Instant Genius - Life on Mars, with Lewis Dartnell

Episode Date: August 18, 2022

Lewis Dartnell, an astrobiologist and research scientist and the University of Westminster, explains what we might find in the search for life on Mars. Hosted on Acast. See acast.com/privacy for more information. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Visit name, from BBC Science Focus. This is instant genius, a bite-sized masterclass in podcast four. I'm Alex Hughes, staff writer at BBC Science Focus magazine. This week, I'm joined by the author and astrobiology research scientist, Lewis Dartle. He tells me all about the search for life on Mars, the work of the Perseverance Rover and the future of Mars exploration. So I think a good place to start and probably quite a big question to start with is why do we think that there might be life on Mars? Well, in many respects, Mars is the most Earth-like place we know about.

And at least it was billions of years ago in the early solar system when Earth and Mars had just formed as young primordial planets. We know that back in those days, Mars was. a lot more Earth-like than it is today. We know that it had a much thicker atmosphere to shield and protect and blanket the planet. It seems to have had a lot of liquid water gushing across its face. And in terms of the possibility of life, liquid water is absolutely a key thing to be looking for. And there's good reasons to believe there have been a lot of organic chemistry as well. So the building blocks of life would have been present on the surface of the young Mars.

So in terms of planetary habitability, Mars seems to tick all of the right boxes. There's no reason to suppose that life didn't get started there when we were getting started here, when life on Earth was beginning. So we're very confident as astrobiologists that there's the possibility Mars had its own genesis, its own independent origin of life on its surface. And how would we know what Martian life? might look or be like or how it might act. We get a lot of insight into what life on Mars might be like by looking into some of the

most extreme life forms on Earth. And these are called the extremophiles or extreme loving organisms that can survive very, very hostile, challenging environments. So if we're looking to the possibility of life on Mars, these sort of extremophile organisms on Earth that we would be most interested in are organisms that can tolerate very, very cold temperatures, so psychrophiles, maybe organisms that could survive in more acidic water, because you think a lot of the water in the early days of Mars and then over the planet's evolution could have been quite acidic, and possibly life that's also very resistant to radiation, to ultraviolet rays

coming off the sun because Mars has had no ozone layer, but also are now linking much more directly into my own research into the cosmic radiation. So radiation coming from outer space, which is very, very damaging to the intricate and complex molecules of life. So this would be things spat up by the sun, by solar flares or coronal mass ejections, or galactic cosmic rays. which are much, much more energetic and therefore much more damaging. And these present a problem to astronauts once we send them beyond the Earth. And this cosmic radiation would also be a very big deal, a very big survival challenge for life right on the surface of Mars, where it's not buried underground and protected. And just then you mentioned about these extreme environments.

What are the kind of extreme environments on Earth that we see life in? and is that something that gives us any idea of the chances for life in the solar system? Yeah, so astrobiologists like me when we're not in the lab, analyzing samples, you get to go on a lot of great fieldwork to some of the most extreme environments on our planet, which overlap with conditions in important ways with the environment on Mars, and therefore tell us about the potential habitability of the Martian environment. which is the Martian environment conducive for the survival of life. And these are called analogue sites,

place on Earth which are like the environment on Mars. And so samples that I work with have come from places like the Antarctic dry valleys. So these are a region down on the South Pole right on the bottom of the planet. And the dry valleys, as I'm able to jest, are exceedingly dry, exceedingly desiccating, as well as being very, very cold. So the emulate the dry, cold conditions on Mars. But the Atacama Desert in Chile, in South America,

is also a very useful analog site because although it's a warmer, a hotter desert, it is also exceedingly dry, and it seems to be dry for a very long period of time. So we go to these analog sites, and we try to isolate life and unhardy bacteria, hardy microorganisms from there and try to understand how that life survives those conditions. But also importantly, what signs of life we should be looking for,

what biosignatures they're called might betray the existence of similar, ultra-hardy, bacterial-like life forms on the surface of the red planet. And say, so we did find life on Mars, is it likely to appear or act in a similar way to what we'd find on Earth? Is it likely to be carbon-based, or is that an unlikely thing to be expecting? Yeah, we'd be talking about microbial life only. So simple, single-celled life forms, you know, akin to bacteria, akin to germs on Earth. But looking at the chemistry of how life, as we know, it's life on Earth works, and then trying to think about how that might be different to what variations there might be for Martian Life.

Martian Life may not use DNA, for example, to store its vital genetic blueprint, to store the information for life. It might not use enzymes and proteins as the sort of workhorses inside its cells. So the specifics of the biochemistry of life on Mars might be slightly different, but in broad brushstrokes,

we would expect it to be similar. We'd expect to be able to recognise it. I'd be based on complex carbon chemistry. It would be organic-based life. And the reason for this is simply that the chemistry of carbon is so rich and diverse and capable of building these hugely complicated large molecules like DNA that are able to perform biological functions. So we think life on Mars would still be organic.

And we also think that most life that we'd be finding out in the solar system or maybe on planets orbiting other stars in our galaxy, is also likely to be water-based. Water seems to be very good biosolvent, a very good kind of wet stuff for dissolving lots of different chemistry and importantly, large complex molecules that life is made out of. And certainly on Mars, the environment of Mars is similar enough to Earth that we would expect to find lots of organic chemistry

and we do see lots and lots of evidence of past water. So it makes sense to look for organic-based, water-based life on Mars. And also that's the kind of life we're very good at looking for now, because we've taught ourselves and trained ourselves, for example, in these analogue sites on Earth, about how to detect even tiny trace amounts of this microbial life. A lot of the time when people talk about life, on Mars, it's either an idea of it being a present experience or maybe something in the future.

How would we know if there was previous life on Mars, something that has existed and is no longer there? Well, to be honest, we're probably only going to be able to find signs of extinct life, past life, right on the Martian surface. Because although Mars was once much more Earth-like, as I mentioned already, Mars suffered some kind of environmental collapse, an environmental catastrophe in terms of life. And much of its early atmosphere has seemingly blown away into space, which is why it's now very cold on the surface of Mars without a significant greenhouse effect. And that low atmospheric pressure means that liquid water can't be present over most of the surface of Mars. So the environment on the surface of Mars today is unrelentingly brutal.

It would be very, very difficult for anything to survive there, particularly with this bombardment of ultraviolet radiation and cosmic rays. But maybe life underground or perhaps a bit deeper in the subsurface of Mars might have survived, might have persisted until the present day. But Odoron will probably only be finding, as we're first searching, we'll probably only be finding traces of long since dead life. So we'll be looking for molecular fossils or what's left behind after cells have died

and then been degraded and broken down by the environment on Mars. So it's a lot of sort of chemical detective work that we're needing to be doing to find those biosignatures, those traces of past life. So say we do find traces of life on Mars, What do we do with this information? What are the next steps if we do discover it? It depends on exactly what we find on Mars, the degree of chemical or molecular complexity of what we can detect there and how badly it's been degraded over possibly very long

period of time, over billions of years of Martian history. But hopefully, with maybe the Perseverance Rover or the next generations of robotic explorers will be. be ascending to Mars, will be able to find unambiguous evidence of biological activity. So find signs of things which we can only explain because life has created them rather than, for example, organic molecules falling onto the Martian surface from meteorites and comets, perhaps. But ideally, and I say that there's a lower chance of being able to find this, but ideally as a biologist, it would be so exciting to find signs of life that's not just long sinks dead and extinct, but has survived until today. So things which are still active bacterial cells. And we'd

hopefully be able to bring those back to Earth and study them and peer under the hood, if you like, of these Martian microbes and see what makes them tick. See if they perhaps do use DNA to store their information, or they use enzymes made out of proteins or something else. Because the most exciting discovery will be finding not only that there is life on Mars, but that it is undeniably alien. It's so fundamentally different from us in the molecular mechanisms of how it works, that it was definitely from a separate origin, that we're not finding contamination or perhaps the descendants or, perhaps the descendants or of life being transferred between Earth and Mars and the early solar system,

but finding the descendants of a separate, distinct origin of life on our next-door neighbour planet. Because by doing that, we'd learn an enormous amount about ourselves. We'd have something to compare ourselves to and how our cells work, and therefore learn a lot about our place in this cosmos, and just how diverse life in the galaxy might be. And if we did find this alien life, what would be the kind of comparisons we'd be making? Would it be around the ways we've built civilization or our biology? It'd just be simple, single-celled life, that there's going to be no Martian civilizations.

There's no Martian pyramids. There's no Mars face on the red planet. It was created by a past Martian civilization. the environmental Mars was only ever appropriate or suitable for hardy, extremophile, single-celled life. But I think that would still be very interesting. And as I said, by studying how that life works and what makes it tick and the molecular mechanisms running within those cells, it will inform us enormously about different kinds of biology, different ways you can put carbon atoms along with oxygen or nitrogen or phosphorus or sulfurate atoms, to make those molecules come alive, to be able to build a cell perhaps using different combinations

of molecular Lego bricks, different combinations of simple organic molecules. Earlier on, you mentioned brief that the Perseverance Rover. Could you explain a little bit more about that, what it does and what it's doing to look for life on Mars? Yeah, Perseverance is the most sophisticated robotic explorer that we've sent to Mars so far. It's a NASA rover. And it was broadly based. It's got the same basic design as the previous NASA rover curiosity. And so this made it slightly cheaper and more reliable because we'd learned lessons on how to make rovers work on the surface of Mars. And what's exciting about? the Perseverance rover is it has a helicopter. So we are basically flying a drone on the surface of Mars now called ingenuity. And it's been allowing us to explore far further beyond the driving range of the rover. So you know, staking out where it might go next, taking lots of pictures. But it's essentially a technology demonstrator. It's just proving that we can fly on Mars,

even though there's such a thin atmosphere. And Perseverance has also got on board an experiment called Moxie, which has demonstrated that you can take the carbon dioxide of the Martian air, of the Martian atmosphere, and create oxygen from that. We can create air that is breathable for humans by running chemical processes with the Martian air. And so this is a very important demonstration for the future of sending crude missions, human missions to explore Mars, and knowing that we can live off the land. We can make what we need when we get there and not have to launch everything from Earth. And for example, make breathable oxygen-rich air when we get there.

But the primary thing that the Perseverance Rover is trying to accomplish is effectively cash samples that it's. drilled from inside Martian rocks and then sealed them little sample containers. And it kind of effectively stowed them in its backpack, stowed them in its sort of geologists' backpack, ready for the next mission to retrieve those samples off the surface of Mars and then bring them all the way back to Earth so we can study and scrutinize and analyze those Martian samples using all of the laboratories and all of the highest tech equipment in labs, all the way around the world on the earth. So that next mission, or one that would come afterwards,

would be called a Mars sample return mission. And so rather than trying to shrink a lab and all the equipment into something small enough you could put on the point end of a rocket with some energy source and some cameras and some wheels attached as a Mars rover, we'd be doing the opposite, which is bringing Mars back to the earth. So we can study it with labs here. and perseverance is a crucial step in that sample return project. You touched on it a little bit there.

What would the procedure be to get those samples back to Earth? And then, I guess, how do you then study those samples once they are back and they're in these labs? So landing on Mars is already a very, very difficult thing to be able to do. Mars is difficult to land on because although it has got an atmosphere, the atmosphere is still very thin. So it makes even landing with parachutes quite tricky. So you need some combination of heat shield so you don't burn up when you first arriving upper atmosphere of Mars, traveling at very high speeds from traveling between the planets. You then need parachute, try to slow yourself down towards the surface,

and then rocket thrusters to take off up that last bit of speed and touch down very, very gently. on the Martian surface. So even landing a rover, and bearing mind that curiosity and perseverance are robots the size of a car. Perseverance is over a ton in mass. It's a big, big robot. And landing perseverance on the surface of Mars was an engineering marvel. It was a very, very difficult thing for NASA to pull off. But trying to do a mile sample return of sending a mission to Mars to land safely to pick up samples and then launch all the way back to the Earth is a lot more difficult than twice as difficult as just landing on Mars in the first place. So there's going to be a lot of, you know, sort of engineering and innovation will go into making that Mars sample return mission

a success. But let's say, you know, sort of early 2030s, maybe late 2020s, when we get these samples back from the Earth, we're going to be very, very careful that we're not contaminating those pristine samples of another world, these pristine samples of Mars, trying to not to contaminate them with the terrestrial environment, with organic molecules or bacteria from Earth, so that it can be sure that anything we find in those samples brought back were definitely present on Mars.

So there's going to be a lot of work going into sample containment and facilities and institutions able to handle and make sure those samples remain absolutely pristine as we analyse them and test them. And we'll eke out many, many years of work and analysis on these samples. For example, we're still studying samples of the moon that were brought back by the Apollo astronauts, you know, in the 1969 and through the 1970s. So once we've got these hugely valuable mass samples, we're going to squeeze as much science out of them as we possibly can.

I assume a lot like what's happening now of the James Webb Telescope, that it wouldn't just be one project to look into information that comes from these samples. There'd be a lot of different topics that people want to address from them. Is this how it work? There'd be different teams that would be looking at these samples to study them, or is it just one exact study that they want to look into of them? Oh, no, no. There'd be a whole spread a whole.

diversity of different studies and different kinds of analyses that people would want to do. And two of the main open questions about Mars are firstly to do with its past environment and habitability. What was the ancient Mars environment like? How warm was it? How wet was it? Were those conditions really conducive for the emergence and development of life? So answering that primary question. And then secondly, did life ever actually get started on Mars? So looking for biosynchinctures, looking for complex organic molecules. And even within trying to answer those two main questions with our samples brought back for Mars, there's a lot of different ways you can look at and analyze these samples using different analytical techniques, different lab

techniques, different instruments. The sort of instruments that I use on my terrestrial analog samples are different kinds of spectroscopy. So Raman spectroscopy, for example, uses a laser to analyze the rock and tells you information about organic molecules and carbon might be in there, as well as the mineralogy of the rocks, and the Perseverance Rover, and indeed the next European Space Agency rover called XMRs, both have Raman instruments on board. It's a really handy technique. So we'll be using Raman and various other kinds of spectroscopy and other ways of almost tasting the rock, trying to detect different kinds of organic molecules in there. So no, we'll be analysing those samples, 101 different ways, using different teams and different

research groups all the way around the planet to get as much science out of these Mars rocks as we can. You mentioned the risk and obviously the many procedures around avoiding the risk of contaminating these samples with samples from Earth. Is there any risk of the opposite of these samples contaminating Earth with martial microbes? I mean, there's been a lot of headlines around that kind of thing. Or is it very much the same that, no, it would just be so carefully handled that there's no risk there. There is a risk, yeah. And there's a body of sort of international law that's been written up and signed by the main space-faring nations all around planetary protection.

So when we send rovers and probes to Mars, how could we certainly we're not contaminating the Martian environment with stuff from Earth, you know, Earth bacteria, earth contaminants? But the other kind of contamination we're also very, very careful about is not potentially contaminate the Earth with stuff from Mars. And it's, you know, it's very much a mainstay of sort of science fiction films and things like the Andromeda strain where a probe comes back from outer space, maybe from the surface of Mars and brings back some Martian life, which escapes from the containment facility and infects the biosphere on our planet and maybe starts infecting people and giving them, you know, sort of space disease. And the reason I'm sort of chuckling to myself in the background is it's not impossible for that to happen, but it's thought to be very, very, very unlikely. And indeed, considering the environment on Mars today where it's exceedingly cold, exceedingly dry, if any life could survive that Martian environment, the only places it could really survive on Earth are like to also be very, very cold, very dry places, because that's

what the life is adapted to. You know, it's never going to contaminate or infect the whole of Earth's environments in our biospheres. And it certainly wouldn't be able to infect like a pathogen inside the human body. But nonetheless, it's something that is worth considering. It's worth taking seriously. And you effectively get to do both kinds of protection at the same time. As long as these samples are kept sealed, contamination from Earth can't get in and spoil the results. and those Martian rocks can't leak out and contaminate the earth.

You get two for the price of one, as it were. So it's very unlikely that we're going to end up in the plot of alien, but it's better to avoid it, basically. It's very, very unlikely, but if it were to happen, it'd be very, very bad. So it's still worth taking seriously, still worth considering and doing as much as we reasonably can to prevent something like that from occurring. Of course. with the samples when they do get to Earth,

how definitive of an answer do you think they could provide to life on Mars? I assume it's something that's very hopeful that we can get some quite extreme results from this. Yeah, so if life is there, if Mars did once have a habitable environment suitable for the origin of life, and if signs of that life are in the rocks that we bring back, from Mars to Earth, we're optimistic, we think there's a very good chance we'd be able to detect that it's there by using any number of these different analytical techniques

that I sort of alluded to. So we might look with a very powerful microscope, an electron microscope, and we might see cell-like structures. In just the same way we can see fossilised bacteria in some very, very ancient rocks on Earth, shortly after the origin of life on our own planet, we might hope to find actual fossilised cells

that you can see in Martian rocks. But actually the best kind of evidence won't be, you know, things that look a bit like little blobs down the microscope. The best evidence will be molecular, will be chemical. And as I've mentioned already, looking into complex organic chemistry, complex carbon chemistry that we don't think could be produced by anything other than biological processes other than life. But also slightly more complicated things, something more subtle things like the isotope.

ratios. So we'd look at the carbon, for example, or the oxygen that might be in these organic molecules from Mars and see if they have a bias in the different isotopes of carbon, of different isotopes of oxygen. Because again, that would be an indicator that it's the product, that's the result of a biological process. And in truth, what will probably happen is we would wait until several different lines of independent evidence all point towards the same conclusion that we found life through several different methods at the same time, rather than relying on just, you know, sort of one thing coming back positive, as it were. So once we've done this and we've got the samples back, what does the future of Mars exploration look like? Well, say the next step

after a Mars sample return, so looking sort of decade into the future, it will certainly happen sooner rather than later, I think, that we will move beyond sending sophisticated robot explorers, probes to Mars, and we'll start sending human explorers, astronauts. And of course, we've explored the lunar surface with the Apollo missions. And even if it's not an effort made on the national level in the way that it was NASA and the Americans that took humans first to the moon, it might be a big international, international collaborative, cooperative project to send the first humans to Mars, but it'll probably involve a lot of private enterprise and corporations as well. And I think by now we've all heard

of people like Elon Musk or Jeff Bezos, who've made a lot of money in technology and the internet, have taken an enormous interest in private spaceflight, either trying to create hotels or private launches into space, they could eventually, in the near term future, start selling tickets, start selling rides on these rockets to paying tourists, but then going further afield, going beyond low Earth orbit to Mars. And I don't think any single company, whether that's one of Jeff Bezos's companies or one of Elon Musk's companies, would ever be able to afford, you know, the eye-watering expense of sending humans to Mars. It's going to be a big collaboration. It's going to be a big collaboration. effort between many different agencies and organizations. But I think it's, you know, it's the

natural next step for us as a species. You know, we're always looking at the horizon and wondering what might lie just beyond it and pushing forward one step at a time. And Mars is very much that the natural next step after low Earth orbit and the moon as we explore out and expand out through the solar system. So it won't just be Elon and his friends alone. It's, it's going to be a bit of everyone having to chip in to achieve that kind of dream. Well, I mean, I totally hope not. I think big projects like this and potentially, you know, sort of history-changing projects, if there's just one or two people in charge of that, I think his start's becoming very, very risky about what decisions are made and what opportunities

are given to people. And I think it would be a much, you know, more equitable and diverse way of exploring Mars if it was done internationally, rather than just a couple of tech bros coming together and sort of unilaterally, if you like, deciding to try and do these things. And there's been a lot of debate recently about other aspects of space and its usage. For example, launching lots of low-earth satellites that might be providing internet service to people in sub-Saharan Africa or in Ukraine, where the sort of normal wired internet has been knocked out by the invading Russian forces. Elon Musk Starlink program has been able to provide the internet to places where it otherwise could not reach. But there's a bit of a flip side to that coin, a bit of a problem for astronomers,

because once you start having lots and lots of satellites in orbit, it basically destroys the night sky, everyone on the earth, trying to look back up at the heavens. Because you try to study something in space and your images and your data, gets ruined by all these satellites passing through it. So we do need to find some kind of compromise, some kind of happy medium between, you know, private corporate interests and the public good and not ruining space or access or limiting it to too few people and being too capitalistic about it. Capitalist about it. Thank you for listening to this episode of Instant Genius. That was Lewis.

Dartnell, talking us through the search for life on Mars. The Instant Genius podcast is brought to you by the team behind BBC Science Focus magazine, which you can find on sale now in supermarkets and newsagents as well as on your preferred app store. Alternatively, you can come find us online at sciencefocus.com. This podcast is sponsored by name, audio and focal. The texture and emotional depth of music can be lost through digital sources or poor signal. Name Audio believes you can have digital precision with analog warmth. Alongside French acoustic specialist vocal, name creates high-end audio systems combining innovation with craftsmanship so you can listen to music, just as the artist intended. Discover more at name audio.com. Ambition comes in all shapes and sizes.

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