sure we do so safely, whether it be here on Earth or in outer space. And of course in outer space, you also have that awful problem of when something breaks.

Jim Green: Well, artificial intelligence requires data and sometimes that data is conflicting. How do you think artificial intelligence is going to deal with conflicting sets of information to make a decision? Are there decision rules that it then makes, or is there... I took the path least traveled by? We do it all the time, but what's a machine going to do?

Susan Schneider: Very good question. There are so many different kinds of AI systems even today. So, some like these deep learning systems are very data-driven. And so you increase the data set and then a human corrects errors in the machine's algorithms. And the idea there is that over a large amount of training sets, then you finally get a system that gets the information right. But there are all kinds of other AI techniques. And one technique which comes to mind is the possibility of neuromorphic computing that is artificial intelligence that is based on actual discoveries in cognitive science about how different parts of the brain compute. So that goes back to the idea that the brain itself is in a sense a computational engine. So for example, there are different parts of the brain right now even today that are characterized by a proprietary algorithm.

Susan Schneider: So for example, the hippocampus, it is responsible for encoding new memory. There are certain areas of the brain like area CA1, which we've already identified the algorithm that it computes. So the idea then is, if an AI is deficient in its reasoning, let's see how humans do it. And I don't take for granted the idea that the first artificial general intelligence is that rival our own intelligence will be like us. They may not because they could be a hodgepodge. You could take algorithmic encoding in the human case for the hippocampus, but do something very different than what humans do for other parts of the brain. Who knows what kind of intelligences will be out there, but I do think that over time they will out-pace us.

Jim Green: What do you think life beyond Earth would be, intelligent life? What should we expect. If we're moving into an AI realm, do we expect them to do that too?

Susan Schneider: I think so. And I call it the post-biological approach in astrobiology. We all understand that if and when NASA finds life, it will probably be microbial.

Susan Schneider: But what I am saying is that if we're getting to the point we're flipping on our own computers, and this is still pretty early in our own technological evolution really. Just think it seemed like just yesterday when we had the television or the automobile or the airplane and now look where we are.

Susan Schneider: So it may be only a blink of an eye in cosmic time really before we start enhancing our own intelligence and becoming partly, if not, fully synthetic ourselves. It could be that the most intelligent civilizations out there are, in fact, post-biological. So they grew out of originally biological civilizations like ourselves, and they're vastly smarter than us. And in fact, they may be so different from us that they're unrecognizable.

Jim Green: Then why haven't we been contacted yet? Where are they, as Fermi used to say to his colleagues?

Susan Schneider: Yeah, where are they? How can one not ask that question and be interested? Everybody's interested. Well, I liked Seth Shostak's answer. It was like, well, do we really get interested in our goldfish? The intellectual gap between us and a civilization on the order of 50,000 years older than us, and that is now no longer biological even, is going to be huge. So why would they find us interesting? And I also say, well, being a Trekkie. I imagine lots of your listeners are. They may have a prime directive against bothering such low level species, and who knows maybe they're waiting for us to evolve into something else.

Jim Green: Well, the only thing I could say relative to that fishbowl is a... They would be interested in the fshbowl if they had a lack of water. H.G. Wells thought of that first.

Jim Green: Well, let's tease on that science fiction portion of it when you had mentioned Arthur C. Clarke's “2001.” I have reread the book and I've watched the movie at its anniversary, 50-year Anniversary. And I've come to the conclusion that in reality Hal did malfunction. Hal's objective was to find life. And the humans that were on board, their objective was to find life, but the difference is, they were looking for life like them, Hal was looking for artificial life. And once he communicated and found it, he did not need the bags of water anymore, okay?

Susan Schneider: Whoa, that's awesome.

Jim Green: Because to me unfathomable that, Hal malfunction exactly at the wrong time. He was executing his program that finding life was his top objective and everything else was secondary and therefore executed that. Well, what's your favorite science fiction work and why?

Susan Schneider: Oh, tough one. All right, so I definitely like “Contact.” Also, I have to tell you, I really liked the film “Interstellar.” So I am a big fan of film, maybe it's because I don't really have time to read science fiction very much anymore. But “Interstellar,” which Kip Thorne, the physicist helped with and that was terrific even the soundtrack was great. But in terms of reading, I love classic works of science fiction, Arthur C. Clark, Isaac Asimov. I'm also a fan of Greg Egan short stories because he writes about brain chips and things like that.

Jim Green: Well, do you think science fiction is important for us in shaping our thinking about our future in space?

Susan Schneider: I really do. It's funny because I noticed I'm very interdisciplinary, so I moved from one field to the next, from neuroethics to AI, to astrobiology, philosophy of mind and the lingua franca seems to be science fiction. And I noticed that that's what gets so many of us conceptualizing the future. And I was going to say for better or worse, but I really think it's clearly for the better. The range of science fiction, there's cyber punk, there's traditional. like civilization and empire type of science fiction. There's just so much there.

Jim Green: Well, we are looking. NASA is looking for life in our solar system, as you say, it's probably going to be microbial.

Susan Schneider: Oh yeah.

Jim Green: And probably under the surface, in particular, whether it's under an ice shell or it's under the crust of Mars, but those are really prime candidates to be looking for. But in reality, do you think society is ready for the announcement that we have found life beyond Earth?

Susan Schneider: I think the society is so distracted right now that anything can happen. But I think it's ready and I think it's coming in the microbial case. And it would be sad if it flew under the radar right now with all that's going on in the world. It would be really sad because it's so significant. And it used to bother me so much when I was talking to reporters about my project for NASA on post-biological intelligence because I always said to them, "You know what's really interesting, even more interesting than this, is the search for microbial life."

Jim Green: Mm-hm.

Susan Schneider: That search is amazing and it's going to teach us so much.

Susan Schneider: There's the possibility that life is related. There are deep philosophical questions about the origin of life.

Jim Green: Well, Susan, I always like to ask my guests to tell me what was that event, that person, place or thing that got them so excited about being the scientist they are today. I call that event a Gravity Assist. So, Susan, what was your Gravity Assist?

Susan Schneider: Boy, that's a good question. Well, I got into Astrobiology late in the game. So I'll tell that story. So I was just called up by Steven Dick and asked to speak at the Library of Congress on... He said, "What it's like to be an extraterrestrial?" And I couldn't believe I got that kind of invitation. And of course, you can't really answer the question, what is it like to be an extraterrestrial? We don’t even know that they exist. But of course, that led me on my little path in astrobiology to arguing that the smartest aliens will be post-biological. I argue that AI may not be conscious. So it may be like nothing to be an extraterrestrial AI.

Jim Green: Well, Susan, thanks so much for joining me in discussing these fascinating topics.

Susan Schneider: Oh, my pleasure. Thanks for having me. It was really fun to talk to you.

Jim Green: Well, join me next time as we continue our journey to look for life beyond Earth. I'm Jim Green and this is your Gravity Assist.

Lead producer: Elizabeth Landau
Audio engineer: Manny Cooper

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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #33 dnia: Lipiec 17, 2022, 09:59 »

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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #34 dnia: Lipiec 31, 2022, 12:46 »
Tytan najbliższym światem z najlepszymi warunkami do życia?
Well, I don't know if we could find life on Titan. But there are several criteria that are satisfied. And make us think that Titan is probably the most habitable environment that we have in the solar system, because it has a stable substrate, you know, there's their surface where an organism can live. It has available energy sources. That's another criteria we need. That's from solar radiation.

Gravity Assist: Why Icy Moons are So Juicy, with Athena Coustenis (1)
Sep 25, 2020

For decades, moons of the outer solar system have proven fascinating subjects for scientists interested in the search for life. Forty years ago this year, NASA’s Voyager 1 spacecraft flew by Saturn’s moon Titan and took the first close images, revealing a thick orange-colored atmosphere that is the most Earth-like in the solar system. The Cassini probe then dropped off a lander on Titan called Huygens in 2004, and studied the moon in detail during its 13 years at Saturn. Now, NASA is preparing to launch the rotorcraft mission Dragonfly to Titan in the 2020s. But Titan is just one interesting moon. Ganymede may harbor an ocean under its icy crust, as does Europa, another moon of Jupiter. The European Space Agency’s upcoming JUpiter ICy moons Explorer (JUICE) mission will study Ganymede, Europa, and another moon of Jupiter called Callisto. Meanwhile, NASA’s Europa Clipper mission will provide complementary observations of Europa. A great era of exploration of the icy moons is about to begin. Athena Coustenis of the Paris Observatory talks about missions to the icy moons of the outer solar system and international collaborations with NASA and ESA. She also reveals that she holds degrees in literature and astronomy – find out why in this episode.

Jim Green: Looking for life in the outer planets, where will we go? Is it in the big gas giants or their moons?

Jim Green: Hi, I’m Jim Green, Chief Scientist at NASA. And this is Gravity Assist. On this season of Gravity Assist we’re looking for life beyond Earth.

Athena Coustenis at the Paris Observatory. Credits: Athena Coustenis

Jim Green: I'm here with Dr. Athena Coustenis and she is the director of research with the French National Center for Scientific Research at the Paris Observatory in Muedan, France. She is involved in several space missions for the European Space Agency and for NASA. Her focus is on the gas giant planets, Saturn, Jupiter, and all their moons. And she's considered one of the foremost experts on Saturn's moon Titan. So today we’re going to talk about the possibility of life beyond Earth in the realm of the giant planets.

Jim Green: Welcome Athena Coustenis to Gravity Assist.

Athena Coustenis: Hi, Jim, happy to be here in chat with you today.

Jim Green: Well, you've gotten very involved in what we call astrobiology that topic of searching for life. How did you get so interested in it?

Athena Coustenis: Jim, it's really easy to get interested in astrobiology, or exobiology as we used to call it, so as you say, this is a study of the, the origin, the evolution, and life in the universe in general. And we consider a question in astrobiology of whether extraterrestrial life exists, and if it does, how humans can detect it. And this is where an astrophysicist like me can play a role. We try to identify places favorable for the emergence and sustainability of life, which we call habitable worlds. So, early in my astrophysics studies at Paris Observatory and the university, I opted for planetology. Okay, so, so planetology obviously, we're studying the planets in our solar system. And the reason I went that direction is probably because I just wanted to be able to go places, far places and check out my models, you know, preferably with a space mission. I'm hooked on space missions, you know, Like, I love imagining, building, flying and exploiting a space mission.

Jim Green: So the Voyagers 1 and 2, which were launched in the 70s, were designed to go and visit those outer planets, those gas giants, and they made fantastic gravity assists to go from one to another. How did you get involved in those?

Athena Coustenis: Jim, those missions were amazing, when you think [about] when they were launched and what technology they're based on. I got involved because I did my PhD thesis on the Voyager infrared data from an instrument called IRIS. And [it] was the instrument that told us everything about the temperature composition of Titan's atmosphere. And can you imagine I did that 10 years after Voyager had encountered Saturn in 1980. And it was one flyby

So anyway, Titan proved to be addictive. I was just so attracted by this world. It is, you know, this. This is a very big satellite, you know, second only to Ganymede in the solar system. And we found it had an atmosphere resembling the Earth, and it kept the secrets of its surface.

Jim Green: Well, the Voyagers were so successful, and really showed us some fabulous things about Saturn in the moons and Titan in particular, we just had to go back. And that's where the idea of Cassini came about. And so, NASA and the European Space Agency got together and they each decided to create a role. What were those roles on Cassini for NASA and ESA?

Athena Coustenis: Yes, it was, it was amazing. Cassini is still what I believe to be the most tremendous, tremendously successful actually, international collaboration for a mission because NASA and ESA came together with shared roles, you know, NASA was going to build the orbiter spacecraft, the Cassini spacecraft, and it carried the Huygens probe which was developed by the European Space Agency. But these two worked together in every scientific aspect that we learned finally for Titan.

Jim Green: Well, how long was Cassini in orbit around Saturn before we decided to drop off the Huygens probe into the Titan atmosphere?

Athena Coustenis:  So, Jim, the Cassini mission, the whole spacecraft arrived in around Saturn and went into orbit in July 2004. And it started immediately making observations. Christmas time 25th of December 2004. It launched the Huygens probe towards Titan. And the probe went down, made a descent, a beautiful descent through the atmosphere of Titan on the 15th of January 2005, landing on the surface and sending back all the beautiful images and data we got during the descent and after we had landed, which was not exactly expected at the time, that we would land and survive, and all of this data was relayed by the Cassini orbiter.

Jim Green: Yeah, that was a fantastic landing. You only needed the parachute because the density of the atmosphere is larger than here on Earth, even though it's dominated by nitrogen just like the Earth's atmosphere. That must have been an exciting time. Tell us about that.

Athena Coustenis: So the first image I saw was the one after we had landed where we sell those pebbles. You know, sprawled around the surface on something that looked very orange and dark. And I looked up, I looked at the image and I said, “Who put that Mars image on the screen? you know, move it away we’re waiting for Titan. And then my colleagues turned around said it is Titan. And I said, “Oh my god, oh my god.” I think I couldn't breathe. It was amazing. It was it was enormous that we could see this surface that we had speculated on for so much time. And during the descent, we saw the channels, we saw the channels, we saw the hills on the side of what ended up being the landing site, which was a dry lake on Titan, recognized immediately you know, by Martin Tomasko, the PI of DISR, who knows about dry lakes in Arizona.

Jim Green: So those channels were rivers that were feeding into that landing spot, that dried lake, is that right?

Athena Coustenis: absolutely, we could even see the base, we could see shores. Um, all of this, you know has been put together in, in, in videos and films the team put together. But for us at that precise moment it was, it was like incredible. We could also identify, at the time we didn't know it, but we could identify the dunes you know, a little further up the beyond the hills. And it was so amazing to find all these features so similar to what we have on Earth, in a faraway object that sits 10 times further from the sun than our own planet.

Jim Green: Well, you know, we now know there's liquid on the surface of Titan, but that's not liquid water. It's methane. So, were those rivers of methane, do you think?

Athena Coustenis: Absolutely. Methane plays the role of water on Titan. If you think water on the Earth, you have the hydrological cycle you have the water evaporating from the oceans going into the atmosphere, condensing, producing rain, producing haze and condensates and clouds and falling on the surface in the form of rain. We have exactly the same thing on Titan. It's amazing, but with methane.

Jim Green: Well, do you think would find life on Titan? And if so, how would it be so different than here on Earth?

Athena Coustenis: Well, I don't know if we could find life on Titan. But there are several criteria that are satisfied. And make us think that Titan is probably the most habitable environment that we have in the solar system, because it has a stable substrate, you know, there's their surface where an organism can live. It has available energy sources. That's another criteria we need. That's from solar radiation. Although it's a hundredth of what we get on our own planet, but it has some solar radiation. It has solid body tides caused by Saturn and even perhaps radiogenic energy production. It has organic chemistry, this fabulous organic chemistry producing prebiotic molecules in the atmosphere, like hydrogen cyanide, which is a key molecule for prebiotic chemistry and a precursor molecule actually for amino acids. And it has two kinds of solvents. At present, inside Titan, we have the water ocean, the subsurface liquid water ocean with perhaps a fraction of ammonia to keep it like that.

Athena Coustenis: But I think if we find life, you know, um, and in spite of all the harsh temperature conditions, minus 180 degrees on the surface, and light conditions, like I said, there isn't very much light. I think it would be different from what we know on our own planet. But then it gets so interesting. Amazing.

Jim Green: Well, you know, NASA eventually decided that we needed to eliminate Cassini from orbiting Saturn completely, so that it wouldn't crash on Titan. And I had a little something to do with that. So, we decided that we needed to ditch Cassini and Saturn in in 2017. So where were you on that day? And how did you feel about that whole idea?

Athena Coustenis: First, thank you Jim. I think it's a wonderful idea to preserve Titan and preserve the environment of Titan.

Jim Green: Right.

Athena Coustenis: It was such a fitting end for such a wonderful mission. It was a great idea this Grand Finale, you know, brave plunge into Saturn. But not before you know, it had accomplished another 22 orbits between the planet and the rings, sending us information up until the end when it burned into Saturn's atmosphere. I was at JPL. I was there with colleagues and friends and watching actually, on the screen yourself and other people describing and talking about the mission. And also looking at the signal that Cassini was sending back a little bit that like what you have in a hospital, with a patient and seeing this signal, disappearing little by little until, the mission was declared dead. And in the French delegation how we had brought a bottle of champagne and some glasses. And we drank to Cassini’s success, you know, and to more such missions in the future.
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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #35 dnia: Lipiec 31, 2022, 12:46 »
Gravity Assist: Why Icy Moons are So Juicy, with Athena Coustenis (2)
Sep 25, 2020

Jupiter’s moon Ganymede, seen at left in this Cassini image, is the largest moon in the solarsystem. Credits: NASA/JPL/University of Arizona

Jim Green: Well, you know, Cassini and the Huygens probe in particular, did such a fantastic job looking at Titan, we just absolutely have to go back.

Athena Coustenis: Oh, of course.

Jim Green: Yeah, now we're moving towards that. That mission is called Dragonfly. So are you going to be involved in Dragonfly?

Athena Coustenis: Jim, I would be involved in any mission that would return to Titan. I would even fly there if I could. Um, we have so much more to learn. You know, about 10 years ago I proposed a mission to return to Titan with an orbiter, a lander and a balloon. It was called TANDEM and became the Titan-Saturn system mission in collaboration between ESA and NASA. And many colleagues joined that effort at the time. Dragonfly is a new generation. It's a great mission. My God, so modern, so fashionable, you know, a drone that goes there.

Athena Coustenis: What can be more fashionable than a drone that goes there and explores the surface of Titan, hopping from one place to the other, you know, to get to get different sites of interest. And it’s a rotorcraft lander mission to sample materials and determine the surface composition in different geologic settings because with Huygens we only went to one place and it will also characterize the habitability of Titan’s environment, you know, to investigate how far this prebiotic chemistry we're talking about has progressed and to search for chemical signatures that could be indicative of water-based or hydrocarbon-based life for organisms but at least study the conditions. I love that concept.

Jim Green: Mm-hmm. I do too. I can’t wait for Dragonfly. But [the] European Space Agency's moving forward with a spectacular mission they call JUICE and so what is JUICE all about? And where is it going?

Athena Coustenis: So JUICE is the first large class mission in ESA’s Cosmic Vision, it’s called Cosmic Vision 2015-2025 Program and it’s planned for launch in 2022 arrival in Jupiter around 2029, 2030, and it will spend more than three years making detailed observations of Jupiter, and three of its largest moons with a focus on Ganymede, but also Callisto and Europa.

Athena Coustenis:  And it’s to characterize the conditions that may have led to the emergence of habitable environments among Jovian icy satellites with again a special emphasis on Ganymede, because Ganymede provides us with such a natural laboratory for the analysis of, of the nature, evolution, and potential habitability of icy worlds in general. But also, it is a class of objects in the universe, in our galaxy that we call the ocean worlds that have these liquid water oceans underneath the surfaces. It's amazing. I was involved from the beginning in the definition of the development of the mission, as a European colleague scientist and I'm sitting on the edge of my seat to see the launch in time.

Jim Green: Yeah 2022 is coming up pretty fast.

Jim Green: Well JUICE is going to end up orbiting Ganymede, and Ganymede turns out to be one of my favorite moons. It's the largest moon in the solar system. What else about Ganymede is so exciting?

Athena Coustenis: Absolutely. It's one of my favorite moons also. Jim, it's amazing. Ganymede is one of the objects also where we find indication on the surface of resurfacing from something that was previously in liquid form, probably under the surface. Where we have indication by the fact that this is a satellite that has an induced magnetic field, which actually interacts with the magnetosphere of Jupiter and so on. But it has an induced magnetic field that indicates the presence of a liquid water ocean underneath its surface. It's the best indication we have today of that. It also has auroras. it's amazing that you find that around such a distant object. So we do need to go back and look closely at Ganymede, not only because, you know, it's our biggest satellite the solar system, because we want to disentangle all of these interactions of the magnetic field in the magnetosphere of Jupiter and try to discover exactly what it's telling us on its ocean properties.

Jim Green: In addition, with ESA’s JUICE, NASA is launching the Clipper mission and Clipper is going to Jupiter. But it's going to study Europa. So when you think about JUICE at Ganymede and, and, and the NASA Clipper mission at Europa, the synergy is going to be fantastic. We're going to learn all kinds of things and I can't wait for that to happen.

Athena Coustenis: Amazing. Can you imagine two missions, two missions in the Jupiter system, it deserves it. And I think more than different they're very complimentary. You know, Europa and Ganymede are the divas, you know, in the Jupiter system. If you're looking for habitable worlds. And while the instruments, some of the instruments are similar, there's overlapping observations that we're going to do, there's a lot of complementarity.

Jim Green: So, you know, all these outer planet moons have energy from tidal forces, and they have fabulous environments. Could they actually have habitable environments?

Athena Coustenis: Absolutely. I mean, I think these icy moons are so far from the, the notions we had that they were dead bodies. You know, a few decades back we thought that these moons are just dead bodies, they have no activity and so on. We know today that they're very much alive. They have processes in there like tidal forces that create cryovolcanismm for instance. This is this is a phenomenon we only find out there, where you have volcanoes that actually do not eject lava, they eject ice. Cryovolcanism is a source of energy very important for these satellites. They have organic chemistry that we find every time we look at their atmospheres, or exospheres. They have liquid water oceans underneath their surfaces. All of these elements put together make those satellites very, very habitable environments that we really need to go back and investigate. These are not things we can simulate in a laboratory on Earth.

Athena Coustenis: So we need to go back. But which one is the best? I think every scientist has their own favorite object. And of course, you know mine. I think Titan is the most fantastic candidate for a habitable environment. But then Europa and Enceladus and Ganymede are all in my favorite places list.

Jim Green: Yeah, I agree. Titan is so exciting because it’s so diverse and if it was going to have life, it’s going to be life completely different than what we have here on Earth.

Jim Green: Well, you know, I heard that you've gotten degrees, not only in astrophysics, but in literature. I mean, I had a tough enough time just getting a physics degree. How did this happen?

Athena Coustenis: So, not without a challenge. Well, I was very much interested in English literature at school at the same time as in physics and astronomy. So when I got my baccalaureate, I came to France and enrolling in two, Paris universities: Sorbonne on one side and Pierre and Marie Curie, you know, for sciences on the other side, because my family wasn't at all convinced that there was a chance for me to get a job in astronomy. So they say, well, do English literature, you can always find a job with that. And so I started my English literature PhD at the same time as the astrophysics one, but haven't finished it yet, Jim. I have to admit, I hope to do that sometime. Maybe when I retire and I'm sitting in front of the sea on some Greek island.

Jim Green: That sounds great. Well, you know, I always ask my guests to tell me, what was that event or person, place or thing that got them so excited about being the scientist they are today? I call that a gravity assist. So, Athena Coustenis, what was your gravity assist?

Athena Coustenis: Jim, I decided to become an astronomer when I was 15, and never wavered or changed my mind. So, but I've got a huge boost in my life from a person and a place. The place is Greece, a home of Icarus, you know, who flew through space and went all the way to the sun and, and it's a land of dreams, coming true also, so because the people there know how to survive in the face of difficult conditions. But I would strongly encouraged by my family and friends but in particular by my father, and my father, Panagiotis, was a pilot in the Greek Air Force, who trained in the States, in Dayton, Ohio, and later became Major General and he had a passion for flying. And he shared that with me and I think somehow he managed to instill this in my mind. My brother is also a pilot. So you see, we come from a family looking at the skies, but I decided to follow and even fly higher and further, but I really got gravity assists from them.

Jim Green: Wow, that's great. Well, Athena, thanks so much for joining me in discussing this really fascinating object, Titan.

Athena Coustenis: Thank you, Jim. It was wonderful talking to you today.

Jim Green: Well, join me next time as we continue our journey to look for life beyond Earth. I'm Jim Green, and this is your gravity assist.

Last Updated: Nov 13, 2020
Editor: Sarah Loff
Tags:  Europa Clipper, Gravity Assist, Podcasts, Solar System

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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #36 dnia: Sierpień 21, 2022, 08:30 »
Nawet mikroby mogą wpływać na pogodę.
Whether or not the microbes or pieces of microbes, if they're damaged, whether or not they're living or dead, they can still influence precipitation and the weather. Now, for precipitation to occur, you need to have a nucleus for water to nucleate onto and that can occur through a biological particle.

Gravity Assist: Life in the Clouds, with David J. Smith (1)
Oct 9, 2020

NASA astrobiologist David J. Smith at the NASA Columbia Scientific Balloon Facility in Fort Sumner, New Mexico, in August 2014. Credits: David J. Smith

High above our heads, even beyond 120,000 feet up, scientists have found tiny organisms called microbes. These high-flyers were swept up from the ground by winds and storms, or spewed out through volcanic processes. While most of these high-altitude microbes are dead, some are still alive, or have produced material called spores that could activate in the future. David J. Smith, an astrobiologist at NASA’s Ames Research Center, uses airplanes to collect these microbes, analyze them in the laboratory, and expose them to even higher altitudes with balloon experiments to see how they will respond. If microbes can inhabit our clouds, what about other planets? While more research is needed, Smith and others are fascinated by the possibility that airborne microbes could also be found elsewhere in the solar system, and beyond.

Jim Green: Did you know the smallest form of life can travel enormous distances? How do they do that? How do microbes fly in the upper atmosphere?

Jim Green: Hi, I’m Jim Green, chief scientist at NASA, and this is Gravity Assist. On this season of Gravity Assist we’re looking for life beyond Earth.

Jim Green: I’m here with Dr. David J. Smith from the NASA Ames research center, and David is an astrobiologist. But he has significant experiment

Jim Green: He's founded the aerobiology laboratory at the NASA Ames Research Center. And David is an astrobiologist but he has significant experience in ecology and evolutionary biology. David spent the first portion of his NASA career as a principal investigator and project scientist specializing in microbiology. He founded the Aerobiology Laboratory at NASA Ames Research Center. Now I also want to mention that David won the 2019 award, the Presidential Early Career Award for Scientists and Engineers.

Jim Green: Welcome, David, to Gravity Assist.

David Smith: Thank you, so much, Jim. I’m happy to be here.

Jim Green: Let’s start out with what are we talking about? What do we mean when we’re talking about microorganisms, and why are they so important in the search for life?

David Smith: When we talk about microorganisms or microbes, we’re really talking about small life. Life so small that you can’t see it with your own eyeball. In some cases, we're talking about single-celled microbes. And the reason we're so fascinated by microbes is because they're so successful on this planet.

David Smith: You could argue that Earth is a microbial planet. And I say that because microorganisms were the first to arrive on this planet, the first to emerge in the evolutionary history of our planet. For billions of years, it was a microbial planet. And even today, when we look at the types of life on Earth, most of it is microbial in terms of the sheer diversity. And so, microbes are really successful, both in the total amount of microbes on this planet, and the adaptations of microbes in nature, the resilience to changing environmental conditions. And for those reasons, we expect them to be perhaps, in the solar system and other places where we're interested in looking for signs of life.

Jim Green Yeah, that's a really important point, you know, when our Earth had microbes for 4 billion years or so, and, and survived many mass extinctions that went on, you know, perhaps that's what happened on other planets. And this is why we're looking for microbial life on those planets.

Jim Green: I remember when microbes were found at high altitudes. And this was really mind boggling.

Jim Green: How would these tiny organisms really get lofted into space? You know, they can't fly, right. So, they have to take off somehow.

David Smith: You said it, they don't have wings, but they can drift due to natural convection and winds that move in Earth's atmosphere that in a sense, connect the Earth's surface to the atmosphere. And all of these patterns are because of prevailing winds around the globe. If you've ever been to the ocean, of course, as soon as you arrive at the beach, you smell it, you smell the salt, you smell the ocean, right? Those are aerosols, a lot of those aerosols are reaching your nose because of wave action and winds on the coastline. So you also get microbes that live in the ocean, pushed into the atmosphere with those same patterns.

Jim Green: What type of microbes have we found?

David Smith: We see the same kinds of microbes in the atmosphere that you would see if you went outside and scooped up some soil, a representative sample. The reason for that is maybe easier to understand if we just talk about how microbes move in air, right? So, if you were to sneeze, and I were to microbiologically sample what's coming out of your sneeze, more or less it would be representative of the microorganisms in your mouth.

David Smith: Now in the atmosphere, you could think of geological and meteorological processes, in effect causing the Earth's surface to sneeze. And therefore, the same signal we get in the atmosphere is representative of what was on the surface. And so the exact signal of microorganisms really depends on where we're sampling, how high we're sampling. the season we're sampling and the local topography. And so it's a complicated question to give a simple answer to, but more or less, because the microorganisms are being swept up from the surface. The samples that we get in the atmosphere are representative of that surface, albeit in a much lower concentration.

Jim Green: So this is going to be pollens and it's going to be you know, fungi.  And well, even bacteria and viruses, right?

David Smith: Absolutely, all of the above, Jim. We see fragments of pollen and other pieces of biological debris in the atmosphere as well, too. And, you know, speaking of sneezing, anybody that suffers from seasonal allergies is acutely aware of pollen in the Earth's atmosphere. You may not know that if you suffer from seasonal allergies, you too are an aerobiologist. But that's just to say that, you know, we, we have been impacted in a lot of ways by the movement of airborne microbes, whether or not we've had the systems to actually start to understand all of these complicated patterns of dispersal. It's a really exciting time to be an aerobiologist, start to answer some of these questions about what is above our head?

Jim Green Indeed, I'm fortunate, I don't have allergies. So I am not an aerobiology detector. But what I want to know is how high do these get? What's the what's the altitude range and do we see different types at different altitudes or is it a mixture?

David Smith: In general, the concentration of bioaerosols decreases, the higher you get above the Earth's surface. We've seen reports anywhere ranging from about 5, even to 50% of the total aerosol signal for aerosols that are larger than about two and a half microns derived from biological particles.

David Smith: Now we can use airplanes, we can use balloons, we can even use sounding rockets. And there's really just been a handful of studies published in peer reviewed literature, that have been able to make detections in Earth's stratosphere, which is very high up above the surface, more or less, above 40,000 feet. And the highest report ever was done not using an aircraft, but a sounding rocket, all the way up to about 250,000 feet in the mesosphere. Now, that was just a single study that was published in the 1970s. And it hasn't been repeated. But it's an interesting and intriguing result, I would put more confidence in a handful of other studies flown using large scientific balloons, were are also able to measure a microbiological signal at around 120,000 feet in Earth’s middle stratosphere.

Jim Green: Wow.

Jim Green: Well, it's also above the ozone 120,000 feet is really up there, which means, you know, they're going to get also get bombarded with ultraviolet light from the sun. How do they survive?

David Smith: In fact, most of the biomass that we collect in the upper atmosphere we think, is dead. We can still detect its presence based on its DNA signal. But most of the bio aerosols that gets swept up into the atmosphere, particularly above the troposphere and into the stratosphere, are not living. Now, some still can withstand those conditions. So there is a portion of really resilient microbes, mostly spore forming bacteria that have been recovered from the middle stratosphere, which is truly extraordinary based on the environmental conditions, that location, and you mentioned it it's very strongly irradiated at that altitude above the ozone in particular, it's freezing. And it's really dry. And all of these things make it even more remarkable that we can recover any, what we call viable signal life that is still hanging on, probably hunkered down in a state of dormancy.

Jim Green: Well, do some of these microorganisms carry disease?

David Smith: I would say first and foremost that the vast majority of microorganisms are harmless. And in fact, most microorganisms in nature are helpful. And so I want to dispel any worries people may have about microorganisms moving in the atmosphere. Now that said, there have been a few reports of potential correlations between the movement of winds across adjacent agricultural fields and the spread of certain plant pathogens. There's also a lot of interest in the so-called meningitis belt and whether or not you can have human diseases moving along, moving along with winds across continents.

David Smith: Now, there's going to be a lot more work required to actually establish such associations. But before we can do any of that we need more efficient methods for making collections in the atmosphere. And so there's still much work to be done before we start to monitor and perhaps even predict movement of diseases in the atmosphere if in fact, it's happening. Now, I wouldn't say to worry about what’s above your head, keep your windows open, I would say the aerobiology of the indoor environment is a lot more likely to be harmful to your health than the aerobiology of the open air outside.

Jim Green: We hear so much about, you know, the transmission of COVID, a virus, you know, and we know that when you sneeze particles move away and can go many feet. So do they immediately go up? Or what happens to them in general?

David Smith: Yeah, most of the particles coming out of your sneeze are large enough that they'll fall to the ground pretty quickly. But that said, wear your face mask. It’s important.

Jim Green: Of course, aerosols do have effects on the weather. Would microbes also affect the weather in any way?

David Smith: Whether or not the microbes or pieces of microbes, if they're damaged, whether or not they're living or dead, they can still influence precipitation and the weather. Now, for precipitation to occur, you need to have a nucleus for water to nucleate onto and that can occur through a biological particle.

David Smith: Now, there's a famous, well studied at this point bacterium, Pseudomonas syringae, which has been examined for its common occurrence and cloud water. And also precipitation that's collected at high Alpine observatories, why do we keep finding this particular bacteria? Turns out that it's got proteins on its outer membrane that actually in produce nucleation more efficiently and particles that are not biological. So this is just absolutely fascinating. It could in fact, be an evolutionary outcome that this plant microbe which resides on the surface of leafs and gets commonly swept up into the atmosphere, may have through natural selection figured out a way through proteins on its outer membrane, to really build its own parachute for returning to the surface quickly.

Jim Green: Wow. Well, you’ve done a lot of experiments not only from aircraft but from balloons, too. Can you give an overview of what you’ve been doing with those platforms?

David Smith The first thing I wanted to do was follow on Dr. Dale Griffin's pioneering studies on NASA’s ER-2 aircraft. And so after his landmark paper in 2004, we flew another mission on NASA's ER-2 aircraft over the open Pacific Ocean, the same altitude around 66,000 feet. And, sure enough, we were able to verify the same findings that Dr. Griffin's team reported earlier, which was not only a signal of microbes over the open ocean at 66,000 feet, but living bacteria and fungi. So despite my skepticism, we were able to verify those results. And it really motivated me to continue making samples using NASA aircraft.

David Smith: Starting three years ago, using a different NASA aircraft, a Gulfstream Jet called the C 20-A, which can't fly as high, but can still reach about 40,000 feet in altitude, we were able to modify a system that more or less was already in place on the aircraft for measuring the vehicle’s airspeed, just a tube that sticks out of the window of the airplane and into the open atmosphere. And we were able to optimize that too, in such a way that we could get very efficient volumes of air moving through our system.

David Smith: I would encourage any curious listeners to go take a look at those surveys, which report all the kinds of diverse microorganisms above our head at altitudes, ranging from 10,000, all the way up to 40,000 feet using this new system.
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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #37 dnia: Sierpień 21, 2022, 08:31 »
Gravity Assist: Life in the Clouds, with David J. Smith (2)

David J. Smith is an astrobiologist at NASA’s Ames Research Center in California’s Silicon Valley. Credits: David J. Smith

David Smith: So how do you get even higher? That's where the NASA large scientific balloons come in. And so we've also flown a series of missions, both from New Mexico in the United States and even Antarctica, on large NASA scientific balloons that can reach all the way up to about 120,000 feet, and can linger at that altitude for hours and in some cases, weeks. So what we do with those studies, instead of trying to make collections at that altitude, we intentionally carry known types of microorganisms, some of the same types of bacteria that we commonly find in the aircraft surveys, we take them to the middle stratosphere on NASA balloons, expose them to that environment, and then return them to the lab after the exposure to measure: Did anything survive? And if so how? And so we're using a variety of platforms to address some of those larger questions in aerobiology that remain poorly understood still.

Jim Green: Well, this really brings me to one of the recent discoveries, you know, that’s been reported by a series of scientists that see phosphine, you know, at 60 kilometers in the Venus atmosphere. And so, we know that the surface pressure is just enormous on Venus, you know, 90 times ours and the temperature is hot enough to melt lead, but it that, that altitude, you know, it's like an atmosphere. Looking at that, do you think that's possible? Could microbes be living in in that altitude on Venus?

David Smith: Well, I'll say, the idea of what a habitable zone is, has certainly changed substantially even in my lifetime. And more generally, in the field of astrobiology, you know, when I was in school, we were taught, you know, there was sort of a Goldilocks zone of where a planet could be habitable. And then suddenly, we started discovering all of this life in the subsurface of Earth. And that totally shattered the idea of what a habitable zone could be, and where we should look for signs of life in the universe.

Jim Green: Yeah, and hydrothermal vents in the ocean too, you know, the hydrothermal vents are just pouring, pouring out material that life loves.

David Smith: Sure, and we do know, based on our own solar system, that atmospheres are relatively common. So you would expect more planets or maybe more moons with atmospheres as well throughout the universe. And so for that reason, I think it's really important to consider whether or not the atmosphere, clouds could, in a sense, be an ecosystem. If not here on Earth, perhaps it's possible with other environmental circumstances and other planetary bodies. Now, the discovery that's been reported at Venus is certainly motivating a lot of scientific debate. And I think that is just such a positive thing.

Jim Green: It is.

David Smith: I think that a lot of important work will come from interdisciplinary conversations and dialogues that are occurring as a result of that study. You know, I see astronomers now debating with microbiologists, I see atmospheric chemists debating with geologists. I think all of these things are so wonderful and so healthy for a vibrant and stronger field of astrobiology.

David Smith: So, as I mentioned before, it's a great time to be an aerobiologist on Earth, because we've got plenty of difficult questions, both here over our head, and certainly as we look elsewhere, for signs of life in the universe.

Jim Green: Well, you know, David, I always like to ask my guests to tell me, what was the event or person, place or thing that kept them so excited about being a scientist, that it propelled them forward and they became the scientists they are today. I call that event, a gravity assist, and many people have had more than one gravity assist along the way. So David, what was your gravity assist?

David Smith: Oh, I very much I've had multiple gravity assists. I've been fortunate to slingshot around a few planets, if you will, on my trajectory to wherever I'm heading. So I would love to give thanks to, back in my public school system in Colorado, some great science teachers, Judy Whitman, who helped me fall in love with the field of biology,  Tim Lenczycki who was so patient with me when I was failing my physics exams and probably wanted nothing to do with science. But you know, in his own free time and lunch breaks, he was able to coach me back into the fold, and help me understand some of the physical principles I was struggling with when I was younger. And then when I got to college, I had just an outstanding thesis advisor who introduced me to doing microbiology, T.C. Onstott. And I was so fortunate to cross paths with T.C., and he introduced me to how I could really make a career out of astrobiology and encouraged me to go to graduate school.

Davis Smith: And then I would give my last major gravity assist shout-out to Bill Parsons, former Center Director at Kennedy Space Center, who saw something in me that I certainly didn't see in myself, which was going to work for NASA, to me just seemed so out of reach. But Parsons was able to convince me otherwise encouraged me to come start work at Kennedy Space Center. And so I'm so grateful to him, and anybody listening to this conversation that has the dream of coming to work for NASA, I want you to know you can do it. You'll need some great mentors along the way. Your gravity assist will be there. And don't hesitate to reach out to people because they are willing to help.

Jim Green: Indeed, yeah. And I want to thank you too, because I’m just delighted you're working at NASA Ames. And got that new laboratory up and running.

Jim Green: Well, David, thanks so much for joining me and discussing this fascinating topic.

David Smith: It was my pleasure, Jim, thanks for the opportunity.

Jim Green: Well Join me next time as we continue our journey to look for life beyond Earth. I'm Jim Green, and this is your Gravity Assist.

Jim Green: If you like Gravity Assist and want even more great podcasts, check out the new season of NASA’s Curious Universe.

Jim Green: Curious Universe takes listeners on exciting adventures with top NASA experts like astronauts, scientists, and engineers. In their second season, you’ll tour the International Space Station, investigate how black holes form, and much more! Here’s a sneak peek of what you can expect to hear.

AMBER STRAUGHN: The thing about astronomy is that it gets to the heart of the big questions that we have as human beings.  Where did we come from? Are we alone in the universe?

HOST PADI BOYD: Our universe is a wild and wonderful place. Welcome to NASA’s Curious Universe. In this podcast, NASA is your tour guide. 

ASTRONAUT SAMANTHA CRISTOFERETTI: For the past twenty years, we have been a spacefaring civilization. If you were born after the year 2000, you haven’t lived a single day without human beings in space. 

DANTE LAURETTA: Almost seventeen years of my career has been focused on this one day to make sure everything goes according to plan.

HEATHER ENOS: It really all happens in less than twenty seconds.

SAM DOVE: Think of something that’s moving very slow, around .8 or .9 miles an hour, moving this big rocket down the road.

JOHN GILES: It just goes Brrrrrrr and it just gets louder and louder. 

JEREMY SCHNITTMAN: We actually think there are close to a hundred million black holes just in the milky way alone all sprinkled around dead ashes of stars.

AMBER STRAUGHN: It’s those mysteries that are out there in the universe that we haven’t even dreamed of yet. I think the universe is going to surprise us. 

HOST PADI BOYD: NASA’s Curious Universe season two. Coming to your ears this October.

HOST PADI BOYD: Subscribe right now, and get ready for a grand adventure.

Jim Green: You can listen and subscribe to NASA’s Curious Universe on your favorite podcast app at

Lead producer: Elizabeth Landau
Audio engineer: Manny Cooper
Last Updated: Nov 13, 2020
Editor: Gary Daines

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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #38 dnia: Wrzesień 04, 2022, 23:55 »
W 1996 roku odkrycie meteorytu Allan Hills 84001 zapoczątkowało, zdaniem wielu, rozwój astrobiologii.

Gravity Assist: The History of the Future, with Steven Dick (1)
Oct 30, 2020

This 4.5 billion-year-old rock, labeled meteorite ALH84001 or sometimes called the "Allan Hills Meteorite," came from Mars and landed in Antarctica. It sparked controversy in 1996 when some scientists believed it contained tiny fossils. Today, the consensus is that it does not have fossils from Mars. Credits: NASA/JSC/Stanford University

People have long wondered whether there is life beyond Earth, but it is only recently that scientists have been able to apply the tools of space exploration to go after this question. In 1996, the Allan Hills 84001 Meteorite shook the world as scientists debated whether it had tiny fossils inside of it that came from Mars. The consensus is that this rock does not contain Martian fossils, but the questions it raised energized many researchers. Today, the field of astrobiology is looking at how life arose on Earth and where else in the solar system and beyond life could exist. Beyond these scientific investigations, there are also philosophical questions one could ask. Would we be ready as a society for such a groundbreaking discovery? Astronomer and historian Steven Dick tells us there are many approaches to consider and many questions we should ask ourselves to get ready, in case extraterrestrial life is found.

Jim Green: Are we ready as a society to discuss what the next steps are, if we find life beyond Earth? Hi, I'm Jim Green, Chief Scientist at NASA. And this is Gravity Assist. On this season of Gravity Assist, we're looking for life beyond Earth.

Jim Green: I'm here with Dr. Steven Dick, and he's an astronomer and author and historian of science, most noted for his work in the field of astrobiology. Steven also has served as Chief Historian for NASA. And he's been the Bloomberg Chair at the Library of Congress in astrobiology.

Jim Green: Today, we're going to talk about the societal benefits, or not, about the discovery of life beyond Earth. If and when that happens. It's all about changing our worldview. So, Steven, welcome to Gravity Assist.

Steven Dick: Glad to be here, Jim.

Jim Green: Well, you know, as I mentioned, you've been the NASA Chief Historian. And I'm sure many of our listeners don't know that NASA even has a History Office. So what do historians at NASA really do?

Steven Dick: Ah, we do a lot of different things. We do a lot of book projects on various aspects of NASA history. We do a lot of conferences, on various aspects. And we do special projects that the administrator wants us to do. And we do our own research also. So it's a it's a very full job. We have a big archives, at NASA headquarters, and several archivists. So people are always calling in and asking questions about NASA history, whether it's the media, or, or other people. There's been a historian at NASA from the very beginning. So NASA realized that it was going to make history and it certainly has and will continue to make history.

Jim Green: Well, I see you've got the perfect two loves, and that is science and history. I mean, I'm really caught up in history. And when I think back about that early days of what we call the birth of astrobiology, of course, the 1996 announcement from the Allan Hills meteorite really stirred up a lot of controversy. Can you give us a little background on what that was all about?

Steven Dick: Well, I write about that in my book. People are surprised that there are actually Mars rocks on the Earth. They do, though, the Earth intercepts rocks that have been spewed off of Mars. And usually they're found in the Antarctic, and the Allan Hills, what's called the Allan Hills 84001 meteorite, was found and recognized as a Martian meteorite.

Steven Dick: Scientists studied it very carefully especially down at Johnson Space Center. And then after three years of that kind of work, they made the announcement that they thought that there might be nanofossils, extremely small, fossilized life in that, in that Mars rock. So they made the announcement, I was on the beach. And my nephew came out and said they found life on Mars! And I said, “No.”

Steven Dick: But that was the beginning. That was the beginning of the controversy. And it was a very interesting press conference that was held at NASA Headquarters with the people who were making the claim, but also some skeptics.

Steven Dick: I use it as a kind of analogy to what might happen if we find extraterrestrial life, you know, in the future. You saw the, you know, the announcement and all the controversy that went on for weeks and months and, and years even. And you had congressional hearings, and you had symposia about this. And I myself was involved in one really interesting meeting with Vice President Gore, who called call the meeting to talk about the implications if this were true. And this was a small meeting with about 20 people. The NASA Administrator Dan Goldin was there and the director of Office of Management and Budget, and other people and… Stephen Jay Gould was there and Lynn Margulis, and some of the scientists who had made the announcement.

Steven Dick: Bill Moyers was there, there some theologians were there. So it was a real chance to talk about the implications. And this went on for two or three hours, going around the table and talking about what the implications might be. So that's also the kind of thing that will happen in the future, I think at very high levels when we're trying to figure out what the impact is going to be.

Jim Green: As you said, Mars meteorites do fall on the Earth and we go to the Antarctic, because blinding white sheets of ice are there. And if you see these dark spots, then they had to come from somewhere. And that's typically from above. And at the time, the time the Allan Hills meteorite was found, we only had in our collection of 11 Mars meteorites that we could identify. Today we have about 170.

Steven Dick: Wow.

Jim Green: So, So indeed, we still have been collecting them. And it's really been a wonderful cache. In the case of Allan Hills meteorite and looking at what looked like fossilized microbes, how did that resolve itself? And how did we determine that perhaps that wasn't the case?

Steven Dick: Well, it's a fascinating problem, both scientifically and philosophically, because you had three or four independent lines of evidence, in that, you know, leading to that conclusion that it might be fossil life. And the… some people said, well, if you have three or four weak lines of evidence that makes a strong argument, and other people said no, four weak arguments don't make a strong argument. So they went back and forth over that. But in the end, it was just, you know, some of those lines of evidence just didn't, didn't pan out.

Steven Dick: And it goes back to, I think, what… something that Carl Sagan said were extraordinary claims require extraordinary evidence, right? And the evidence, there was evidence, but it just wasn't extraordinary enough to make that claim, which is certainly an extraordinary claim. It's possible things will change. You remember, the Viking experiments showed that there were no organic molecules, parts per billion on the surface of Mars. And so people would go, well, if there’s no organic molecules you can’t have life.

Steven Dick: Now, they're thinking a little differently about it because of things called perchlorates. And, and all kinds of other things that maybe, maybe they did find life, or maybe they didn't do the right experiments, you know, that gets back to the to the definition of life. Maybe they didn't do the right experiments. And so that's still open in the eyes of some people.

Jim Green: Yeah, indeed, Viking just scratched the surface in one location.

Steven Dick: That's exactly right.

Jim Green: And Mars is huge, with a very complex geological history. And, you know, we're finding by going to certain places, like what perseverance is going to do, land in an ancient Delta, where water spewed into the ancient ocean, leaving material from hundreds of miles. Wow! What, what are we going to find in those rocks? And we're going to bring them back.

Steven Dick: Yeah, I can hardly wait for the results.

Jim Green: Me too.

Jim Green: You've written about the history of the way people think about life beyond Earth also. And so, are these all key moments that change the way people thought about the possibility of, of life beyond Earth? Or are there some other really important milestones in that area?

Steven Dick: Well, there have been at least a half a dozen cases where, you know, throughout history where people have thought that they might have discovered extraterrestrial life. You can go all the way back to Percival Lowell, you could go even further back than that to Kepler, and Galileo. Galileo in 1610, pointing his telescope to the Moon saw what looked like a perfectly round crater and Kepler, who was a very imaginative kind of guy said, “This must be artificial, built by the inhabitants of the Moon.”

Steven Dick: And then, of course, Percival Lowell of the late 19th century had this idea, which, based on observation, although very controversial observations, that there might be canals on Mars, and that these were the artifacts of a dying planet that the inhabitants were building canals and trying to get the water to where they, where they needed to be.

Steven Dick: But especially with the especially with the Mars rock, you started to see, you know, what the implications might be. It wasn't… just not just the scientific facts, but the newspapers at the time, were filled with questions about what does this mean? You know, does this mean that there might be life all throughout the universe? And what would that mean for theology and philosophy and all kinds of different areas? So the idea of the impact of astrobiology on society also really picked up with this discovery of the Mars rock, even though in the end, the consensus now I think, is that those are not nanofossils, they're probably, you know, not biogenic but it certainly precipitated a lot of a lot of different areas in in what we now know as astrobiology.

Jim Green: Yeah, I really love that history part of it. In fact, as you mentioned, Percival Lowell, really looking at Mars thinking, that there were canals with water being moved on this what may be a drier planet than then Earth, of course, really spurred the imagination and a few years after he, his first book came out, called the “Abode of life on Mars or something on that, or HG Wells wrote War of the Worlds.

Steven Dick: That's right. And he knew about Percival Lowell.

Jim Green: Yeah. And so, you know, our science affects our culture. Just like in science fiction, we like to think of things that we write about the future and how we might be able to make things happen. So it works both ways.

Steven Dick: That's right. I was a big science fiction fan when I was a youngster. So I think that when I was at NASA, I found that when I asked a lot of the scientists, they many of them were influenced by science fiction. And people, of course, like Carl Sagan was, so that's right, it really fires the imagination to go out there and, and really see what you can find.

Jim Green: Well, you've said that intelligence is key to cultural evolution. What do you mean by that? What is the intelligence principle?

Steven Dick: Well, there's this the Drake equation, I think a lot of people know about the Drake equation, which is Frank Drake in 1960, you know, was searching for, made the first search for signals from, from a possible extraterrestrial intelligence, and came up with the Drake equation, which was just the number of technological communicative civilizations in our galaxy. And it has all these factors in, and one of them has to do with a fraction of planets that might have intelligence on it.

Steven Dick: The intelligence principle to get to your question, is the idea that any society any civilization that can improve its intelligence will improve its intelligence. And so my claim is that extraterrestrials out there are highly likely to be post-biological, artificial intelligence. Because you're, you know, the brains inside of our heads are limited. And with artificial intelligence you can do, you can do a lot more. And that would affect your SETI search. If you're looking for post biologicals, rather than biologicals, like us. They're not going to be like us.

Jim Green: Wow. So that really elevates you know, the possibilities of different kinds of life. So let's say if we find life beyond Earth, what do you think will be the reaction by the public and what will happen next?

Steven Dick:  Well, I wrote a whole book about that. So it's hard for me to condense it all. But I usually put it in terms of, uh, worldviews I think our cosmological worldview would change, our philosophical and theological worldviews would change and our cultural worldviews would change.

Steven Dick: by cosmological, I mean, that we will, we will know that we no longer live in a physical universe, entirely physical universe, where we are the only kind of freak biology, the freak intelligence, that we live in what I call a biological universe. And that, you know, that that makes a big difference for, for our future, our sort of human destiny if you have a biological universe where we have to interact with intelligence.

Steven Dick: So there's the cosmological aspect, then there's the philosophical and theological aspect. If we engage with extraterrestrials, we will find out something about our own knowledge. Do they know the same things that we know? Do they see the universe the same way that we do? Do we have objective knowledge? Will our knowledge be the same as their knowledge? So that's a huge question in philosophy. And when you go to theology, people have been arguing about this now for 500 years since Copernicus, but in the last few decades, it's really, really picked up as the possibility of life as has increased, what the theological implications might be. And of course, there are all kinds of threads to that. And it depends on which theology you're talking about. And every religion has its own questions that will arise in that case.

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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #39 dnia: Wrzesień 04, 2022, 23:56 »
Gravity Assist: The History of the Future, with Steven Dick (2)
Oct 30, 2020

Jim Green: Yeah. Well, you know, a couple years ago, I was at a meeting, it turned out was in Europe, and a reporter asked me absolutely out of the blue, if we discovered life, is society ready for it? And it took me back and I said, “No, I don't think so.” And that was the hot, that pretty much got the headlines everywhere. I was getting emails from all over the place, people saying, “Of course, we're ready to, you know, to find life beyond Earth. What was I thinking, right?”

Steven Dick: I don't think we're ready.

Jim Green: I don’t think we’re ready, either.

Steven Dick: That's one of the reasons that I think we need to prepare for discovery because you can have a better outcome if you're if you're prepared. One of the points I like to make is it very much depends on what the discovery scenario is, you know, it's almost, it's almost meaningless to say, what's the impact of discovery life? Are you talking about microbial life, or intelligent life or intelligent life with a signal, or the signal that's deciphered and what do they say? Those are all different scenarios that you're having to consider when you're talking about what's the reaction going to be?

Jim Green: Well, you know, you've written also about ethical issues involving the discovery of extraterrestrial life. What kind of ethical questions should we be asking each other?

Steven Dick: Well, that's, that spreads all the way from the spectrum of microbes to intelligence. If you find microbes on Mars, there's immediately an ethical question: Is Mars for the Martians, even though they're just microbes? Should we interfere? And you have scientists and ethicists on both sides of that question.

Steven Dick: And then, of course, when you get to intelligence, things are really multiplied, because you may have to actually interact with that intelligence. And, and, you know, it depends on what your theory of moral status is, we have enough trouble on the Earth with, you know, in terms of dealing with animals and that sort of thing. But the, the theory of moral status, if you have an anthropocentric theory of moral status, that's probably not what you want to do if you're talking about extraterrestrials, because everything would be focused on what's best for us, not what's best for them, and, and vice versa.

Steven Dick: Who knows what their ethics would be? And, you know, if you get a an example of some ethical questions, if you get a SETI signal, who answers? If it's if there's a decipherment? Who answers? Another question is, there's this thing called METI, messaging extraterrestrial intelligence, where we actually send signals ourselves in a more proactive way, should people be doing that? And what should we be saying? And who speaks for Earth? All those kinds of ethical questions. Yeah, they're very important. And I think that's why we need to be talking about them now. And not just when that happens.

Jim Green: Wow, a lot to consider. Well, Steven, you know, we're making all kinds of progress, you know, who knows what would happen? Maybe somebody tomorrow will announce, we have found life? What would be the first thing you would do?

Steven Dick: I would say, yay! I’ve spent a lot of my career on writing the history of this debate, and writing about what the impact might be. You know, you would have to go through several stages. Follow the evidence and have follow up research, we would live in a much more fascinating universe if we have other intelligence out there. I mean, it's still possible that we are, you know, the only intelligence in the universe, but it seems very unlikely to me. And so, I think that, that's one of the great unsolved questions in the, in the history of science, maybe the greatest unsolved question, if you're looking at a very broad point of view.

Jim Green: Yeah, I agree with you entirely. You know, it's that level of confidence that the whole scientific community’s got to get there. Right. And that takes time. No matter how you present the evidence, and what evidence you have available, it has to be interrogated. It has to hold up the scientific scrutiny. And that's what makes it very fascinating.

Jim Green: Steven, I always like to ask my guests to tell me what was that event or person, place or thing that got them so excited about being the scientists they are today? And I call that event a gravity assist. So, Steven, what was your gravity assist?

Steven Dick: Well, I'm a, I'm a farm boy from Southern Indiana. So we had dark skies on that farm. And all you had to do is look up and see all those stars and wonder

Jim Green: Wow.

Steven Dick: I remember asking how many are there? And what? What do they like? And oh, and are there planets around those and that sort of thing. And, of course, I grew up during the time of the early space age, you know, when Alan Shepard and John Glenn and I followed that all very closely. And I also was in contact with NASA already. NASA used to put out something called NASA Facts. And I always waited for this big brown envelope to come with NASA facts about various things. And so I was very much, you know, I think the initial spark was that dark night sky. But then it was the space program itself. And these NASA Facts that kept coming in from, from NASA Headquarters and firing my imagination even more.

Jim Green:  Wow, you know, that beckons back to also why you're, you're very much into history, because, indeed, with clear skies at night, our ancient ancestors looked and marveled at the sky, and looked at the wonders, even the Greeks looking at things that wander called planets. You know, and so indeed, that's true inspiration.

Steven Dick: Let me say one more thing, and that is that when I was getting my bachelor's degree in astronomy, I was at Indiana University, which is one of the few places that it also has a history and philosophy of science department. And so I would take courses over there because I always wondered, how do we get to know what we know when I'm learning about this astronomy stuff.

Steven Dick: And so I actually then after I got my bachelor's in astrophysics, went to get my Ph.D. in history and philosophy of science. And the interesting thing is that I suggested doing a dissertation on the history of the extraterrestrial life debate. And they said, well, there's two problems with that, in the history of science department. First of all, it has no history worth writing about. And it's not science.

Jim Green: Wow.

Steven Dick: This was, well, this was back when, when exobiology was still somewhat, you know, a not, not so reputable, sort of taboo subject, so to do the history on something like that was considered very, you know, sort of far out. But I actually stuck with it. I had to switch advisors to do that. But I did a dissertation on the early history of the extraterrestrial life debate from Democritus, all the way up to Kant.

Jim Green: Wow.

Steven Dick: And yeah, and then, and that came out as a book by Cambridge University Press, way back in the early 1980s. And then somebody else picked up there and went up to Percival Lowell. And then I wrote the 20th century history with a book called The Biological Universe. So it turned out to be a pretty good, I think, dissertation, and I always tell graduate students to stick to your guns. Don't let your dissertation advisor try to change your subject.

Jim Green: That's right. Yeah. Well, Steven, thanks so much for joining me in discussing this fascinating topic.

Steven Dick: It's been a lot of fun, Jim, thanks. It's good to see you again.

Jim Green: Well, join me next time as we continue our journey to look for life beyond Earth. I'm Jim Green, and this is your Gravity Assist.

Lead producer: Elizabeth Landau
Audio engineer: Manny Cooper
Last Updated: Nov 13, 2020
Editor: Gary Daines
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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #40 dnia: Wrzesień 19, 2022, 01:03 »
Gravity Assist: Mars Takes a Breath, with Jen Eigenbrode
Nov 13, 2020

The Curiosity rover has been probing the secrets of Mars since its arrival in 2012. Its discoveries include chemical signatures that could be related to life – or, alternatively, to geological processes. The Sample Analysis at Mars (SAM) instrument has found organic molecules, which are fundamental building blocks of life on Earth, but can also be produced in non-biological ways. Scientists have also observed sudden rises and falls in methane, a gas also associated with life, but which can be geological in nature, too. But with such a thin atmosphere, cold temperatures and scathing radiation from the Sun, the surface of Mars would be hostile to life. Where could life be hiding, if it were on Mars? Jen Eigenbrode, astrobiologist at NASA Goddard Space Flight Center, discusses.

Jim Green: Does Mars have the ingredients for life? Well, let's find out from the latest observations from our Curiosity rover.

Jim Green: Hi, I’m Jim Green, chief scientist at NASA, and this is Gravity Assist. On this season of Gravity Assist we’re looking for life beyond Earth.

Jim Green: I'm here with Dr. Jen Eigenbrode and she is an astrobiologist at NASA's Goddard Space Flight Center, specializing in organic chemistry, geology, and potential biology of Mars and ocean environments. So today, we're going to concentrate on what we know about the potential for life on the planet Mars. Welcome, Jen, to Gravity Assist.

Jen Eigenbrode: Thanks for having me, Jim. Happy to be here.

Jim Green: Well, you know, you're part of a fabulous team working on a spectacular instrument on the Mars Curiosity rover called SAM, which is the Sample Analysis at Mars instrument.

Jim Green: Since curiosity landed in Gale crater in 2012, August 2012. I mean, I know exactly where I was when that happened. What's it been up to since then? And how far has it gone?

Jen Eigenbrode: Yeah, so after we landed at Bradbury landing site, we drove to the Yellowknife Bay, which is this, the deepest part of Gale crater. And at that location, we found evidence, the first evidence, of an ancient lake on Mars. That was a significant finding, because it was the first time we had identified what we thought was an ancient habitable environment on Mars. That means it's a place life could have been supported, it doesn't mean that it was there. So we kept looking. From that point, we drove to Pahrump hills, and that's about 5 miles I believe, as the crow flies. And what we discovered there was that, indeed, we had come across more Lake sediments. And from that location, we started chugging up the mountain.

Jen Eigenbrode: It's 3 miles tall. It's gigantic. And we're lucky enough that we don't have to go too far.

Jen Eigenbrode: Of course, we don't have evidence of life from the Curiosity Rover, it wasn't really designed to get all of those types of details that we have found evidence of organic materials, which could be from life or maybe not.

Jim Green: Well, why are you so interested in the organic molecules. What about them is that connection to life?

Astrobiologist Jen Eigenbrode injects a chemical into a rock sample. Credits: NASA/Chris Gunn

Jen Eigenbrode: When we look up at the Red Planet, it's a red, it looks like it's just rusty. And what we found out so far is not really rusty, it's just dust on the surface that's like that. And underneath, it's actually darker gray in a lot of places. And that darker gray tells us there's a different chemistry that's been preserved. When we started this mission, there were a lot of scientists who really doubt[ed] we were going to find any organic molecules at all.

Jen Eigenbrode: And it was because we thought the planet was rather quiet, not doing much, old and rusty. But we're actually finding things. And that means that if we're finding organic molecules in 3 billion-year-old rocks, that they have been preserved over that time period. So the question is, do those organic molecules tell us anything about whether life was there or not? Certain types of organic molecules, or collections of molecules, are considered signatures of life, meaning, they're most likely to be formed by life rather than other processes. Sorting through those and making sure that it's a life process versus a non-life process is kind of challenging at times. But when there's evidence of life in our Earth sample, usually you find multiple lines of evidence for that life.

Jen Eigenbrode: The fact that we found organic material in these ancient lake sediments, tells us that if we look in the right place, perhaps we're going to find that evidence of life.

Jim Green: What are some of the measurements that SAM makes?

Jen Eigenbrode: What Sam does is, it takes a powdered sample, that could be something that was drilled. And in some cases, it was even something that we scooped from the surface, say like, you know, a sand patch or something like that. Anyway, it takes those sediment fines, and it sticks some into the top of the rover body, there's a little inlet up there, and it sticks it in there. And then SAM shakes it down into a little tube, and all that sediment ends up in an oven. So then we close the door, and we heat up that oven. And as we heat up the oven, the organic molecules and some of the other inorganic stuff that's in there starts to evolve as a gas.

Jen Eigenbrode: So, for instance, if there's water on any of those sediments, it goes off as water vapor really quickly, and we detect it. But the organic molecules, some of them come off really quickly. And some of them take a lot of temperature to get them out. So we heat that sample very slowly, up to about 1000 degrees. And when we do that, we can see what types of gases come off at different times. And we can compare those types of data to what we find on earth to try and understand what it's, what those gases are telling us about the composition of the sample as a whole.

Jim Green: So is it stuff that can be generated biologically?

Jen Eigenbrode: When we look at organic materials that are formed by non-life processes, such as in a meteorite that was formed in our solar system before the planets really got established that I mean, there's organics all over our solar system, and most of them are non-life related. And when we process it in an instrument like SAM, we see similar types of molecules coming off at high temperature, just like we did at Parrump Hills. And if we take a sample of, let's just call it an ancient soil, maybe something that's 60 million years old. So, it's been around for a while, it actually looks more like a rock now than a soil. But you know, that was around when there were plants, and there was organisms, you know, in the mud. So it's been geologically processed, but it still originated from life. And when we process that in [a] SAM-like instrument, we see the same type of molecules that we saw at Parrump Hills.

Jim Green: Wow.

Jen Eigenbrode: So it's hard, we do not have enough information to tell what the source was.

Jim Green: Okay, so what do we need to be able to supplement these kind of observations to carry on to the next level of understanding? Do we have to bring samples back from, from Mars?

Jen Eigenbrode: And that's one idea that people have had, yes, another is to drill deep. And so we actually, the human race, is actually going to see this unfold in the upcoming years.

Jen Eigenbrode: We have the Mars perseverance rover, that is heading to Mars right now, we expect it to land in February. And it has the capability of looking for organics in a different way than what we did with SAM. It's going to look for traces of the organics and how it, it's packaged in the sediments, both at a really fine scale, and then at a scale that a human eye can see. And both of them will tell us a lot about how organics were preserved, how they got into the sediments in the first place, and sometimes, they may give us additional features that are suggestive of life, like what you'll find in a stromatolite on Earth. Now the other Now, the other parts of it, and if we find any signs of organics, package those samples up because we're bringing them home.

But the other possibility that I mentioned was ExoMars. And ExoMars is going to drill deep. So if ionizing radiation is playing a big part, in what we see at the surface, and then perhaps drilling deep will get us away from all of that, and we'll get something that's a little more pristine and less altered. But until we get those results, we just.. I'm sure Mars is going to Mars surprises all the time.

Jim Green: As it always does. Now, the ExoMars rover is a European Space Agency rover that's going to be launched in 2022.

Jen Eigenbrode: That’s correct.

Jim Green: And so we'll see, we'll see what they find. And they have the ability to go down several meters. That will be fantastic.

Jim Green: Another spectacular thing that Sam does is just sort of open that port on the deck and let the atmosphere come in. And then it goes through that same process. Tell us some of the things that we're finding out about the atmosphere of Mars.

Jen Eigenbrode: So on Mars, there is a 1% of the density of air and atmosphere around that we have on Earth. So there's not a lot of atmosphere to begin with. But there's definitely a lot going on. There's, we're seeing methane.

Jim Green: Wow.

Jen Eigenbrode: And then on Earth, methane is except for localized areas where there's a lot of methane coming out of the ground or from industry or something like that, methane is pretty stable in Earth's atmosphere. The amount of it doesn't change. But here's a weird thing of Mars: it does change. So it’s trace amounts. And we see a change in the methane abundance seasonally. So it gets low in the cooler months. And then when summer comes around it, it rises. But then it drops again.

Jen Eigenbrode: Okay, what's going on there? And then on top of that, SAM has detected what we call methane burps. I mean, it's just like this instantaneous rise. And, quick, do another measurement. Wait a second. That methane signal’s gone. What happened? It was there. And then it disappeared.

Jim Green: Yeah, so methane is one of those things that can be generated by life. I mean, all life emits methane. But it can also be generated abiotically. Have we sorted out which one it is that Mars is emitting in these, mostly in the summer months?

Jen Eigenbrode: We don't know. We don't know. But what we do think is that the methane is probably largely coming from the ground somehow.

Jim Green: Leaking right through the ground.

Jen Eigenbrode: There's scientific rationales for how that might happen. But we wouldn't really know what's controlling it. And we don't know how widespread it is.

Jen Eigenbrode: It's one of the most exciting observations I think we've made, but also one of the most perplexing because we really don't understand it. And yes, it's an incredibly important molecule because it could be from life.

Jim Green: Mm. Wow. Well, you know, another important molecule that SAM has been measuring is oxygen. Hasn't been making some really great measurements of O-2, two oxygens together.

Jen Eigenbrode: It sure is, and you know, oxygens changing to which we never expected, oh, it rises in the spring. And then it starts to kind of drop off when that thing starts coming up. What's interesting is that you're talking about two molecules that readily react with each other. And they have different patterns, we don't understand why they're changing like they do. And the fact that we do see it changing means that there are active processes going on on Mars that we still haven’t uncovered yet. They're going on right now. So there's a lot more to investigate to understand what that is.

Jim Green: Very cool. Well, so we've got methane and oxygen coming and going, and you know, complex organic molecules in the soils. All these are fantastic, possible indications of life on Mars. So, Jen, do you think that Mars had life in its past and maybe even life there today under the surface? What do you think?

Jen Eigenbrode: As a scientist, I think it's very possible. Because early Mars was probably very much like early Earth in its environments, protected with a magnetic field so it didn't have all of the ionizing radiation. There was lots of heat around, because we had impact events happening, hydrothermal vents, all of the chemistry of Mars tells us that there is geochemicals that could have been a fuel source for or for life. It's just a matter of, did all the right steps happen to actually get life there? And did life actually persist?

Jen Eigenbrode:  So it is possible that life did exist on Mars. But the next question is, did it persist into later, into Mars history, and even possibly into today? One thought that a lot of astrobiologists have been thinking about is that if life ever did get going on Mars, when the ionizing radiation hit, and the climate changes started happening, perhaps it got too tough for life near the surface, and it went into the subsurface. And that's where it persisted. So if that's the case, then the records of the ancient life -- meaning after the magnetic field was gone -- might be in the subsurface.

Jim Green: Well, you know, in addition to looking at Mars, you've also done some interesting field work here on Earth. What are some of the things that can be done on Earth that are sort of Mars analogues?

Jen Eigenbrode: Sure, we look at ancient rocks on Earth that have modern life living in them. So we can try and pull apart multiple records of life, and understand how you take all these signatures, signatures of non life, signatures of old life, signatures of modern life, and separate them apart so that you can understand what's going on. And it's important to look at things like that on Earth, because on Mars, we may be looking at contributions from meteorites, contributions from Mars as a planet from a non-life perspective, and possible Martian life.

Jen Eigenbrode: And there's ice on Mars, we might actually be exploring that someday in the future. But then there are other places in our solar system, where we have these moons that have a rocky core, an ocean around that, and then a thick layer of ice. They're like snowballs, going around bigger planets. And what's really interesting about that is that there's enough heat generated around that rocky body that it could be generating hydrothermal vents, and, into the ocean. And we know that they have salts.

Jen Eigenbrode: So we could be looking at a scenario that's very similar to the hydrothermal vents we have on Earth’s oceans, in the deep, deep, deep part of the oceans where there's so much chemistry happening. They’re ideal spots for not only perhaps starting some of the biochemistry of life and the origin of life, but also allowing it to diversify. And so if it's, if it happened here on Earth at those locations, perhaps it happened in these icy moons at their locations, those oceans may have an independent genesis of life.

Jim Green: So have we seen any hydrothermal vent-like systems in the ancient ocean of Mars?

Jen Eigenbrode: Curiosity has looked at some, both minerals and isotopic chemistry, that tells us that there was a hydrothermal influence on some of the materials that we found, or that's important. It may not have been right there at Gale crater, but the sediments could have been transported from a hydrothermal area to where it was found. We don't know those details yet. However, at Jezero crater, there are a few locations where we think there may be actual evidence of hydrothermal vents. And I know that the Perseverance mission is trying to get to those places in their drive plan. So I would just say: Be patient.

Jim Green: You know, I thought I was excited enough about Perseverance. But that just blew my mind.

Jim Green: Well, you know, Jen, I always like to ask my guests that there must have been something, a person, place, or thing, event or something that got them so excited to become the scientists they are today. And I call that event in their life a gravity assist. So Jen, what was your gravity assist?

Jen Eigenbrode: Yeah it’s a good question. I think that I've always asked the question “why” maybe too many times. But even as a young kid, I was very interested in science. But it wasn't until I got outside and started hiking around and enjoyed nature for what it was that I started asking: How did it all get here? And that's when I became the scientist that I am today.

Jen Eigenbrode: Looking around the mountains, looking at the rocks that you see, they're all so different, all the life that we have on our planet, and then you look compared to something like Mars, which doesn't seem like it has anything from a distance. How did Earth become what it is today, and is it really special? How special is it, compared to everything else in our solar system? Why do we exist here today? These are the types of questions that made me the scientist that I am now. And, you know, searching for life in our solar system is just one aspect of that, that I've devoted my career to.

Jim Green: Well, you know, I really hope and I'm sure you do, too, that we're alive when we answer that question, “are we alone?” Because I think the answer to that is, life is everywhere. And try to find, we don't necessarily know always what we're looking for, if it's not going to be like us. And yet, evolution takes it in different ways that, that we are really going to have to have some great evidence to be able to understand.

Jim Green: Well, Jen, thanks so much for joining me and discussing this fantastic topic of looking for life in our solar system and Mars in particular.

Jen Eigenbrode: Thank you for having me, Jim.

Jim Green: Well join me next time as we continue our journey to look for life beyond Earth. I'm Jim Green, and this is your Gravity Assist.

Credits: Lead producer: Elizabeth Landau
Audio engineer: Manny Cooper
Last Updated: Nov 16, 2020
Editor: Gary Daines

« Ostatnia zmiana: Październik 02, 2022, 23:57 wysłana przez Orionid »

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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #41 dnia: Październik 02, 2022, 23:51 »

Gravity Assist: Set Sail for Europa, with Bob Pappalardo
Dec 4, 2020

NASA’s Europa Clipper mission will give us the most detailed look yet at Jupiter’s extraordinary moon Europa. Smaller than our own Moon, Europa is one of the prime candidates for life beyond Earth because it has a deep ocean under its icy shell. The Europa Clipper spacecraft, named for speedy 19th century merchant ships, will map the surface, learn more about the ocean using ice-penetrating radar, and see if there are plumes of water shooting out from the cracks in the ice, among many other scientific activities. Project scientist Bob Pappalardo at NASA’s Jet Propulsion Laboratory discusses this mission as well as the possibility of life on Europa and how it would be able to survive without sunlight.

Jim Green: Ocean worlds around our giant planets are there to be discovered. Europa Clipper is being built to do just that. Let's find out what it can do.

Jim Green: Hi, I’m Jim Green, chief scientist at NASA, and this is Gravity Assist. On this season of Gravity Assist we’re looking for life beyond Earth.

Jim Green: I'm here with Dr. Bob Pappalardo and he is a senior scientist at JPL in the planetary science division. He's also the project scientist for the NASA Europa Clipper mission that's going to Jupiter's moon Europa, a beautiful ocean world. Welcome, Bob, to Gravity Assist.

Bob Pappalardo: Thank you, Jim. It's so good to see you. And I'm so excited to be here.

Jim Green: Well, how did Jupiter get so many moons and why are they so different?

Bob Pappalardo: Well, Jupiter has something like 79 moons. Most of them are little shards from collisions, or Jupiter captures objects that are passing by. Some of them go around the wrong way. So we know that those are captured, but it's these four big ones, the Galilean moons, that are the ones that are much more like worlds. Ganymede is larger than the planet Mercury. And those four were created along with Jupiter, from the same cloud of gas and dust.

Bob Pappalardo: And the inner one, Io, lost most of its H2O, most of its water. It does not have an icy surface. The outer two, Ganymede and Callisto, have lots of rock and lots of ice and Europa is kind of in between, with a bunch of rock and then a skin of H2O, some of which is solid ice at the surface where it's so cold and some of which is liquid water, we think, down below the surface, which makes Europa so fascinating that there's a liquid water ocean in there today.

Bob Pappalardo: Europa's ocean is really special because it's pretty close to the surface about 20 kilometers -- what's that, 13 miles or so -- below the surface and probably it's in contact with rock below. So nutrients can seep into that ocean and potentially serve as a fuel for life.

Jim Green: So they were all made at the same time, and yet they look so different. So the tidal forces of Jupiter really, you know, when you look at each of the moons, have really shaped them so much.

Jim Green: What's happening with these moons with tidal forces? What does that mean?

Bob Pappalardo: Europa is going around Jupiter in a somewhat eccentric orbit, it’s not quite round. And when it's closer to Jupiter, it stretches more because Jupiter's gravity is pulling on it. And when it's farther from Jupiter, it contracts a bit. And, this creates friction. Europa's stretching and distorting as it orbits around Jupiter, every three and a half Earth days; every 85 hours. So that's pretty quick. And it flexes by about 30 meters when it does that. So that creates heat within Europa enough to melt ice and, and keep the interior warm.

Bob Pappalardo: This is somewhat similar to Earth’s tides. Earth’s oceans have tides because as, uh, Earth rotates and the moon orbits, the, the Moon is pulling on the Earth and the Earth is pulling on the Moon.

Bob Pappalardo: If you're standing on the right part of Europa, you'd be rising and sinking about 30 meters every three and a half Earth days. And the, the stresses would be rotating around you, the direction at which the stress is pulling would change. And this creates just bizarre, fascinating geology.

Jim Green: That's gotta be cracking the ice, like crazy. Is some of the cracks caused by that or are there other things that caused those stresses on Europa?

Bob Pappalardo: Yeah. We think some of the cracks are related to these tidal forces. There might be longer term stresses, which create other cracks as well. If you were on Europa and put your space helmet down against the ice, it would probably be creaking like a boat.

Jim Green: Well, you know, in our ocean at these hydrothermal vents, we see life all over the place and it doesn't require a light from the sun. Is that a similar process that may be going on at Europa? Or do we need sunlight to have life?

Bob Pappalardo: Beneath Europa’s is icy shell, light is not going to penetrate, so it's not life that's depended on photosynthesis that we're talking about. Instead life that's dependent on chemical reactions, similar to some life on Earth that isn't dependent on sunlight, but where the metabolism is powered by chemical reactions, chemical disequilibrium, that's the kind of life that we're wondering might exist in Europa's ocean.

Bob Pappalardo: We're not talking about fish and whales, that'd be exciting, giant squid or something, but instead, probably just, just single cell organisms down there. And that's because complex life needs a lot of energy. And at Europa, we think probably if there's the energy for life in the ocean, it's probably, you know, at a low level, so maybe enough to power just single cell organisms. But that would be so exciting because if there's life at Europa's ocean, it would almost certainly be an independent origin of life. You can't transfer life, right, from Earth way out to Europa, maybe between Earth and Mars, but not out to Europa, that'd be pretty tough to do.

Jim Green: Over the last several years, another set of fantastic research has been done concerning the possibility of seeing geysers coming out from cracks. When we look at Europa, we see these crack structures everywhere, it seems, and yet maybe some of them are active. So what do you think about the possibility that life gets scooped up and ends up in these plumes?

Bob Pappalardo: Yeah, there's tantalizing evidence of these plumes from the Hubble Space Telescope and other observations that that says maybe every once in a while Europa lets out a big burp of activity. When we're there with the Europa Clipper, we might be able to fly through such plumes. If they're there, we need to confirm them. There might be a range of sizes. We don't know, are they consistently active or sporadic? So we need to find that out. We have some time before the spacecraft arrives, and then when it arrives, uh, to identify, are there plumes coming out and can we fly through them to, um, to directly sample the interior of Europa.

Jim Green: Well, you're the project scientist of a fabulous mission, Europa Clipper. And, and you guys are building that right now.

Jim Green: How big is the spacecraft? What does it look like?

Bob Pappalardo: The Europa Clipper is solar powered and the solar panels would stretch from one end to the other of a standard U.S. basketball court. Some said it looks a little like a scorpion. It has, it has these big solar arrays, and it has a magnetometer sticking out of it like a stinger. And it has, um, uh, the big radar antennas hanging off of the solar arrays. It's very distinctive and cool looking spacecraft.

Jim Green: And of course, it's got this big, huge dish that is used to radio back to Earth, all that fantastic data it acquires.

Bob Pappalardo: Exactly.

Jim Green: What are some of the other measurements Europa Clipper is designed to make?

Bob Pappalardo: So, cameras, we've got a camera suite, two cameras, to map out the surface, um, completely and in stereo. So 3-D and in color. And we can get with the narrow angle camera images as good as a half a meter per pixel. So those, those pictures would see my desk if it were on Europa.

Jim Green: Wow, love it. Love it.

Bob Pappalardo: We've got an infrared spectrometer to look at the chemical fingerprints of the surface material and try to understand what it is. And what does that say about the ocean? Are there organic materials? We have an ultraviolet spectrometer. That's great for finding plumes and characterizing them and for seeing, uh, what the surface composition is too. We have a thermal instrument to look for hotspots, places that are warm enough, that we can see them essentially glowing in the dark. There's an ice-penetrating radar, sends out a long wavelength radar signals that can penetrate right through cold ice, bounce off liquid water, and back to the spacecraft.

Jim Green: Wow.

Bob Pappalardo: So we’ll be able to map out the plumbing beneath Europa's surface. Then we go to the particles, fields and particles instruments. We have a magnetometer.

Bob Pappalardo: That can tell us not just that there is an ocean like Galileo data hinted, but how thick it is and how salty it is, how conductive that ocean is. And the magnetometer needs the plasma instrument. The plasma instrument tells us about the charged particle environment, and that's needed to better understand the magnetometer data and tells us about the plasma environment, which is exciting in itself and what particles are there. And then, we have two different mass spectrometers, one to get at the dust particles and one to get at the gas particles to tell us their composition, to hunt for organics and let us know about the chemistry. Oh, and last but not least, we use the, the communication system to look for the Doppler shift of the spacecraft signal, as it flies by Europa, to get out the gravity around Europa. By flying by Europa lots and lots of times when Europa is in different places in its orbit, we can actually sense how Europa is flexing. And that'll tell us about the properties of that ice shell and the ocean beneath. So it's going to be an incredible mission.

Bob Pappalardo: We'll actually be orbiting Jupiter and making flybys of Europa. We're in an orbit that brings us by Europa about every four weeks. And we're also looking into the option of maybe flying by every six weeks too. So we'll see where we land with that. And, um, so, so every several weeks we're going to have new data just pouring in.

Jim Green: Yeah. What I really like about that whole concept of orbiting Jupiter, and then getting into the belts, flying by Europa and then radioing the, the, the data back is you have time to analyze it. You have time to really pore through it, figure out what's happening and fine tune those measurements that you want to make.

Jim Green: So, with all that it does, is there a possibility that it may be able to find life?

Bob Pappalardo: The Europa Clipper mission isn't designed to search for life itself. What we're trying to understand is habitability. Is Europa a potentially habitable environment? Does it have the ingredients for life water, the right chemical elements and, and the chemical disequilibrium that could power life?

Jim Green: So we may have to wait ‘til our next mission where we get down to the surface and go into one of these cracks.

Bob Pappalardo: Exactly. By sending a lander down to Europa's surface someday we could scoop up some of that dark reddish stuff and examine whether they're organic materials in there, or perhaps some signs of life in there. So the Europa Clipper mission will also scout out places where we might want to send a future lander.

Jim Green: So Bob, when will Europa Clipper be on its way?

Bob Pappalardo: We're scheduled to launch sometime in the mid 2020s. And then depending on the launch vehicle we take, it'll take a few years, or up to maybe six years, to get out to Jupiter and we might go on a direct path, or we might need a gravity assist. In this case, we're looking at the possibility of a gravity assist by Mars and then to swing back in past the Earth and out to Jupiter and Europa.

Bob Pappalardo: You know, Jim, I was so lucky to have been able to work, even though just for a little while, with Carl Sagan and to audit a couple of his courses and to do a project under the tutelage of his postdoc, the late Reid Thompson. And, you know, I first saw Carl when he did the broadcast on TV of the Viking landings back in 1976 on PBS live, waiting for that first picture of the foot of the lander. And then he would appear on the Johnny Carson show and communicate science, on that late-night talk show. And, and then of course in 1980, the original cosmos series and the reason I investigated Cornell as a possible school to go to as an undergraduate was, well, I knew Carl Sagan was there. They must have some good stuff. And I went there thinking I was going to do astronomy.

Bob Pappalardo: But then I moved to, to the geology side of things. And then I found out, wait, there's something called planetary geology, like do both. And, I really learned about that because there was, uh, the course catalog, “Ices and Oceans in the Outer Solar System” taught by Carl Sagan, where I first learned about Europa and about Titan and Triton.

Bob Pappalardo: And I'm kind of still doing the same thing today. So, Carl was great, even when I went back to visit Cornell after I finished up and moved to grad school at Arizona State University. And I remember running into him in the hallway and he's like, ‘Bob, come on in the office, tell me how it's going.’ And it was, it was just so nice that he remembered my name, that he cared enough to take a few minutes, to help a new grad student along and, and, and push them along in their careers. It was, it was quite inspiring.

Jim Green: Well, I, I never had the privilege to meet Carl, but I, all the stories I hear about Carl was just such a fantastic scientist, but also as you say, really cared for his students really cared for what they were doing.

Jim Green: So, Bob, thanks so much for joining me in discussing this fantastic topic.

Bob Pappalardo: You bet, Jim. What a blast. It's been a lot of fun and, we're all looking forward to Europa, getting there and all this great data that's going to pour in.

Jim Green: Absolutely. All right. Europa Clipper onward.

Jim Green: Join me next time as we continue our journey to look for life beyond Earth. I’m Jim Green and this is your Gravity Assist.

Lead producer: Elizabeth Landau
Audio engineer: Manny Cooper
Last Updated: Dec 4, 2020
Editor: Gary Daines

« Ostatnia zmiana: Październik 23, 2022, 01:53 wysłana przez Orionid »

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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #42 dnia: Październik 16, 2022, 23:55 »
Gravity Assist: The Bright Spot of the Asteroid Belt, with Britney Schmidt
Dec 18, 2020

Between the orbits of Mars and Jupiter is a mysterious dwarf planet called Ceres. Its surface is dark and muddy, but has hundreds of patches of bright material. The salt-covered dome and other bright features in Occator Crater are so reflective that they looked like flashlights in distant images. NASA’s Dawn spacecraft got a close look, and pointed scientists to the idea that liquid brine has come up from the interior of Ceres, forming the Occator dome and other bright features. Ceres’ crust also contains a significant amount of ice. Astrobiologist Britney Schmidt discusses the implications, as well as her fieldwork in Antarctica.

Jim Green: In the asteroid belt is a huge dwarf planet. It's called Ceres. Does it have an ocean underneath its icy crust?

Jim Green: Hi, I’m Jim Green, chief scientist at NASA, and this is Gravity Assist. On this season of Gravity Assist we’re looking for life beyond Earth.

Jim Green: I'm here with Dr. Britney Schmidt, who is an astrobiologist and an associate professor in the Earth and Atmospheric Sciences department at Georgia Institute of Technology in Atlanta. Britney, welcome to Gravity Assist.

Britney Schmidt: Thanks very much. Excited to be here.

Jim Green: You know, I think your favorite objects are cold, or you know, very cold.

Jim Green: Why are you so interested in ice? What about it really gets you going?

Britney Schmidt: Well, for me, I got really interested in ice because I was thinking about water. Right? One of the first things you learn about life on our planet is that life needs water to exist. And if you look across the solar system, the most common form of water is ice. And most of the water in the solar system is hidden by that ice. And so, I got interested in ice and everything it tells us from its chemistry, to how it forms, to its crystalline structure, to the geology, to the processes that it creates. And so now even to how it interacts with the ocean has been a big focus. So it's, it's the most common need for life to have that water. And so, ice in the solar system is, is one of the questions that we have to, have to answer.

Jim Green: You know, Ceres, is one of those coolest planetary bodies that many people might not have heard about. It's, you know, it's the largest body in the asteroid belt. It's rounded by its own gravity.

Jim Green: So, where is Ceres in our solar system? And how big is it?

Britney Schmidt: So Ceres is in the main asteroid belt, just about smack dab in the middle of it, it is at kind of halfway between the orbits of Mars and Jupiter. And the kind of neat thing about it is actually how big it is, you know, when you think of asteroids, you might think of something small, maybe something the size of your house, but actually Ceres is about the size of the state of Texas. So it's absolutely gigantic.

Jim Green: So, what makes it so special?

Britney Schmidt: It's the innermost icy world, and a miniature version of maybe what some of the other planets looked like early on. It's one of the only planets that's really made of this kind of frozen ground on the, on the outside. So I kind of like to call it a permafrost planet, if you will. So if you think about the Arctic on the Earth, where the ground is frozen, year round, it's the same thing on Ceres. It's kind of this frozen mud up on top. So that's kind of special. And it's really a weird object in that way. It has something in common with Mars has something in common with the Earth and with places like Europa and Enceladus in the outer solar syste. But we call it a dwarf planet, it basically means that it is round, as you say, and so it has self-gravity, it's done some really interesting things that planets do. So when you picture an asteroid being like kind of a twisted hunk of metal or rock, then you're really missing the picture with Ceres, which is a big sphere, made of this kind of ice-rich, rocky material.

Jim Green: Well, you know, NASA's Dawn spacecraft first visited Vesta, also a very large asteroid that that is smaller than Ceres, and then left Vesta and went out to Ceres. It spent more than three years orbiting that dwarf planet and took spectacular images and other measurements. Tell us a little bit about what we learned from Dawn.

Britney Schmidt: Dawn was a fantastic mission. It was the first planetary spacecraft to go into orbit around one body, leave it, and go to the next. So that was pretty exciting. And Vesta, that mission was spectacular. But with Ceres we really saw something special. And as you're zooming in on a planet getting closer and closer, those first images where it becomes more than a point of light, it starts to become a real place, I remember those first images because we could start to see every rotation, this kind of brightness that would kind of show up, and then as we zoomed and we got closer and closer, you could see it looked like a flashlight and some of the images coming from this crater. And as we got closer, we could see that what it was is that though Ceres is very, very dark, there's also these really bright deposits in this crater called Occator Crater. And those bright deposits were reflecting a huge amount of light back at us.

Britney Schmidt: And when we got up close, what we could see is that these are definitely salts. And so salts are created in the interaction between water and rock. It happens on the Earth, it happens on other planets. And so what we think is that that is briny material, material from deeper inside Ceres that has come up.

Jim Green: Well, as you say, liquid water, in fact, must have some aspect to do with these, these briny salty deposits. So, do we think that Ceres has an ocean inside it or liquid water at some layer?

Britney Schmidt: It looks like there probably is. The gravity data is consistent with that. It's very, very round, which is really hard for, for solid materials to do that very well. So, liquids, but ice is another good way to make something kind of round. It can relax over time. So there is some evidence to suggest that deep down there might be some liquid layers. There's certainly evidence to suggest there might be brine pockets or former brine pockets, so a little bit of heat from an impact or something could really warm those up. So, it's one of those questions that we, we think there's really good evidence for it. But it's not clear whether that's constantly liquid now or was recently liquid in the past.

Jim Green: Here on Earth, everywhere we go, where there's liquid water, we find life. And so, if Ceres even has liquid water, is there a possibility that life may exist there?

Britney Schmidt: So, Ceres is a little bit different than a place like, you know, like, like the Earth, or places like Europa, or maybe even Enceladus, where we think there's an ongoing source of energy. So, on Earth, it's leftover heat from when the planet formed. And so things like hydrothermal vents and plate tectonics mean that you keep cycles of chemical energy alive, that that allows life to persist. And so that's really important on our planet. One of the reasons that we're interested in like the ocean worlds in the outer solar system, is that this could be going on on those. Europa is a great example, a moon of Jupiter that we think could have seafloor activity, it could have… it's got a really young ice shell, so it's reworking itself all the time. So that tells us that there's energy right now.

Britney Schmidt: With Ceres, it's not really the same deal. It has many of the same ingredients, and maybe 4 billion years ago was really cooking, literally cooking the rock in the water together and making energy and maybe making prebiotic materials. We just don't think it probably went all the way.

Britney Schmidt: And one of the neat things about it is that even if life never got started on Ceres, one of the hardest things to do on the Earth is to understand what the geochemistry was like before life got here. Life is really messy. It kind of messes everything up. It gets its fingers literally in everything. And so it makes it hard to understand what the geochemistry looked like when water and rock were kind of the only games going on this planet.

Britney Schmidt: So, studying places like Ceres, even if they don't have bugs crawling around right now means that it's a really neat opportunity to understand planets as they form or as they existed just before life took hold.

Jim Green: Well, it's so different, as you say, from all the other asteroids. Where do you think it was created? And how did it get where it is today?

Britney Schmidt: It's actually one of the biggest questions that we have. There are things about it that make Ceres seem like maybe it came from the outer solar system, but we know that there's ice and water and a bunch of it in the inner solar system too.

Britney Schmidt: So it's actually, Ceres is cold enough to hang on to the ice for a really long time, but warm enough that it's not actually stable, really on the surface. So the surface of Ceres is kind of this muddy rock ice mixture. And that's special because it means it has a geology style that is really different from a lot of other planets. It means that ice is kind of stable towards, towards the poles, but not, not right at the surface at the equator. And so that kind of governs what we see on the surface. And so this kind of interplay of how hot the surface gets and where they're, you know, cold traps or colder areas, has played a lot, or it has really played out on the surface of Ceres. And that's why we see what we see today.

Jim Green: Yeah, indeed, in fact, the high-resolution imaging that Dawn did in many areas, but the Occator region in particular, really allows us to think about the future of going back to Ceres, not orbiting again, but getting down to the surface. So what are some of the ideas about future missions going to Ceres?

Britney Schmidt: There is a study that's being looked at in the Decadal Survey, there's been a few mission concepts floated even proposed. And in fact, people have even suggested maybe we could return a sample from Ceres, to do some of this work in the lab.

Jim Green: Well, you know, you've done some really fascinating fieldwork here on Earth to look for formations that resemble structures on Ceres as well as Jupiter's moon Europa, what have you found out from what we call these Earth analogs?

Britney Schmidt: Yeah, so one of my research group’s favorite things to do is to go to the places on Earth that allow us to study those processes that are happening here that are the same on other planets. So, you don't have the exact match. You know, nothing here is the surface of Ceres or the surface of Europa, but there are places that remind us of that, and that teach us about the same kind of physics and, and geology that we need to understand and this idea about subsurface water and subsurface ice. As I mentioned, permafrost is one of the really key ideas here is that we have environments on the Earth where water and ice interact in really special ways and have cool geologic processes.

Britney Schmidt: And I'll mention two of them. One is ice-rich landslides. Across the solar system, they look really different. And they are formed a little bit differently. They just have different properties than other landslides. And we see them across the surface of Ceres. But we also see them on Earth, and Mars and even on Pluto's moon Charon. So we've seen similar ice rich landslides across the, across the solar system. So we could go study places, even in Colorado, to look for examples of Ceres.

Britney Schmidt: But my favorite one are called pingos. And pingo is just a great word in general, but it basically means it's an ice cored mountain. And the way it is happen is just like we think maybe you know a giant impact into Ceres heats up the surface and creates pools of water in the subsurface. The surface is very cold, the water is down below. And as that refreezes, it actually exerts pressure and it causes the water to move around.

Britney Schmidt: As that refreezes, it can actually refreeze onto each other. So the water wants to freeze onto ice, wants to freeze onto more ice wants to freeze onto more ice. And what you do is you're actually slowly grow these mountains. And on Earth, the tallest mountains are around, you know, 50 meters or so tall, so pretty tall, and they're filled entirely with ice. So, you'd be in the Arctic hiking along you'd see these little domes they look a little bit like a kind of like a fatter, rounder, volcanic dome. And it's rocks on top, maybe you'd see you know grass and stuff. Obviously we don't see grass growing on Ceres. But if you were to walk up to that and dig a hole, then you'd find out that the entire mountain below that permafrost layer is made entirely of ice. And so our group has been doing some work now. We're about to go actually out on our first pingo field season hopefully in the spring, COVID-19 allowing. So ice mountains, hiking around with a bunch of geophysical equipment, cannot wait.

Jim Green: It sounds fantastic. But you've also been working on a robot that explores icy waters. And I think you call it Icefin. Can you tell us a little bit about that?

Britney Schmidt: Yeah, so this whole idea of how ice and water work in cryospheres, right, the frozen parts of planets, it's a process that we don't understand even all that well on our own planet. I guess the that my favorite thing to tell people is you know, if you look at Mars and most of the pictures of Mars, they remind me at least of like Tucson, where I grew up, you know, rocks and stuff. And you can imagine what your mission would look like if you went to Mars if you've lived in Tucson, or you've lived in many places in the US to be honest. But if you think about what a mission to Europa would look like, especially the parts that we want to get to the ocean down below, there's really no option but to go down and get underneath the ice.

Britney Schmidt: And so we've been doing work with Icefin, which is an underwater robot that we built using NASA's funds, but is now working for NASA and NSF to try to understand ice shelves on the Earth, which are these big, thick sheets of ice that are floating out over, over the ocean. And so we actually drill holes in the ice, and put this robot down underneath. And it's teaching us not only how our own climate works, but also how we might one day explore places like Europa where we're going to need autonomous navigation and, and different types of science sensors. And we're going to need to understand what those exchange between the ice and the ocean, all that really works, like how that happens. And so we've been using Icefin to do that. So it's kind of like practicing for Europa, but it's also doing really important fundamental climate science here on the Earth.

Jim Green: Well, for you to be able to do that. I'm sure you've had to go down to Antarctica on a number of occasions. So can you tell us what one of your more interesting or favorite experiences in the Antarctic is all about?

Britney Schmidt: Yeah, so this last season was so in 2019, was my seventh trip to Antarctica. And it really was lucky. It was a fantastic experience. So, we actually made a second copy of Icefin, and we continued our NASA work and then part of our NSF work, we went out to this really special place called Thwaites Glacier.

Britney Schmidt: And what we did there was to work with our British Antarctic Survey colleagues and some other folks from the US to put a hole through 600 meters of ice and put Icefin down. And we swam almost 2 kilometers back to the point where the ice and the sea floor actually touch. And it's a really important place. It's where all the melting of these fast-changing glaciers starts. And it's something we'd never seen until January of 2020. So it was the most amazing experience to be someplace that maybe 10 people have been before them to see something that no one had ever seen before, to be piloting our pseudo-Europa robot back to the grounding zone of this glacier. It was just, just amazing experience. Living out on the ice, we were out there for five weeks, living out of tents and, you know, winds and storms and then warm days and beautiful days, all intermixed, just an amazing experience.

Britney Schmidt: So it's, I don't know, it's like the little piece of feeling like you're a part of the whole system, and still trying to figure it out that is really just so special. And for me, it's because, you know, we built the robot ourselves. And it was working with students and postdocs, and like our staff very, very closely, all a really young team to do that. And so it just feels like this amazing, you know, experience to really be actively living your science and to live in this very crazy distant place, that's a part of our own planet, a little bit of planetary exploration in your backyard.

Jim Green: Well, Britney, you know, I always like to ask my guests to tell me, what was the event or person place or thing that got them so excited about being the scientist they have become today. And I call that event a gravity assist. So, Britney, what was your gravity assist?

Britney Schmidt: Yeah, so my gravity assist was actually when I was an undergrad. So, you know, I always pretty much liked everything. I just liked being in school. And like many people, when you're first heading into college, it’s kind of a rough time. And, I felt kind of lost. To be honest, I was doing fine in my classes, but I really didn't think I'd found what I wanted to do. And I happened to take a really amazing class from, from Robert — or Bob as I know him  —  Brown at the University of Arizona. And it was a big, general education class. And I teach a class like that now partially why I do it was that this class really meant something to me and having this professor who was he had a spectrometer that was on the Cassini spacecraft that was flying in the middle of space. And yet he was spending his, you know, his office hours, with me answering all the questions that I had about how planets worked and finding me books.

Britney Schmidt: And eventually, you know, he sat me down and said, ‘Britney, you ask more questions than any grad student I know. I think this is what you should be thinking about.’ So we sat down with the class course catalog, and he helped me pick out with the classes I was going to take the next semester to try it out. He was like, you've tried everything else out theater and English and everything else. Why don't you try this? And so I took a math class, I took an astronomy class and I worked in Bob's ice lab. And so Bob taught me that ice was fascinating. When he first proposed that I work with him freezing ice, I asked him if he instead had any paint drying available. And instead it's become like what I do for my living, right? He, he did that. And he took a chance on me. And he spent time with me at a time that I really needed it. And it turned out to be what I love to do, and I'm good at. And I think that's a really important kind of an assist.

Jim Green: Britney, thanks so much for joining me and discussing these fantastic topics.

Britney Schmidt: Thanks very much for having me. It was my pleasure.

Jim Green: Well, join me next time as we continue our journey to look for life beyond Earth. I'm Jim Green, and this is your Gravity Assist.

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« Odpowiedź #43 dnia: Październik 31, 2022, 04:49 »
Pytania nt. życia w US. Marsjańskie badania powierzchniowe rodzą więcej pytań niż odpowiedzi.

Jim Green: We only get hints of that. For instance, Mars, on occasion will burp methane and we find that this methane is leaking through the surface. Okay. And that's pretty exciting, ‘cause methane is one of those gases that that we call a biomarker. You know, it could be generated by life, doesn't mean it is, because there's also abiotic, meaning non-biological methods, for which methane could be generated. And now we're seeing Mars also burp oxygen, molecular oxygen, O-2. And so that's another one of those gases that that that, you know, we are familiar with as an important element of life here on Earth. So, we just, one of these days got to understand much more about what's going on below the surface on Mars.

Gravity Assist: Your Questions About Life Out There and Down Here
Dec 23, 2020

These six infrared images of Saturn's moon Titan represent some of the clearest, most seamless-looking global views of the icy moon's surface produced so far.  Credits: NASA/JPL-Caltech/Stéphane Le Mouélic, University of Nantes, Virginia Pasek, University of Arizona

Why don’t we go live on Saturn’s moon Titan? What would it mean if we found life elsewhere? How did life get its start on Earth? NASA’s chief scientist Jim Green and astrobiologist Lindsay Hays discuss these and other audience questions from social media.

Jim Green: Is there life on Mars or Titan or Venus? Where would we go to look for life? We're here to answer your burning questions about life in the universe.

Jim Green: Hi, I’m Jim Green, chief scientist at NASA, and this is Gravity Assist. On this season of Gravity Assist we’re looking for life beyond Earth.

Jim Green: I've invited Dr. Lindsay Hayes back to sit down with me and answer your questions.

Jim Green: And she's an expert in astrobiology. In fact, she's the deputy program scientist for the Astrobiology Program at NASA.

Jim Green: Welcome, Lindsay to Gravity Assist.

Lindsay Hays: Thanks, Jim. I'm really glad to be here.

Jim Green: Now, helping us today is Liz Landau, and she's been the fabulous producer of gravity assist now for quite some time and doing as, you all know, a super job. So I want to thank Liz, bottom of my heart, and, and turn it over to her because she's gonna really give us the questions you want to know about is there life beyond Earth. Liz!

Elizabeth Landau: Well, thank you, Jim. It's been such a pleasure working on Gravity Assist, and we've learned so much about life's origins and the search for life beyond Earth. So let's go into social media and see what our audience is asking.

Elizabeth Landau: So the first question comes from @nsulakshna, who asks, “age old question: Is life possible outside Earth? Has anyone found any living organisms?”

Jim Green: Okay, I would say from a professional opinion, we find environments all over the place that we feel, could be habitable environments. And that means regions where we think life existed or could have existed in the past. So, we haven't found life yet. But those regions are of particular importance.

Lindsay Hays: Yeah, I mean I’d add, like, I think that, you know, we know on this planet on the Earth, there's sort of diverse environments in terms of where we find life, you know, we find life in very hot environments, very cold, very salty, very radioactive, all of these things. So, the range of what we know, based on what we've seen on this planet as habitable, sort of, is quite wide, and we see diverse environments throughout other bodies in the solar system.

Lindsay Hays: So, it's likely that somewhere there is, somewhere as habitable for life as we know it. And even more likely that there's probably somewhere that is habitable for life as we don't know it, you know, something that we, something that's different enough from Earth life that may have a different range of temperature or whatever that, that, that may exist somewhere in our solar system or beyond.

Lindsay Hays: I would say, Jim, I don't think we've really been to a place and said, yeah, this place is definitely habitable for Earth life. But we haven't technically been to that many places in our solar system yet. “Yet” being the operative word there. And so, you know, I think I think as we continue to explore, we may find more habitable places that we know are likely out there.

Elizabeth Landau: Excellent. Well, let's go to our next question, from @HomelanderAdc, who asks, “What's the most plausible theory of how life appeared on Earth?”

Lindsay Hays: You know, I think that the way that we as astrobiologists think about how life appeared on Earth, it was sort of a very gradual process. Organic chemistry, sort of the abiotic chemistry, things that happened just because you have the right chemicals and the right energy in place, you know, slowly turns into, you know, in places that have enough energy to push these reactions forward, but not sort of spin them out of control. These things slowly happened, the chemistry continued over a lot of time, that's the good thing about the solar system is, we have a lot of time for these things to happen. You know, a lot of complex chemistry was probably what was happening early on. We probably wouldn't look at it and recognize it as life.

Lindsay Hays: And then there was selection processes that happened on this, it was very messy, I would think that, you know, our most plausible theory is that the origin of life was something that may not look a lot like life, would have been a very messy and a very complex chemical soup, and very inefficient, right? You may have done some of the processes that we think of but not as not as well as life does them now. Metabolism, replication, all of these things, eating, you know, eating, and, you know, breathing and reproducing, all of these things may have happened, but in a very inefficient kind of way.

Elizabeth Landau:  And a question that came from Twitter and was getting a lot of attention was from @PaigeEtheridge1. She asked, “Are you open to the idea that not all life forms might be carbon based?”

Jim Green: Oh, absolutely. In fact, you know, what happened about 15 years ago, was, was really quite fascinating to watch when the astrobiologists were struggling, I think, for the really first time to create a definition for life, okay. So, so that definition has got to be such that it doesn't just mean it has to be carbon life, you know, you, so you, it's got to be all-encompassing. And I remember the time Mary Voytek and I talked about this, and Mary is the head of the astrobiology program at NASA.

Jim Green: So Mary told me, life has three attributes. Okay. It metabolizes, that means that it brings in a liquid, which, with, with material that then is a solvent that takes the nutrients out, and then the liquid is used to eliminate the waste from that material. That's the metabolism aspect of it, and then it, and then it reproduces, and then it evolves. And that's it. So that doesn't say anything about its composition, you know, whether it's silicon-based or carbon-based. And so, that's, that's the top definition I think of when we talk about life.

Lindsay Hays: You know, that's, that's all very true. Although I will also note, you know, I've had a lot of conversations with people, I mean, life without carbon base, non-carbon-based life non, you know, other elements that we're used to based life, is certainly possible. Although, you know, I've also had some conversations with our, with our astrobiologists, who point out that, you know, a lot of the abiotic chemistry in our solar system looks like the chemistry of the life that we know, right?

Lindsay Hays: And that has to do with the fact that, you know, given the way that elements form in our universe, the smaller elements, the ones that we think of the CHNOPS, ch, n, o, p, s, carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur, those are some of the most abundant elements in this universe. And therefore, you know, on one hand, it's certainly possible that life could form on other planets where the energetics are different.

Lindsay Hays: But it's also worth noting that when these elements are the most common elements, there's also a likelihood that life will pick up and use at least some of them in their, in their general chemistry, and that the sort of state of chemistry in the solar system, at least in our solar system, is such that a lot of the chemistry that we see does tend to be carbon-based, and those sorts of things. So not ruling it out. But certainly the likelihood indicates that carbon-based life form is possible. I mean, we're here.

Elizabeth Landau: Awesome. Well, let's talk about some places in the solar system that are interesting in terms of astrobiology. @WarlockAdventur asks: “Why if Titan has an atmosphere similar to Earth’s, are we not entertaining the idea of a base on Titan, as well as the Moon?”

Lindsay Hays: Oh, boy, would that be cold! You know, the comment, the idea that Titan's atmosphere is similar to Earth's. Well, it’s certainly similar in pressure. It’s about what, one and a half times Earth’s? And its predominance of nitrogen, right, just like the Earth, it's high nitrogen. But it's very, very different in terms of temperature, it's, you know, minus 290 or so Fahrenheit, which is quite. quite cold. And, and it's non-nitrogen content, you know, we think of our Earth as an oxidizing atmosphere. If you leave iron on the surface, it will rust and other types of things like that happen because of the high content of oxygen we have.

Lindsay Hays: Whereas on Titan, you know, lots and lots of hydrocarbons of various forms and types. Our human exploration, people could speak to this, probably more than I could, but keeping a base warm on Titan would be really, really difficult. Because you've got this thick, very cold atmosphere, and that you'd be you know, be kind of, kind of difficult to do that. Also, being as far out as it is in the solar system and the opaque atmosphere would make solar energy a really hard thing to come by, you know, and would require figuring out a lot about how to use sort of local chemistry for energy.

Jim Green: Yeah. In fact, Titan, although has similarities of Earth, as we pointed out, there are also some dissimilarities. Here on Earth, we have also enough greenhouse gases, like carbon dioxide. Water vapor is a greenhouse gas, so is methane, that actually our atmosphere is warmed well above, you know, maybe about 80 degrees Fahrenheit, if we didn't have those constituents. Titan is different in the sense that it doesn't have the greenhouse gases, in effect, because of the haze reflects sunlight. And so it's colder than what it would normally be if it's sat in orbit around Saturn.

Jim Green: But one thing about Titan that we absolutely have to mention relative to the life story, is that when we talk about the metabolism part as the first definition of life, that metabolism included, remember, having a liquid. And on Titan, there is a liquid, it's liquid methane. There are lakes of liquid methane, in fact, in the southern hemisphere, right now, it's raining methane.

Jim Green: And the drops are really big, you know, they’re several times the size of our own drops. So if you're walking around on Titan, you know, this stuff is, is coming down slow, and it's big drops, so, so very exciting, very exciting atmosphere. And so, the “weird life” scientists really want to go to Titan because if life exists on Titan, it's gonna be completely different than what we're familiar with here on Earth.

Elizabeth Landau: Definitely. And while we're not going to build a base anytime soon, we are sending the Dragonfly mission later in this decade to investigate Titan. So, very exciting stuff.

Elizabeth Landau: Let's move on to Mars. @masada_osamu asks: Anything so far on Mars, any creatures or bacteria or anything with life?

Jim Green: Well, nothing that we've found so far. But the, the more we, we explore Mars, and you have to remember, we're only exploring the surface. What we see in that surface is a lot of the history of Mars is coming through in the rock record, even that laying on the surface. So we see, we see ancient river valleys, we see ancient deltas, we see areas on Mars that had water in the past and a lot of it for long periods of time. So then the concept would be: life could have existed in those environments millions of years ago, because Mars has had rapid climate change, and has been pretty arid on the surface for several billion years since then. What we don't know as much about the environment below the surface.

Jim Green: We only get hints of that. For instance, Mars, on occasion will burp methane and we find that this methane is leaking through the surface. Okay. And that's pretty exciting, ‘cause methane is one of those gases that that we call a biomarker. You know, it could be generated by life, doesn't mean it is, because there's also abiotic, meaning non-biological methods, for which methane could be generated. And now we're seeing Mars also burp oxygen, molecular oxygen, O-2. And so that's another one of those gases that that that, you know, we are familiar with as an important element of life here on Earth. So, we just, one of these days got to understand much more about what's going on below the surface on Mars.

Lindsay Hays: Yeah, you know, my background in organic chemistry, I'm always interested in looking for biomarkers and biosignatures and whether or not those are things like gases, methane, oxygen, those types of things or, you know, lipids.

Lindsay Hays: If you're really, really lucky, the part of you that will last a billion years is your cholesterol. You know, what are the extraterrestrial life equivalents of those? You know, if there was Mars life, are there are there some type of lipid, some type of hydrocarbon that was preserved on the surface? You know, those are the kinds of things that we're looking at and looking for. We haven't found anything yet, as, as Jim said. But you know, there's some there's some really tantalizing hints about Mars's past habitability, which I think is what keeps us going back and keeps us exploring and wanting to learn more about our red neighbor.

Elizabeth Landau: Absolutely. Well, let's move on to Jupiter's moon Europa, @Zero_grav1ty, except the “i” is a “1,” asks, “What about the moon Europa? How hopeful are you guys finding life on Europa?”

Jim Green: Okay, for my, from my perspective, Europa is a real gem in the sense that it's got a wonderful liquid environment, we know that it has perhaps twice as, twice the amount of water underneath this icy crust in an ocean that surrounds a core, a rocky core on top of that, and, and when we look at the ice structures in this crust, we see hardly any craters, which means that the ocean must be communicating to the surface somehow. In fact, there's some indications that that these cracks that we see are because of one plate of ice is moving under another, like subduction that we see here on Earth with one layer moving underneath another. This means Europa is a living world, a body where the geology is changing on, on a regular basis. And in therefore, it has a lot of Earth analogies, you know, Earth is that living planet too, where the geology is moving and changing and active. And so that environment for Europa, we talked about it, is is indeed, you know, if it has all the right chemicals, and it has that water, does it have the time to create life? And Europa has been this beautiful moon of Jupiter with all these features for the last four-and-a-half billion years! Okay, so it is had gobs of time, if it has all the right stuff, to have developed life.

Lindsay Hays: Yeah, time is certainly one of those things in astrobiology and you know, origin of life and chemistry that is hugely important. We often think about going and exploring as snapshots, we go and look at what it's like right now, or we get a snapshot, a geological snapshot of a point in history. That's one great thing about Mars, right? We can see so far into the past on Mars in ways that we can't even on this planet. And you're right, Europa is great for that time. The fact that it looks like it's this active planet with this, you know, this, this cycling of the surface and all of that, is hugely important. I'm really excited to see with the, what the upcoming Europa mission tells us more about this, really, as you said the gem in the solar system, Jim.

Elizabeth Landau: Definitely. I'm also really excited about Europa Clipper. And another person, @ScottBSNRN, asks, “Will you ever look for life on Neptune's moon Triton?”

Jim Green: Right. Well, Triton is a fabulous object. Because it we now believe it is a captured moon. And, and if you captured this, where did this body come from? Well, we believe it came from the outer reaches of the solar system. And those objects that were formed, we call Kuiper Belt Objects. So we believe Triton is a Kuiper Belt object. It's more like Pluto than anything else. It doesn't look like an asteroid, doesn't look like a comet, it is really a mixture where a lot of these ices we see in the outer part of our solar system have, have been formulated into this beautiful round body Triton. Triton also is active.
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Gravity Assist: Your Questions About Life Out There and Down Here (2)

Jim Green: You know, when the Voyagers flew by Neptune, they see these geysers and it, these are things black soot, I believe they think it is, that’s upwelling in pockets on the moon. And in so any body like that, it could be active. So there's some sort of energy activity going on. And if it's anything like Pluto, we believe Pluto also has an under-ice-crust ocean. And that means it there's water there. We don't know if that ocean connects to more ice. But we just have to go there and investigate it further.

Lindsay Hays: Chemicals, water, energy, time, it's got a lot of really promising components. You know, I would say, “ever” is a long time, you know, so hopefully, yes, we will sometime go look at Triton to see what's there. You know, it's very far away. And as Jim said, there's other targets in our solar system that are closer, easier to explore, because of just, you know, the vast scales of space in our solar system. But yeah, there, there are lots of things in our solar system that we've only begin to peek at. And I think there's a lot to learn, you know, just within our neighborhood.

Elizabeth Landau: We also got some very interesting questions about the possibility of Earth life to go to other worlds. @VasudevR4385 asks, is it possible for us to survive beyond the Earth?

Lindsay Hays: yes, but you know, right now, humans need to bring our environment with us, you know, when it comes to, I was talking about extremophiles. And of course, that's extremophiles, from our own perspective, right, things that live at hotter temperatures, or colder temperatures, those kinds of things. But we as humans are very sensitive, we have a very narrow range of conditions that we like to live at. And you know, in places that we’re able to bring our environment with us, bring our oxygen bring, you know, create the temperature that we like, bring our food, figure out either or, or figure out how to get, you know, the types of things that we need to consume -- water, those kinds of things from the environment. We could, but certainly we don't know of any place right now where the environments are suitable for human life, right on the surface of anywhere else.

Jim Green: Well, you know, from a human exploration perspective, Mars is really the most attractive target for us to be able to go live and work for long periods of time, and change the environment. Humans, humans are, you know, terraforming the Earth. And when we show up at Mars as humans, we're going to be terraforming Mars. I mean, yeah, that's what we call changing the environment, to, to be able to sustain our life as humans.

Jim Green: And so, we want to go to Mars, we want to be able to use the environment, so that means we're going to be looking for water resources that are there. There's plenty of water on Mars, it's trapped in ice. But you know, we know how to extract it, and melt it, and use it. We would drink it. Of course, water is great for creating an atmosphere because you can break off the hydrogen and, and keep the oxygen and we need the oxygen, of course, that's another critical thing.

Jim Green: And then water, if you break out the hydrogen and the oxygen, you know, water is H2O, we need one hydrogen, two oxygen, if you break it apart, you use that as rocket fuel, you know, hydrogen and oxygen can be used as fuel. Those are really essential features. And so, we would begin the process of using that environment to allow us to be able to live and work on the surface and survive.

Elizabeth Landau: And a related question, from @NideeshSooriya: “Can a seed germinate on any of the other planets?”

Lindsay Hays: You know, I think it's kind of similar to the question about humans. Right now, we don't know of any other place in the solar system where the native environment as it is, you know, you could just throw a seed onto the surface and they could really grow a seed long enough to grow into a plant. Mars may be a place where hardy microbes or tardigrades might be able to survive in the surface. And that's part of the reason we have this whole group that works on planetary protection, to make sure that if we go to these places, you know, we are we and bring Earth life with us, you know, we we do it in a way that is careful and considered and you know, doesn't do it accidentally and those sorts of things. So, you know, at this point, you know, Terran, life, life from the Earth, is very well suited to life on this Earth. And all of those different environments throughout the solar system are pretty different for, for the advanced life, like seeds and trees and people and things.

Jim Green: Yeah, I love that question. You know, it's basically can plants grow with, you know, like on Mars? So, if you take a look at Mars, we know enough about Mars to really look at the essential plant nutrients. So, there are macronutrients in the soils like an oxygen, carbon, hydrogen, nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. There's also micronutrients. There's iron, magnesium, zinc, copper, molybdenum, boron and chlorine. So in reality, it's got all the right stuff. The problem is, the temperature extremes are huge. So, in one day, the temperature will vary by 170 degrees Fahrenheit.

Jim Green: Okay, well, there's no place on Earth that does that, you know, maybe over a year, we can see temperature extremes that are close to that on Earth, but, but not like that on a daily basis. So that makes it hard. And the other part of it is that the atmosphere is really thin. Now, that doesn't mean we're not looking at this idea. In fact, the University of Kyoto is a developing a chamber, that's Mars-like in terms of its atmosphere. And, and, and actually trying to grow trees in that environment. You know, they've decided to look at sycamores. So, they're overall taking that environment and lowering, lowering the temperature and see what it takes for the trees then to be able to, to live and, and grow in that environment. And so, this is a this is a research topic right now that is really important for us. Because if humans go to Mars, and therefore the temperature of Mars changes, we might be able to easily get into the temper, temperature regime where trees could grow, or other kinds of, of plant life.

Jim Green: Another idea is to take this fabulous substance called aerogel. It's a series of silicon molecules that are connected in a very loose string. And it's a great insulator, and if you put it down on the ground, you actually can keep the ground at a certain temperature without it going through these huge cycles too, and that might be an environment that you could grow grass or something else. So, these are all new ideas. These are things that are being tried. And I think over the next several years, we'll get some exciting results from that.

Elizabeth Landau: That's really cool. I hadn't heard about the aerogel idea before. I've seen a little chunk of it at JPL. And it says it's like more than 99% air.

Jim Green: Yeah, it's, it's what we call nanotechnology. And, and, and it is, it is, indeed, mostly air. But it is a substance that that is a wonderful insulator. We put it around our batteries to keep the batteries warm.

Elizabeth Landau: That's awesome. Well, @Walker314159265, clearly a reference to pi, asks: “Of you find extraterrestrial life, will you report it publicly?”

Jim Green: NASA is not one to keep secrets. You know, we work really hard to have the public trust, that as we find out things, we want people to know what we have found out, it's just really important for us to be able to communicate those results. The problem is, we need to communicate it in a way in particularly when they're tough topics to talk about that, that everyone can understand them. Sometimes these things that we find out may seem what we call esoteric, you know that, that's too hard to understand unless you're really in the field. And, but they make progress, they keep moving towards answering that question. And, and make positive indications of environments and, and where life might, where life might exist. Sometimes, though, we, we get it wrong.

Lindsay Hays: Yeah, you know, I would say that the signs that we would be likely to find about, about extraterrestrial life, would really require the context. This is what we found, this is why we think, you know, it has no other explanation. This is why we think it's quite obviously this. But it you know, it's likely to be, you know, a squiggle on a graph somewhere, or, you know, something that seems out of place in some other observation. And so you have to really understand the whole observation and, you know, we need to find a way to communicate it, which is why we have fantastic science communicators at NASA, you know, it's just as important at NASA that we have scientists and engineers as we do, people who help us explain what we're doing to everybody else. And so, you know, I know I personally would be extremely excited about finding extraterrestrial life, it would be one of, you know, the height, certainly the highlight of my career to be part of, you know, to be part of NASA at that point.

Jim Green: Yeah, me too.

Elizabeth Landau: Absolutely. And I hope we get to see that. And a related question from @JTwinkie1: “If NASA did end up discovering intelligent life outside of Earth or even out of our solar system, how do you think that would affect us here on Earth?”

Jim Green: That concept of finding life and announcing it, intelligent life beyond Earth, it is one we would call a worldview change. When Copernicus came up with the concept, based on things that had been done in the past, but really putting things together and moving forward with the idea that planets go around the sun, and not the sun and all the planets going around the Earth, he literally changed the view, that worldview, that we weren't the center of everything. So, it just was an incredible change that, that rippled through, you know, everything from religion to philosophy to science, and, and was an important new observation scientifically, that affected the world.

Jim Green: Finding life beyond Earth, in particular, extraterrestrial life that is intelligent, would be an enormous worldview change, you know. It will have the same effect.

Jim Green: Finding life beyond Earth that’s more microbial, which is what we expect in the solar system area, still will be an enormous worldview change, once again, taking the focus off the Earth of us being the only living creatures or beings, recognizing that there are other places that have life, changes that worldview. And the result of both of those will, will be astounding. You know, we will want to know, the next set of questions about what that life is like, what does it know? How can we communicate with it?

Jim Green: Whereas looking at this microbial life that's living and growing in an environment that is evolved completely different from ours, they have evolved mechanisms to be able to live in those harsh environments, things that we would like to know how they do that, and therefore how we might be able to do that, if we're able to crack that, if we're able to crack the concept of being able to live and grow using, using new changes in our in our DNA structure that maybe other life forms have really done, then we can go anywhere in the galaxy we want to, I mean, it just opens up everything!

Lindsay Hays: As you said, microbial life is the thing we're most likely to find within our solar system, intelligent life we may find outside of our solar system, which means the ability to communicate with that intelligent life may be low. You know, vast distances in the universe, make it hard to, to communicate, but, but you know, even seeing that it's there, even knowing that it's there, even sort of watching it from afar, I think can have a huge effect on, on a lot of wide ranging things.

Lindsay Hays: And, and the other thing I wanted to note is, you know, you were talking about microbial life, the potential for microbial life within our solar system. You know, I think whether or not that microbial life has a unique origin, right, a different origin from us, whether it's a unique origin or whether or not it's just like us, you know, we have the same origin of life as that life but broke off, you know, our distant cousins far back along with, you know, far back on our mother's side kind of thing. There's interesting things to learn either way, sort of, regardless of where of where we see that.

Elizabeth Landau:  Absolutely. Well, I think that's all the time we have for our audience questions. Thank you to everybody who submitted them on Twitter and Facebook.

Jim Green: Thanks so much, Liz, for all your effort on Gravity Assist. And behind the scenes helping her make it happen is Manny Cooper and Sonnet Apple, the fabulous audio and visual engineers that really, really make Gravity Assist so popular.

Jim Green: Well, this is the last episode of season four of Gravity Assist: The Search for Life Beyond Earth. And I want to entreat everybody to get excited about our upcoming season five, where we're going to look at the new and exciting discoveries NASA is making, and also look at the engineering miracles of how we pull missions off. We'll be interacting with scientists and engineers and if I'm lucky, maybe even pull in an astronaut or two. So, thanks again, so much, Lindsay, for all your help in answering these fabulous questions on Gravity Assist.

Lindsay Hays: Thanks again, Jim, for having me.

Jim Green: I’m Jim Green, and this is your Gravity Assist.

Credits: Lead producer: Elizabeth Landau
Audio engineer: Manny Cooper
Last Updated: Dec 23, 2020
Editor: Gary Daines

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Odp: [NASA Gravity Assist] Searching for Life
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