Planetary Radio: Space Exploration, Astronomy and Science - Where to Look for Life on Mars

Episode Date: October 6, 2008

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Where would you look for life on Mars? This week on Planetary Radio. Hi everyone, welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. My opening question is not just rhetorical. Scientists and engineers are working right now to select the landing site for the Mars Science Laboratory, a sort of super rover that will look for past evidence of life on the red planet. We'll talk with Roger

Buick of the University of Washington about the advice he just offered the MSL team. We'll also hear what our own Emily Lakdawalla had to say about this subject in a recent webcast. Bruce Betts will join me for an on-location edition of What's Up, including a new space trivia contest. Bill Nye? Well, as I speak, he is returning from a trip to Scotland, accompanied by Planetary Society Executive Director Lou Friedman. We hope to tell you more about that next week. The bad news for the Hubble Space Telescope came out last week. With Shuttle Atlantis on the launch pad,

nearly ready for the fourth and last repair mission, NASA announced a new and serious problem. The 1970s-era computer that controls critical functions on Hubble has malfunctioned. The repair mission has been postponed as engineers try a workaround and consider whether to add replacement of the system to the repair mission's already ambitious agenda. Have you caught one of Emily Lakdawalla's UCAS? The Planetary Society's Science and Technology Coordinator does live and interactive web shows on a semi-regular basis. You can find them in the archives of her blog at planetary.org.

On September 17, she reported on the Mars Science Laboratory landing site selection process and priorities. Before we hear Roger Buick on this and other subjects, let's check out a bit of what Emily had to say. Who will make the ultimate landing site decision and when will it happen? I actually don't know the answer to that question for MSL. For the Mars Exploration Rovers, the final decision was made by the project management, project scientists working together. And then presenting, they had to present their selection with also the deselected ones to NASA headquarters and have NASA headquarters sign off on the selection. They had to convince headquarters that they had made the right decision. So I'm assuming that the process will be similar for MSL.

They need to pick a landing site that will have lots and lots of evidence of water. And there are certainly lots of places on Mars that have excellent evidence for past water. And there are certainly lots of places on Mars that have excellent evidence for past water. But also important in figuring out where to land this mission on Mars is the issue of landing safely. It's less of a problem for this mission than it has been in past missions, but it's still tough to land on Mars. And it's still the single after launch, it's the riskiest moment. And so here is a cartoon that you probably can't see very well showing what the landing is like. Up until just throughout the area that's sort of shaded in brown here, the landing is very similar to most other landings on Mars in that it comes in with a heat shield, it deploys a

parachute, it screams through the atmosphere supersonically, the parachute slows it down, it gets rid of the parachute. But then what happens next is very different for MSL than it is for any past mission. Instead of having airbags like the rovers did or just retro rockets like Phoenix did, it has this thing that is being called the sky crane maneuver where the back shell will lower the rover on cables. And you can see the cables lowering there. There's also some little blips indicating that it's sensing the surface through radar. It lowers the rover on cables.

It gently touches the rover to the ground. This is after the rover has deployed its wheels. And then it cuts the cables, lifts off, and flies away, and then crashes on the ground someplace far from the rover. That last maneuver is extremely important. You don't want your back shell falling on top of the rover. This landing method, to me, seems fairly crazy, but actually less crazy than bouncing a $400 million spacecraft off the surface inside airbags.

So it seems like it could work. I hope it works. Everybody hopes it works, but it's never been tried before on Mars, and it's going to be a very, very scary day when this thing is heading in for a landing on Mars. What's also scaring a lot of the scientists is the fact that the landing is being done on the mobility system. So you can easily imagine a failure scenario where the landing generally works okay, but something is very rough about those last few meters, and it breaks some wheel or part of the suspension system, and we have this excellent spacecraft that survived all the way to Mars, and yet it can't move very well. That's Emily Lakdawalla of the Planetary Society talking in her September 17 UCAST about the Mars Science Laboratory, the big rover that NASA hopes to launch in just one year.

By the way, the MSL team has narrowed the list of possible landing sites to seven. Their final choice is likely to be influenced by the advice they received from Roger Buick. Roger's search for the earliest forms of life on Earth has benefited from his expertise in several intersecting fields, including geology, biology, and chemistry. The University of Washington professor is a member of the Earth and Space Sciences faculty and teaches in the astrobiology programs at both Washington and the University of Arizona. Roger, thanks very much, first of all, for joining us on Planetary Radio. Why is it that geology may become so important in a search for biology on places like Mars and elsewhere in the solar system? Well, there are two reasons. One is that the origin of life may

have been intimately linked to the geology of the planet where it started. There's a strong school of thought in the origin of life community that interactions on the surfaces of minerals may have played an important role in catalyzing prebiotic organic compounds into the more complex polymers that are involved in life. But secondly, geology records the relics of early life. So on planets that may not be inhabited now, the only way to find out whether they are inhabited in the past would be to investigate the geological record on those planets for fossils of now extinct organisms. So in a sense, the geology may be both the cause and provide the evidence for this earliest of life. Yeah, that's quite right. It's a way of looking back at the past, but it's also a way of creating

new components in living systems. And that's what may have happened on the early Earth and could conceivably have happened on other planets. It is therefore easy to understand why you were able to give a presentation at the recent meeting just a couple of weeks ago, the third landing site selection meeting for the Mars Science Laboratory, which was basically a gathering of a lot of scientists like yourself trying to decide what's going to be the best place

to drop this incredibly sophisticated wheeled laboratory on the Red Planet. Is that fair? Yeah. The mission's designed to go looking for signs of past life on Mars, and the best analog we have is the early Earth and signs of life on the early Earth. My talk was based on the premise that the strategies that one uses for looking for signs of life on the early Earth could be applied on Mars,

and the instruments that are on the Mars science lab could be utilised in exactly the same way that geologists looking for early life on Earth go about their field campaigns for searching for ancient fossils. You spend a good part of your professional time looking for studying the earliest evidence of life on this campus. On this campus. Speaking as an academic myself. Very narrow, isn't it? Well, there is adequate

evidence of intelligent life on most campuses. But for this planet, how far back can we now say that we actually can point to microfossils and say, yes, there was definitely stuff acting like a living thing at this point in our planet's history. Well, microfossils are only one sign of ancient life.

They're perhaps the best, but they're not the easiest to find. And they're pretty hard to interpret the further back you go in time. to find and they're pretty hard to interpret the further back you go in time. Microfossils being fossils of microbial organisms are pretty simple and often just sticks and balls in shape and they're pretty hard to distinguish in many instances from non-biological aggregates of reduced carbon that assume the same shapes. So the oldest microfossils that we know of that are absolutely for sure and certain remains of once-living microorganisms probably only date back to about 2.6 billion years ago.

Now that's in the context of a planetary history for Earth that's 4.567 billion years old. So only back a little bit more than halfway through Earth's history. But you can go further back in time with other less direct forms of evidence for life and trace life absolutely, surely, and certainly back in Earth history to about 3.5 billion years ago. So that's almost another billion years before the earliest microfossils. Where do we have to go on Earth to find this very early evidence? Well, there's only a few places that preserve relics of the earliest history of Earth.

Earth's a dynamic planet. It changes its surface rapidly through weathering and erosion and burial and subduction and volcanic eruptions. And so there's not much of a record left of the early history of the Earth. There's only a few parts of the world that preserve 3 billion-year-old rocks well. Australia's one of them. Northwestern Australia has a very good record of rocks back to about 3.5 billion year old rocks well. Australia is one of them. Northwestern Australia has a very good record of rocks back to about three and a half billion years old. South Africa is another.

Greenland's another. And Arctic Canada has the oldest rocks on the earth, four billion years old. As you look back this three and a half billion years for this perhaps slightly questionable evidence of life, but it sounds like you may be convinced, what do you actually see? I mean, is it similar in form to bacterial or other life that is still kicking around on Earth? Well, what you can see in three.5 billion-year-old rocks are not microfossils but trace fossils of microbial activities, things called stromatolites, which are layered, mound-shaped lumps of sediment

that are accreted by the activities of microbial photosynthesis. And you can find well-preserved stromatolites that are almost certainly of biological origin in rocks just a little bit under 3.5 billion years old. But the other thing you can go looking for is chemical evidence of early life. You can look at the fossil chemicals derived from biological molecules.

We can trace them back to almost 3 billion years old now. You can also go looking for atomic fossils of life. That is the fractionation of stable isotopes of various biologically important molecules that are imparted by metabolic processes of microorganisms. And we can look at fractionations of elements like carbon and sulfur and trace a biological input into those fractionations back to 3.5 billion years old, maybe even a little bit older,

though that's controversial. I'll be right back with Roger Buick of the University of Washington. This is Planetary Radio. I'm Sally Ride. After becoming the first American woman in space, I dedicated myself to supporting space exploration and the education and inspiration of our youth. That's why I formed Sally Ride Science, and that's why I support the Planetary Society. The Society works with space agencies around the world

and gets people directly involved with real space missions. It takes a lot to create exciting projects like the first solar sail, informative publications like an award-winning magazine, and many other outreach efforts like this radio show. Help make space exploration and inspiration happen. Here's how you can join us. You can learn more about the Planetary Society at our website, planetary.org slash radio or by calling 1-800-9-WORLDS. Planetary Radio

listeners who aren't yet members can join and receive a Planetary Radio t-shirt. Members receive the internationally acclaimed Planetary Report magazine. That's planetary.org slash radio. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan.

Roger Buick is telling us about the earliest evidence of life on Earth and how his attempt to find its origin may help us find signs of past life on Mars. As we look at this evidence, do we see that apparently the processes of life as we know it today were already established three or more billion years ago? which is called dissimilatory sulfate reduction that's carried out by a moderate range of bacteria and one group of archaea at present. And the atomic fossils suggest that the metabolic pathway was absolutely identical to that employed by modern microorganisms. And that's quite a sophisticated metabolism. It's a form of respiration, which is what you and i are doing now except we're aspiring carbon compounds not sulfur compounds and so from that we can infer that early archaean microbes at three and a half

billion years ago were just as sophisticated in their metabolism and biochemistry and presumably internal structure as modern microorganisms. There's little reason to believe that they were substantially different. How much further do you suspect we would have to be able to look to find something back at the origin of species, if you will, and is there much chance at all that we're going to be able to find such evidence on this dynamic planet? It would be very difficult on Earth. As you go further back in time, the rocks get fewer, and not only that, their preservation gets worse.

I mean, how many people do you know who are 130 years old? And if you do, I'll bet you that they're not really very well preserved and don't look very much like they did when they were young. Paradoxically, Mars might be a better place to go around finding evidence of the very beginnings of life on a planet because Mars hasn't been extensively resurfaced or metamorphosed or deformed as old Earth rocks have. So, you know, a lot of Mars' surface remains from the first billion years of its history, a lot more than there is on Earth.

So it might be a better place to go looking. I'd certainly hope so. So what was your specific advice to this group that will be deciding where to drop the Mars Science Laboratory? Well, I suggested that they should employ similar strategies and techniques and protocols that early Earth paleontologists use when we go around looking for signs of early life on Earth. In other words, go looking for places where there's persistent water, where there is a diversity of minerals that preserve signs of life, minerals like clays, for instance, or the sort of sulfate minerals

that the current Mars rovers have discovered on Mars, and also places that look like they had a relatively equable environment, not too hot, not too cold. Even though life on Earth can inhabit extreme conditions, it's most abundant in relatively pleasant climates. And so those sorts of places on Mars are likely to have the most abundant yield of biosignatures. Regular listeners know that I like to make scientists squirm now and then. Would you like to hazard a guess as to, knowing what we already know of Mars,

whether we have much chance of finding evidence at least of past life. I'll leave current life alone. It'll be hard. It really will be hard. Mars was probably a less hospitable planet to life early in its Earth history than Earth was. And Earth wasn't very good. I mean, the sun was less bright, and so we had to have a much stronger greenhouse effect on Earth to keep temperatures equable and to keep liquid water on the surface of the planet of Earth. Mars is a more difficult proposition because it's further from the sun, and it's smaller,

has a smaller gravitational attraction, so it's harder to the sun and it's smaller has a smaller gravitational attraction so it's harder to maintain a dense atmosphere full of lots of greenhouse gases so it will be hard but there is abundant evidence of liquid water and there is abundant evidence of minerals that will be conducive to preserving relics of early life. So there's a chance, but I wouldn't like to bet my retirement money on it, what little there is remaining of it. We're almost out of time, Roger. Give us an idea of where your current research is taking you. Well, I'm looking right at this monument,

the very oldest sedimentary rocks on Earth, and looking at them to try and interpret what sort of environment they formed in. And we are certainly looking for traces of life in them. We think we've got them. Fascinating. I'm sorry, go ahead. What was that last? That's a secret. It's a secret?

For the moment. We haven't published it yet. Ah, when might we see this as something that we could speak openly about? Well, if you stop interrupting me, I'll be able to get back to it. Please, go ahead. No, just kidding. We will let you do that right now. Thank you so much for joining us. This has absolutely been a fascinating conversation,

and we'll look forward to the publication of that research that will push the beginnings of life back a little bit further on the planet we know best. Yeah, I look forward to it, too. Thanks a lot, mate. Roger Buick is a full professor at the University of Washington in the Earth and Space Sciences Department. He went there to join the Astrobiology Program, which is mostly a teaching program preparing the biologists and geologists of tomorrow to look for life and try and figure out what it might look like elsewhere in our solar system and perhaps beyond.

His work is, as he says on his website, at the intersection of geology, biology, and chemistry. We're going to move to astronomy when we pick up a regular visit with Bruce Betts, this week's edition of What's Up. That's just a minute or two away. First, we're going to hear from Emily Lakdawalla. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, How come Earth's big storms are low pressure while Jupiter's are high pressure? Earth's cyclonic storms and hurricanes are indeed low pressure systems,

while Jupiter's red and white spots are high pressure systems or anticyclones. But cyclones and hurricanes are not Earth's best analog for Jupiter's spots. After all, such storms blow themselves out in a matter of days, while Jupiter's spots can last for many years. By contrast, high-pressure systems in Earth's atmosphere can actually last for much longer. So-called blocking highs often sit stubbornly for months over the continental United States and also over Russia. These high-pressure anticyclones block the normal track of rainstorms,

causing flooding around their edges and creating droughts at their centers. They last months rather than years because Earth's atmosphere is such a thin layer over its solid surface that there's not much elbow room between jostling weather systems, and all of them shred each other eventually. On Jupiter, the lack of a solid surface allows anticyclones to persist for much longer. Jupiter does have cyclones too, but they have shorter lives. When low-pressure cyclones drift over patches of deep, moist air, the storms explode like bombs, blowing the circulation apart into so-called filamentary cyclones.

Eventually, the loose jumbles of clouds settle back down, and the whole life cycle repeats itself. Got a question about the universe? Send it to us at planetaryradio at planetary dot org. And now, here's Matt with on Planetary Radio. We are on location in my hometown, the city of Long Beach, California, a little way south of Pasadena, where Bruce Betts, the director of projects for the Planetary Society,

has just joined me for a presentation at something called University by the Sea. And we got to talk about planetary society type stuff. It was a lot of fun. It was indeed. And I love what you've done with the city. Thank you. We try. We try.

It's getting better and better. We have a special guest coming up for Random Space Fact. But first, tell us what's up. All right. Well, in that evening sky, it's getting neat. You can check out Venus quite easily now for a little while after sunset over in the west, and it looks like a very bright star-like object. And then if you turn to your left about, oh, I don't know, roughly 90 degrees

and look towards the south, you'll see another bright star-like object, and that's Jupiter. So Jupiter and Venus both quite lovely in the evening sky. Pre-dawn sky, we've got Saturn looking like a kind of bright star-like object over there in the east, and it's going to get easier to see as time goes on. You didn't bring the trumpet, did you? Oddly enough, no. What a shame, because we're in this beautiful room at the old Lafayette Hotel, the Dome Room, which actually used to be a nightclub. And the reverb in here would have been tremendous, I think. But I don't know. We'll find out when we get to random space fact.

We'll just have to keep teasing people. Yeah, I'm just hoping you forget at some point. Never, never. Not going to happen. All right. Well, I think it's time to go on to our special segment. Oh, really? Okay.

I can't wait. We're going to turn over here to Eli. Eli, come think it's time to go on to our special segment. Oh, really? Yeah. Okay. I can't wait. We're going to turn over here to Eli. Eli, come over here for a second. And you're going to help us out, I think. You just came through our class. We talked about space stuff, right? Mm-hmm. Okay. Do you know what to say? Yeah. Go for it. Random space fact. Excellent work. Thank you so much. You better watch out. Your job's in jeopardy.

Wow. You're right. That was really good. Nice job. On to the actual random space facts. We're talking Mercury. I want to make sure people are paying attention. As even before this broadcast is out there to anyone, a messenger will have flown by Mercury for the second time, filling in more of the unexplored part of the planet. I love that. Mariner 10, of course, saw only about half the planet 30 years ago, and then Messenger flew by a few many months ago and filled in another 25% or so, and they're going to get more here along with a whole wealth of other

instruments. And so we talk Mercury. Mercury is a weird kind of cool place. It's got this big, giant iron core. But by the way, Earth does beat it on density. We're denser, but only because of gravitational collapse. If you didn't have gravity pushing in from a bigger body, Mercury would be denser. Because of this higher gravity than the moon at the surface, even though it looks like a lunar surface,

you look close, the crater impact ejecta is all going to fall closer to the crater than it does on the moon. It gets pulled back down faster. And it's in this weird 3 to 2 resonance with its day and year as it goes around the sun. So all sorts of cool things with Mercury. Check out the new information and data as it's coming in this week. On to trivia. and data as it's coming in this week.

On to trivia. We asked you, constellations in the night sky, what is the name of the dolphin in standard constellation-ness? Constellation-ness or constellation-less? No, constellation-ness. Constellation-ness? Yes, it's totally not a real word, but shouldn't it be? I mean, I think so. Indubitably.

Yes. We had a huge response to this. I don't know why, but people just love be? I mean, I think so. Indubitably. We had a huge response to this. I don't know why, but people just love dolphins, I guess. And so lots and lots of entries. Surprisingly, a charter member of the Planetary Society, Jamie Vogel of Raleigh, North Carolina, I don't think he had ever entered before, but he did say would love to wear a planetary t-shirt to the gym, to church, and anywhere else that people might see it so I can engage them and the society and its mission to explore space for all mankind. Kind of gets you right here, doesn't it? That's really cool. Why

do you say surprisingly? Well, because it's his first time entering, although he's been listening. We had already decided that we were going to send him a shirt because he's a charter member and all that. We've got to send this guy a shirt. Well, random.org. He won. So we don't have to send him a shirt. We have to send him a shirt. It is his destiny. Good. And what did he tell us? He told us it was Delphinus. Delphinus, which turns out to be one of the original Ptolemaic constellations. Not a very bright one. But it's pretty. Yeah, it is pretty. They just kind of go together somehow. They're very uniform in brightness, the stars.

It's right below the so-called Summer Triangle, off there, and quite lovely. Did you know that Delphinus is named after the dolphins who supposedly saved the great singer Arion from the depths of the Mediterranean Sea, or so our friend Tom Hendricks with a rich imagination tells us. No, I didn't know that. What do you got for next time? Back to Mercury. If you took Mercury and you squished it around and you made duplicates and you tried to shove it in the volume that's Earth, how many would you fit in there? How many mercuries would fit in Earth, volume-wise? Go to planetary.org slash radio, find out how to get your entry to us. So this hot planet walks into a bar.

We'll save that for next week. You need to get that to us by the 13th of October, October 13, Monday, at 2 p.m. Pacific time, and we welcome your entry. Good. Everybody, go out there, look up at the night sky, and think about domes. Thank you, and good night. We are standing under the dome in the Dome Room at the Lafayette Hotel in downtown Long Beach.

I'm going to turn it over to Eli. Eli, would you like a little Planetary Society pin? Okay. It's all yours. Thanks for helping us out. a little Planetary Society pin. It's all yours. Thanks for helping us out.

Anyway, that's Eli, and over here is Bruce Betts, the director of projects for the Planetary Society, who joins us every week for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California.

Have a great week. Thank you.