In Our Time - Mars

Episode Date: January 11, 2007

Melvyn Bragg and guests discuss the planet Mars. Named after the Roman god of war, Mars has been a source of continual fascination. It is one of our nearest neighbours in space, though it takes about a year to get there. It is very inhospitable with high winds racing across extremely cold deserts. But it is spectacular, with the highest volcano in the solar system and a giant chasm that dwarfs the Grand Canyon.For centuries there has been fierce debate about whether there is life on Mars and from the 19th century it was even thought there might be a system of canals on the planet. This insatiable curiosity has been fuelled by writers like HG Wells and CS Lewis and countless sci-fi films about little green men.So what do we know about Mars – its conditions, now and in the past? What is the evidence that there might be water and thus life on Mars? And when might we expect man to walk on its surface?With John Zarnecki, Professor of Space Science at the Open University and a team leader on the ExoMars mission; Colin Pillinger, Professor of Planetary Sciences at the Open University and leader of the Beagle 2 expedition to Mars; Monica Grady, Professor of Planetary and Space Sciences at the Open University and an expert on Martian meteorites.

This BBC podcast is supported by ads outside the UK. What makes people want to believe in aliens? I'm Tristan Redmond, one of the hosts of the Global Story podcast from the BBC. Donald Trump last week announced that he'd be releasing the US government's UFO files. So why the renewed interest in life out there? And what deeper spiritual meaning might people be searching for? Check out the global story. We are serious journalists on BBC.com.

or wherever you get your pods. Thanks for downloading the In Our Time podcast. For more details about In Our Time and for our terms of use, please go to BBC.co.com.uk forward slash radio 4. I hope you enjoy the program. Hello, today we'll be discussing the red planet. Mars has long been a source of fascination. The fourth rock from the sun is one of our nearest neighbours in space,

though it takes about a year for us to get there. It's rather inhospitable with ferocious winds blasting across frigid deserts. But it is spectacular, with the highest volcano in the solar system and a giant chasm that dwarfs the Grand Canyon. And there's the life issue. For centuries there's been a debate

about whether there is life on Mars, and from the 19th century, it was even thought there might be a civilized system of canals on the planet. This curiosity has been fueled by writers like H.G. Wells and C.S. Lewis and countless sci-fiction films. So what do we know about Mars,

its conditions now and in the past? What's the evidence that there might be water and thus life on Mars, and when might we expect to walk on its surface? With me to discuss the Red Planet, are three members of the Centre for Earth, Planetary, Space and Astronomical Research at the Open University. Colin Pillinger, Professor of Planetary Sciences

and Leader of the Beagle II Expedition to Mars. Monica Grady, also Professor of Planetary and Space Sciences and an expert on Martian Meteorites, and John Zanecki, Professor of Space Science and a team leader on the ExoMars mission. John Zaneke, why do you think mankind has always been so fascinated with Mars? Well, as you've already said, Melvin, it's one of our nearer neighbours. It's visible to the naked eye.

And with relatively simple optical aids, with a small telescope, it presents a changing face to us. You know, it appears to be changing colour. We now know this is partly due to dust storms. Also, there are polar ice caps. which expand and recede, and that gives, you know, a changing appearance. So I guess that for a long time this changing appearance has led to speculation that it's a dynamic place.

People even suggested that there was vegetation perhaps on Mars and that, of course, fueled ideas of exotic civilizations and so on, which have, you know, been such a constant part of our culture, our fiction and so on. But we've long projected a lot of our own wishful thinking onto Mars, haven't we? It's been a place where we felt fearful where aliens are. It's been a place when we felt grand where friends are and so on and so forth. We've put a lot of our wishes there, haven't we? Yes, absolutely.

I suppose it's far enough away that it's perhaps not too threatening, but close enough that they can threaten us as, you know, H.G. Wells and others have, have threatened us with Martians landing on Woke in Common, wasn't it? Yes. But there's a tumult of books. There's a new one by Oliver Morton, Mapping Mars, had just come out. There was a book of poetry, Craig Rayne, where he used a Martian, sends a postcard home.

There's the business of a Martian looks at the earth all day. If a Martian came here, they'd think that we were, and so on and so forth. So it's really entered into the system in many ways. It has indeed, and I mean, this was fuelled, I suppose, since the last century, when the first detailed observations were done, in particular by Chaparrelli, who produced detailed drawings with lines and features on Mars,

which some then interpreted as canals and then wonderful stories of civilisations, under threat, melting the polar ice caps with these canals to provide them with water. Can you tell us, let me go to how close, and neighbour is Mars to Earth, can you give us some facts, even though they're unimaginable most of these facts that Yucchap's produced, but here we go.

Well, we use funny units in astronomy. It's about at its closest. It's half an astronomical unit, I think, which is how far? That's about, is it, 75 million kilometres, yes. 45 million miles. 45 million miles. Which is in our, you know, absolutely our backyard in astronomical terms. But it's about the limit, I think, of where we can expect as humans to travel.

That's probably with the technology we can imagine over the next few centuries. That's about as far as we're going to be able to reach. So it's just reachable by ourselves. And Colin Pillar is just reachable by the naked eyes, I understand it from, if you're not in my eyes, but people who can really see. And in ancient civilizations it was brought into their culture and their scheme of things as well, wasn't it, with the Babylonians and the Greeks and the Romans associating with war

because of this redness. Yeah, it's more than just visible with the naked eye. In fact, it's very obvious with the naked eye. And it does do this very peculiar excursion where it appears to be going across the sky in one way and then every two years about, it reverses and goes back in the opposite direction before reversing again and going off in the original direction.

And this was one of the clues that led to us knowing that in fact the planets went round the sun rather than the opposite, the sun going around the earth. Why does it do that? It's an optical illusion. It's because Earth is going around on the inside of Mars and as the Earth catches up, Mars appears to go backwards. And then, of course, when you get past it, you can see which way it is actually going.

And it was that that gave Copernicus the clue that, you know, it made his astounding statement that we're not the centre of the universe. But even for, let's go for a moment of just further back, Colin, the Babolians, the Greeks and the Romans. What did they, as it were, assume from it? Well, virtually all these early civilizations believe that this object must be different. You remember all the stars and the sun appear to go in the same direction. This strange meandering across the sky must mean this was a rather special object.

And because it was red and looked angry, then it became a god of war or some non-benevolent deity. Because the association with blood? Yes, and in fact the association with blood carries really rather well into Mars because the colour is because of the oxidised state of the iron on the surface of the planet. Now, when Mars actually gets a little bit further away from Earth, it doesn't look quite so red and it looks more yellow.

And so sometimes in some civilisations, it's associated with the god of agriculture. But it's God, a Weijungara, who is their warlike god. They painted themselves with red ochre to match the planet when they went off to fight with other people. It becomes a story of technology as well as a story of curiosity, doesn't it, the expiration of Mars. And that's one of the facts. And there were some very accurate calculations from quite early on.

I'm thinking of, I'm reading of the Danish astronomer Taiko Brahe and his observations. Can you tell us about them and when they were and why they were so remarkably almost accurate? Well, Brahe was a very fastidious man and he was ultra careful with his you know his naked eye observations and charted where the planet was in the heavens for long, over long periods. He had a student who worked for him

who was better known as a very famous mathematician called Kepler. Kepler used to fight with Brahe all the time and eventually Kepler went off taking Brahe's calculations with him and use the numbers to calculate that planets move in ellipses. And, of course, he produced the laws that tell us about the motion of objects through space due to gravity.

He didn't know about gravity, but he knew where the planets went. And we still use Kepler's laws when we fly spacecraft to Mars because you don't go across space in direct lines. You have to fly on ellipses, and you have to judge to be in a particular place at the same time as the planet actually arrives there. So are you saying that Taiko Brahe made his calculation, if you can tell us what that was, with the naked eyes still? Is he not using any technology at all?

He used to use a technology like he would hold something at the end of his arm and work out the angle where it was against the fixed background stars. And so he made the observations. He wasn't the mathematician. It was Kepler who used the numbers to work out where the planets worked. How they worked. Sorry. Monica Grady, was it Galileo then, who used the first person to use a telescope to observe Mars? Yes, we're talking about the beginning of the 17th century here.

And Galileo was one of the first people to turn a lens up to the sky to observe. Most famously he observed for the first time the satellites of Jupiter, but he also made observations of Mars showing for the first time that it wasn't just, an orange disc that there were patches of dark and light on it. So what did he, did he make massively more of Mars than had been made even by Kepler and Brahe? Well, he could make more, he could see changes which Kepler, well, which Brahe couldn't, changes in position of the, of the planet, whereas Galileo could see changes on the, apparent changes on the face of the planet.

But it was much later astronomers. who made the first really detailed maps, and that was in the, towards the end of the 19th century. Let's see with Galofer moment. Can you give the listeners some idea of the strength? We've talked a lot, people have talked over lots of programs. I've been not about the telescope. Is there any way you can give us a notion of the strength of the telescope he was using?

Oh, crumbs in terms of... I'll probably dig moniker out here. About a factor of times six. Yeah, I was going to say it's... Very, very primitive. It's only what we would call a magnifying glass these days, if that. I mean, it was not well-rounded or polished, blurry, very sort of almost double vision. You wouldn't get decent colours.

I mean, very, very primitive now. But a huge leap forward in terms of the technology available. And how did his observations, how were they reacted to by people? who knew about the area at a time. What was their reaction? Well, a lot of people just didn't believe that these observations were actually possible that, you know,

the people sort of divided into two camps. There were those who thought this is absolutely wonderful. What can we do with this? I mean, he was sort of navigation and security purposes of the time rather than pure science. And so there were people who thought, well, you know, why waste your time looking at the heavens when you can actually use this to see where other people's ships and things are?

John, at the beginning of the programme, mentioned another Italian astronomy, and so of you, Shaparelli, who caused great excitement when he observed what he called Canali in 1877. Now, can you tell us the strength of the telescopes then, or can you churning chip in and give us one to the power of whatever it is? And why the canali caused such excitement? I can tell you, I can't tell you the exact magnifying power here,

but I can tell you a little bit about Chaparale. He was an entrepreneur. He was, he made his observations when he first saw what he called canali, channels. When he made these observations, he went and gave a presentation to the then king of Italy, in which he threw in, and of course if I had a bigger and better telescope, then I could see even more. and I think he got a telescope which the lens was about

somewhere just below 20 inches about 15 inches maybe something like that. And that's the sort of size of lens which is still capable of making significant observations today but I could do more if I had a bigger telescope is still

the refrain of astronomers. I mean absolutely nothing has changed that but part of Chaparrelli's the interest that came from Shaparelli's observations is this word canali, which in Italian means channels. But to people who don't speak Italian, it can also mean canals or the immediate translation was canals.

Now, a channel could be natural. A canal is artificial. And so the idea of if you have canals, you have some civilization, digging the canals. And the observations that Chaparrelli made showed regular features on the surface of Mars, which somebody else called Percival Lowell took on and made very, very detailed maps of these canals and built up a huge idea of a civilisation on Mars, building these canals and moving over the surface of the planet. And from the late, sorry, from the late 19th century and to well into the 20th century

that obtained, didn't it? Yes, I mean that that was a driver for a lot of the observations that were made and by that time the telescopes were getting to be very significant indeed in terms of what they could see but again still not good enough to be able to see that these actually

weren't features on the surface of Mars but were dust storms and dust clouds and that's why they seem to change because as the seasons on Mars change and the winds change, the dust clouds moved. Colin Pellinger, can we talk about Mars itself? How old is it and how do we date it? This is an interesting question

because we have to assume it's the same age as the solar system, which is 4.5 billion years plus a little bit. We don't have any other absolute dates of Mars other than the dates that we have gotten from the Martian meteorites. Now, the Martian meteorites are predominantly younger than that. There have been ones found that are older. However... We find about 30.

About 30 of them are being found on Earth. There's about 30, 35. It's going up all the time. Okay. So we have those dates from the Martian meteorites. When we look at the surface of Mars from here, of course, all we can try and do is get relative dates. We can say that piece looks to be

older than that other piece. And the way in which you do this is to actually count the craters. And you use the number of craters that exist on the moon in areas of the moon, which we have dated because we had rocks from the moon. And you use that as a yardstick. And you say, look, a lot of craters on this area must be very old. Not so many craters on that might be much younger. And so we only have relative numbers. One of the things people too was actually going to deal with make blue detour one such a choice. Why is Mars seen as red

in certain positions? Well, it's the predominant material oxide of iron which, you know, has this characteristic colour. It's not dissimilar from certain desert areas here on the earth, you know, which have that

characteristic colour. So it's just the sort of... Think rust. It's the way it reflects sunlight, essentially. And so that gives it the natural hue. Can you give Monica, can you give us to some idea of what the surface of Mars looks like, this, this rock?

The surface of Mars looks like this. What I've got here is a piece of a Martian rock, a piece of a Martian meteorite. And it's actually quite green in colour, which is extraordinary. Holding a bit of Mars, mops. Well, well, well.

So as you can see, it's a pale greenish colour. And this is a rock that's come from a magma, from a larva, and it's rich in iron, and it's the oxidation of that iron. It's the rusting, which then causes it for the soil to have the red oxide colour.

But the actual rocks themselves are pale green, pale grey, the colour of basalts on the earth. It's smaller than earth, and if you were standing there, looking round, what would you see? What would it look like? Well, if you were looking, many people have seen the pictures from missions on the surface of Mars. You see in most places you would see an undulating barren land with rocks strewn over the surface. If you're in the right sort of place, you might see towering volcanoes.

You might be standing on the edge of a chasm looking down, something like a dried up riverbed or glacial channel. If you think of maybe the badlands of America or something like that, somewhere very, very dry, desert-like and sterile, but with a whistling wind going past you, but no tumbleweed sort of being blown by the wind because, of course, there's no vegetation. But what you do see also are these dust devils, these sort of mini whirlwinds. Yes, little dervishes. Yes, which are quite common on Mars. and there's some wonderful images from the recent rovers,

you know, showing these, I think, half a dozen of these dust devils sort of floating through the past the rover. Colin, how does this atmosphere differ from Earths? It's much, much thinner. It's less than a hundredth of Earth's atmosphere. This is one of the reasons why it's so difficult to get down onto the surface of Mars. if you're trying to use a parachute,

then you have a very little stopping power. It's a very, very hard job to slow your spacecraft down from 12,000 miles an hour to rest with no atmosphere to help you. The atmosphere is made up predominantly of carbon dioxide, 96% carbon dioxide. In actual, there's more carbon dioxide in the atmosphere of Mars and there is carbon dioxide in the atmosphere of Earth.

But unfortunately, it doesn't warm the planet up because there's nothing else there to, you know, dust storms, however, is that when you get a little bit of dust in the atmosphere, that absorbs the heat from the sun, that makes the atmosphere warm, makes it sort of turbulent and swirl around. And so you get these dust devils most of the time. For periods of the year, you get ferocious dust storms.

And going back to the old days of observing, when people actually saw the first, you know, saw dust storms at the turn of the 18th, the 20th century, they actually thought Mars was being destroyed by some terrible event. And there was huge arguments about what was going on at the time. John Zaneke, we seem to have gone in the space of not many years from the late 19th century to the middle of the 20th or just later than 20th century. From, excuse me, from Mars being a place where massive, as it were,

Mayanesque civilizations could build a great system. of canals and there they were waiting to welcome us if we turned up there to a place that is inhospitable, uninhabitable, lifeless and a rock, a sort of dead rock now then. Where are we now? Is there, the water issue seems to be at the basis of this as I understand it. Can you tell us why that is and where we are in finding out whether there is or is not liquid water? Well, it's sometimes described as the Holy Grail of life, you know, fire. find the water and then you have a chance of finding life. I mean, as far as we understand,

you need water, the sort of universal solvent to give you the environment in which the chemical reactions can take place that will produce primitive life. That sort of life. There might be other sorts of life. There might indeed, but we can't quite imagine, you know, without the evidence, life without liquid water. So it's really, it comes down to hunting for water. And with the early spacecraft observations,

although there was clear evidence for past water, you know, early in the history of Mars, the general consensus, I suppose, in the 60s and 70s, was that Mars is pretty arid now. And that coupled with some experiments and biology experiments carried by Viking spacecraft, I think changed the opinions, such that for the last 25 years perhaps

it was regarded as being pretty arid and therefore not likely to be a place. The pendulum is swinging again. There's perhaps a reinterpretation of the data from those biology experiments and we are now seeing that in fact Mars probably does have water not liquid water, there is ice

just below the surface and there's even just recently tantalising evidence that perhaps water does flow periodically now and also coupled with the fact that here on earth we are finding that life in very primitive form exist in the most extreme environments these are the so-called extremophiles

that exist at the bottom of the oceans in nuclear reactors. Absolutely. So life is much, much tougher. So these factors combined I think have led to the pendulum swinging. Because that was a change with life needed sun and then you discover creatures that the sun cannot reach and they're still creatures. Absolutely. Life is time.

Monica, can you take that on a bit? One time, as I understand it, there seems to be some evidence of floods, catastrophic floods on Mars, and that so there seems to have been something. And where are you on this issue? Well, that's right. I mean, we've had fantastic images of the surface of Mars and the channels that have been cut, possibly by running water, possibly by ice. Now, we know that there has definitely been water there on the power, because evidence from these little rocks again,

they have got this rust in them. The one you're tantalising you're holding up. It's about as big as the thumbnail, isn't it? Yes, yes. Let's say it's almost sprout-sized. A small sprout. A small sprout. But in there are secondary minerals

that have been formed by water. So there are grains in there that must have been formed by water on Mars. and we couple the evidence from the rocks with the pictures that the satellites are sending back, the orbiting satellites, and we see that there are these images. Now, there have been orbiting satellites

with very high-resolution cameras that can go back to the same place and take a picture of the same place and compare the features on that place over a period of five, ten years and have seen changes. And they think some of the changes in the side of canyon walls could be caused by slumping,

which has been caused by the movement of water underneath and perhaps seepage in the way that we get landslides and landslips. And that's perhaps by a buildup of dust on the surface, which causes warming, which then causes some of the ice underneath to melt and evaporate or sublime away and then cause a landslide. Before we turn to the missions, in the last 50 years or so, Colin Pillinger,

can we just stick with this in a moment? Is it a sort of desperate need to have somewhere convenient where we might find life? Wouldn't it be so terrifically convenient for everybody if Mars had life? And maybe it's much more likely that the sort of life

or any sort of comparable life is way, way, way, way, way out there. Well... It would be very neat if it were there, wouldn't it? Well, I believe this is actually one of the fundamental questions. of human existence. Are we alone?

Are, is life on earth unique? Now, if, I think it would be terribly arrogant to believe that this was the pinnacle of evolution. You and me and Monica talking this morning. Me, anyway. You're three pinnacles, but... My philosophy goes a bit like this,

Valvin, the elements it make up life, carbon, nitrogen, hydrogen and oxygen. They are four of the five most abundant elements in the universe. Hydrogen is actually the most abundant. Oxygen is the third most abundant. Hydrogen and oxygen, when they come together, they actually explosively combine. So my logic says that water must be the most fundamental and easiest to produce compound. So you've got all the ingredients of what is called a primitive soup here.

Now, if you think logically about that, people are fascinated by knowing whether they're alone and they're also fascinated by where they come from. And we don't know the answer to either of these two questions. But if we could find another place as close to us as Mars where life had started to evolve, then we would, yes, we would know it. We weren't the only people in the universe, but we would have something to compare and contrast with our own life. and then maybe we'd understand why life started and how we got to be where we are.

I think this is a really, really first, you know, really top-level question that humankind want to know the answer to. John and Monica. That is, of course, right. But if we do find traces of life on Mars, we don't know, do we, whether it was independently, whether it evolved independently,

or was it perhaps ceded from Earth? because just as we have meteorites from Mars on Earth, it's possible, well, it's almost certain, isn't it, that there are fragments of the Earth on Mars which have been ejected. It is possible, perhaps, that life forms from Earth travel to Mars and perhaps existed there or the other way around. We might have invaded them already. Absolutely.

Well, just picking up again from what Colin was saying, Earth and Mars formed from the same cloud of dust, cloud of stuff, And it was physics that made the Earth and Mars. It was chemistry that then took those building blocks and made the hydrogen and the oxygen into water and carbon and hydrogen into methane. And it was chemistry that reacted those bits and pieces together that evolved them into amino acids and so on.

And it was chemistry that formed DNA. And then we've got the biology. Now, at some sort of level, you've got a mixture of biology, chemistry, physics, and geology, the substrate bringing together to make biology, the life and that happened on Earth and there's no good reason why it shouldn't have happened on Mars

but then you know you've got the Joker in the pack which is evolution and we evolved from some primordial sludge in a reasonably regular fashion punctuated now and again by the odd meteorite impact Mars unfortunately though the planet has had accidents along the way it lost its atmosphere. It's dry. There's no water on the planet. So if life got going on Mars, it certainly hasn't evolved to the pinnacle, as you call us here. It might have been sort of stopped at some

very, very primitive level. So if there is life there, it's probably going to be hidden and quite, quite simple, not complex life. Colin, can you take us into the recent examinations of Mars and where where we are. There was a flyby in 1965. You'd want to start there and then move on. Just to answer to what Monica said first there, to preface this, people need to know a time scale. Life on Earth apparently began

as soon as the planet was strong enough to support it. And life on Earth actually was very, very primitive for millions, billions of years. You know, people have only been around on Earth. for the last two million years. So we're talking about huge amounts of time. 4.5 billion down to 2. Yeah, when there was scope for this evolutionary effect to take place.

But right, okay, to come back to your question about the exploration of Mars, when you explore the solar system, there is a logical progression of doing things. You set off with a spacecraft, you try to fly where you're going and fly as near as you can to it, take some pictures, shoot past, send those pictures back. And that was what happened in the early 60s. And the first successful missions were the Mariner missions from NASA.

Then your next phase of operation is that, well, we want to look a bit closer and we want to look a bit longer. So the next thing that happens is you try to put something in orbit around a planet and you go around continuously taking pictures over and over again and this gives you more detailed knowledge. When you believe that you know enough about the surface, then you go for the next step, which is to land there, use a robot spacecraft, and do some experiments. After that, you believe that, well, I now know enough about the engineering required to get tomorrow's or wherever,

I need to move on a stage. And the next logical stage is you bring samples back. because if we have samples in our hands in the laboratories, we can use the very latest techniques to analyse them and tease out the information that they carry. After that, it becomes, well, now we have to go there ourselves. And we aren't yet at the point of bringing samples back from Mars. We're fortunate and we have the meteorites.

But before we bring those samples back, we need to answer this question about is there life on Mars? because if you bring samples back and you were to bring some Martian organism now I'm really wildly speculating but if you brought some Martian organism back and it was it evolved to survive

in a very very harsh environment you let this loose on Earth then it would be rampant now this is a subject called planetary protection there are strict laws that say you must not take your biology somewhere else no there must you bring someone else's biology back to Earth It's dangerous.

What you really want is to dig a big lump out of Mars, put it in a sort of space wheelbarrow and bring it back. But you're forbidden to do that because if it came back, it might infect us all. You're not forbidden. What I would like to be in back is a lot of lumps. But you're not forbidden to do this, but what you have to do is to make sure, when you go there, first of all, you have to make sure the spacecraft is sterilised.

You mustn't take any earth microbes, which you would run out into the market and damage the Martian ecology. So the spacecraft has to be built sterile. You imagine how difficult it is to build something with no organisms on it. And then when you come back, it has to be even more carefully handled, has to go into quarantine so that you can test whether there is anything there which could be harmful to Earth. Well, we've had the overview then.

Now, that's terrific. Now let's split that up. In the time we've got left, just dive in wherever you want to tell us what is going on and how, because I've read about the sort of technologies you now have to examine stuff that you can get back to Earth to look at without sending persons there which seems to be extremely expensive and in a far, far distant future.

So can you dive in where you want to, John, on following Colin? Well, I mean, there are all sorts of things that we want to do that we're planning to do. We in Europe are involved in a mission that's being built at the moment called Exo Mars, which is going to Mars with the ability to rove around a little bit more than the current rovers. But importantly, also to do that.

drill down below the surface. I think Monica's already alluded to the fact that if there is life there, it will have evolved to cope with the environment. And the environment, because of the thin atmosphere, is the radiation environment is terrible. So you've got to hide from it. So you've got to go below the surface.

And up till now, I think we've only literally scratched the few centimeters off the surface. So XMRs will drill down, we'll extract material from below, and analyze it for biology. Now, had been Michael got there.

Right, quickly, after you, you said, had Beagle got there, Beagle would have gone down below the surface. He had a device called a mole. But I'll tell you what,

the extension of what Beagle would have been if you'd listen to Monica first. I've certainly listened to Monica first, listen to the Monica anytime. What I was going to say was following on from what John was saying and what Colin was saying earlier about bringing rocks back.

You might say, well, hang on, you've got meteorites back. They haven't infected the earth. they haven't had any rampant, you know, disease or anything. They've been brought back with no planetary protection, control whatsoever. But they have come from more or less the surface of the Earth, sorry, the surface of Mars, blasted by impacts. So the surface of Mars is sterile. It's sterilised by the sun's ultraviolet radiation.

So we don't know what's below, which is why we need to dig with exomars, which is why we would have burrowed with the mole, to get below those, centimeters of soil, which is sterile, to get into the rocks below, to find out if there's anything there. Also, the meteorites have presumably spent, what, thousands, millions of years in space. And have been sterilized again by cosmic radiation.

So when you go below the surface, do you expect to find something very different from what is on the surface, Micah? Certainly you'll find stuff that isn't oxidized. So the soil is orange, red, because of the oxidation from the surface chemistry. So once you go below into bedrock, it's just the same as digging below the soil on the earth

to find the rock. So yes, we do expect to find something we hope that will be unaltered and that might be able to preserve an original ecology if there was one. Colin Pellinger, you were the leader of the Beagle II project which disappeared in 2003, trying to land on Mars. People have even spoken about a Mars curse because a lot of landers have not managed to landers have not managed to land.

What were you trying to do? You hinted, alluded to what you were trying to do there, mentioned what you're trying to do there. What was it? And secondly, why do you think it hadn't, it didn't deliver in that sense? Well, this is where I part company from my colleagues here because Bigel 2 was a spacecraft which was designed to look for evidence of both past and present life. It was going to use an experiment which was going to detect carbon.

No carbon other than the carbon dioxide in the atmosphere of Mars has ever been detected on Mars. We've already said, life involved carbon. So Beagle was aiming to find some carbon. It was going to go below the surface, as Monica has pointed out, so we were going to get around this oxidizing problem. Now, we didn't, the experiment that it was actually going to do was the simple experiment that you do on Earth to show that life began almost four billion years ago.

So it is actually the simplest and first experiment that you should actually do in terms of looking for life on Mars. Now to come back to another subject that we touched on just now about where's the water and where's the exciting parts of the water? Well, the water we now believe might exist in the last five years because we see these pictures of places where there wasn't something and then suddenly there is. I've actually been talking to the Americans about trying to go to one of those places

because where liquid water is might be the place where you might actually find carbon in its compounds. Can you just briefly say why you think the Beagle II disappeared in 2000? I wish I could answer the question. There are lots of reasons and it's nothing to do with my management. No, no, no, I remember the excitement. I remember the disappointment. We did unfortunately choose to land a period of time

just after the dust storm season. And for 100 days after Beagle attempted to land, there was an awful lot of dust in the atmosphere. That dust makes the atmosphere turbulent. It makes it difficult to stop with the parachute. So that I think is a contributory factor. We have seen pictures on the surface. We've seen features on the surface,

which we think might be where Beagle 2 is located. If it's where we think it is, then it could have been the subject of a very unfortunate accident. Instead of doing as it was designed to do, which was to take the impact flat on the bottom in the most convenient way to absorb the impact, it could actually have taken the impact on the side which might have stopped its opening procedure

and it might have stopped its solar arrays falling out to get power. Now we are still searching. There's a spacecraft around Mars now, the most sophisticated camera of all. It has a capability of seeing 20 centimetre sized objects. This camera is going to look in the places where we think Beagle might be. Briefly, John and then, Monica, where are we now? We are building further spacecraft.

There's a battery of planned experiments. And of course, long term, there is the expectation or the planning to put humans on Mars. I mean, that really is very, very challenging. And we're talking of, I don't know, 20, 30 years away. But there's no fundamental reason why that shouldn't happen. Before that can happen, we've got to. to take steps and in the same way that Chaparrelli was describing things that Lowell then took on and inspired other people to explore, where in Europe, the Americans, the Japanese, the Chinese, the Indians,

are all on the verge of a new sort of era of planetary exploration, which at the moment is focused on Mars, but with the major stepping stone of the moon. So one of the things that people are doing is considering using the moon as a place where, yes, we can test as a test bed for technologies, which will then eventually allow humans to explore Mars. And one of the things that we've got to do is we've got to capitalize on this new era of exploration

to use this, to use this, to keep the excitement of exploration at the forefront of the media, of schools, of students, to build up an interest and an excitement in exploration, because we need that so that we can have new generations of people to carry on the exploration. Well, thank you very much, Monica Grady, John Zarnacki and Colin Pillinger, professors all. And next week we'll be talking about the Jesuits, once called the Schoolmasters of Europe. of thanks for listening.