Planetary Radio: Space Exploration, Astronomy and Science - Life in the Extreme

Episode Date: March 10, 2003

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This is Planetary Radio. Matt Kaplan welcoming you to this week's edition of our show. Everywhere we look on Earth, even in the most extreme environments, we find life. Not just life, but whole ecosystems where scientists once thought it impossible. Our guest this week, NASA planetary scientist Chris McKay,

has been to an amazing number of these extreme locales, always wondering if the even more extreme conditions on Mars have allowed life to eke out a similar existence. He has devoted his adult life to that question, and he'll share his thoughts with us. Later on What's Up, Bruce Betts will put us between a rock and a hard place with this week's trivia question. But first, Emily provides some background for our discussion of the Martians that may be.

I'll be back with Chris McKay in a minute. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, how could there be life on Mars if there's no water or air? Mars is a pretty inhospitable place. The daily surface temperature swings from a freezing minus 5 Celsius during the day to a desperately cold minus 85 at night. The atmosphere is so thin that except at the frigid poles, any water or ice exposed on the surface would rapidly boil away into vapor. This may not always have been the case. There's lots of

geological evidence that Mars could once have been a warmer and wetter place. But under present conditions, Earth-like life exposed to the surface of Mars would be instantly freeze-dried. So even if life once existed on Mars, it doesn't seem likely that there can be anything living there today. At least that's what we used to think. But recent discoveries of organisms on Earth called extremophiles have given some scientists hope that there could still be

life not on Mars, but in Mars. How is this possible? Stay tuned to Planetary Radio to find out. Chris McKay, thanks for joining us on Planetary Radio. My pleasure. What question would you most like to know the answer to before you shuffle off this mortal coil? Well, the question that really motivates me is the question of life. Is life on Earth alone?

And by life, I mean all of life is life on Earth alone. And by life, I mean all of life. We know now that all life on Earth forms the same life set, I call it. We're all descended from a single common ancestor. We all are related on this planet. I'd like to know if there's anything out there that's not related to us. Now, this is an interesting thing for a guy who was trained as a physicist and a mechanical engineer to pretty much devote his life to, and that's pretty much what you have devoted it to. Is that fair? That's a fair assessment.

I've spent most of my time going out on places on Earth which are extreme in terms of the connection to Mars and thinking about how we might search for evidence of life and for this second genesis, this other type of life on Mars. There are some wonderful pictures of you here and there on the web, and we will post links to some of these sites that mention you and your work on the Planetary Society website along with this radio show. But there's a great shot of you by what looks like this lonely little shrub in the middle of Mongolia, many others of you in parkas in the Antarctica or the Arctic.

Why go to these far-flung, forlorn places? Well, it seems to me that the best chance we have of finding another type of life in the near term is on Mars, where we have good evidence that at one time Mars had water and possibly had a biosphere. So what I've been doing is going to places on Earth that are like Mars. And when I say like Mars, I really mean two things, cold and or dry. Hopefully cold and dry, but some of the dry places, like the deserts, tell us a lot about how life survives under dry conditions. And also in the polar regions, we learn how life survives under cold conditions. And these two dimensions of extreme environments, the cold dimension and the dry dimension,

I think are the challenges that life on Mars had to face. And so by studying how life on Earth copes with these challenges, the coldness and the dryness, I think we learn how to appreciate how life on Mars might have done it and where we might find evidence of that life when we go to Mars to search for it. Have the last 20 years of this kind of research by you and others given you some encouragement regarding life's amazing tenacity? I think there has been a resurgence of interest in exploration in these life and extreme environments.

And over the last 20 years, there's really been a lot of discoveries of ecosystems, entire systems, like in the deep-sea vents and in Antarctic lakes, living in places that we wouldn't really have expected them to be living in. These aren't just isolated organisms. I want to stress that these are actually ecosystems, and that's an important point because when we imagine life on another planet, what we're imagining there is an ecosystem, not just an odd organism here or there. A lot of species, or at least several species, that depend on each other to form this system. Exactly.

Finding life pretty much everywhere we look on Earth is inspiring, it's exciting, but it is not direct evidence of life on Mars. And I wonder if that troubles you or if it just says to you, we need to do more. Well, you're right. When we look at life on Earth, we're just seeing one example. And hopefully what we can do is use that as a basis for the search for life on Mars. But our target really is life on Mars. At least that's my target.

Now, there is a lot to be gained scientifically by studying life on Earth. And this is true. And we contribute to that scientific question. But ultimately, I want to use that knowledge of life on Earth to search for life elsewhere. So the real goal here for me is to find aliens, in this case little tiny microscopic aliens on Mars, but something that's different, something that's an alien life form compared to Earth life. Nonetheless, we still use Earth life as the example to base our search on, partly because we have no other choice.

We have only one example of life. So of necessity, our search for life elsewhere is rooted on our knowledge of that one example. And who knows? I mean, we've talked about the concept, the theory or hypothesis maybe of panspermia on this program. Would you be terribly shocked if we found life on Mars and if it looked a lot like primitive life on Earth? In fact, this is a distinct possibility that we'll go to Mars, we'll find life, but we'll find that it is not alien, that they are related to us, that they in fact are part of the same life set that we have here on Earth, that life on Mars shares a common origin with life on Earth.

That would be an interesting result. Scientifically, it's not quite the profound philosophical result that finding a true alien life form would be. But from what we know about Earth and Mars, that's a distinct possibility. We may find that life from Mars came to Earth and vice versa, that the planets exchanged biological material and they share a common biological history. I would prefer that that wasn't the case, that when we go to Mars, we'll find organisms frozen in a permafrost long since dead, but we'll be able to study their genetic and chemical makeup

and realize that they really are different. They really are alien, different from us. Yeah, I can't imagine anything much more exciting other than finding their leftover furniture or buildings or something. You have been wrapped up in this planet, the Red Planet, for a long time, at least back to the mid-'70s. I mean, the case for Mars, the red planet, for a long time, at least back to the mid-70s. I mean, the case for Mars, the Mars underground, even helping a little bit at the very beginning of the Mars Society, which you're still affiliated with, as you are the Planetary Society. Why,

when, I guess I should start by saying, when did you become so fascinated with this planet? Well, I really got interested in Mars when Viking landed in 1976 and started sending back data. This was our first real landing on Mars, the first glimpse of the surface of that planet. I was still in school at the time, and I remember the results coming back. And in a nutshell, what it said was, here's a world a lot like Earth. It has all the elements needed for life, and yet there doesn't seem to be any life here. And I thought that was a very interesting and curious result.

I thought I'd just look into it for a little while. Here now, 20 years later, I'm still looking into it for a little while. It turns out to be a deep mystery, the whole question of why do planets have life? What kind of life? What are the limits of life of why do planets have life? What kind of life? What are the limits of life? Why does Earth have life? When did Earth get it? Where did it come from? It turns out that to understand the question of life on Mars, you have to roll back into all these other questions, too, and I just got deeper and deeper and deeper into this question of planets and life, and I'm still deep inside of it.

There were, of course, some people after the Viking mission failed to find really superb evidence for life who said, okay, case closed, that's probably the end of it. And things are turning around. The very newest findings about the possibility of water on the surface of Mars, perhaps protected by ice? And I'm sure that's a story you've been following. Right. Well, when the Viking results did come in, there was some people who thought, well, this is it. There's no biological interest here.

But as you mentioned, the physical evidence of water in its past history, water even present today, albeit as ice and snow, I think indicated that there was more to the story possibly. So we're still investigating that. I think it's going, not surprisingly, at least in two directions. One is maybe early in Mars history it had a wet, Earth-like period, and life could have been present then. It had a wet, Earth-like period, and life could have been present then. And maybe today there still are in limited places and special little niches, water, snow melt, ice melt, liquid water occasionally,

and that could be supporting life. It's pretty hard to imagine that, but it's not impossible. We do need to take a quick break, Chris. We'll be back right after this. We hope you'll stay with us and with Chris McKay in the Space Science Division of the NASA Ames Research Center here in California. Planetary Radio will continue in just a minute. This is Buzz Aldrin. When I walked on the moon, I knew it was just the beginning of humankind's great adventure in the solar system.

That's why I'm a member of the Planetary Society, the world's largest space interest group. The Planetary Society is helping to explore Mars. We're tracking near-Earth asteroids and comets. We sponsor the search for life on other worlds, and we're building the first-ever solar sail. You can learn about these adventures and exciting new discoveries from space exploration in the Planetary Report. The Planetary Report is the Society's full-color magazine. It's just one of many member benefits. You can learn more by calling 1-877-PLANETS. That's toll-free, 1-877-752-6387.

And you can catch up on space exploration news and developments at our exciting and informative website, planetarysociety.org. The Planetary Society, exploring new worlds. Planetary Radio continues in a conversation with Chris McKay, planetary scientist who works at the NASA Ames Research Center in California, but doesn't stay at home very much. He's in Mongolia, Antarctica, Siberia, studying those extreme places on Earth where almost invariably you can find life. And Chris, again, thanks for joining us. I do have one more Mars question for you before we move on. A couple of years ago, I think, you made an interesting suggestion,

and that was that while we're extremely curious about life that is indigenous to Mars, maybe it's time to consider, as we consider sending rovers and other probes there, maybe it's time to consider sending something from Earth, like maybe a flower? Right. Well, we all are familiar with the paintings of bases on Mars, human bases with explorers, and often these images show greenhouses. And the logic there is that if we grow plants on Mars, they'll provide life support, and that that will allow us to do more extensive exploration when humans are present. And this is certainly the case, that when humans go to Mars,

they will bring other life forms with them, and particularly plants in a greenhouse. So the logical question is, well, how do we get ready for that? What's the first step? And so I've been arguing, along with many other people, that the first step is to put a little tiny greenhouse on a near-term mission, a little tiny greenhouse with maybe just one or two plants inside it, just to see how things grow. There's a lot of differences between Mars and Earth, gravity, radiation, the nature of the soil, and so on. And it's not obvious, although we're optimistic, it's not obvious that plants will necessarily grow well on Mars. We need to test that out long before we rely on a greenhouse to provide essential food and life support.

So my concept, our concept, is to send to Mars a little tiny greenhouse with a plant in it. I call it a flower just because that's such a powerful symbol. Imagining a flower blooming on Mars being recorded by a camera and the images coming back to Earth, I think would be very engaging for the public and even for the science community. But the real scientific goals of this would be to explore the possibilities that we could grow plants on Mars, and this is an essential part of virtually all concepts for eventual human exploration. You have written about, well, sort of the opposite end of the spectrum from growing one flower on Mars,

and that is the idea of terraforming, turning Mars into a place that would be much friendlier for Earth life, including humans. Does it still seem like this is going to be practical someday with technology perhaps somewhat advanced beyond ours? Well, I think if we look at Mars' history, we can see that in the past it had a biosphere, possibly. It obviously had water and a thicker atmosphere. We think it might have had a biosphere. So in a sense, what I'm arguing is let's bring back that biosphere. Now, if there's Martian life still on Mars, dormant or in the subsurface,

then it would make the most sense, I think, for the Martian biosphere to be composed of these Martian organisms. But if there is no Martian life, or if Martian life turns out to be the same as Earth life, then the Martian biosphere of the future could be composed of Earth life as well. Either way, I think Mars should have life in its future. It should once again have a biosphere. We could bring it back to life, restore the biosphere that it once had, if it once had one, and generally make, I think, an advancement in terms of life in our solar system.

It really has this question, in a sense, has two components. One is a science question, can we do it? And the other is a more ethical, philosophical question, should we do it? I've been working on both of those, and I think the answer to the can we do it is probably yes. Everything we know suggests that we could warm up Mars and bring back the habitable conditions it once had. The question of should we do it, of course, is not a scientific question. My own personal answer to that question is yes.

Mars with a biosphere, with life, once again, would be, I think, an amazing thing. The planet today is amazing as well. But I think it would be even more amazing and even more interesting if it had its biological legacy restored. Sounds like kind of a win-win situation even if the planet does turn out to be

long dead. Let's say that that happens, would be a sad thing to learn, but an important thing. Where would you look next in the solar system? If Mars didn't have life, or if the life there was just the same as us, the next place to find an alien life form, a second genesis, something different, would be, I think, Europa.

There, in the ocean that we think exists underneath the icy surface, there may be life there. And the chances of that life sharing a common origin with Earth slash Mars maybe is much less. And so if there was a second genesis and we don't find it on Mars, maybe we'll find it on Europa. And so much harder to reach for tourists. Much harder to reach. It's a long way out there. There's dangerous radiation fields from Jupiter.

It's a much harder search on Europa. Then when you reach there, you might find stuff on the surface or you might have to drill down. It's just a much more daunting task and much harder to imagine a direct role of humans in the search for life on Europa than on Mars. Let's move even further out in the solar system, at least one gas giant farther out, to another moon, a moon called Titan. And you have an article that's going to be appearing in the next issue of the Society's magazine, the Planetary Report, about that moon

and some exciting research, unprecedented research, that's going to happen there pretty soon now. Right. We have a spacecraft en route to Titan and Saturn, the Cassini orbiter and the Huygens probe. It's a joint NASA-ESA mission. NASA built the Cassini orbiter, and the European Space Agency built the probe that will go into Titan's atmosphere. And this mission has been flying through space for years and is scheduled to reach the Saturn system in late 2004. The probe will enter the atmosphere of Titan in January 2005, and it will fly through that atmosphere and do a series of

analyses on the nature of the organic material and composition and temperature. Titan is very interesting to us because it is the only moon in the solar system that has an atmosphere. It's the only atmosphere other than Earth that's dominated by nitrogen, so in that sense it's like the Earth. It also has in its atmosphere organic reactions, organic chemicals being produced by sunlight, producing a brown haze material. And many scientists think that this set of reactions, going from methane and nitrogen into these organic molecules, could be telling us the steps that might have led to life on our own planet billions of years ago. So I suppose this is a little bit like those experiments of the late 40s, early 50s, I

think, where the scientists put some gases in a glass tube and added some electricity and came up with some of these types of organic compounds. Precisely. We think that incense tightens the atmosphere. It's a natural example of these kind of prebiotic reactions that were first done in the 50s, and people have been continuing with them since. And many people think we're a key step to the origin of life on Earth. Chris, we are just about out of time.

Seeing as how you were probably not going to make it up there to Mars for a few more years at least, are you going to continue your research in the extreme places on Earth? Definitely. I leave in a couple weeks, in fact, for what we think is the driest place on Earth, the Atacama Desert in Chile in South America, to study the organisms there. So, yeah, waiting for the trip to Mars. We'll continue to go to these dry and cold places on Earth. Okay, so here's the most important question of the interview.

What's the best thing for chapped lips? I don't know. I guess chapstick works pretty well. Chris McKay has been our guest on Planetary Radio. He is a man of extremes, and we'll be returning to them, as you heard shortly. But when he's at home, he's often found at the NASA Ames Research Center here in California, working in the Space Science Division. Planetary scientists eager to learn more about our solar system and the secrets that it holds.

Chris, again, thanks very much for joining us on Planetary Radio. My pleasure. I'm Emily Lakdawalla, back with Q&A. Though life on Mars' surface would get freeze-dried and sterilized by solar radiation, there is a place on Mars where life could possibly still exist, buried beneath the surface inside rocks. How can this be? In the last few decades, scientists interested in life outside the Earth have been studying a type of Earth organisms called extremophiles. Extremophiles are organisms that are adapted to extreme conditions of temperature, pressure, acidity, or salinity.

Some extremophiles live in deep sea vents, surviving without sunlight in near-boiling, highly acidic water. Others live inside Antarctic ice sheets. Most interesting for Mars, though, are microorganisms that have been discovered living inside rocks. Living microbes have been discovered in rocks as far as three kilometers below the Earth's surface. These microbes need no sunlight. They survive by metabolizing hydrogen and carbon dioxide gases released from deeper in the Earth. Looking again at Mars, the rocks two or three kilometers below the surface don't look like a bad place to live. At this depth, the rocks are warm enough that there is probably liquid

groundwater and the thick crust of rocks above would protect microbes from harmful solar radiation and the freeze-drying action of the thin atmosphere. Does this mean that there is life on Mars? There's no way to know for sure until we go there and look for it. Got a question about the universe? Send it to us at planetaryradio at planetary.org, and you may hear it answered by a leading space scientist or expert. Be sure to provide your name and how to pronounce it, and tell us where you're from.

And now, here's Matt with more Planetary Society's Director of Projects, Dr. Bruce Betts, joins us for What's Up. Bruce, welcome back. What's up? Thank you. I am skipping with excitement about today's show. First, we've got our big planets up in the sky. Look in the evening for Saturn and Jupiter. You can see both of them in the early evening. Saturn practically overhead in the early evening. Jupiter overhead by later in the evening.

Jupiter really, really bright. It's the brightest thing you're going to see in the evening. Saturn above Orion. I had the telescope out last night. Jupiter was spectacular. Looked great. Excellent. And you can also remember, see very often some of the Galilean satellites of Jupiter. The moons appear like little dots in a small telescope. Even binoculars, if you hold them steady enough, will look like

little stars to the side of Jupiter, and you can watch them move from night to night. In the morning, you can see Venus before dawn, extremely bright in the east. Mars considerably to its upper right now and much dimmer and reddish. And we move on now to this week in space history. March 13th, 1781. Going back a ways for William Herschel discovering Uranus. Long time back. We also had March 16th, 1975, Mariner 10's third Mercury flyby. Remember Mariner 10, an interesting mission that never went into orbit around Mercury,

but did three flybys, and actually only saw half the planet, even in doing that. So we look forward to some future missions coming up, including Messenger, in a few years that we'll see the whole planet. Now it's time for Random Space Fact! A Jupiter day. The time required for the planet to rotate once, is only about 10 hours long. Jupiter has the shortest day of any planet in the solar system. And yet, it's big. That thing is really trucking, isn't it?

It's moving, because yes, of course, the largest planet in the solar system. And so if you're up on those cloud tops, floating around, you're moving. Do I remember correctly that Jupiter, because it's big and liquidy and gaseous, that it's spinning so fast that it actually is not quite a sphere. It's actually more of a, what would you call it, an oblate? What is that word? It's an elliptoid. No, it's not.

It's not an elliptoid. I like that. I made that up, but it's close. You've stumped me once again. We are from the planet elliptoid. No, it's not. It's not an elliptoid. I like that. I made that up, but it's close. You've stumped me once again. We are from the planet elliptoid. People probably don't know that Matt just asks random things and tries to stump me every week. Anyway, yes, let's get back to the science, which is, yes, it flattens out. All of the planets do it, actually.

Even Earth is broader at the equator than at the poles because of the action of the spinning, sort of throwing that middle material outwards. But the gaseous planets like Jupiter and Saturn, Uranus and Neptune, really it's a very strong effect, especially Jupiter spinning so fast. Now, this actually has an interesting relation to something, though you knew it, you knew not what you said, but it has an interesting and complex relationship to an interesting story in the news right now, which is some studies of Mars Global Surveyor data and also Mars Pathfinder data

that have shown much more conclusively that Mars has a liquid core, at least a liquid outer core if not a completely liquid core, and they're doing that through really some pretty crazed observations using the radio tracking of the spacecraft to look at its exact orbit and how it's tweaked from just a standard ellipse based upon the shape of the planet. And they see there's also these other effects that actually smush the planet out in different directions. And one of them is that you have the gravity of the sun pulls a little more on the near side of the planet and a little less on the far side. So the near side is a little stretched out, and so is the far side. And that's kind of fundamental to what they're measuring.

And basically they're seeing the planet is more stretched out than you could get if it were solid all the way through. So some liquid in there. If you want to know more, it's a complex thing, go to planetary.org, and you can read more about that. And a few of you may have noticed in the last few days there was an article in the New York Times in which our co-host here of What's Up, Bruce, was quoted on this very subject, this possibility of a liquid core on Mars. Let's move on quickly to the trivia question. All right, last week's trivia question,

what gas is primarily responsible for the bluish color of Uranus and Neptune? The answer being methane. Methane absorbs red light and so ends up looking blue. Turns out they don't actually have that much methane percentage-wise, but it dominates the visible color, and that's what we see. So how do our people out there do in radio land? Boy, what a smart bunch of people, or at least they sure know how to use those search engines, because virtually everyone who entered this time, and we had a lot of entries, got it right. Some also included the proportion of methane in the atmosphere of those gas giants.

Our winner, though, was Fred Pallarito of Raytown, Missouri. Congratulations, Fred. You'll be getting that Carl Sagan Memorial Station t-shirt. Congratulations, Fred. You'll be getting that Carl Sagan Memorial Station T-shirt. Congratulations. And now for the opportunity for this week. What is the nickname of the relatively large rock a few meters from the Viking Lander 1 spacecraft? This was a very photographed rock. A lot of Viking Lander 1 pictures you look at will show it.

It's about two meters in size and a few meters away from the spacecraft. And the scientists gave it kind of a fun nickname. What is that? I want to make sure people understand that Bruce said Viking 1. We're talking back in the mid-'70s, folks, not more recently when a whole bunch of rocks near a certain probe got kind of crazy names. Exactly. So go to planetary.org, follow the links to Planetary Radio.

You can find out how to enter, and we look forward to seeing your entries. Bruce, we're out of time. We'll talk to you again next week. All right. Remember, people, when you look up in the sky, think good thoughts. And remember, thank you. Good night. Bruce Betts, the Director of Projects for the Planetary Society,

with us every week here on Planetary Radio. Next week on Planetary Radio, we'll talk with Dan Wertheimer on the eve of his departure for Puerto Rico, home of the Arecibo radio telescope and our SETI at home search. In an unprecedented effort, the great antenna is about to take a detailed second look at a few of the most promising candidates for Messages from the Stars. And I bet you'll also want to join us for the last week of March, when our special guest will be Arthur C. Clarke.

In the meantime, send your own messages to planetaryradio at planetary.org. We promise to be listening. Have a great week.