Autor Wątek: [NASA Gravity Assist] Searching for Life  (Przeczytany 5010 razy)

0 użytkowników i 1 Gość przegląda ten wątek.

Online Orionid

  • Weteran
  • *****
  • Wiadomości: 21592
  • Very easy - Harrison Schmitt
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

Source :
« Ostatnia zmiana: Czerwiec 11, 2022, 20:50 wysłana przez Orionid »

Online Orionid

  • Weteran
  • *****
  • Wiadomości: 21592
  • Very easy - Harrison Schmitt
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

« Ostatnia zmiana: Czerwiec 27, 2022, 07:05 wysłana przez Orionid »

Online Orionid

  • Weteran
  • *****
  • Wiadomości: 21592
  • Very easy - Harrison Schmitt
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

« Ostatnia zmiana: Lipiec 10, 2022, 08:15 wysłana przez Orionid »

Online Orionid

  • Weteran
  • *****
  • Wiadomości: 21592
  • Very easy - Harrison Schmitt
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

« Ostatnia zmiana: Lipiec 24, 2022, 13:19 wysłana przez Orionid »

Polskie Forum Astronautyczne

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

Online Orionid

  • Weteran
  • *****
  • Wiadomości: 21592
  • Very easy - Harrison Schmitt
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.
« Ostatnia zmiana: Wrzesień 05, 2022, 00:43 wysłana przez Orionid »

Online Orionid

  • Weteran
  • *****
  • Wiadomości: 21592
  • Very easy - Harrison Schmitt
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

« Ostatnia zmiana: Wrzesień 05, 2022, 00:44 wysłana przez Orionid »

Online Orionid

  • Weteran
  • *****
  • Wiadomości: 21592
  • Very easy - Harrison Schmitt
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.
« Ostatnia zmiana: Wrzesień 05, 2022, 00:55 wysłana przez Orionid »

Online Orionid

  • Weteran
  • *****
  • Wiadomości: 21592
  • Very easy - Harrison Schmitt
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

« Ostatnia zmiana: Wrzesień 05, 2022, 00:55 wysłana przez Orionid »

Online Orionid

  • Weteran
  • *****
  • Wiadomości: 21592
  • Very easy - Harrison Schmitt
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.

« Ostatnia zmiana: Wrzesień 17, 2022, 18:59 wysłana przez Orionid »

Online Orionid

  • Weteran
  • *****
  • Wiadomości: 21592
  • Very easy - Harrison Schmitt
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
« Ostatnia zmiana: Wrzesień 17, 2022, 19:00 wysłana przez Orionid »

Online Orionid

  • Weteran
  • *****
  • Wiadomości: 21592
  • Very easy - Harrison Schmitt
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.


Polskie Forum Astronautyczne

Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #40 dnia: Wrzesień 19, 2022, 01:03 »