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[NASA Gravity Assist] Searching for Life
« dnia: Grudzień 31, 2020, 22:06 »
1)  What is Astrobiology? With Mary Voytek April (2) 17, 2020

2)  Life on the Rocks, with Heather Graham (2) April 17, 2020

3)  Could We Find Billion-Year-Old Cholesterol? With Lindsay Hays (2) April 24, 2020

4) Persevering on Mars, with Mitch Schulte (2) May 1, 2020

5) What If We Found Life On Mars? (3) May 8, 2020

6) A Special Delivery of Life’s Building Blocks, with Jason Dworkin (2) May 15, 2020

7) Deep Oceans in Deep Space, with Morgan Cable (2) May 22, 2020

8 ) There’s Life Under Ice in Antarctica. How About Mars? (2) May 29, 2020

9) Is Our Solar System Weird? With Shawn Domagal-Goldman (2) Jun 5, 2020

10) Puffy Planets, Powerful Telescopes, with Knicole Colon (2) Jun 12, 2020

11) Where are the Goldilocks Stars? With Giada Arney (2) Jun 18, 2020

12) If They Call, Will We Listen? The Search for Technosignatures (2) Jun 26, 2020

13) She Protects Other Planets from Our Germs (2) Jul 17, 2020

14) Gardens at the Bottom of the Sea, with Laurie Barge (2) Aug 7, 2020

15)  Looking For Life in Ancient Lakes Aug 14, 2020

16) Our Sun, Our Life, with Vladimir Airapetian Aug 21, 2020;topicseen#msg177390

17) Is Artificial Intelligence the Future of Life? With Susan Schneider Sep 11, 2020

18) Why Icy Moons are So Juicy, with Athena Coustenis (2) Sep 25, 2020

19) Life in the Clouds, with David J. Smith (2) Oct 9, 2020

20) The History of the Future, with Steven Dick (2) Oct 30, 2020

21) Mars Takes a Breath, with Jen Eigenbrode Nov 13, 2020

22) Set Sail for Europa, with Bob Pappalardo Dec 4, 2020

23) The Bright Spot of the Asteroid Belt, with Britney Schmidt Dec 18, 2020

24)  Your Questions About Life Out There and Down Here (2) Dec 23, 2020

25)  Driving on Mars, with rover driver Sophia Mitchell (2) Feb 12, 2021


Introducing Gravity Assist Season 4: Searching for Life
April 15, 2020

Hi. I'm Jim Green, NASA's chief scientist and your host on NASA's podcast Gravity Assist.

You know, life on Earth is just about everywhere we look - from the depths of the ocean to even the Antarctic Tundra. Here on Earth, we find that against all odds, life survives and thrives. But what do we know about life beyond Earth? Are we alone?

Life on Earth just occupies a teeny portion of all of time. To me, life seems so inevitable and the universe is so broad and vast, that I can't imagine that we would be alone in all of that space. If we're the only game in town, it's an awful waste of space. We do not know if there is life beyond the Earth. You just have to search and search.

If you've ever wondered if there's life out there beyond our planet, you won't want to miss this season's Gravity Assist. In each episode, I'll be talking with scientists that specialize in the field of astrobiology. I'll be asking them, "How do we define life? What is life anyway? What do we know about how life got started here on Earth and how it developed in this beautiful complexity that we see today? What could life be like beyond Earth and how do we look for it?"

So there are a lot of wild and crazy places that we could search for life. The moons of Saturn and Jupiter are so compelling- Ganymede,Titan, Europa, Enceladus. Life might have existed on Mars in its past and might even exist there today. On exoplanets, because there's a lot.

On average, there's an exoplanet for every star in the sky and for every 10 stars there's one that might have liquid water oceans. Advancing the technologies for one helps us look for it in any place that we might be looking. Here at NASA, we have a fleet of spacecraft going out into the solar system and beyond and a lot of fabulous scientists that are piecing together this puzzle from the observations these missions make.

Join me on this journey to find out what's out there. Tune into gravity assist wherever you get your podcast.

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Odp: [NASA Gravity Assist] What is Astrobiology? With Mary Voytek
« Odpowiedź #1 dnia: Grudzień 31, 2020, 22:09 »
Gravity Assist: What is Astrobiology? With Mary Voytek (1)
April 17, 2020

Astrobiologists think about not only where in the solar system life could exist, but also which planets orbiting other stars could be habitable. Credits: ESO/M. Kornmesser

How did life originate and evolve here on Earth? What form could life take elsewhere – and where else could life survive beyond our planet? These are questions that scientists called astrobiologists tackle every day. By using space telescopes, doing laboratory experiments and studying extreme environments on Earth, astrobiologists hope to uncover new insights about what it means to be “life” and get more clues to the ultimate question: Are we alone in the universe? Mary Voytek, head of NASA’s astrobiology program, discusses in this episode.

Jim Green: Are we alone? What is NASA doing to answer that very important question?

Jim Green: Let's talk to one of the top astrobiologists in the country.

Mary Voytek: As we look for unusual life here on Earth and life elsewhere, we look for the unexpected.

Jim Green: Hi, I’m Jim Green, NASA’s Chief Scientist, 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. Mary Voytek, she's the lead scientist for astrobiology at NASA headquarters, and she manages the entire astrobiology program for NASA. Welcome Mary.

Mary Voytek: Thank you so much for asking me to do this, Jim.

Jim Green: Well, you've been doing this now for many years and the concept of astrobiology is really coming on strong. We talk about it all the time in science, but what really is astrobiology, what does it mean?

Mary Voytek: NASA defines astrobiology as understanding how life emerged and evolved here on Earth and where it could possibly exist elsewhere beyond Earth.

Jim Green: When I talk to the public and I say, "NASA is looking for life beyond Earth," the first thing they think of is, "Wow, we're looking for little green men." But are we really doing that?

Mary Voytek: So NASA’s strategy for looking for life has been informed by what we understand about Earth.

Mary Voytek: We think there's been life on this planet for maybe about 4 billion years, but that's been single cell microbial life. It's only been in the last few hundred thousand years or several hundred million years that we've had forms of life that would be more recognizable and would be able to be seen without the unaided eye.​

Mary Voytek: So most of the time on this planet, the only life that was here was microbial, single cell, very, in terms of form and structure, very simple. And so in terms of searching for life, just in terms of probabilities, it is more likely that we would find microbial life on other worlds.

Jim Green: So what are the kinds of things that we're doing in terms of looking for life here at Earth?

Mary Voytek: One of the most important things is an understanding how you go from a planet where there's no life to a planet that is teeming with life, is to look at those transitions and the condition of the planet, as well as how it affects the processes that are steps towards the emergence of life. So we're looking at things like, what are the physical and chemical conditions on early Earth that would be conducive to the production of molecules that end up becoming extremely important in life? And that includes molecules that can provide energy, as well as molecules that can be built on to provide structure and function, and basically the components that we see in life today.

Jim Green: Well, one aspect has really excited me, and that is looking for life in extremes. You look out into the solar system and it's hot or it's really cold, or the environments are so much different than ours. And so extreme environments are really important. And I know we do that here on Earth.

Mary Voytek: Absolutely. And in fact, in addition to understanding the steps towards life emerging and looking for the earliest signs of life here on Earth, we also want to understand those limits to life because as you said, the environments in our own solar system beyond Earth are not Earth-like, they're not the conditions that we all find pleasant. It's not the lovely climate of California out on those planets, and so we need to understand how life can actually persist in something that is beyond our comfort zone.

Mary Voytek: So our comfort range is, we know what room temperature is, we know what standard pressure is. And so organisms that seem to thrive and enjoy or love conditions that are more extreme than that or outside our comfort zone are called extremophiles. We can certainly live in cold temperatures, but not without putting on cold weather clothing and building shelters and generating heat for ourselves. But there are organisms that don't have coats, microorganisms that aren't hooked into the power grid and generating enough heat to live, and they're called psychrophiles because they love the cold.

Mary Voytek: And then there are organisms that really love the heat that can live at temperatures above the temperature at which water boils, so that's 100 degrees C. And so these allow us to start looking for environments that would be suitable to support life, even if it's extreme life.

Jim Green: Well, one of the common threads between all those extreme environments is water. No matter where we go, where we find water, even in small amounts, we have the opportunity to find life.

Mary Voytek: Yeah. We always struggle amongst scientists with definitions of life. And in fact, I usually like to say if you ask 100 scientists what is life or how to define life, you'll get 120 definitions. But one thing is really common to all definitions is it requires a solvent.

Jim Green: Mary, what do you mean by solvent?

Mary Voytek: Well, in chemical sense, it's a medium or a solution that allows reactions to take place, and so it facilitates transfers of electrons and modifications to chemistry. It also provides a liquid, also provides structure, and we are mostly water. And so that solvent or that liquid actually is responsible for our structure as well.

Jim Green: So we are what we eat and at the end of the process--

Mary Voytek: We are what we drink.

Mary Voytek: Here on Earth, the life that we know requires water. It's how it moves materials around, it allows the fluidity within cells so that cells can actually function. And so that has been one of the primary strategies at NASA for looking for places that could support life. So we go to extreme places here on Earth, like the dry valleys of Antarctica or the Atacama Desert where to the eye, it appears as if there is no water, but even a tiny bit of water, as you mentioned, life can take advantage of.

Mary Voytek: And so as we go beyond Earth, we're now then looking at environments on say, Mars that might have the same level of water that we see in these deserts here on Earth.

Jim Green: I remember the day you came into my office and we had this great discussion on how we would define life and how that should be viewed and a definition that would encompass all kinds of different life, things that we can't even imagine right now, life not like us. You told me it had three basic parts. What were they?

Mary Voytek: Well, of course it required a solvent to support a particular type of chemistry. It requires a mechanism to acquire energy, because everything requires energy to do anything. And then it had to be able to reproduce. I guess I'm going to extend it a little bit to four.

Jim Green: It sounds like it.

Mary Voytek: It needed to be able to evolve because our environment is not static. And as Earth has changed, life would not survive if it weren't able to adapt and evolve to actually be able to thrive in the new environment.

Jim Green: Well, I know you were really excited about that definition because it's all encompassing in the sense that it doesn't require that it be water or that it requires a carbon-based life form. But I was in the doldrums because indeed I can't run out and build an instrument that measures reproduction and evolution and then a have that operated on some planet. So that's really tough. But the water theme for us, for life like us, or the liquid aspect of it really helped us start a process of looking for life beyond Earth.

Jim Green: Well, why should we care about this particular topic?

Mary Voytek: I'm going to break down the question to something a little bit different, which is, are we alone? That's a really compelling question. It's philosophically important, it challenges our identity as human beings. And I think people in general are just fascinated by that question and they want to have that question answered.

Jim Green: Yeah. Me too. Right.

Mary Voytek: In addition, we now know more about how our own cells function. Some of the work that we do in astrobiology informs us about how cancerous cells may have actually played a role in a positive way towards evolution because it's kind of growth out of control, and maybe that's what you need to initially establish yourself on a planet.

Mary Voytek: And so it has all these ramifications for just understanding biology here on Earth. And I have to say, I'd be extremely excited for us to find something that was different than life on Earth because in science, you learn often the most when you find something to contrast.

Mary Voytek: And so any kind life is going to be exciting, but finding something that is very different would be really exciting as well.

Jim Green: Even here on Earth, we're looking for that. We're looking for something really different, something, maybe not carbon-based and maybe not requiring water, but still another liquid. Where are we in that search and have we found anything?

Mary Voytek: Well, I like to tell people that when we define life or we understand life here on Earth, we're looking at the winner. So the very beginning of life as it started to emerge, there were probably a lot of different solutions to what kind of solvent, what kind of molecules were important for structure. What kind of energy was it acquiring? What form it took? What elements it actually may have used. And at some point in time as life continued to reproduce and evolve, there was a form that was the most successful here on Earth given Earth's conditions. And we call that the last universal common ancestor. And at that point, most of biology, if not all of biology have those basic things.

Mary Voytek: But at the same time, there could be less successful organisms that exist still here on Earth, but the challenge in finding them on a planet that is overwhelmingly populated by all of those successful forms that come from that winner is a real challenge.

Mary Voytek: And so looking in extreme environments allows us to start looking for that.

Mary Voytek: We think about at some point in time on Earth, life became so predominant that it affected planetary processes, and you start seeing evidence of it. So you don't see growth and reproduction, but you see a change in the composition of our atmosphere. We went from an environment that was anaerobic to an atmosphere dominated by oxygen, and that was because of microorganisms. And so as we look for unusual life here on Earth and life elsewhere, we look for the unexpected. We learn more and more about how planets and planetary bodies function, we have an expectation of what their surfaces will look like and we understand what we expect from an atmosphere if it has one.

Mary Voytek: And then we look for something that just isn't what we expect. We look for a disturbance in the force, you might say, something that is just unusual that we can't explain any other way. And that's where we begin. And that's to some extent, in our enthusiasm for searching for life, some mistakes we've made in the past where we thought we understood what we were looking for and didn't spend quite enough time dispelling any other possible explanation.

Mary Voytek: But we're much smarter now and that's exactly how we take how we approach the search for life.

Jim Green: Well, we've done so much work in this area and there's so much detail, why haven't we found life yet?

Mary Voytek: That's a really good question, and I pause because it just swims around in so many ideas in my head for why that's possible. And one is, of course as we've already discussed, the challenge of, if life is not as we know it. And so again, how do you look for life as we don't know it? The other issue is, it is pretty clear that based on life as we know it, that Earth is the premier planet. It is perfectly situated in relationship to its Sun, it's got a magnetic field that protects it. It's gotten many, many environments across the entire surface and into the subsurface that can support life as we know it. It is just an incubator, a perfect incubator.

Mary Voytek: And so as you start looking into environments, even on Earth where say nutrients are limiting or there're extreme physical conditions, you notice that the number of cells decreases. And so as we look beyond Earth and we look at places like Mars or we look even beyond to the moons of Saturn and Jupiter, these environments are much more extreme than Earth, much less hospitable. And so just because of what we know about Earth, the inhabitability of an environment can control how much life you see, we would predict the amount of life on any of those other bodies is going to be very dilute, there isn't going to be much of it.

Mary Voytek: Finding something very small, it's like looking for a needle in a haystack. Relative to the bulk of materials on these bodies, life is going to be a small component. It's going to make less of an impact on the environment. And so detection limits are essential. And really, really refining where we go to look for life is going to be essential because in biology, one of the things we do is grab a sample and grind it up and then analyze it. We can't take a giant sample of Mars and just grind it up and hope we find a cell in it. We have to be very smart about where we think it might be and figure out how we can most effectively look at that very, very small signal.

Jim Green: Well, there's another dimension to this that I've come to realize and appreciate, and that dimension is time. When we go out to planets and we're looking at their current environments, because the solar system is 4.6 billion years old, things have changed over time. And so that dimension is really important. So how do we think about how life might exist in the past on other objects?

Mary Voytek: Particularly now that we have exoplanets to look towards, the possibility has really exploded in terms of what environments might support life. And one of the strategies for people who are interested in exoplanets has been to look at the environments on Earth over time. At the very beginning, the solar system was kind of a violent place to be situated, with bombardments from objects out there like asteroids and comets. And that changed the Earth both on its surface and its atmosphere.

Mary Voytek: There's also just the differentiation or the evolution of the planet itself. And it turns out that's a huge, huge deal for organisms dealing with oxygen. On one hand, of course we know we can't live without it, but when that change first happened, it was a toxin. Oxygen is a way that we actually get rid of organics. Hydrogen peroxide is an oxygenated compound that we use to sterilize things. And so organisms had to figure out how to deal with that first. And then as a result, once they were able to adapt to oxygen, it turns out that oxygen is a fantastic molecule to pair with other molecules to actually generate energy.
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Odp: [NASA Gravity Assist] What is Astrobiology? With Mary Voytek
« Odpowiedź #2 dnia: Grudzień 31, 2020, 22:09 »
Gravity Assist: What is Astrobiology? With Mary Voytek (2)

Mary Voytek, head of NASA’s astrobiology program, with NASA Chief Scientist Jim Green. Credits: NASA

Jim Green: So this really exciting. What do you think are some of the best payoffs that we've gotten by making this kind of research viable for NASA?

Mary Voytek: Well, I think that there are a number of areas that we've had a major impact, as NASA has in general. A lot of our scientists that we fund to work on origin of life questions are also doing medical research and they're quite related. I also mentioned synthetic biology. And synthetic biology is where basically we look at what organisms have managed to do on their own and modify them to our own needs to make them do things that we need to have them do.

Mary Voytek: So for example, bio-remediation. The best way to clean up oil spills or contaminants in groundwater in particular is to apply organisms that can use those contaminants either as an energy source or food for making materials in the cell. And in the process, they convert it from something toxic to something that is benign. In addition, we have an instrument that we developed from a researcher out at Ames, Dave Blake that's called CheMin. It looks at the mineralogy of systems and their oxidative states.

Mary Voytek: And one of the things that's currently being used for is... Well, there are two interesting ones. One is it's used in the detection of counterfeit drugs, which is a gigantic problem for the World Health Organization. And in addition, they've used their instrument to detect fraudulent artwork. And so you can use this to understand minerals that go into paints that weren't present, say during the Renaissance. It's important in terms of paint restoration, but also in detecting actually, you may all know that that canvas is for painting were reused multiple times, and so you might find a Rembrandt that has multiple layers of different paintings.

Mary Voytek: And some of this, the CheMin was the tool that could be used for the materials that were generated in that paint, and any kind of change may lead to other kinds of detection for looking for things like that as well.

Jim Green: And that instrument is on Curiosity on Mars.

Mary Voytek: Yeah. Go Curiosity.

Jim Green: Right. And it’s doing fantastic. Well, where are you most excited to look for life and why?

Mary Voytek: I have two answers to that. One is in our own solar system. As the head of the Astrobiology Program, I'm excited about all places, but I'm very, very much intrigued by the news-

Jim Green: You love all of children equally, as I like to say.

Mary Voytek: You know. Absolutely. I love all of my habitable environments equally. I'm very excited to learn more about the moons of Saturn and Jupiter. I just think that between the possibilities with Europa and Enceladus and the fact that we are sending out missions to study them better and just how bizarre Titan is, which is a moon of Saturn, with the only other body in our solar system that has liquid on the surface, but that liquid is methane and ethane and it's not water. And so what kind of biology can you expect from something like that? If we find life there, it's going to be, I just can't even imagine, it's going to be so different than life here on Earth.

Mary Voytek: One of the most amazing discoveries we made in the end of the '70s, so right around the time that Viking had landed on Mars looking for life, was discovering weird life here on Earth. And that was life that we found kilometers away from the surface at the ocean floor, at hydrothermal vents systems. And this was the first time we discovered that life could be supported by energy other than the Sun. Up until that point, we thought every single thing on the planet ultimately derived from energy provided by the Sun, but we find this oasis of really odd organisms supported entirely by chemistry, chemical reactions that can generate the energy necessary for organisms to thrive.

Mary Voytek: And so on these ice-covered oceans, we expect that we could possibly have the same system. We have evidence, at least in one of them, that we definitely have hydrothermal activity, that is, water interacting with rock of the planet or the planetary body at higher or elevated temperatures. And that causes a certain kind of chemistry than on our own planet has led to supplying molecules necessary for the energy that can support life. And so we think that that could be happening on either Saturn's moon in Enceladus, or Jupiter's moon, Europa.

Mary Voytek: And then of course, the possibilities that have recently in the last five to 10 years with the number of exoplanets we've detected. Oh my goodness, it's almost any planet you could imagine. I feel like it's almost, we're at the point of having a video game or a game where you just dial different things and you create a planet and it could support life, "Oh, I want it a little warmer. I want it a little colder. I want more water, less water. I want to have this mineral present or not."

Mary Voytek: I just think that the possibilities are just astronomical and I mean that intentionally.

Jim Green: That's a really neat idea because as you turn around and turn those dials and create that planet, that planet exists out there somewhere.

Mary Voytek: It does, I think.

Jim Green: That's right. I just never thought of it that way, but we've got like four thousand planets that we've identified and that number is just going to increase over time.

Mary Voytek: Well, those are ones we've identified. If you go by what we predict, if you look up in the sky now, we're not looking at stars anymore. We're looking at solar systems.

Jim Green: So Mary, with all this said, what do you think, are we alone?

Mary Voytek: I think, absolutely not. I believe that, I'm not sure when we're going to find life, but I am certain that there is life beyond earth.

Jim Green: Yeah. I am too.

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

Mary Voytek: I think I can identify a person that helped me, pushed me forward, and that was my mom. And although she was not a scientist, she was extremely bright and very interested in the natural world and very interested in science fiction. So I have memories as a child going to the beach in the summer and being encouraged to set up aquaria and to study the organisms in the ocean. And I have memories of every Thursday night, I think it was, I might be wrong about the day, assembling with my four other siblings to watch Star Trek on TV with the entire family.

Mary Voytek: And so I think that the very force of personality that my mother had, the hope, the imagination is what really sent me into science and really nurtured and stimulated my curiosity that led me to where I am today.

Jim Green: Mary, let's say one of our scientists calls you up and says, "I found it. I think I have found life on this planet," what do you do next?

Mary Voytek: So extraordinary claims require extraordinary evidence, and that comes from our most famous and inspirational scientists, Carl Sagan. And in fact, this happened to us in 1996 -- a scientific group out of Houston came to us with evidence, four lines of evidence that they thought that they had actually found evidence of life in a Martian meteorite. And very good scientists, excellent, reputable scientist, respectable scientists said they had the evidence and it came out in a peer-reviewed publication, and after that the entire scientific communities started examining it and challenging it.

Mary Voytek: And one of the things that we discovered is you can do great work, but you can still be wrong. And in fact, I like to say that astrobiology is 60 years of doing research, proving ourselves wrong as we move towards understanding what life is and how we can detect it. And so the first thing that I would do is find out what that evidence is. We'd make sure that it was put to the test by other scientists before we would do anything with that. So the peer-review process and publications is the start. We've learned too that some people can be so enthusiastic that we might even need greater challenges, but we would basically take it to the global scientific community and put it to the test.

Jim Green: Okay. And then if it turned out to be true?

Mary Voytek: Once I stop screaming with excitement, we would go back onto... I think that a lot of us have talked about what would be the next step.

Jim Green: Well, we certainly wouldn't keep it a secret.

Mary Voytek: No, absolutely not.

Mary Voytek: One of the things Astrobiology Program does is, we have talked to individuals about what it would mean to you to find life, does it challenge your religious beliefs? Does it challenge how you think about yourself, or whatever? Are you frightened by the concept?

Mary Voytek: And so, it would be really important to think about how to deliver that messaging, and I think that there is tremendous excitement that we could convey. I think we can convey hope and leading to a better understanding about ourselves. I think we'd also need to know like, "So, where did you find it and how can we find out more?"

Mary Voytek: Initially, after I stop screaming myself, it's like, "I want to get some more of that. I want to go to wherever that came from. I want to... " More work, more science, more characterization, more to understand.

Jim Green: It's the next set of questions you now want to ask.

Mary Voytek: Absolutely. Absolutely. That's what I'd do after I stop screaming. What about you Jim?

Jim Green: Oh, what would I do?

Mary Voytek: Yeah, if it's you.

Jim Green: I'd be screaming too.

Jim Green: Well that’s fantastic, and Mary, thanks so much for joining me today and talking about, of course, one of my favorite subjects too, astrobiology.

Mary Voytek: Thank you so much, Jim. This has been a blast.

Jim Green: You're very welcome. Thank you. 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: Emanuel Cooper
Last Updated: April 17, 2020
Editor: Gary Daines


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Odp: [NASA Gravity Assist] Life on the Rocks, with Heather Graham
« Odpowiedź #3 dnia: Styczeń 02, 2021, 00:59 »
Gravity Assist: Life on the Rocks, with Heather Graham (1)
April 17, 2020

Illustration of DNA strand, adapted from a Creative Commons image. Credits: Nogas1974 CC BY-SA 4.0

To study the history of life on Earth and look for it beyond our planet, scientists in the field of astrobiology look for signs called “biosignatures.” NASA Goddard researcher Heather Graham discusses some of the oldest evidence of life on Earth and what scientists are searching for when they look for biosignatures in ancient rocks. By looking at what life on Earth was like millions and even billions of years ago, astrobiologists can make predictions about what signs of life could be hiding in the rest of the solar system and beyond.

Jim Green: Life starts with chemicals. The chemistry of life is so important to understand.

Jim Green: So how do we know it's life, if it's life like we don't know it?

Heather Graham: There's a lot of ways that life could be different, but not related to life on Earth.

Jim Green: Hi, I’m Jim Green, NASA’s Chief Scientist, 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. Heather Graham. She is an organic geochemist at NASA Goddard Space Flight Center. Heather has a profound curiosity about the natural world, the history of life, the vast connections between biotic and abiotic systems, and what evolution can tell us about our future. Welcome to Gravity Assist, Heather.

Heather Graham: Thank you so much Jim.

Jim Green: Well first off, what the heck is a biosignature?

Heather Graham: So a biosignature is just a physical indication of past or present life. That can be something as simple as a bone that a paleontologist might find, a footprint, an imprint, on the environment. Or a chemical compound that's highly specialized for life.

Jim Green: So how do we know if a biosignature actually came from life? Can we be fooled?

Heather Graham: Oh yeah. That's a probably the most important part of biosignature science is making sure that you are looking at something that came from life, and not being fooled by something that can be made by a physics, by nature, by geology, by abiotic chemistry.

Heather Graham: There are a lot of things that we associate with life that are actually very common, being made out in stars. A lot of the chemicals that we associate with life are really an inheritance from the universe. We also have to be very careful to keep our work clean, so that we're not contaminating it with contemporary life when we're trying to understand past life.

Jim Green: Biosignatures require certain chemicals. Is there some underlying composition that you look for in a biosignature?

Astrobiologist Heather Graham holds a 600-million-year-old fossil. Her tattoos represent high-speed particle collisions. Credits: NASA

Heather Graham: Yeah. So it really depends on where you're looking, and what you're looking for. For example, a really common biosignature that we hear about a lot is DNA. And that's something that's universal. Every organism has it, so it's easy to say, "Oh yes, this is definitely from life. This is a molecule that's too hard to make without biology being involved."

Heather Graham: But DNA is very ephemeral. It goes away quickly in nature. It's broken down by other organisms, and reused very quickly. But there are other chemical compounds that last for a really long time, especially in the geologic record, in the rock record. And those are the things that we can look at as being a more robust signal of life on long time scales.

Jim Green: So getting down to the basics, the really important chemicals, carbon seems to be one. If we look at what we have inside us, it's carbon, hydrogen, oxygen, nitrogen, phosphorous and sulfur. So are those the fundamental compounds we ought to be looking for?

Heather Graham: So those are the fundamental compounds that we associate with life on Earth.

Jim Green: Life as we know it.

Heather Graham: Life as we know it, correct.. The kind of work that we're doing here at Goddard, and the research group that I'm involved in, doesn't always presuppose that though. We're interested in biosignatures that might not just be about those particular elements. Or more importantly, other elements that might be biosignatures as well.

Jim Green: How do we figure that out? How do we figure out what are the more important elements?

Heather Graham: That's really from just observing nature in its completeness, in its totality. Not just by looking at life, but by looking at nature in context of its environment to understand what it's taking from a chemical system to build itself, what it's eating, what it's respiring, breathing out, what the by-products of its metabolism are. And then you can track down what are the important things that are moving through a system. And that movement is the essential signature of biology. If something's static, it's unlikely to be involved.

Jim Green: So the concept of you are what you eat is true?

Heather Graham: Absolutely.

Jim Green: So we actually pull things out of what we eat, and plug them into our body.

Heather Graham: Yep. So we take carbon from all these other sources. And interestingly though, carbon dioxide is our major by-product. We all breathe it out. But there are lots of organisms that don't do that with carbon. They use metals and other strange things. And we find all these metals in certain places in the geologic record. And even though we don't see that organism, we know that this is something it left behind.

Jim Green: So where do we find biosignatures?

Heather Graham: Usually, when we're thinking about biosignatures, we think about the rock record, we think about geology. And really, that's just because that's a really stable repository. To find a biosignature, you have to find a place where a molecule or a part of an organism is protected from degradation. So, we think of places where there's not a lot of oxygen, since most other critters that would want to eat that organism are going to be using oxygen.

Heather Graham: We look for rock, areas of sediments, that have been protected from oxygen in the atmosphere. And the rock record’s interesting, not just for people who are interested in land, but a lot of the rocks are actually old ocean. It's all the ocean sediments. So we can peer into past ancient oceans just by going to certain rocks on Earth.

Jim Green: Well you brought a really nice friend with you. It's a fossil. What is that?

Heather Graham: So this is a really special fossil. This is from the Ediacaran period. That's about 600 million years ago. And this was a time in Earth's history when biology got really experimental. And during this time period, we find all sorts of crazy organisms that only exist during that time period. Biology was trying just all sorts of body plans, and ways of living on the surface, or just below the surface, in really neat ways.

Heather Graham: And these kinds of fossils are only found in a couple of really special places on earth, Nevada and Namibia.

Heather Graham: So this fossil, as you can see, there’s these long tubes, and there're ridges along them, and they crisscross. And what's sad is this piece that I brought to you is only about the size of my palm

Heather Graham: And what you'll see is there's all these tubes weaving back and forth over each other. But not in a random way, in a very special pattern. And that's part of what makes us realize this is biology, and not just rocks that happened to fall in a really interesting pattern. This has intentionality and there was energy put into a system to leave this texture.

Heather Graham: This strange structure, there's a couple of different ways you might be able to try and explain it. Maybe it's a texture on a rock from a biofilm. Maybe it was a tube worm that was living below the surface. But what's really important about this is we don't have any physical way, without biology, of making a pattern like this. And that's what makes it a biosignature. You can do all sorts of experiments with different sizes of rocks, and different chemistries of solution was of water, but you'll never make something that looks like this.

Jim Green: Yeah, it looks creepy.

Jim Green: So I heard there's like 4,700 minerals on earth, and about 300 of them could only be made by life.

Heather Graham: Yes, absolutely. So I know I am a chemist, so I'm biased towards organic chemistry and I'm giving a lot of examples of organic chemistry that are biosignatures. But really, there are lots of minerals that are biosignatures as well. There's a lot of great work that's been done to show what minerals you absolutely need.

Heather Graham: For example, oxygenic life, the kind of life that made oxygen, all the algae in the ocean that made oxygen. There are minerals that would only be associated with those really high levels of oxygen, that those organisms created. So if those organisms never developed on another planet, we would be unlikely to see many of those minerals on those planets.

Jim Green: How long do these biosignatures last? Once they're in the rock, is that it?

Heather Graham: No. Actually, one of the real arts of biosignature science is knowing what things look like when they break apart. Unfortunately, a lot of the chemical compounds that we use as biosignatures don't last in that state that your body or another organism's body made them. They break down in very particular patterns. And so, we find those degradation products in the rock record.

Jim Green: So once life is created, and it decomposes, you end up with the parts. And so figuring out, do you have all the right parts, or even some of those parts, may or may not be preserved over time.

Heather Graham: Yeah.

Jim Green: That ends up being a real problem. So what kind of tools do you use to really identify these parts and pieces in biosignatures?

Heather Graham: Yeah, this is a real puzzle. So this is the kind of area we would really think of as interdisciplinary science. When I'm looking at a particular sediment for example, I'm looking for particular compounds, I'm taking a lot of information that I've learned from other geologists that have described that rock. So I will know something about, was this rock once a lake? Was it the ocean? Was it buried and heated? So I'll have a lot of information from geology to help me direct those tests about what sort of molecules I'm likely to find.

Heather Graham: And the other important thing about these molecules that we think of is biosignatures that are being preserved in the rock record, is there an example of a community. They're usually not just one particular organism, you're looking at a habitat, you're looking at a whole bunch of different metabolisms. So you're really not just saying, was there life, was there not life, but you're getting a sense of what the ecosystem was.

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Odp: [NASA Gravity Assist] Life on the Rocks, with Heather Graham
« Odpowiedź #3 dnia: Styczeń 02, 2021, 00:59 »

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Odp: [NASA Gravity Assist] Life on the Rocks, with Heather Graham
« Odpowiedź #4 dnia: Styczeń 02, 2021, 01:00 »
Gravity Assist: Life on the Rocks, with Heather Graham (2)

Astrobiologist Heather Graham with NASA’s Chief Scientist Jim Green. Credits: NASA

Jim Green: Another thought I had, relative to biosignatures in rocks, is a structure. A structure that, how geologically could that have possibly have happened? Like a stromatolite. So when we study biosignatures, how does that help us think about the origin of life here on Earth?

Heather Graham: Yeah, that's really interesting. So a lot of these chemical compounds that we're thinking of don't really last on really, really long timescales. And when we’re thinking about something like the origin of life, a lot of what we're looking at is physical structures in the rock. Really old evidence of cells, really old evidence of biofilms, which are just big accumulations of microbiota together.

Heather Graham: So we're looking for those physical things in the oldest rocks. And that's where textures and rocks become really important. And also something that you want to be able to make sure that those textures aren't something that nature makes all by itself without biology being involved.

Jim Green: So the key to finding life way in the past. Is to start looking at the old rocks. Well, how old are the rocks here on Earth?

Heather Graham: So that's a bummer about Earth, is that most of our rocks have been recycled-

Jim Green: Oh no.

Heather Graham: And heated, and cooked, and moved, and washed with lots and lots of water. So it's really hard, actually. We think of Earth as being this life saturated planet. And so, it must be so easy to find life. But when we look in the deep past, it's actually hard, because much of that evidence of life has been destroyed by tectonics, by the planet moving around. We're a very dynamic planet.

Heather Graham: So we have to look for what we call quiescent parts of the planet. These are old cratons, the oldest rocks on earth that are up in Canada and Greenland, and places like that, where we find really interesting textures in the rock. And we like to think that those are probably the earliest forms of life. And then that gives us a sense of, what was the chemistry in that early ocean? What was the planet like? And that gives us a sense of the kind of chemistry that was possible.

Jim Green: So just recently, a team from the Mars 2020 Rover group, this is the group that is going to be looking at the rock record from Mars, trekked out into Australia. And I was wondering, why are they going to Australia for a meeting? Well, they're out in the middle of nowhere in Western Australia, and they went to the Australian chert.

Heather Graham: Cool.

Jim Green: Yeah, so-

Heather Graham: Jealous.

Jim Green: And it's a trek, let me tell you. But that's old rock.

Heather Graham: Yep.

Jim Green: Yeah. So what do we know about that Australian chert?

Heather Graham: Yeah, so those are some of the really old rocks where we find the oldest evidence of life. What's really special about some of those rocks in Australia is, you can find really old evidence of microbial biofilms, these mats, microbes that form these layers and they grow up, up, up upon each other in these layers. And that's a stromatolite, like you mentioned.

Heather Graham: And what's really interesting is, you can see living examples of those right off the coast in Australia. So it's such a special place, to be able to have that window into the deep past, and then see something that's contemporary, that still has the same lifestyle. And is conducting its biology in pretty much the same way for billions of years. It's a really special place.

Jim Green: Yeah. In fact, when they measure the date at these rocks, they find they're 3.6 or 3.8 billion years old.

Heather Graham: Yeah.

Jim Green: But yet, we know the earth is 4.6 billion years old. So there's nearly a billion years record that we've lost.

Heather Graham: Yeah. And the really sad thing is... Because that's our earliest evidence, we know that somewhere in that time period between formation and that 3.8-ish number that you give, that's the exciting part. That's when life evolved, and we don't have really anything to go on there. And that's where experiments in the laboratory can become really illustrative for giving us a window, and giving us something to imagine for that past.

Jim Green: Well, this is where Mars comes in a really neat way, because it doesn't appear to have had some plate tectonics, but not like Earth. And it appears to have been a blue planet like earth early on, but then went very arid. And so maybe the record of life starting, perhaps, on Mars before 3.8 billion years, is attainable in the rock record there that we can bring back.

Heather Graham: Yeah, that's what's really exciting, is: It hasn't had that heating and cooling and moving and crushing that Earth has. And that really can tell us a little bit about why we choose to go the places we go on Mars. That we're looking in these sediments, that we know were buried once upon a time. And if there is something organic there, we're looking in the best places to find something that wasn't exposed to the surface where it could be altered.

Jim Green: So, what's an agnostic signature of life?

Heather Graham: So that is a biosignature where we're not presupposing a connection to Earth biology.

Jim Green: A carbon-based life, like we know it?

Heather Graham: That could be one or it could be carbon-based life that has different informational polymers besides DNA, something like that. There's a lot of ways that life could be different, but not related to life on Earth. And these kinds of studies get really interesting as we're starting to move farther and farther out into the solar system, where there's less and less likelihood that we're related to creatures out there, if they exist.

Jim Green: So do you think we're alone in the galaxy? Do you think life is confined to just Earth?

Heather Graham: I tend to think not. And I base a lot of that on probability. This is another area of expertise that there's lots of people working in biosignatures, and that's the kind of people who think about statistics in likelihood and probability. And it's rare you see something as a one-off in nature. If something works, it usually happens again and again. And so I just can't imagine that we're the only instance of that kind of unique chemistry happening.

Jim Green: So if you think we can find life beyond Earth, where do you think we'll find it?

Heather Graham: Where? Oh, that's interesting. Boy--

Jim Green: In other words, will we find it first in the solar system? Or will we find it in exoplanets first? Planets around other stars.

Heather Graham: I would tend to say that we're probably going to find something unambiguous in the solar system first. And I would say that's really just because for this kind of evidence, you really do need a bunch of different ways of viewing the problem to be convincing. We can't just find one molecule and say, "Oh look, that's life," because you need to be able to see it in context.

Jim Green: So I noticed you have some really unique tattoos. Just long streaks that are emanating from particular points. What are they?

Heather Graham: Yeah, these are high-speed photographs taken from inside a bubble chamber where they were crashing particles into each other in a very particular way to see what kind of other particles are made. And this is imitating processes that happen in certain kinds of stars that make light that has mass. So light from our star is massless, but that's not always true. And I got these tattoos because light was something that was a big part of my PhD work. I actually looked at biosignatures to tell us about light harvesting molecules and photosynthetic organisms.

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

Heather Graham: Oh, I think if I think of any person, place or thing, the place that immediately pops to mind is the community college that I went to, Santa Monica College in LA. It's a really great place, and I think what made it so great is I got to take so many different classes. There's all these different people who work on biosignatures, and you need to have a really firm grasp of physics and geology and chemistry and math.

Heather Graham: And that's something I was able to do at this community college because I had the grace to just explore every topic I wanted to. I took every, every science class they had. I took field ornithology. And I had a wonderful organic chemistry professor there, Jamie Anderson, who just pushed me into every research opportunity he could find. And I think if I hadn't been given that allowance to have all that curiosity, I wouldn't have the background I really benefit from in biosignature science.

Jim Green: You had mentioned to me earlier that you were the first one in your family to go to college. How hard was that?

Heather Graham: Yeah, I am the first person. And I think it's hard because I don't think it was something I ever expected I would do. I didn't actually go to college until I was an adult. And I'm not saying that people that are 18 coming out of high school aren't adults, but I was a real adult. I was 30 when I went to college. And I think it really changes the intention, and how you approach your studies. I wasn't doing it because my mom and dad told me to. I was doing it really because these were things I wanted to know.

Heather Graham: This was interest that I had. And I took it really seriously because I didn't have any examples in my family of how to do this. And I was really helped by a lot of wonderful professors. And when I think about the way I approached it, and that curiosity that I brought to studies, there's a saying by an old author, Charles Baudelaire, "That I sought the why of it, and turned pleasure into knowledge."

Jim Green: Well, thanks so very much. This has just been a delight, and you're a wonderful biosignature.

Heather Graham: Oh, why, 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.”

Credits: Lead Producer: Elizabeth Landau
Audio Engineer: Emanuel Cooper


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Odp: [NASA Gravity Assist] Could We Find Billion-Year-Old Cholesterol?
« Odpowiedź #5 dnia: Styczeń 13, 2021, 02:07 »
Gravity Assist: Could We Find Billion-Year-Old Cholesterol? With Lindsay Hays (1)
April 24, 2020

When we search for life beyond Earth, we have to figure out what we could measure that would tell us that life was, or is, there. And the starting place for that search must be Earth itself, the only place where we know for sure that life has lived. Every rock tells a story, and so does each fatty acid called a lipid. Your cholesterol, which is part lipid and part protein, could last for billions of years, and contains the information that you are a mammal. Could we find lipids beyond Earth? NASA astrobiologist Lindsay Hays explores this and other topics in her research. She also discusses places interesting for the search for life in our solar system and beyond.

Jim Green: When we go look for life in the universe, what are we looking for? Did you know your cholesterol could last for billions of years?

Lindsay Hays: It's a really great way to understand, sort of, the history of the microbial life on this planet, since they don't always leave fossils in the way that dinosaurs do.

Jim Green: Hi. I'm Jim Green, Chief Scientist at NASA, and this is Gravity Assist. This season is all about the search for life beyond Earth. I'm here with Dr. Lindsay Hays, and she's the deputy program scientist for the astrobiology program at NASA. Welcome, Lindsay.

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

Jim Green: One of the things that the astrobiologists do is they really look at the history of life here on Earth. Now, why is that important for us to do that instead of just go looking for life beyond our Earth?

Lindsay Hays is an astrobiologist at NASA who is interested in the idea of looking for fatty acids called lipids beyond Earth. Credits: Lindsay Hays

Lindsay Hays: It's our one example of life that we know of. And so it's really important that we understand not just what life looks like on this planet today, because it's our only example, but also what life looked like in the past on this planet, how we got to this point is a really important way… it's a really important thing to understand, how mass extinction events or mass radiation events, where you go from a couple of different families into many, many groups of families, how those kinds of things happen on this planet or on any planet.

Lindsay Hays: And the other really interesting thing about looking at the history of life on Earth is that past Earths are almost entirely different environments. There was a time on this planet where there was almost no oxygen on the surface of the planet. And it was still teeming with life. So what does a planet that has no oxygen, what does that look like? What does the life on that planet look like? And by studying the past Earth and the history of life on Earth, you can get an idea for some other, sort of, states of habitability that we don't see today but that we might be able to see as we're looking to bodies within our solar system, or extra solar planets. Past Earth can be the clue, it can teach us about not just this planet but a lot of other places as well.

Jim Green: Well, let's see, about 3.8 billion years ago we believe life really started here on Earth, and it was really simple for long periods of time. And then it got to be more complex, meaning cells were getting together and forming much more complex structures. What happened that made that change? Do we know?

Lindsay Hays: Well, I mean, one of the things, one of the interesting things about studying the history of life is we can only, sort of, see the winners. We see today how things worked. And so when you look back, when you look back at Earth, and you look back at Earth's history, you could understand, sort of, how we got to where we are. But we don't necessarily know all of the different things that we're acting on that life, all of the different factors.

Lindsay Hays: But one of the things that we always see as a way to, sort of, drive new innovations and drive new evolution is competition, things for resources, place where you can get energy, understandably the places where energy is easy to get and abundant, those are places that life probably started and probably started inhabiting very quickly. And as those areas, those niches filled out, you would expect evolution to become more complex in a way to get our energy that's harder to get at.

Lindsay Hays: So we think about the abundance of life on this planet today that uses sunlight for energy, but that's actually a relatively difficult thing to evolve. It's much more easy to get chemical energy and then the ability, evolving the ability to create what we call photosystems, complexes of proteins and metals and things that allow you to take energy from sunlight, that's just one stage of complexity as you evolve.

Lindsay Hays: The next thing is multi-cellularity. And as you were sort of alluding to, more complex structures, those sort of thing. It's really hard to try and understand exactly what drove those evolutions, but actually there's a recent study that came out that showed that predation, single cells that eat other cells, can actually drive those prey cells to create more complex structures, to become multi-cellularity as a way to sort of protect themselves from predation. Think animals living in herds makes it harder for any one animal to get attacked.

Jim Green: Early on when plants came on this Earth, what kind of plants do you think started here first?

Lindsay Hays: Well, so we're definitely talking, early on, we're talking single-celled organisms. So, cyanobacteria. These used to be called blue-green algae. But as we have understood them better we recognize that they're not algae at all. They're in fact a single-celled organism called cyanobacteria. They live in communities. But you probably know them as chloroplasts. So, at some point in the past couple billion years a different organism ate a cyanobacteria. It became incorporated in the cell. It wasn't digested for some reason or another, and became a chloroplast.

Lindsay Hays: And that's where we start to see algae and all those kinds of things. And then algae evolved into bigger things as life — first water, plants, and things like that. And then plants on land have only been around the past couple hundred million years. So early on, we’re definitely talking about, not even algae, but even single-celled bacteria that are photosynthetic.

Lindsay Hays: With the evolution of photosynthesis, we sort of see two stages. The first stage in the evolution of photosynthesis is just the ability to take in light at all. But then as those photosystems, those complexes became more complicated and started grouping together, a group of organisms that are probably like modern day cyanobacteria, or the ancient historical version of them, evolved the ability to split water. And in the process they started creating oxygen, which fundamentally changed the chemical composition of the atmosphere and sort of the surface environments on Earth.

Lindsay Hays: And the really neat thing about oxygen is that it allows you, it's a really high-energy molecule, and it allows you break down more complex compounds. When you can consume oxygen and sugars, you can, sort of, get the full amount of energy out of those sugars. And that allowed things to become more complex because they can sort of get more energy out of the food they are eating. So, those processes and, sort of, a whole series of evolutionary steps allowed us to take the steps from being, sort of, simple life to this very multiple complex organisms we see today, all of the different kinds of singled-celled through elephants and whales and these huge enormous things that we see on our planet.

Jim Green: Well, you know, can you tell us about some of the places in the solar system that you're excited about for looking for life?

Lindsay Hays: Ooh. Okay. Do I have to stay within the solar system?

Jim Green: No, actually. Beyond Earth, where would you go look for life beyond Earth?

Lindsay Hays: So, of course, there's a lot of interesting things outside of the solar system. Whatever you can imagine, there's probably some really cool planet outside of the solar system that's like that. But I like thinking about our solar system because it's a much more approachable environment. These are places that even in the farthest regions of the solar system ... We've been to Pluto. It took us a long time to get to Pluto, but we've been there and we've been able to do that. So I'd say that there are a lot of places that I find really interesting in the solar system.

Lindsay Hays: And most of them are, sort, of in the sub-surface. Right? Deep under the surface of Mars in the rocks, under the oceans and the moons in the outer solar system. The things that I'm most excited about in our quest to look for life is to understand what makes an environment habitable on a planet or on some other body in the solar system, a moon or something that's potentially less habitable as a whole than the Earth.

Jim Green: Well, you already mentioned a couple of really great places. You mentioned Mars and you mentioned the icy moons. If life is in both of those places, would they be similar or how different would they be, do you think?

Lindsay Hays: You’d have to see different evolution, different systems that would have evolved to live in those different places. When we look at our planet here, extremophiles are very different depending on the environments that you look at. When you look at things that live in deep sea environments, like the kinds of environments that we imagine we would see in some of the subsurface oceans on the moons of the outer planets. We see organisms that are evolved to live in high pressures and high temperatures.

Lindsay Hays: When we see things that live in rocks on the earth, we see things that are evolved to take advantage of tiny little bits of energy over very long lifetimes. Those things on the Earth eat hydrogen and other things like that that come from radioactive decay. But those two organisms have evolved into, sort of, very different types of systems. And so I would imagine that you would expect to see different kinds of lifes if you're looking at different environments.

Jim Green: Well, we know a lot about Mars, and I think we could say there's probably not life on the surface of Mars, at least we haven't found it yet. But that gives us the opportunity to think about life below the surface. Would we rule out life below the surface on Mars?

Lindsay Hays: Would I rule out life on the surface, in the subsurface below Mars? Any time that we look for life, almost any place that we've looked on this planet for life we have found it, which tell me that life is incredibly robust. It stays wherever there is energy to be had. So I think that if there was ever life on Mars, it may be somewhere on the surface today. And I think ruling out life ... I'm an astrobiologist, so I never want to rule out the potential for there to be life somewhere. I think that life is clearly not abundant on the surface of Mars today. And so I think looking in the subsurface is exactly the kind of thing that we should be doing.

Jim Green: But do we know enough about Mars to rule it out, or is it still a possibility that there might be life on Mars below the surface?

Lindsay Hays: I think that there’s, I think that there are enough tantalizing hints that I think it would be interesting to go and look for life in the subsurface. I definitely don't think there's anything that we've been able to rule out with regards to Mars at this point, other than, like you said, the fact that life is clearly not abundant on the surface of Mars today. So where could it be and what would it look like? Those are really interesting questions.

Jim Green: Well, what are some of the signatures of life that we should be looking for, then?

Lindsay Hays: Well, on Mars or anywhere?

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Odp: [NASA Gravity Assist] Could We Find Billion-Year-Old Cholesterol?
« Odpowiedź #6 dnia: Styczeń 13, 2021, 02:07 »
Gravity Assist: Could We Find Billion-Year-Old Cholesterol? With Lindsay Hays (2)

Astrobiologist Lindsay Hays holds Martian meteorite ALH84001. Credits: Lindsay Hays

Jim Green: Yeah. On Mars or any place. Let's start with Mars.

Lindsay Hays: Things like chemical fossils. The simplest things, really, are looking for evidence of disequilibria. I mean, fundamentally life takes advantage of a place where there's energy to be exploited and takes that energy for itself. So something that indicates that there's been some kind of chemical reaction that's going on there. I am a organic chemist, so I always want to look for organic fossils, things like lipids or amino acids, things like that. Micro fossils, you might see traces of single-celled organisms or sometimes those single-celled organisms live in, sort of, communities and create macro-fossils.

Lindsay Hays: On Earth, we see these things as stromatolites where evidence of, sort of, sticky microbial mats that haven't gotten broken up in storms and things like that and redeposited and indicate that there was something there that was doing something.

Lindsay Hays: There's a whole range of biosignatures. And some things, you may be more likely to see them on Mars. Some things, you'd be more likely to see them in the subsurface ocean or in a plume from a subsurface ocean, those kinds of things.

Jim Green: Well, we've been talking about the building blocks of life for a while. And everyone knows about amino acids. But you mentioned one thing, lipids. And so, what are lipids and how would we look for a lipid as a biosignature?

Lindsay Hays: Sure. So, I like to think about lipids in this way, and that is if you are very, very, very lucky, the parts of you that may last for billions of years, that says that you were here, is actually your cholesterol. Lipids are the things that make up our cell membranes. They are the things that sort of make up the envelopes around our cells. And unlike DNA that would say, "This was Jim Green who was here," these lipids are produced by, sort of, whole families of organisms. They can tell you this was a human or this was a mammal who was living here.

Lindsay Hays: But they last a really, really long time. These are basically oils. One reason that we can find oil is that it can be preserved for millions or even billions of years on this planet. And these hydrocarbons, they last for a really, really long time. They can be a really good record of the deep past, and different families make different compounds that allow us to say, "Hey, look. Something that was making that compound lived here at this time in the past." And you can see whole groups of lipids. It's a really great way to understand, sort of, the history of the microbial life on this planet, since they don't always leave fossils in the way that dinosaurs do.

Jim Green: Yeah. That's really fascinating. I mean, you know, and most of history of Earth, animals didn't have a skeletal structure. They were much more cellular in nature. So as you say, we're going to have to find the right pools of chemicals to be able to see that these are markers of ancient life. Well, what kind of instruments or technologies do we really need to develop to be able to make those kind of measurements?

Lindsay Hays: Well, as I said, I'm partial to lipids. They last for really long periods of time. So, I'm always interested in things like the spectrometer.

Jim Green: What is a spectrometer and how would it work?

Lindsay Hays: So there's a couple of different ways. A spectrometer ultimately is something that is looking for wavelengths of light. And so we can think about a spectrometer as a way to look at how different compounds, what different compounds there are in a gas or something like that. We also have things like mass spectrometers which helps us to look at the ranges of mass that we get out of compounds that we have broken down. And these are all things that allow us to, sort of, do an inventory of the chemicals that we are looking at in a place.

Lindsay Hays: You can detect other compounds as well with a spectrometer, like amino acids, like you were talking about. or make atmospheric measurements depending on sort of how you set it up. Some people have argued for a camera as a way. to sort, of detect life. This could be a very hard thing to do.

Lindsay Hays: But if we send a camera, say, to a subsurface ocean, you’d have to do a lot of filtering of sea water to find microbes and stuff like that. And how would you even know what you were looking at? But the stuff that I'm most interested in looking at is in the deep subsurface. So, instruments, we have some idea of what kinds of instruments we may want to create. But really the technologies, I think, that are important are about how to get into that subsurface, how to get below the ice, how to get samples of stuff below of ice, how to get below the rocky surface of Mars.

Lindsay Hays: You have to think about getting sampling systems that are robust. Remember, we have no mechanics in outer space. You have to make sure that it's going to be able to do what it's going to be able to do, and you can't fix it. And also how to keep them very clean. We don't want to run the risk of bringing Earth life with us, detecting it, and saying, "We found life." But really what we found was ourselves. So, I think that those are some really interesting technologies that when we combine them with the instrument development that some of our great teams are doing, can get us to not just being able to measure things but getting the samples that we may want to measure.

Jim Green: It just occurred to me as you were talking about it, getting below the surface, if you go to Mars, there are some really deep craters that really get below the surface. I mean, they can be hundreds of meters below the surface. Maybe that's where we should land and begin our interrogation, because it's down already at a low level.

Lindsay Hays: The rocks can always tell a story. We use the rocks on this planet to tell a story about the deep past. The most interesting thing I think about the history of Mars is that the rocks on the surface of Mars are on the whole even older or significantly older than the rocks on the surface of the Earth. And so, they also tell the history of Mars right there on the surface. And because they've got craters and because they've got other things like that, that's exactly, that’s your window into those deep subsurface rocks.

Lindsay Hays: And a really cool way to look for either these chemical fossils, lipids, those kinds of things I was talking about or microfossils, as long as you can find rocks that, sort of, are sedimentary, they're unaltered. They may have these fossils ... If those fossils exist, those would be the right places to look for them.

Jim Green: Yeah. Now, the one thing about Mars, as you mentioned, is the surface rocks are older. And it's because the rocks here on Earth have gone through a whole evolutionary stage of being modified by plate tectonics and wind

Lindsay Hays: Yeah

Jim Green: And weather and ocean. And so, we don't have any of the old rocks on the surface anymore. It's really, kind of, turned over.

Lindsay Hays: There's a really active question within the habitability community, which is do we need plate tectonics for life to live on the surface and to be abundant on the surface? So, understanding not just local environments for habitability, but global environments for habitability. Plate tectonics are great because they, sort of, keep refreshing your stores of chemical energy. They turn it over and they reprocess it, they repackage it into new pieces that microbes or larger organisms can eat.

Lindsay Hays: But at the same time, they destroy all of those old signals. They destroy all of those old signs. And so it's a two-fold kind of thing. What are you looking for? Are you looking for the rocks and the history of the old life? Or are you looking for something that's active today?

Jim Green: So indeed, if life started on Mars at the same time it did Earth, then the way we could find how life started originally would be on Mars.

Lindsay Hays: Yeah.

Jim Green: What kind of studying and training does someone have to have to become an astrobiologist?

Lindsay Hays: So, astrobiology requires that we think about big questions. And so, to answer big questions, you have to get people who have a lot of different kinds of backgrounds. So, you know, the study and training, you have to be very interested in science. You have to be very interested in engineering, that kind of thing. But really, you've got to be thinking about how to work with other fields.

Lindsay Hays: So, I trained as a geologist and a biologist, but I also took a lot of chemistry classes. I took some classes on planetary science and understanding how planets form and what makes a planet habitable. It’s really… the kind of training that you need is really focused on teaching people to have an open mind. In astrobiology you have to know no matter how good you are in your field, the kind of questions we want to answer are the big questions. And so you're going to need to be able to work with other people to figure those out. So, think lots of science, but also learning how to work with other people.

Jim Green: Well, Lindsay, I always love to ask my guests to tell me about what happened in their past. What person, place, or activity that got them so excited about being a scientist that, I call that a “gravity assist.” So Lindsay, what was your gravity assist?

Lindsay Hays: Ooh. Can I give two. Can I give some rocket going into the outer solar system, needs a couple of swing-bys to get me where I am?

Lindsay Hays: Well, the first thing is sort of a quirk of fate. I actually grew up in a little town called Jupiter, Florida. And Jupiter is cool not just because, of course, it's named after the coolest planet in the solar system, but because it's close enough to Cape Canaveral, to the Kennedy Space Center, that you... When I was growing up, you could see the space shuttle launches. Now, you couldn't see the rocket, of course. You could just see the trails and the lights from the engines. But you could see them.

Lindsay Hays: And so a couple times of year if you knew when to look and you knew where to look, you could see people launching into space on a regular basis. And that was just a really cool thing to grow up in the shadow of. The other thing is I had a fantastic teacher in high school. I was not necessarily a great student in elementary school. And in middle school things started to sort of pique my interest. But my high school biology teacher really, really inspired me to get into science.

Lindsay Hays: She’s an amazing woman, very smart. She actually got her Ph.D. while teaching high school in biology and made the material really fascinating in a way that I hadn't been able to engage with before. And so she's actually now the vice principal of the school that I went to. But without her I probably would have been, I don't know, a certainly actor or writer somewhere, because those are things I was always interested in but was never very good at. So, that was Dr. Raiford at Suncoast High School. I would list her as my second gravity assist.

Jim Green:  Oh, that's fantastic. Teachers are so important to all of us.

Lindsay: Definitely.

Jim Green: And it's all about being receptive at the time that they're teaching us. So I'm delighted that occurred for you. Well, Lindsay, thanks so much. It was really a joy talking to you about looking for life and your perspective on finding it out there.

Lindsay Hays: Sure. Thanks so much for having me, Jim.

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

Credits: Lead producer: Elizabeth Landau


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Odp: [NASA Gravity Assist] Persevering on Mars, with Mitch Schulte
« Odpowiedź #7 dnia: Styczeń 28, 2021, 00:17 »
Gravity Assist: Persevering on Mars, with Mitch Schulte (1)
May 1, 2020

NASA’s Mars rover Perseverance will land on Mars in February 2021. Credits: NASA/JPL-Caltech

Mars has long been the subject of fascination among those who have ever wondered if there is life beyond Earth. NASA’s upcoming Mars Perseverance rover, scheduled to launch in July, is bringing a set of technologies to explore the Red Planet in new ways. The rover will search for signs of ancient microbial life on Mars in the astrobiology portion of its mission. Perseverance will also characterize the planet's climate and geology, collect samples for future return to Earth, and pave the way for human exploration of the Red Planet. Perseverance is also bringing a helicopter named Ingenuity to test out aerial flight on another planet for the first time. Mitch Schulte of NASA Headquarters discusses this mission and the effort to explore whether Mars had life in the past, or even now.

Jim Green: We're going to Mars, and we're taking with us this huge rover called Perseverance.

Mitch Schulte:  One of the interesting things that Perseverance is going to do that none of the rovers has ever done before, is collect rock samples. And we're working on plans to bring those rock samples back.

Jim Green: Hi, I'm Jim Green, NASA's chief scientist. And on this season of Gravity Assist, we're looking for life beyond Earth. Let's follow the Perseverance rover going to Mars and find out what it can tell us about that.

Jim Green: I'm here with Dr. Mitch Schulte, and he is the program scientist for the recently named Mars Perseverance rover. So today, we're going to talk all about this fantastic rover, and what it might tell us about the habitability of Mars today, and perhaps in its past. So welcome, Mitch, to Gravity Assist.

Mitch Schulte: Thanks, Jim. Great to be here.

Jim Green: Well, Mitch, we had Spirit and Opportunity, then Curiosity. Now we've got another one, Perseverance. Why a new rover?

Mitch Schulte: Well, Jim, every time we go to Mars, we learn something new. And what we're really trying to establish on Mars is whether there was life there in its ancient past. Early in Mars' history, we know that it was a warmer and wetter climate, as we see from this evidence of liquid water on the surface. So now that we've established that there was liquid water early in Mars's history, we think that it could have been habitable, like Earth was and is now. So we really want to get after this idea of establishing what kinds of places on Mars were habitable and whether life actually did get a start on Mars.

Jim Green: Yeah, so let's go to a place where we know water existed in its past on Mars.

Mitch Schulte: Right. And so that's one of the reasons that we're going to Jezero Crater,

Mitch Schulte: J-E-Z-E-R-O. This is actually a crater that was once filled with a lake. And it's in a really ancient part of Mars about three-and-a-half billion years old.

Jim Green: So this is really a neat place. We want to go to a lake because of why? What's the significance of that?

Mitch Schulte: Well, for one, lakes of course contain water, liquid water, and we think early in Mars' history, this area of Jezero Crater, which is now dry, there's no liquid water in it now. But there's evidence in the rock record that there was a liquid water lake there, three-and-a-half billion years ago. And everywhere we go here on Earth, where we have liquid water, we find life.

Jim Green: Yeah, that's right. This makes it a really fantastic area. In fact, the whole area around it looks like a delta, which is where flows of water have occurred, flowing into the ancient ocean of Mars. And that makes it another really exciting place. If life started in an ocean here on Earth, maybe it started in an ocean on Mars, and then moved to the land.

Jim Green: Well, you know, Perseverance is set the launch from Kennedy Space Center on July 17th. That's when the window opens. So our highway to Mars opens up, we have about a month and off we go. So how long does it take for us to launch Perseverance and get it to Mars?

Mitch Schulte: Of course, we have these windows for a reason. And in the case of Mars, it's when Earth and Mars are relatively close together. So we want to make sure we hit that window so that we take the least amount of time and the least amount of fuel to get the rover there. So launching on July 17, we have about [a] three week period when we can launch. July 17 is the first day of that period. Regardless of what day we launch during that period, we will land on Mars on February 18, 2021. So it's about a seven-month trip.

Jim Green: So, what are we looking for in terms of the rock record?

Mitch Schulte: Well, we're looking for a bunch of different things. Obviously, the very interesting part would be looking at rocks that might have been deposited or influenced in some way by the presence of life. The other really interesting thing is we want to actually be able to date these rocks. And so we're looking for some lava flows or some igneous materials that will tell us the exact age of the deposits that we're seeing. The really other interesting thing about this delta is that deltas here on Earth are real good places where we see deposits of fine grain material grading all the way up to some coarser grain kinds of sandstone. And in those deposits, we often find evidence of organic matter. And if there was life on Mars and producing organic matter, we might expect to find that in the deposits in the delta.

Mitch Schulte: One of the interesting things that Perseverance is going to do that none of the rovers has ever done before, is collect rock samples. And we're working on plans to bring those rock samples back. So there's a drill out on the end of the robotic arm, and that drill, we'll be able to put tubes in it. Sample tubes inside the drill bit, and as the drill goes into the rock, it's going to actually capture those rock cores into these tubes that we're going to cap and seal up and store for later to bring them back home.

Jim Green: So those tubes of metal that contain this rock core, there are a couple of inches long, it's sort of like a piece of chalk, or today, based on kids not understanding what chalk is, sort of the big Crayola-crayon-sized objects. So what are we going to do with those and how are we going to get them back?

Mitch Schulte: Well, what we're going to do with them is first collect them, and we're going to very carefully choose which samples we want to sample or which rock we want to sample. Once we have those, we're working on plans to send another set of missions to Mars, to go retrieve the samples and bring them back. So we're working with our international partners to provide all of the hardware that we're going to need to land a rocket on Mars, have a rover that will go collect the samples that Perseverance is going to collect, bring them to the rocket and launch it off of a platform off the surface of Mars. Once they're in orbit around Mars, they're going to be captured by an orbiter and the orbiter, then we'll leave Mars orbit and return those samples to Earth.

Jim Green: Wow, that sounds complicated. But I guess that's the easiest way that we can get it. But this fetch rover that's going to go and collect the samples, where's it going to find the samples? Does it have to run down Perseverance and get them from Perseverance?

Mitch Schulte: Well, we have a couple of different options for that and we're still working a little bit on the plans for how we're going to do this operationally. One idea is that Perseverance can actually keep the samples on board and help deliver those samples to the Mars Ascent Vehicle or the rocket that's going to bring them back. The other idea is that we could leave the samples on the ground on Mars, in particular designated locations that the fetch rover can go and retrieve those samples and bring them to the Ascent Vehicle.

Jim Green Well, what are some of the other instruments on the rover?

Mitch Schulte: Well, we have instruments designed to really look at different scales of materials on Mars. So before, we've really been investigating things at really large scale from orbit. And even with the rovers, you look at things, the rovers that we've sent so far, you look at things on a fairly large scale. So for example, Curiosity when it analyzes samples on Mars, takes rocks and powders them up. And so you lose all of the information about textures and locations of particular features inside the rock.

Mitch Schulte: So the instruments on Perseverance were really selected in order to get down onto the scale that microbes live at. And so we really want to look at those scales and textures to see where the water was flowing, and to measure the chemistry and look for organic material on that kind of scale.

Jim Green: Yeah, so those are higher resolution imaging systems. But we also have some other things like a weather station, what is that going to measure?

Mitch Schulte: So the weather station is really impressive. It's being provided by Spain. And it's going to include all the kinds of weather measurements that you see here, that we take on Earth. So it's going to measure the temperature of the air and of the ground, it's going to measure the relative humidity, it's going to measure the pressure of the atmosphere. It's also going to measure the ultraviolet radiation that's reaching the surface of the rover. And finally, it's going to be looking at the dust particles that are falling on top of the surface of the rover because as you know, the dust is a really interesting and key feature of the weather and the atmosphere of Mars and really understanding what that dust is like, is really going to help us out when humans eventually go to Mars.

Jim Green: Well, another instrument is a radar. What are we using the radar for that's tucked underneath the rover?

Mitch Schulte: Yeah, so it's called a ground penetrating radar or GPR. And this radar is designed to look at subsurface structures. So we use this on Earth all the time to look for what I like to refer to as buried treasure. So you can see ancient cities, you can see ancient riverbeds, you can see all kinds of different things, large storage tanks that have been abandoned in the past, really interesting if we're looking in environmental kinds of issues. But the real key to ground penetrating radar is being able to see the subsurface structures of the rocks themselves so that we can identify features that might not we might not see at the surface so easily, we also might be able to detect the presence of any ice, deep under the surface of Mars.

Jim Green: So that's a really neat concept. That tells us perhaps how the water deposited material onto the crater floor over time. Well, in that concept, how deep does the radar go?

Mitch Schulte: So the radar generally looks between about 50 and 100 meters deep.

Jim Green: Wow.

Jim Green: So there's another instrument that really piques my interest on Perseverance. And that relates to human exploration. What's that instrument?

Mitch Schulte: So that's an instrument called MOXIE. And it's intended to be a technology demonstration. So for when we eventually send humans to Mars, we're really going to want to be able to rely on some of the resources that Mars has. One of those resources is carbon dioxide. So the atmosphere of Mars is made primarily out of carbon dioxide, even though it's very thin, it's about 95% carbon dioxide. So MOXIE is going to take atmospheric gas, so it's going to take carbon dioxide out of the atmosphere of Mars, and electrochemically extract oxygen out of it. And of course, oxygen has a number of uses for humans, including air that we can breathe, but what we're really designing this for is to be able to create what we call propellant grade oxygen, so that we can use it as rocket fuel.

Jim Green: Interesting. Well, that will be an exciting instrument. Now, you mentioned the dust. There's dust in the air in Mars, all over the place. And we always worried about that with Spirit and Opportunity because they were using solar power from solar panels. Is that going to be a problem with Perseverance?

Mitch Schulte: That's not going to be a problem with Perseverance, because Perseverance is bringing its own power supply. It's going to be nuclear powered.

Jim Green: Wow. Okay. Well, once we core the rock and pull it out, and then put it in these tubes, do we have instruments that can look into the holes and interrogate what the rock record is inside them?

Mitch Schulte: So we have a couple of have different instruments that will be able to do that. Obviously, we have cameras and so we can take pictures with the cameras mounted on the mast or out on the end of the arm. But we'll also have two instruments that use lasers to help do their measurements. One of them is called SuperCam, and this will be able to shoot a laser from the mast into the hole and be able to determine a number of things, including the chemistry of what we're seeing inside the hole and looking for organic material in there. It'll also be able to look at some mineralogy with its visible and near infrared spectrometer. Another instrument that we have that uses a laser is called SHERLOC and it has an ultraviolet laser that will be able to look into the hole to detect organic compounds and certain types of minerals that we think form in liquid water.

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Odp: [NASA Gravity Assist] Persevering on Mars, with Mitch Schulte
« Odpowiedź #8 dnia: Styczeń 28, 2021, 00:18 »
Gravity Assist: Persevering on Mars, with Mitch Schulte (2)

Mitch Schulte is the program scientist for the Mars rover Perseverance at NASA Headquarters. He is seen with NASA Chief Scientist Jim Green. Credits: NASA

Jim Green: So these lasers are so intense, they actually evaporate the rock and you get a spectrum?

Mitch Schulte: So that's true for SuperCam and in fact-

Jim Green: It's true for SuperCam.

Mitch Schulte: Yeah. And so the technique is called laser-induced breakdown spectroscopy or LIBS. And what it does, is fires a very intense beam of laser light at a surface, that causes it to vaporize and turn into a plasma. Now that plasma emits different wavelengths of light, depending on what chemicals are in that sample. And so the SuperCam instrument can then detect those chemicals.

Jim Green: That sounds great. Well, we're going to bring the samples back, hopefully by the end of the 2020s, somewhere around there. And what's going to happen to them once they get here on Earth?

Mitch Schulte: Well, we're still working on that as well. So first, we need to figure out a place where we're going to keep the samples because unlike other missions that have brought samples back from celestial objects before, like comets and asteroids, this time, we're bringing samples back from a planetary body, Mars, that may have had life on it. So we have to be careful about what we call planetary protection. So we want to make sure that the samples are safe, before we allow scientists all over the world to look at them.

Mitch Schulte: So we'll have to have a facility to receive them. Once we have that facility and figure out what to do with them, what we'll probably do is open it up to the scientific community once we've determined that they're safe. And so that scientists from all over the world can apply to obtain samples and study them.

Jim Green: This is not a new idea. You can think back, at least I can, because I was a teenager during the Apollos, but indeed, when those astronauts came back from the moon, they went into quarantine and they were there for several days. And the samples they brought back went into quarantine. What were they looking for?

Mitch Schulte: Well, so one of the ideas, especially for Mars, is that life might have existed on Mars in its past and might even exist there today. Back before we had the samples from Apollo, we thought the same kind of thing about the Moon. So we weren't sure what we would find, we weren't sure if there were any bacteria or viruses or anything like that in those samples that they brought back from someplace we hadn't been before. So they were just trying to be careful about making sure that we didn't contaminate Earth with anything.

Jim Green: Yeah, so what happened is they eventually let them out of the trailer.

Mitch Schulte: That's right.

Jim Green: They were allowed to go home because the Moon, didn't look like it was going to support any life. So that also enabled them to open up the samples. So this is going to be an exciting time for the sample scientists to really study this material for decades.

Jim Green: Well, we're sending Perseverance to Mars right now, how does this relate to our overall Artemis program?

Mitch Schulte: So the goal of the Artemis program, of course, is to get humans back into deep space. First to the Moon and then hopefully, eventually to Mars. We in the Mars Exploration Program like to point out that we've been sending things to Mars for quite some time. And we'll be happy when the humans finally get there. But we've got an entire planet inhabited by robots at the moment. And so what we're doing in sending all of this technology and these technology demonstrations and this hardware to Mars, is really helping us move forward in the technologies that will enable humans to visit Mars.

Jim Green: So the Artemis program will land humans on the Moon where they'll learn to live and work on a planetary surface. And Mars is such a different place. We just got to know everything about it before we send humans there. And that's what we're doing with Perseverance.

Jim Green: Perseverance is going to be taking with it a helicopter. We just announced its new name. It’s called Ingenuity.

Mitch Schulte: Well, Jim, we're actually going to fly a helicopter on Mars for the very first time, and it's--

Jim Green: Wow.

Mitch Schulte: ... going to ride along with Perseverance.

Jim Green: So how does that get deployed? Once the rover lands on Mars, what happens next?

Mitch Schulte: Yeah. So we've built a little house for the helicopter on the underside of the rover. And so after the rover lands, it's going to get lowered down to the ground. It's folded up inside this house. It's going to get lowered down to the ground on cables. The cables are going to get detached from the rover, the rover will drive away and then the helicopter will unfold itself and be ready to fly.

Jim Green: So it’s a copter with two major wings, right, that are crossed like a big X?

Mitch Schulte: That's right. Yeah, so it has two large blades. They're each about a meter long. The helicopter itself only weighs about 1.8 kilograms, though. So it's fairly light. And most of the mass is actually because of the battery that's going to power the blades. And so we have two blades that sort of cross each other, as you've pointed out, and the reason for that is they're going to spin in opposite directions.

Jim Green: Wow.

Mitch Schulte: So it'll stabilize the helicopter when it's flying.

Jim Green: So it doesn't have this tail prop, so to speak?

Mitch Schulte: Yeah, if you've seen helicopters flying here on Earth, they have the big rotor at the top, but they also have to have a blade that spins on the back of the tail. And that's to keep the helicopter from spinning around as the torque of the blade spinning on top makes it want to spin in one direction. So by having two blades that spin in opposite directions, we won't have that problem.

Jim Green: All right. So we're going to send it a command, "Take off." And so it's going to go up and how high does it go? And what is it supposed to do?

Mitch Schulte: So we what we've planned for it is not necessarily how high it's going to go, we can see what it does. But what we're really interested in is making sure that we can operate the helicopter for certain periods of time. So at the moment, we have five demonstration flights planned, each one a little bit longer than the last one. And so we're going to first, make sure that it actually lifts up off the ground and can actually fly. And then we'll test and see how long we can do that. And then if we get creative, we can start to maybe maneuver it around a little bit.

Jim Green: So I'm sure during those early tests, we'll be able to, from the imaging from the Perseverance rover, look at the helicopter raise up and get an idea what it's doing.

Mitch Schulte: Yeah, that's right. So we have lots of cameras on Perseverance. So we'll be able to take all kinds of great pictures and probably some video of the helicopter doing its thing. We'll also have a video camera on the helicopter itself, so it will be taking—

Jim Green: Wow.

Mitch Schulte: ... video as it's flying.

Jim Green: Okay. So how many days does it take to really test the helicopter out?

Mitch Schulte: Well, so we're going to want to make sure we check everything out. After we do the first test flight, assuming that goes well, then I don't think it'll take us very long to get the rest of those flights done. If things do go well, then we are thinking maybe we could do a couple of extra test flights. But this is intended to be a technology demonstration.

Jim Green: Right, right.

Mitch Schulte: So we have some serious science to do with Perseverance. So we'll want to get to that pretty fast, too.

Jim Green: But this opens up a whole new idea — a whole new series of things one can think about doing. So if the helicopter works well, what are the kinds of things that we anticipate we could use aerial flights on Mars in the future for?

Mitch Schulte: So you could imagine all kinds of things. One would be a very obvious thing, which would be a scout. So you could fly the helicopter over a hilltop that you might not want to send the rover to, to check out the terrain and make sure it's safe for the rover to go operate over there. If you've ever been in an airplane and looked at the ground below you, you see very different scales of geology, from different elevations as well. So walking, hiking the trail is one thing, being in an airplane is a little bit different. Being in a jetliner flying high above it, you see very different scales of geologic features. So you could do some interesting geologic work with the helicopter.

Mitch Schulte: And then finally, of course, just as a transportation mechanism, again, to get things moved around relatively quickly. You could imagine, not that we were planning to do this, but you could imagine having a helicopter to go pick up samples and bring them to a particular place.

Jim Green: Well, I have another one I'd like to do, and that is have a helicopter land in a major crater where we see what may be water actually leaking out of aquifers and running down the sides of the crater during the summertime and fly up and look into these craters. Look into these potential aquifers.

Mitch Schulte: That's a great idea, Jim. And again, places where you wouldn't want to send a rover or can't send a rover, if it's on the side of a cliff where there may be active water coming out then, the helicopter would be a great idea for that.

Jim Green: Yeah, wow. Okay, this is a really exciting mission and I'm so delighted that we're doing some technology demonstrations along with it. Fantastic.

Jim Green: Well, Mitch, 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 a scientist. That propelled them to become the scientists they are today. I call that a gravity assist. So, Mitch, what was your gravity assist?

Mitch Schulte: Well, I'll give you two. I'll give you an event and a person.

Mitch Schulte: So, like you, I'm old enough to remember the Apollo missions. And I was 3 when Neil Armstrong first set foot on the Moon so-

Jim Green: Wow.

Mitch Schulte: ... a little too young to remember that exact event. I know I was watching it because my parents told me I was. But I sort of grew up then, with people walking on the Moon as they were sending people, all the way up through Apollo 17. I was watching that on TV and thinking, "What a great place to go, the Moon would be." So that was one of the reasons I got interested in doing science. At the time, of course, I grew up in St. Louis, which is where McDonnell-Douglas at the time, had its headquarters. And they are the ones who built the Mercury capsules and did a lot of work on the space program. So it was all around me and it was a natural thing to do.

Mitch Schulte: The person that most inspired me, I would have to say, was one of my earliest geology professors at Washington University, Lynn Walter, who's now at University of Michigan. I took historical geology class from her and she was just the most caring, creative professor that I ever had. And she's the reason I stuck it out and became a geologist.

Jim Green: Wow. Okay, that sounds exciting. We all have our different paths. Mitch, thanks so much for a really exciting preview of Perseverance and its landing on Mars.

Mitch Schulte: Well, thanks, Jim. It was great to be here. And everyone should pay attention for the launch on July 17, and landing seven months later on, February 18, 2021.

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

Credits: Lead producer: Elizabeth Landau
            Audio engineer: Emanuel Cooper


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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #9 dnia: Luty 08, 2021, 01:54 »
Gravity Assist: What If We Found Life On Mars? (1)
May 8, 2020

Climbing "Vera Rubin Ridge" provided NASA's Curiosity Mars rover this sweeping vista of the interior and rim of Gale Crater. Credits: NASA/JPL-Caltech/MSSS

Imagine a future where the Perseverance Rover actually found definitive evidence of life on Mars. What would happen next? The Explore Mars Society recently held a virtual discussion on this topic with NASA’s chief scientist Jim Green and astrobiologist Penelope Boston from NASA’s Ames Research Center. Hosted by Mat Kaplan of the Planetary Society’s Planetary Radio podcast, the panelists talked about the current evidence for chemistry associated with life on Mars, what we can learn from life in extreme environments on Earth, and how finding evidence of life on Mars would change the world.

You can watch the full presentation on YouTube.

Jim Green: The results of finding microbes might be as revolutionary as cracking DNA. That is awaiting us with this kind of discovery if we do indeed find microbial life on Mars, I think.

Penny Boston: The entire community would go into a frenzy of trying to test whatever features this potential life would have.

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

Jim Green: Recently, I was invited to speak at a very special virtual event that really dug deep into the question of life on Mars, but in particular, what would happen if we found it there? The event was sponsored by Explore Mars, and hosted by Mat Kaplan. You may know Mat since he’s also the host of Planetary Radio. Mat facilitated the conversation between me and a really fantastic astrobiologist and good friend of mine, Dr. Penny Boston from the Ames Research Center. Penny has traveled the world and has found all kinds of exotic life hidden in caves; some real extremophiles. Here’s a slightly edited version of that conversation and I hope you will enjoy it.

Mat Kaplan: Let me set the stage for today's conversation with a hypothetical. We've jumped forward to 2024. A rover named Perseverance, that we'll be talking more about momentarily, has been rolling across Mars for three years. Another visitor from Earth, a more recent arrival, named Rosalind Franklin, has been pulling up samples from below the surface of Mars. NASA and the European Space Agency have just announced a joint press conference that is going to reveal images and other data indicating that we just may have found strong evidence of life. Will this news, as my boss Bill Nye likes to say, change everything? What do we do next and how will it affect plans to send men and women to Mars?

Mat Kaplan: But I'm getting ahead of myself. So hold that thought for now as we meet two very distinguished guests that will be joining me here. I really can't think of anyone else. I would rather have onboard to talk about this topic. Beginning with Dr. Penelope Boston. She is the Senior Advisor for Science Integration at NASA Ames Research Center in Silicon Valley. Penny's personal expertise is the geomicrobiology of extreme earth environments, especially caves and mines and astrobiology. As a lifelong human space exploration advocate, she co-founded the Case for Mars conferences in the 1980s and 1990s. That makes her a founding member of the Mars Underground as well.

Mat Kaplan: She's a member of Explore Mars. She looks pretty great in a fake space suit. She earned her Ph.D. in Microbiology at the University of Colorado, Boulder. She was, ‘til recently, the Director of the NASA Astrobiology Institute based at Ames. And as a former professor and chair of the Department of Earth and Environmental Science at the New Mexico Institute for Mining and Technology. Also, the former associate director of the National Cave and Karst Research Institute. Welcome Penny.

Penelope 'Penny' Boston poses with Naica Cave gypsum crystals. Credits: Dr. Tom Kieft, New Mexico Tech

Penny Boston: Thank you. Great to be here.

Mat Kaplan: Dr. Jim Green is the NASA Chief Scientist. He received his Ph.D. in Space Physics from the University of Iowa in 1979 and has worked for NASA ever since. That included 12 years as the director of the Planetary Science Division at NASA Headquarters. Under his leadership, more than a dozen planetary missions were successfully executed including the Curiosity rover and Insight lander, both of which are still quite active and delivering great science on Mars. Jim is NASA's representative on the COSPAR Planetary Protection Panel where planetary protection guidelines are created and agreed to internationally. COSPAR, that's the Committee on Space Research. In 19, excuse me. 1915? You're not that old, Jim.

Jim Green: No, I'm not. [Laughing].

Mat Kaplan: In 2015, Jim coordinated NASA's involvement in one of my favorite movies, The Martian.

Jim Green: [Laughing]

Mat Kaplan: Talk about infecting a planet. By the way, he also hosts the excellent NASA podcast called Gravity Assist. Welcome, Jim.

Jim Green: Thank you very much, Mat. I'm delighted to be here.

Mat Kaplan: So let's back up a little bit and talk about the current status of exploration on Mars now and what's going to be happening there, well, in less than a year now with the arrival of this new rover. Tell us, what's the status of Perseverance?

Jim Green: Well, Mat, Perseverance is actually moving forward. It’s all down at the Cape and in fact the radio isotope power system is already connected. It's checked out in many ways. It still has a number of things to do yet but we're making great progress. So, it is on track for a July 17th open window for us to be able to launch. And that's when that highway opens up for the next three weeks that can get us to Mars.

Mat Kaplan: This is like almost everything NASA sends around the solar system nowadays an international effort, right?

Jim Green: It is and indeed. This particular rover has got fabulous set of instruments where we have participation from Spain on a, on a weather system. We have Norway having a ground penetrating radar. We have the French working with us on some really great camera and laser systems. And we have an Italian retro reflector. But the whole point of this particular mission is, really, at the end of the arm. This is where we have high resolution images that we wanna be able to really look at the rock record and then make decisions in terms of creating cores. It's got a core at the very end of it.

Jim Green: What these cores look like, it's a, they're like a piece of chalk in size or, or for those that are young enough that don't really understand what you know, chalks and chalkboards were all about and their education, like a Crayola crayon, you know, one of the large sizes. Once those cores are made, they're, they're stuck indeed and, into an aluminum sleeve and then dropped on the surface for then later pickup and bring back.

Jim Green: So by the end of that decade, the 2020s, we hope to be able to have these samples back in our Bio Level 4 facility and begin the process of really looking through them to determine their viability and allowing scientists to get access to them for further research. So we're doing great.

Mat Kaplan: And even though she resembles her sister on Mars, Curiosity, you've given at least a couple of examples in that image and with those cores, especially, of the new capabilities that Perseverance is bringing to the Red Planet. Pretty powerful machine, isn't it?

Jim Green: Oh, it absolutely is. And the rock record is so important to us, you know. We know that Mars was a blue planet early on in its history. It went through rapid climate change. It was a blue planet during the time we know Earth had life started on it. And so maybe life started on Mars, too. And so we're really quite excited about going there and interrogating that, being able to bring back those samples and look at them. You know, for all the minerals we have here on Earth, there are hundreds of minerals for which life is such a key part of that create those minerals. And, you know, so if we can find the right set of information, indeed that press conference you talked about would be really lively.

Mat Kaplan: So, sample return. And you know, I often refer to it as the holy grail of robotic exploration of, of Mars and could be for other places as well.

Jim Green: This was how we envision right now working with our international community to be able to get those samples back and it all requires NASA landing a Mars ascent vehicle. We then have fetch rovers that pick up those samples that we laid on the ground and deliver those. And then we launch off of Mars, those samples, in a, a container, and then that container goes into orbit for which then ESA satellite will come down using ion propulsion into lower, low Mars orbit. Pick those samples up and then bring them back to Earth. It's indeed a, a multinational effort and the planning is going real well.

Mat Kaplan: Penny, you're a long time Martian. What's it going to mean to scientists like you to get those samples back here and into our nice big labs on Earth?

Penny Boston: Well, you know as you say Mat, it's been a holy grail for many decades and  pretty much my whole career. I'm sure that's true for a lot of us. The opportunity to actually get our lab facilities here on Earth to bring all of their power to bear on samples is a new step really, in, in marching forward to be able to analyze Mars materials. The missions that we've had so far and the ones to come are magnificent. But there's only a certain amount that you can smash onto a spacecraft and a lander and a rover before you run out of power and mass and all of that. And so the ability to do these really in-detail studies of the geochemistry, the mineralogy, the foundational bedrock materials, perhaps even some of the fine materials on Mars, will give us insights into the climate history of that planet which is very important to our understanding of climate in general on our own planet and beyond. And also potentially allow us to look at organic materials and various other things that may be significant for the potential history of any life that may have arisen on Mars.

Mat Kaplan: Jim, I wanna get back to you. I gave short shrift to all of the success we've already seen on Mars with two active spacecraft on the surface and that flotilla on orbit above the planet. Where are we in what we've learned? I mean, we found the water. Are we still following it? And what else have we found?

Jim Green: That's a really great question in the sense that you know, there are more, there's more to it than just following the water. You know, we've seen evidence of water all over the place on Mars, that's clear.  We've seen what we call, a recurring slope lineae where water may actually be pouring down the sides of craters in a seasonal way. This is during a time period during indeed that summer, where, where the sunlight shines on the crater walls, perhaps it sublimated water plug that's sitting, holding back water in an aquifer and then that water pours out and runs down the slopes.

Jim Green: We've measured that. We know it's water. Now, some of these actually may be drifts of of dust and, and, and therefore producing some discoloration. But there's so much of it and there's so many places where, where it's occurring. You know, we're pretty convinced that that indeed there is a significant amount of water locked inside the planet. Now, in addition to that, Mars seems to be emitting what we would call, traces of life gases like methane and like oxygen.

Mat Kaplan: I'm knocking on wood.

Jim Green: Yeah. Right. [Laughing]. And indeed, although those things can be generated abiotically, for the methane, we've been observing methane from telescopes on earth since the early 2000s but now with Curiosity making those measurements directly over and over again, we do see that seasonal bloom, what we'd call this rush of methane coming out. Although it's still a trace gas, you know, parts per billion we're talking about. That is coming from underneath the surface.

Jim Green: Now, that could be generated abiotically. It requires water, requires certain minerals and a heat source like magma or it could be old methane from old life in the past that has also been trapped over time and is, is being released. Or indeed it could be an indication of life there today in the aquifers, is what we would think. So those trace gases now are extremely important. We're making fabulous measurement of those.

Mat Kaplan: Both for methane and oxygen, there've been some conflicting data, hasn't there? Depending on the observer?

Jim Green: Yeah. Indeed, the oxygen observations that we just released over the last several months is a, is a long-term trend. It's about five years worth of observations. And it's a surprising trend. You know, as the planet goes through, its seasonal cycle, we expect during the winter because it's so cold that a lot of the atmospheric gases, in particular, the trace gases, will collapse down under the surface. And then as it warms up, it, it, it actually then releases those. And what we're finding is an excess of oxygen during, during certain times. And then at other times we see that the oxygen actually is being removed.

Jim Green: So this has really caused quite a puzzle. We've had many scientists really working, trying to figure out what are the, abiotic, in other words, the non-biological reasons that this is happening and we really haven't come up with a good explanation. So the oxygen observations are really one we wanna stay abreast of and see what Curiosity is gonna find in the future.

Mat Kaplan: Penny, have we seen evidence other than what Jim has just talked about that could indicate biological activity or at least past biological activity up there?

Penny Boston: Well, you know, so far we haven't had the opportunity to closely examine materials getting back to our previous discussion about sample return. But what we have been able to do, of course, is hook up what we understand about extreme environments on Earth and try to tease out the parts of those environments that are relevant to Mars. It's pretty clear we have nowhere on earth that is just like Mars; it’s a very, very challenging environment. But we have challenging environments on Earth that have components that really go into that Mars picture.

Penny Boston: And so microorganisms in their vast diversity, they're unbelievable diversity on this planet have adapted to, you know, wild variety of conditions. Many of them are the conditions that we see in the Mars surface. And particularly of course from my point of view as someone very interested in, in the subsurface, both near and deep subsurface, where there's more protection from some of the nasty things that you get on the, on the Mars surface.

Penny Boston: So I think that the importance of the gases that Jim has just been articulating is really because the atmosphere of a planet is its breath, essentially. And the breath of life on earth is very, very clear. We have a very complicated atmospheric spectrum, which is, the sum total of all of the complex gases that life on our planet puts out. When we're looking at a planet like Mars, if we're looking at life that has been, not as ro- globally, as it is here on earth for a long time, that is something of a relic biosphere.

Penny Boston: Then we would expect to see a much more subdued signal. But the fact that there is this oxygen, um variability and the fact that we see these traces of methane, are very exciting. Because what that might say about life is that, if it exists in a subsurface, there's a certain leak rate just like we have with spacesuits and spacecraft and Earth itself. And that we may be catching little whiffs of what's going on underneath. In any case, whether or not it's biology or it's non-biology, when you have, a life bearing solar system like ours, in my view, every planet matters to understanding that life even if that life only occurs on one planet. And of course we certainly hope that it occurs on Mars or has occurred on Mars as well as other places in the solar system.

Mat Kaplan: Penny, you have spent a good part of your life going to places most of us would not wanna, go looking for how life has found a way to survive. One of those more milder locations. I remember being with you in Carlsbad Caverns and you pointed to a spot on the wall and you said, "You see that? That's life eating copper." So it does sure look like the enormous variety of extremophiles that we find on our planet, It's gotta give you some encouragement, right?

Penny Boston: Oh, very much. Even though I, I'm a Mars fan for my entire life, of course I have an eye on the other potential habitats. And I think that the fact that we have organisms that appear to be able to tolerate almost everything including high radiation and organisms that have been retrieved from, you know, space exposure and complete desiccation. And, living amongst metals that we find toxic but they're busy using inorganic chemistry to make those into energy sources, makes me really understand the, the sweep of what our type of life — meaning organic carbon, you know, water matrix is capable of — it's really quite extraordinary.

Mat Kaplan: Life as we know it. Yeah.

Penny Boston: Yeah, life as we know it. And of course, you know, many of us consider life as we don't know it and that life as we don't know it extends to other ways of making life even out of organic carbon. So there are, there are people thinking about other alternative sets of chemistry that might work on other planets. But from the point of view of Mars, my conviction is that we're really looking for carbon-based life in a water matrix because Mars is not all that different from Earth.

Penny Boston: And certainly as Jim pointed out, early in its history, it was much more similar. And so that early childhood of our rocky terrestrial planets together seems to me very significant. And even Venus in its current state which is quite inhospitable to life as we understand it, but its early history may have also shared in, in a habitable zone. So it's not, not just Mars alone that is compelling but really Mars as this beautiful red jewel within this entire spectrum. This entire crown of jewels that we have in our solar system and, and what they offer for life.

Mat Kaplan: Have your, your studies and, and what we've learned from others in looking for biosignatures, that, that key term. Has it led you to the point where you think that if we had life staring us in the face, we would, we would recognize it?

Penny Boston: Well, yes, maybe.  the slide that was just put up shows a variety. And this of course is for my, from my own work. All of these colorful and drippy gooey things that you see are all examples of microbes, as tiny as they are, but making major changes in the rock and mineral environments that they live in. They orange stuff that you see that looks sort of like a pizza or the surface of Io, that's all rock breakdown material that's been chewed through by organisms that use manganese and iron, rather than, you know, eating hamburgers for lunch, they eat rock.

Mat Kaplan: Wow.

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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #10 dnia: Luty 08, 2021, 01:55 »
Gravity Assist: What If We Found Life On Mars? (2)

Penny Boston is a leading astrobiologist who explores caves and finds life in extreme conditions. Credits: NASA

Penny Boston: And they use those minerals and then they poop out, so to speak, all of this fluffy stuff. And so they're, you know, they're major geological agents on Earth but it shows that they can make their living off a geological source. You can see the screaming blue patch that one of my French colleagues is standing by sort of in the middle lower part of the, of the screen. And you can see an example of the same process. You were talking, Mat, about the copper material that I showed you. These are organisms all over the world.

Penny Boston: They're different and very unrelated but they still are able to do the same thing. And so, that makes me even more excited because it doesn't have to be the same organisms. It's finding a pathway of organisms in different places that can use the same energy sources. And so, to me, that seems like an encouraging sign for extraterrestrial life.

Mat Kaplan: Jim, on a jump back now to that hypothetical that I posed of the outset. That press conference which you would very likely be a part of, as I hope you're still on the job in 2024. You've got big news for us.

Jim Green: Right.

Mat Kaplan: What's this going to mean if indeed we find evidence better than we've gotten in the past? I'm thinking of a certain meteorite ALH84001, that, that seems hard to argue with that maybe we have found at least evidence of past life on Mars. What's that going to mean to us here on Earth?

Jim Green: Well, let me just mention, of course, there is, an important aspect of thinking about that future when we start that announcement. And that really boils down to looking at what's happened in the past by analogies. The ALH84001 is a good one in the sense that we would organize that press conference. On that press conference, we would have the, the scientists that are announcing the discovery but also scientists that are a little skeptical. That announcement then would go out to the public and then there would be a period where the community of scientists would really dig into the results.

Jim Green: Perhaps if we've returned samples soon after that they would then be able to have those in the laboratory, et cetera, and really tease it out and then public reaction. And then an education has to go on to everyone in terms of the context of what, what this means. But if we just take that supposition that indeed in the long run it proves to be true and we have found that second genesis and it is on Mars, what does that mean? And here by analogy, I think we have to look at, perhaps, several. One, one comes to mind, is what Copernicus did.

Jim Green: At the time Copernicus was coming out with a theory that the planets went around the Sun and not everything went around the Earth. It changed the world view. Everyone, mentally, had to now rearrange their thoughts about their place in the solar system in the universe. And it had a profound effect. People thought, well, we are the center of the universe because everything goes around us and now they go around the Sun, just like the other planets. And then, to them that means, well, maybe there are other societies like us on other planets. This was a really profound change.

Jim Green: I think, indeed, we're gonna have to come to grips with that. Many people because of our literature and our movies are, you know, all set to accept that there's a second genesis out there. And in fact many scientists, and that would include me, think it's almost inconceivable that there isn't some sort of life out, not only in on in the solar system but certainly is certainly on other planets.

Jim Green: And so our worldview then, once again, will have to change. And I think it will change many different things. The, the results of finding microbes might be as revolutionary as cracking DNA. You know, the concept of what, what's come out of microbiology, which is only a handful of decades old, has just been phenomenal. That is awaiting us with this kind of discovery if we do indeed find microbial life on Mars, I think.

Mat Kaplan: Penny, what would this mean to you and, and your colleagues, this announcement and the provision of this data?

Penny Boston: Well, you know, I spent my entire life doing this and so have many of my colleagues. So [laughing] I have dreamed about that happening in my lifetime. I hope it does. I'm trying to stay as healthy as possible to get the maximum chance. [Laughing]. And you know, the minute we got any kind of indication that there might be extant life or even extinct life, okay, ‘cause I also do paleomicrobiology and I'm interested in the entire deep history of planets with life. The entire community would go into a frenzy of trying to test whatever features this potential life would have. And so there would be an enormous flourishing, maybe in directions that were already pursuing, maybe a new directions. It depends on what those results would find. And then I would throw one heck of a big party.

Mat Kaplan: [Laughing]. I'd like to attend that.

Jim Green: [Laughing]. Please invite me.

Penny Boston: I will.

Jim Green: [Laughing].

Mat Kaplan: We should get into a, the topic that topic maybe our, our sponsors here that explore Mars are most interested in after all, they are the humans to Mars people. And that is, what the possibility evidence for, not just pass but possibly existing life on Mars stuff that's still kicking up its heels there today, would mean for sending humans there? Jim, you were a, a, a big contributor to that movie, “The Martian.”

Jim Green: Yes.

Mat Kaplan: It would not be a good idea for us to head there and, and plant poop potatoes, would it?

Jim Green: Uh uh. No. Actually, Curiosity has found the, the nitrogen, oxygen carbon, phosphorus and sulfur on Mars. All the right stuff. The soils are, are moist and indeed, there's nitrates in the soils. Now, where Curiosity is sitting, turns out to have alkaline soils, not acidic. So what would grow better here would beans and asparagus. And, and, and I don't know about you but if I had to eat two or three years’ worth of asparagus, I'd just take my helmet off and walk outside.

Penny Boston: [Laughing].

Mat Kaplan: [Laughing].

Jim Green: But I'm assuming — I could do the potatoes — I'm assuming, we all are assuming there'll, there'll be more acidic soils to elsewhere. And so indeed the analogies between Mars soils and Earth soils is really strong. That's really quite important. If we found evidence for current life, that current life has to be below the surface. We haven't found evidence of life on the surface. And for human exploration I think we'd have to talk about how we're gonna share Mars, and I think we can share Mars.

Jim Green: There are many approaches unlike “The Martian” where the concept was, you land Ares 1 and the next time it's Ares 2, Ares 3, Ares 4. We would plan to go to one particular area, perhaps 150- or 200-kilometer area called an exploration zone where we land in one part, live in another part and then have the ability of mobility to go around and perform a whole variety of scientific experiments but really confine ourselves to that part of Mars.

Jim Green: And in so doing then, it gives us a wonderful opportunity, perhaps over several decades of, of continuing to go there and continuing to build and develop things at that site. An opportunity to really learn and obtain a deep understanding of what Mars is all about. And then we can take it to the next step with that kind of knowledge. So I'm all for sharing Mars.

Jim Green: Now, you may know that many scientists, particularly Carl Sagan, thought that if we found microbes on Mars, we need to leave Mars alone and go to the, go to another body in the solar system. But, I think because life also has to evolve over time, the evolution of that life is going to be completely different than ours. And that gives us, I think, an opportunity to coexist. And, and those are some of the new ideas that are coming out now.

Mat Kaplan: Penny, what's your view about all this? I mean, I think you wanna see boots on Mars as well. But you—

Penny Boston: I'd like to see my boots on Mars actually.

Jim Green: [Laughing].

Mat Kaplan: [Laughing]. Me too.

Penny Boston: But I'm going to be too old, I'm afraid. But, it's something I've wrestled with my entire career because I have this desire for exploration for our species to go beyond other bodies in our solar system. And who knows, someday even out of our solar system in some number of hundreds of years. But at the same time, of course, I'm very, very aware of the deep ecology aspects of another biosphere. And this applies to Mars or any other biosphere that we may find in our solar system.

Penny Boston: And that is, how do we study it? How do we, perhaps, co-habit with it as Jim points out without doing damage to it? And in turn without doing damage to us. I think that many years ago, probably 25, when I first started writing about the Mars subsurface as being the best place to look for life on Mars, it was not taken very seriously. We knew a lot less about the planet at that time but we've plugged along on that theme and I think it's become manifest that, that is the place, as Jim says, where we would have the highest chance of finding subsurface life, even if Mars once was covered in life at the surface.

Penny Boston: That the subsurface, in many cases, particularly even on Earth, is a refugium, a refuge for organisms when circumstances change on the surface. We see this in microorganisms and macro organisms. So there are caves with fish and invertebrates that have been separated for 20 million years from the surface and things of that sort. So I think that the expectation that I have is that any Mars life is going to be quite deep. And that helps us with this conundrum. Because as long as we don't contaminate aquifers as we're trying to get resources for human use then the surface Mars environment is very harsh.

Penny Boston: And while I wouldn't call it entirely self-sterilizing, it will do a lot to reduce the plume of biological contaminants within some distance from a human colony. And then of course, if we want to study things like the slope lineae, these trickles of water, a briny water that Jim mentioned early on in our, in our discussions, those are juicy targets literally and figuratively.

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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #11 dnia: Luty 08, 2021, 01:55 »
Gravity Assist: What If We Found Life On Mars? (3)

NASA Chief Scientist Jim Green at the NASA Headquarters audio studio. Credits: NASA

Penny Boston: We can't wait to get our hands on them, but our hands will not be our hands. Our hands will hopefully be sterilizable robotic sampling devices that we'll be able to send out and bring those samples back for analysis. So there are ways to do this and you know, we're living through it now with this pandemic that we're all experiencing. How do we separate our activities from, in this case, a pathogen, but in the case of humans on Mars, how do we se-separate ourselves from potential organisms that are the Martians and keep all of us safe?

Penny Boston: And so all of these real world things are being worked out in real time. And as, as where you mentioned that Jim is on the COSPAR panel, that dates back to the 1950s and the early part of the space age. So it's not like we just discovered that, oh, gee, there might be a problem. Many of us have served on panels and workshops and we're writing about it all the time. So it's very, very much foremost in our minds about how to do this safely. I think we can do it. I hope I'm not being naïve.

Mat Kaplan: Jim, I'm, I'm really glad that Penny brought us back to that COSPAR committee that, that where you are the planetary protection representative from NASA, from the United States. How is this being considered by the international community? These questions are protecting Mars but also wanting to go there and like have humans explore?

Jim Green: Well, indeed COSPAR over the years has looked at each and every one of the bodies in the solar system that were being considered by space agencies to go to. And indeed, early on, we didn't know much about the Moon in terms of whether there'll be pathogens there. And so consequently, those guidelines that came from the COSPAR committee, that the international community signed up to, meant that we, for, for a NASA perspective, wanted to implement a quarantine system.

Jim Green: So when samples came back from Apollo 11, you know, the astronauts went into quarantine and the samples went into quarantine. And then we went through our processes of indeed interrogating those and understanding what they are, what we had, whether there were pathogens, et cetera, watching the astronauts over a period of time. And then finally recognize that indeed we could have uncontained sample return from Mars. We didn't need to go through the quarantine process.

Jim Green: And so then, that means the guidelines were revised. So the committee, indeed, takes it very seriously that as we learn new things about each of the bodies that, that the space agencies are planning to go to, we take that into account to modify those guidelines. And that's been working really well.

Jim Green: In fact, just recently we took a good look at Phobos. And we recognized that Phobos indeed, one of the moons of Mars, we could actually back off some of the more stringent guidelines on returning samples. And so we've categorized Phobos as our location where we can have unrestricted Earth return of those samples. And the, and the Japanese-JAXA mission is, is being planned to go there and has many international connections and components to it. But that required for us to bring all the knowledge we knew about Phobos forward, and not consider it like Mars in a category of more restriction. And so we're gonna continue to do that. And that process is working well.

Mat Kaplan: Penny, you touched on it. But it's the question that Explore Mars, our CEO, Chris Carberry posed before we started this. And that is whether what we have learned about both, how we might handle isolating ourselves from life on Mars or anything else in the field of astrobiology might have helped prepare us to deal with the challenge that we're facing around this planet right now. The pandemic. I mean, do you see any relationship there?

Penny Boston: Yes, I, I, I do. I think that one of the things that this horrible circumstance will maybe help is eventually in better public communication. You know, when you are trying to talk to people who are not microbiologists or scientists of some other sort about microbial life, it's very hard to communicate the size of these individual entities, their capabilities and just how easily spread they are. You know, in many cases that's very benign. There are many microorganisms that we need in our environment.

Penny Boston: They basically run a lot of the biogeochemical cycles on our own planet. So on balance, they're beneficial. We only sort of noticed them on the broad scale when they're deleterious. Like in the case of the COVID-19. But you can derive some lessons from this, you know, the fact that we have a new virus on the scene means, even though it's related to other Earth viruses and similar to others in its group of coronaviruses, it's many different properties. And so a lot of the scrambling that's going on now in the medical and research communities is to try to figure out its properties. The way that we, that we do that in real time is orders of magnitude accelerated compared to what we would have been able to do with something like this even 20 years ago.

Mat Kaplan: Mm-hmm.

Penny Boston: So within mere weeks we had an entire genomic sequence for this RNA type of virus that was propagated around the world. The biggest issue is, you know, we are a world full of people with different traditions, different levels of technical sophistication and different access to communication. And so it's the human response to that, that's been the trickiest part. One of the things that I think is important to communicate is that microorganisms, for the most part, are benign and absolutely essential to us. And so one of the things I don't want to see is an increase in sort of mindless germaphobia from this. And you know, that could be a natural outgrowth of this. But we are talking about studying microbial scaled life on another planet. Although, we're mostly looking at bacterial size things.

Penny Boston: And if you look, if you look at a bacterium, you can probably line up maybe 80 or a 100 of them across the diameter of one of your hairs. But if I were going to put viruses across the diameter of your hair, I would probably put a thousand or 2000, right? So they're even more minuscule. So I think we're mostly focusing on bacteria-size organisms. So those are actually much easier to control and work with for the most part than the viruses, because the viruses are, are tinier than dust specks.

Penny Boston: Whereas the bacteria are much chunkier, you know? And so our, our methods of controlling bacteria and working with them in many ways are easier.

Jim Green: Yes. Penny, did a wonderful job explaining the various aspects of that. What's critical also to understand is, you know, viruses aren't considered alive. They really are cellular parasites. If I, if I were to describe them in some way and they, they invade the body and they have some genetic material associated with them, but in reality, for them to live and grow, they actually have to co-evolve with a host. And so when we think about bringing material back from Mars that is alive, that life has, perhaps, a second genesis, perhaps is related in some way to us in terms of the fact that it started in a similar environment like Earth, but it has a completely different evolutionary track. And so the current thinking is, um, yes, we're going to quarantine those samples. Yes, there'll be in, in what we call a Bio Level 4 facility, you know, where they handle anthrax and everything else and it will be closely monitored.

Jim Green: But I think as Penny points out, our ability to understand the, the microbiome and virus environment will allow us to those current tools to interrogate those samples and begin the process of releasing things to the science community, which will be really important to do because that's where those laboratory equipment really comes into, into play. Many places around the world that will really tease out some of the most spectacular science in terms of really having a deep understanding of that planet, then we, then we can dream up today.

Mat Kaplan: Mm-hmm [affirmative].

Jim Green: So, those are all, those are all just right around the corner, you know. And, I'm, I'm hoping also to be to be around when we start cracking into that next generation.

Mat Kaplan: You and me and Penny, all of us and everybody watching this program, I am sure.

Jim Green: Now, I was alive and in high school at the time of the lunar landings and it was just, awe inspiring even with the grainy, yucky—

Penny Boston: Oh, yeah.

Jim Green: You know, black and white [TV.

Penny Boston: Yeah.

Jim Green: And so today we're gonna be doing it in the high definition. And the colors will be spectacular ,and the shadows will be long, and it will be incredibly eerie but it will be just as inspirational. So everyone, you know, that hasn't seen that original lunar landing of any of the Apollo astronauts, have really got a treat in store for them. And that's coming up.

Mat Kaplan: What a great way for us to, to end this wonderful conversation. I wanna thank both of you. Um, there truly were no better people to be a part of this discussion of life on Mars and why, we, examples of life down here, are so excited about it. Thank you. Jim Green, NASA Chief Scientist. Thank you Penny Boston of NASA Ames, astrobiologist.

Penny Boston: Thank you. Thank you.

Mat Kaplan: And thanks to all of you for tuning in, for joining us for this a-and to Explore Mars for making it all happen and the great people there who have been helping us out. Wade, Janet, Chris Ron Sparkman, Adrianne. And keep looking up there at Mars. We're there and we're going back. Thanks for, again, for joining us. Have a great day and stay safe.

Penny Boston: Live long and prosper.

Jim Green: [Laughter]. Live long and prosper. Thanks Mat.

Mat Kaplan: My pleasure.

Penny Boston: Thanks Jim. Thanks Mat.

Jim Green: Take care, Penny.

Jim Green: That was really a great event. I had a fun time talking to Penny and Mat. You know, there’s so much more we have to learn about the possibility of life on Mars, and I can’t wait for the launch this July to the Red Planet of the Perseverance rover along with its traveling companion the Ingenuity helicopter. Tune in next week for more as I continue our quest for the search for life beyond Earth on Gravity Assist.

Credits: Audio from the “Life on Mars” conversation provided by Explore Mars and the Planetary Society.

Lead producer: Elizabeth Landau
Audio engineer: Manny Cooper
Last Updated: May 8, 2020
Editor: Gary Daines


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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #12 dnia: Luty 17, 2021, 00:17 »
Gravity Assist: A Special Delivery of Life’s Building Blocks, with Jason Dworkin (1)
May 15, 2020

This global map of asteroid Bennu’s surface is a mosaic of images collected by NASA’s OSIRIS-REx spacecraft between Mar. 7 and Apr. 19, 2019. Credits: NASA/Goddard/University of Arizona

When Earth was just a baby, meteors and asteroids rained down, delivering all sorts of chemicals to our developing planet. These small objects could have delivered the chemicals needed to spark life on Earth for the first time. The OSIRIS-REx mission will collect and return a sample from asteroid Bennu, a 4.5-billion-year-old fossil of the early solar system. By looking at pieces of Bennu in laboratories, scientists will be able to look at its composition and see whether some of the building blocks of life came from objects like Bennu.

Jim Green: How do we know what the early solar system was like?

Jim Green: How does life come from a lifeless beginning?

Jason Dworkin:  Bennu is a fragment of the ancient solar system.

Jason Dworkin: We can learn the types of ingredients that were available on the early Earth that could have gone into life, and maybe understand more about ourselves by looking at Bennu.

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

Jim Green: I'm here with Dr. Jason Dworkin and he is the project scientist for OSIRIS-REx and a research scientist at the Goddard Space Flight Center. Jason's realm of research is the chemistry of early solar system and the early Earth. Welcome Jason.

Jason Dworkin: Thank you, thank you for having me.

Jim Green: Well you know, how do we know what the early solar system was like and what it had to start with?

Jason Dworkin: The earlier solar system is a period in time that's a long time ago and is therefore very difficult to understand. We understand the early solar system from looking at spacecraft and ground-based observations with telescopes of our solar system of other star forming regions. We also use our understanding of geology, of the Earth and of other planets to extrapolate what the early Earth would have been like.

Jim Green: But there must have been a spark, something must have happened that changed the chemistry into life as we know it. What do we know about that period and what would have happened?

Jason Dworkin: The so-called spark of the origin of life is a massive question, which has been pursued for decades if not centuries. Understanding how life formed and then subsequently evolved into life as we know it, we can use evidence based on how biology works across organisms today looking at metabolic and genomic factors to understand what life has in common. We can look at the geology of ancient rocks on Earth, to look back and understand what kind of conditions would have been present.

Jason Dworkin: We can look at the formation of the solar system by a number of different means to understand what kind of conditions would have been present. My favorite method of understanding what materials would have been present on the early Earth or early Mars, what have you, is by looking at the rocks that were present at that same time, in the form of meteorites, asteroids and comets. Looking at the same materials that have the same chemistry, the same exposure.

Jim Green: So those things formed in space and became Earth, became terrestrial planets and even bombarded Earth after it came together. Well, where do these meteorites come from?

Jason Dworkin: The meteorites we get on the Earth come from a variety of places, some come from the moon, some came from Mars, some came from asteroid Vesta. The other ones, we don't really know. We can look at the chemistry and the mineralogy of these rocks and make guesses. Did they come from different kinds of asteroids maybe even comets? There are some that are solid chunks of metal that look like they came from the core of an asteroid, like for example, the mission Psyche will be going to an iron-nickel core of an ancient body, but knowing where a meteorite came from is a current mystery.

Jim Green: So how do we collect these meteorites? Where do we go to get them if they are falling on Earth all the time, how do we differentiate a rock that's been here on Earth for billions of years and a meteorite that just fell?

Jason Dworkin: Meteorites fall all the time everywhere, everyday. Most of the mass comes in forms of dust, interplanetary dust particles are picked up. For example, high flying airplanes can collect some of these and NASA has a great mission campaign collecting stratospheric dust from space. NASA and NSF [the National Science Foundation] have a joint program that goes to Antarctica every year, as does Japan, to pick up meteorites, which are on the ice. That's a fantastic place to get meteorites because, well, for one thing, meteorites tend to be black and ice tends to be blue-white, so that makes it easier, but also the Transantarctic Mountains bisect Antarctica and meteorites are carried by ice floes up against these mountains, the ice melts away leaving high concentration meteorites.

Jason Dworkin: Other places like deserts are a good place to find meteorites and they're a couple cases, two in fact, where an asteroid has been seen in space and then fallen to the ground and been picked up. It was actually, the fireball was imaged as the meteorite was turning from a asteroid into a meteorite.

Jim Green: Yeah, in fact, we have whole teams within NASA that once we alert them that there is something coming in, they get ready to go out and pick up the pieces and bring them to the lab. So it's a really fascinating opportunity for us to determine how early things in the solar system came together. Well what don't meteorites tell us?

Jason Dworkin: Meteorites invariably land on the ground and when they do so they become contaminated with biology which is present everywhere.

Jim Green: Earth biology?

Jason Dworkin: Earth biology, yes and understanding the contribution of Earth biology that overprints the organic compounds and other materials from extraterrestrial sources is a massive problem. Furthermore, with very few exceptions we don't know where meteorites came from. Is this piece of rock from a comet? From the main belt? All kinds of things that we don't know about just by looking at a rock that has been separated from its parent.

Jim Green: Well so there is one way to get around that, of course, and that is develop a mission and go out and meet them. Now you're a project scientist on a really exciting mission to an asteroid and it’s there right now and it’s called OSIRIS-REx. Tell us a little more about this fabulous mission.

Jason Dworkin: OSIRIS-REx is an acronym that stands for the purpose of the mission: Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer. At asteroid Bennu, it’s orbiting it today, to pick up a sample of rock from the surface, a large sample as these things go. 60 grams is the minimum and the capacity is 2 kilograms, which is a massive amount of sample for scientists to study.

Jim Green: So how long does it take OSIRIS-REx to get to Bennu? It’s got to run it down in the solar system.

Jason Dworkin: So OSIRIS-REx launched, September 8th, 2016, the 50th anniversary of the first episode of Star Trek, flew out around for a year in an Earth gravity assist—nice name—to change planes of the orbits to an inclination of six degrees. Then the following year, finally caught up with Bennu.

Jim Green: And it's been orbiting it ever since.

Jason Dworkin: The spacecraft has been, has had had two world records, one for the closest orbits, which we then broke with an even closer orbit, and consequently a very slow orbit, also the smallest object ever orbited.

Jim Green: Wow.

Jason Dworkin: We'll collect the sample bring it back to Earth in 2023, for worldwide analysis.

Jim Green: So what do you think Bennu will tell us about life here on Earth?

Jason Dworkin: Bennu is a fragment of the ancient solar system. By studying this fragment that has not been contaminated by landing on ice and dirt on Earth, been handled with an exquisite chain of evidence, we can learn the types of ingredients that were available on the early Earth that could have gone into life, and maybe understand more about ourselves by looking at Bennu.

Jim Green: So this Bennu it's as black as coal. I mean the images that are coming back from OSIRIS-REx are really exciting. What can we tell about its shape? How did it get the way it looks?

Jason Dworkin: Bennu is a rubble pile about half-kilometer across. It’s a collection of loose rocks that came from some sort of catastrophic breakup of its original parent body in the asteroid belt. These relaxed to this spinning top shape, this was actually observed on the ground of radar images largely from Arecibo and Goldstone that gave us a really accurate shape model of the asteroid so we knew what we were going after. It gave us the spin rotation, orientation, the length day, all these sorts of great things.

Jim Green: So now you've been at Bennu for a while, you’ve studied it in great detail and you've picked several sites to consider and now you've decided on a particular place on the surface to go after. How did that process go?

Jason Dworkin: One of the things that surprised us about Bennu was how rocky and bouldery it is, in our initial model we figured there would be these large sandy beaches that would make sampling the surface very, very simple. The spacecraft has a 3-meter-long pogo stick with like an old car air filter on the end, not literally an old car air filter. A highly designed piece of machinery that collects sample material by blowing nitrogen gas and collecting it.

Jim Green: Sort of like a vacuum cleaner?

Jason Dworkin: Indeed, the initial name for it was Muucav which is vacuum sort of backwards.

Jim Green: (laughs) Okay.

Jason Dworkin: Because it blows nitrogen gas in the vacuum of space and picks up dust. So we predicted large swarths of sand essentially that we can pick up.

Jason Dworkin: Well it turns out that there are big chunks of rocks, making navigation much more complicated than we had anticipated. Fortunately we have an impeccably well designed spacecraft and a top notch navigation team. So we were able to adjust our strategy to find four potential sampleable locations that we can get material from to bring back to Earth. We went through an extensive process of figuring out which one is the ones we can get to on the spacecraft safely, we can make sure we can navigate to precisely, that have loose regolith and are also the most exciting for science, and of those we found our number one and our number two site, which we've named Nightingale and the backup is Osprey, which are names of birds that live in Egypt. Bennu is the name of the asteroid, which is named after an Egyptian bird god.

Jim Green: So Bennu is really fascinating. Now it spins, what is the spin rate?

Jason Dworkin: A day on Bennu is 4.3 hours.

This artist’s concept shows the trajectory and configuration of NASA’s OSIRIS-REx spacecraft during Checkpoint rehearsal, which is the first time the mission will practice the initial steps for collecting a sample from asteroid Bennu. At a diameter of 1700 feet (510 meters), Bennu is slightly wider than the height of the Empire State Building.
Credits: NASA/Goddard/University of Arizona

Jim Green: Wow, and you're going to come to this in a way that then allows you to set down on it and suck up some material. That sounds really challenging.

Jason Dworkin: Yes and no. So it is in principle challenging but we worked for many, many years on developing the technology to make sure that we can do it safely. We only need to touch the surface of Bennu for five seconds, so the spacecraft does a free fall from a low Bennu orbit. Takes about 20 minutes because Bennu is such as small object, we touch the surface and then bounce off at minuscule speeds, a literal snail's pace, blow the nitrogen gas to collect the rocks and dust and then fire our thrusters and get out.

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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #13 dnia: Luty 17, 2021, 00:18 »
Gravity Assist: A Special Delivery of Life’s Building Blocks, with Jason Dworkin (2)

NASA’s Chief Scientist Jim Green, left, with NASA Goddard scientist Jason Dworkin. Credits: NASA

Jim Green: Yeah, that process is called “touch and go.”

Jim Green: So, one of the surprises then is that you didn't see dust fields that you were hoping for, and now you see a more of a pebbley field. What are some of the other surprises?

Jason Dworkin: I’d say the most surprising thing that we discovered is that Bennu is ejecting rocks. We had wondered, well, could Bennu be an extinct comet? And so we had a campaign looking for dust plumes. We didn't see any, but then we saw these surprising couple-centimeter rocks being spat off.

Jim Green: Yeah, like popcorn, just popping off the surface.

Jason Dworkin: Right. And we see this popcorn continuously, not every day, but many days. And we've seen particles that are ejected and leave Bennu, some that go into orbit and some that crash back down. Their orbits are stable for, for days.

Jim Green: So what do they think is causing that? The popping going on? Is it the heating of the water that's in the rocks that then some reaction explodes?

Jason Dworkin: That's one model, but it's not totally supported by the data. Another model, which is right now, well, there are two favorite ones right now. One is thermal cracking of rocks, that then, release energy and spit off rocks. And other one is, this area of the solar system has very fast moving particles, like bullets could hit the surface and then the gravity in Bennu is so small on the order of three to five micro G, which is similar to the sort of gravity experienced on the International Space Station. Very, very low gravity. And so a small energy can actually kick off a lot of rocks very far.

Jason Dworkin: The Earth should have been showered with meteorites like Bennu and like other types of asteroids and comets. Actually, since we've discovered that Bennu is emitting particles right now, and crossed the Earth, there is almost certainly somewhere, in September in the Southern hemisphere, there should probably be a very small Bennu meteor shower. We have teams trying to understand—

Jim Green: Oh, neat

Jason Dworkin: …to look for that. It won't be very big, but it's Earth-crossing asteroid that is emitting particles. So they're probably already hitting the Earth now.

Jim Green: Got it. Interesting.

Jason Dworkin: We just don't know what they look like.

Jim Green: Well, you know, the Japanese Hayabusa 2 mission is at a similar asteroid called Ryugu. Are they seeing any of the same phenomena?

Jason Dworkin: Ryugu seems to be, it's about double the size, a similar shape, but much, much drier. They see a very low level of, of hydrated minerals and not ubiquitous like we see on Bennu. Hayabusa 2 collected two samples and is on the way back to Earth right now. They collected... we won't know until the sample comes back, but perhaps as much as a couple hundred milligrams, maybe a gram, if they're lucky, we don't know. And we’ll, when the OSIRIS-REx sample comes back, we'll be able to do a face-to-face comparison to understand how these two different asteroids compare.

Jim Green: And we have an arrangement with the Japanese Space Agency, where are we going to actually trade samples. So this is really an important international cooperation to understand this asteroid population. So, isn't the thinking that it's old, like the origin of our solar system, it was there and pelted the Earth right after the Earth formed and then brought material to the Earth that's so important that perhaps started life?

Jason Dworkin: Yes. That's my interest in it, is to understand the chemistry that went into life, the chemistry of the early solar system by looking at these ancient objects, four and a half billion year old objects that have been relatively unchanged since their accretion and see what they deliver to the Earth and what they're delivering now.

Jim Green: When the samples come back, what kind of systems do you have in your laboratory? What kind of instruments are there to really be able to tease apart and answer the questions you want to know about them?

Jason Dworkin: My favorite part of OSIRIS-Rex of, in fact, sample return missions in general, just like the Apollo missions, we'll be able to use the best instruments around the world and better still instruments that have not yet been invented. So, 25% of the sample was being analyzed by the science team when it comes back. A half percent goes to Japan in exchange for Hayabusa 2 sample and also a discussion of orbital maneuvers and operations around the small bodies.

Jason Dworkin: 4% goes to Canadian Space Agency. But then the rest of it goes into an archive, mostly at the Johnson Space Center. The ANGSA program, which is now opening up samples from 50 years ago from Apollo. They analyze with bond and techniques, we'll be able to do similar things with, people who are not yet born answering questions that we haven't thought of, using techniques that are not yet invented. We can interrogate these samples.

Jim Green: So one of the things that you want to do then is, once you get the sample in the laboratory is understand what you have. What is the composition? So what do you expect to find?

Jason Dworkin: My interest is in things like, amino acids and their chirality, their left and right handedness, which is an observes amino acid to be asymmetric, to have a bias of left-handed, just like life. Looking for sugars, nucleobases or the DNA bases. Lipid-like compounds, organic acids, all kinds of the same sorts of chemistry that we see in biology, but in a sample that has been left alone by terrestrial biology and tightly controlled with a solid chain of evidence from construction, to sample recovery, to analysis.

Jim Green: Yeah, that sounds really fantastic to be able to tease that apart and look at the details of the composition. Also, as you mentioned, these are hydrated samples, so that means they're carrying water. And to understand the amount of water that they carry is important to know.

Jim Green: So we're really looking forward to these samples returning. So what's the schedule? When will they get back to Earth?

Jason Dworkin: The first thing we asked to do is finish surveying the prime and backup sampling site. That happens in the spring. And then we do rehearsals to make sure that we can fly the spacecraft to just above the sampling sites. And then we actually do the sampling. And that happens this year.

Jason Dworkin; After sampling, we have to wait for a departure window because as there's a launch window, there's also a departure window when the planets align so we can bring the spacecraft back. The spacecraft comes back, to Utah, September 24th, 2023, it's a Sunday, just in the morning, just before 9:00 AM. After that, the sample comes to Houston for the preliminary examination period of six months followed by a worldwide distribution.

Jim Green: And indeed that will spark a whole new series of questions, after we get some of the fundamental answers we're seeking. Well, do you think we are alone in the galaxy? Well, do you think we are alone in the galaxy?

Jason Dworkin: I would love not to be alone. I have opinions based on the ubiquity of organic compounds, that it seems like life might be easy or easier than had been believed, but it still has been a challenge to come up with the exact mechanism of the origin of life in the laboratory. I would love to find non-Earth life in my lifetime. Right now we don't understand life that isn't Earth life. Seeing it's somewhere else. Seeing it on Mars, Enceladus, Europa, where have you, would be, the discovery of a millennia.

Jim Green: Well, it sounds like you're in favor of the concept that we'll find life in the solar system first, before we find it on some exoplanet.

Jason Dworkin: Well, finding an exoplanet would be challenging to verify. At least--

Jim Green: Right, they're so far away.

Jason Dworkin: And so we could look for something that is obvious life. Obviously you could look for technology, but I want to understand the chemistry and so we don't have a telescope good enough to tell us what the codons are in extraterrestrial biology without getting it into a laboratory.

Jim Green: Yeah, that's right. So bringing back the samples is where it is at. Well, Jason, I always like to ask my guests to tell me what was the event or person, place or thing that really got them so excited that they became the scientists they are today. And I call that event a gravity assist. So Jason, what was your gravity assist?

Jason Dworkin: My gravity assist was actually a chain of events starting when I was very young, and I thought dinosaurs were awesome. I wanted to know, "Where did dinosaurs come from?" That meant I had to learn about the origin of life. So I had a little book for elementary school kids on dinosaurs and like, things of that sort. And then that evolved into understanding about the solar system.

Jason Dworkin: Then I saw a PBS show on the origin of life and got excited about that in high school. But I liked chemistry. I had to do a science fair project in 10th grade, which is biology. And I didn't really like biology. I wanted to do chemistry. I thought to myself, "What part of biology is really chemistry? Oh, I will do my science fair projects on the original life." That hooked me up with a—

Jim Green: Science fair. Wow.

Jason Dworkin: Exactly. That hooked me up doing a research internship that The University of Houston, that turned into another project, that turned into a paper that sent me to college and then graduate school. And then I got a postdoc at NASA, where I could then turn my interest in the origin of life, from understanding what happens on the ancient Earth to constraining the lack of information by looking at the stars and studying more and more constraints from looking at the chemistry of the interstellar medium, to then the chemistry of meteorites, even more constrained than finally the chemistry of a sample from a specific object.

Jim Green: So that is all real important and fundamental science and you were right there at the right time to be able to use the tools and capabilities. So that's a fantastic story. Well, Jason, I really appreciated talking to you today about meteorites and their connection to life, in particular here on Earth. So thanks so much for coming in.

Jason Dworkin: It's been a pleasure. 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.

Jim Green: Since we recorded this episode of Gravity Assist, OSIRIS-REx has finished surveying the mission’s primary and backup sampling sites and it has completed its first rehearsal of the sample collection event. The mission will run one more rehearsal before it makes its first sample collection attempt later this year. Good luck, OSIRIS-REx!

Lead producer: Elizabeth Landau
Audio engineer: Manny Cooper


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Odp: [NASA Gravity Assist] Searching for Life
« Odpowiedź #14 dnia: Luty 26, 2021, 01:00 »
Gravity Assist: Deep Oceans in Deep Space, with Morgan Cable (1)
May 22, 2020

The Europa Clipper mission will conduct an in-depth exploration of Jupiter's moon, Europa, and investigate whether the icy moon could harbor conditions suitable for life. Credits: NASA

Some of the most fascinating targets in the search for life in our solar system are moons of giant planets. Did you know If you had wings, you could fly on Titan, a moon of Saturn? Did you know that Europa, a moon of Jupiter, is thought to have more water than Earth under its icy shell? NASA is planning to send spacecraft to both of these places in the coming years to look for signs and ingredients of life. Another intriguing moon of Saturn is Enceladus, which is spouting a wall of water nearly 100 miles high. Morgan Cable, an astrobiologist at NASA’s Jet Propulsion Laboratory, discusses these wondrous worlds, the exotic locations where she has done fieldwork, and the research she has done on the chemistry of life that could thrive on Titan. 

Jim Green: Is the Earth the only ocean world in our solar system? No, it’s not. There are moons around giant planets with enormous amounts of water under their ice shells.

Morgan Cable: If we were to land in the right spot with the right instrument, we could find life even if there were only trace amounts of it there.

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

Jim Green: I'm here with Dr. Morgan Cable and she is a research scientist and group supervisor in the astrobiology and ocean worlds group at the Jet Propulsion Laboratory. Welcome, Morgan.

Morgan Cable: Hello! Thank you so much, Jim. I'm so happy to be here.

Jim Green: You know, when we look in the outer solar system at Jupiter and Saturn, we see these spectacular ocean moons. How come our Moon isn't an ocean moon?

Morgan Cable: I know. Why doesn't Earth have one, huh? Well, it's actually because of science and because of physics. And it has to do with the fact that some things boil off more quickly and turn into what we call the gas phase, vapor, than others. And so as our solar system was forming, things that melted or boiled off more easily tended to move further out from our Sun. And so that means that things like metal and rock tend to be concentrated more closer to our sun like Mercury, Venus, Earth, and Mars.

Morgan Cable: And then as you step further and further out in our solar system, now you get to these gas giants that have a lot of these volatiles. So Jupiter, Saturn, those systems have a lot of things like methane, water, ammonia, and those are what coalesced and congealed and formed these moons. And so it turns out there's a lot of water that is liquid further out than we ever thought when we first started exploring the solar system.

Jim Green: You've been analyzing data from Cassini, looking for chemical signatures of life. Now Cassini orbited Saturn for about 13 years and observed some really exciting moons. Tell us about your work on the moon Enceladus.

Morgan Cable: Oh so Jim, Enceladus, as you know, is one of my favorite places in the solar system. It is one of the smaller moons around Saturn and in our solar system in general, but small can be mighty and Enceladus has absolutely proven that to be true. I was very fortunate to get involved in the Cassini mission right near the end, around the last two years of Cassini's travels in the Saturn system and over Cassini's mission, we made some very surprising discoveries at Enceladus. We found that it has this giant plume of material, mostly water, spewing out of its south pole. This comes out of these four giant cracks that we call the tiger stripes. They're massive. They're about, let's see, 120, 130 kilometers long. What is that? Like three marathons, I think. And they're about a marathon spaced apart, about 42 kilometers. Jim, you know 42 is the answer to everything.

Morgan Cable: Yeah, out of these cracks is coming liquid water but also some really tantalizing evidence of the ocean below. We find salts, some salts that are similar to Earth's oceans and we've also found organic molecules, not just small tiny ones. We found ones as large as the instruments aboard Cassini could detect. Now when we built Cassini, it was meant to study the Saturn system, but at that time we didn't know there was liquid water out that far. We had no idea there was complex organic chemistry going on and so its instruments weren't designed to look for life. But we're hoping that a future mission might be able to answer that question in the Saturn system one day.

Jim Green: Well those tiger stripes, as you say, are really exciting. They only exist in the Southern hemisphere and we believe they're open all the time and so water is constantly pouring out of them. Now think about that. As you said, they go up 100 or 150 kilometers. That's almost like a wall of water going from the surface of the Earth up to space station. Well, we don't see that here on Earth. So that moon is doing an incredible job of showing us that there's huge amounts of water in these ocean worlds

Jim Green: Well, there's another moon of Saturn that may also hold great promise to where life might exist and that's Titan. So what aspects of Titan really excites you and other astrobiologists to be looking for life there?

Morgan Cable: Oh goodness. There are so many fascinating things about Titan. Did you know it's bigger than Mercury?

Jim Green: I did.

Morgan Cable: Yeah. And it's actually, if you count its atmosphere, it is the largest moon in our solar system. Its atmosphere extends over 1,000 kilometers. It's huge.

Jim Green: That's cute. Yeah. I hadn't thought of that, but indeed that would make it bigger than Ganymede, which is our largest moon.

Morgan Cable: You're right. But we'll let Ganymede have a win because Titan is so fascinating. It doesn't need to take that title of largest moon.

Jim Green: No it doesn't.

Morgan Cable: The pressure at standing at the surface of Titan, if you were there standing at the surface of Titan, it will be about if you took a breath and went down to the deep end of your swimming pool. That would be about the pressure that you would feel and because that atmosphere is thicker and the gravity is less, it's about one-sixth, one-seventh that of Earth. If you were standing on the surface of Titan and you had wings and you flapped them, you could fly, which I just think is very cool.

Morgan Cable: But in terms of astrobiology, there are so many fascinating things about Titan. Titan's atmosphere is made of nitrogen with a little bit of methane and because of solar radiation and a bunch of charged particles from Saturn's magnetosphere that whack into these molecules, it splits them up and they recombine into pretty much any combination of carbon, hydrogen and nitrogen you can think of.

Morgan Cable: So if you have your chemistry set at home, like I do, any listeners, if you have that, try to make sort of any combo. Small tiny molecules to really massive ones, the size of proteins. We have found all of those, at least some evidence of them in Titan's atmosphere and we think they're raining depositing down on the surface too. And so Titan seems to have all of this organic goop. We call it a massive chemical inventory. And this is really exciting for us because a lot of these molecules, if you make them in the lab in a way similar to how they're made in Titan's atmosphere, if you make those, we call them tholin. Actually, Carl Sagan was one of the first scientists to make these. So he coined the term. It's from the Greek tholos, which means muddy or not clear, which I love because they're muddy color, the reddish brown.

Morgan Cable: But it's also not clear exactly what's in them because it's so complicated. But if you take that tholin and you dissolve it in liquid water, you make amino acids like that. You make a bunch of other prebiotic molecules, things that life as we know it uses. And so since Titan also, most people don't realize this, Titan has a liquid water ocean underneath all the cool stuff on its surface. So if any of these organic molecules are getting sucked or pulled down into that ocean, you could have some really fascinating chemistry that could lead to life as we know it.

Jim Green: Well, there's an upcoming mission that you're also involved in. It's called Dragonfly and that is a quadcopter.

Morgan Cable: Oh, I am so excited to be a part of this mission. Yeah, so Dragonfly, actually Jim, it technically it's an octacopter because it has four sets of two counter-rotating blades.

Jim Green: Oh that's right. Okay.

Morgan Cable: Picture the size of one of our big Mars rovers, like Curiosity or the Perseverance, the Mars 2020 rover. It's that size, but take off the wheels and put on two skis like you're going skiing instead. And then it's got these, like I said, these four sets of two helicopter blades that are big. They're about the size, one of them, of my arm. I'm not a super large human, I'm like five-foot-two but you can picture that. These are big. That's just one blade of this giant system. And because of Titan's atmosphere being so thick, it's actually more efficient to do these flying hops that Dragonfly is planning across the surface than it would be to drive like our traditional rovers. This allows us to sample a lot of different places of Titan's really diverse terrain that it has, features across the surface.

Jim Green: So how many hops will it do and how far will it go?

Morgan Cable: We don't have an exact number of hops explicitly stated. I think we're going to start by collecting samples first when we land and do as much as we can and then we'll see how far we can get during the nominal mission lifetime. Dragonfly is going to be powered and planned, for at least three years, hopefully longer than that, and we are hoping to do a lot of really cool science along the way.

Jim Green: That sounds great. I'm really excited about that mission. Now that will launch in this late decade or early next and then land on Titan and then radio its data directly back to Earth. Now I know you've helped discover a variety of minerals, but one in particular, a hydrated mineral that might actually exist on Titan. What is it and how did you do that?

Morgan Cable: Oh, this is so cool. Okay, so I'm a chemist and I work in a lab and a lot of the laboratory work that we're doing can help inform or be informed by a lot of the space missions that we have going out to visit these worlds.

Morgan Cable: And what we've done is we've started taking a lot of these simple molecules that we know are abundant in Titan's atmosphere and we think are solids on the surface. Now, these are things that you have to wrap your brain around what it's like on Titan to understand because most of these are either liquids or gases at Earth conditions, things like acetylene or butane or ethane.

Morgan Cable: These are actually flammable or sometimes hazardous gases. But around Titan, there's not a lot of oxygen. It's all trapped as water, so it's frozen. We just basically dissolve things together or mix them together at these cold temperatures to see what happens. And about half the time, we get surprised.

Morgan Cable: Now one of these minerals you talked about, this is, we call it a hydrated mineral because that’s the role it's taking on Titan. Here hydrated minerals means they have water that are liquid trapped in their crystal structure. But on Titan, water is frozen solid. It's not a liquid.

Morgan Cable: Instead, you have methane and ethane that form the liquid phase and just like water does on Earth, they form clouds. They rain or even snow. They carve gullies and features on Titan's surface and they pool in lakes at the poles. Now what we found is one of those molecules, ethane, liquid ethane, if you mix it together with a rather hazardous compound, benzene, here on Earth, we do this very carefully in the lab.

Jim Green: You better.

Morgan Cable: Yeah. When you mix these two together, it actually makes a new structure where the benzene molecules rearrange to let ethane inside of its crystal structure. And so it's just like a hydrated mineral on Earth but made of different stuff.

Jim Green: Wow, that sounds fascinating. So in reality, looking for life on Titan is not going to be life like us because we use water as a liquid because on Titan, as you say, water is in solid form. But methane as a liquid, that's a completely new dimension.

Morgan Cable: Well, so there are two different ecosystems on Titan. Right? That's a really fascinating thing. There's this liquid methane and ethane on the surface, and so that would be life as we don't know it, but don't forget Titan still has that liquid water ocean deep down inside. And so if we were able to, say, find a place where some of that liquid water ocean has squirted up and frozen on the surface, we might be able to search for life as we know it too.

Morgan Cable explores the Pisgah Lava Tube in California’s Mojave Desert. Credits: Morgan Cable

Jim Green: Wow.

Morgan Cable: That's one of the reasons I'm so fascinated by Titan because we could find potential for two completely different genesis. Genesi? What's a plural of genesis? Of life. It would be really cool and so hopefully Dragonfly will give us some hints that may be able to tell us whether or not that's happening.

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