 I'm going to give you a little overview of why some of the things that are interesting about Mars. I won't be able to tell you that much in 15 minutes, but I'll hopefully give you a flavour of why we're interested in the planet. And I'll then tell you a bit about how we get there in general and some specific details of the Sceparelli lander, which you may have heard about last October, of which I was co-principal investigator. So I'm going to start with a little bit of history. This is a map of Mars made by a man called Giovanni Sceparelli in the late 19th century. He actually made this in 1890, and he was a telescope observer, an Italian who worked in Paris. And actually, many of the details on this map are things that you'll hear about again later. A lot of the things about Mars he got right, this is the time when telescopes were getting better, and he saw lots of features. One I'll draw your attention to is the Hellas Basin here, which you'll see again in very modern maps. This is a real feature. It's an astronomers' map, I should say, so it's upside down. So south is at the top, and west is on this side because a telescope's turned images upside down. So astronomers draw maps this way. But notably, he saw, or thought he saw features, actually I'll show you on Sceparelli's map first, he saw linear features, which he described as canalei. Now I'm sure your Italian is good enough to know that canalei means channels, not canals, but it was mistranslated by a famous American astronomer called Percival Lowell, a very good and famous astronomer who took up this idea around the same time and was convinced that Mars had a system of canals. I'm sorry, I should have gone back to that. So what Percival Lowell saw, this is just one plate from his book about Mars that he published in 1896, were dark patterns on Mars. Now these are quite real, and he saw these dark patterns moved, so he thought they must be vegetation. He realised they moved with the seasons. You'll hear what they actually are later. They're not vegetation, but he believed they were. And he also saw, or thought he saw these canals, and he drew cities at the nexus between them and believed that Mars was inhabited, that the civilisation was dying near the equator and needed to bring water from the poles by these canals. And this is not an unusual view at the time. The idea of other planets being inhabited was not a wacky idea. It was relatively mainstream, not everyone believed him, but it's an interesting observation in psychology that one person says there's canals and then everyone else sees them, especially if he's a famous person. It's probably just the human eye joining up random dots. We like to make patterns out of random things. So when we actually get to Mars, what did we see? Well, it was a bit of a disappointment really. This is a horrible picture, but it's of some historic interest. It's actually been taken by the Mariner 4 spacecraft, which flew by Mars in 1965, and it's the first photographic image of Mars taken by a spaceship, which is why I showed it tonight. And it shows something that doesn't look unlike the moon. People were very disappointed. There's craters, there's a boring surface. The next two images are taken by the first landers that returned images from the surface, the Viking landers, which landed in 1976. And this was a fantastic mission. It was amazingly successful, lost it for more than six years, and we're still working on data from these landers today. But what they found was not what they were hoping to find, which was lots of life, but a dead-looking planet with a dusty sky. At first, the sky was coloured wrong, but it would be this sort of dusty orange colour, lots of dust on the surface. And in fact, this lower image is a blown-up one from a Viking lander 2, and this was actually only reprocessed in 2016, believe it or not. But what it shows you is not only these rocks, they're basaltic rocks that have come from volcanic activity and the ubiquitous red dust, but a white substance on the surface, and this is water ice frost. This was a frosty morning on Mars in the northern hemisphere. Viking lander 2 was about 45 degrees north, so a little south of us, but similar sort of mid-latitudes. Well, this for some time set Mars research back because people thought, well, it's just another dead planet like the moon, or a dead body like the moon. But we now have a rather more nuanced picture of Mars, and we believe it's an interesting, active place even to this day. So this is an image of Mars actually taken on the 8th of May last year, when Mars was quite far from the sun and quite close to the Earth. And you can see lots of things going on, not least to some people's surprise, a lot of water ice clouds. All these bluish-white smudges are water ice clouds, so they're thin clouds, a bit like the surus clouds we have on Earth. And many of them are tied to mountains, so in fact, up here there's a row of three volcanoes on the Tharsis ridge, and these clouds are hanging around the tops of the volcanoes, and the biggest volcano is over here, right on the limb. You can just see the clouds from that. So that's the low latitudes. Otherwise, the atmosphere is clear and thin. It's about 100 times less mass than the atmosphere of the Earth, and it's mainly carbon dioxide. But near the poles we see weather, and in fact there's some quite exciting weather going on. This is autumn in the northern hemisphere, it's the end of summer, and this is down near the south pole, which is just coming into spring, and the bright white you can see here is frost on the surface. But the yellow sort of billowy stuff is dust storms. There's a whole lot of dust storms going off, and this is signs of weather coming around the south polar cap. So here there's a huge regional dust storm. Doesn't look big compared to the planet, but this will be the size of a large, very large country on Earth. We don't tend to see storms this big. And in fact the same is going on in the northern hemisphere, and most intriguingly there's a dust storm here which you can maybe just make out this curve just to the right of centre, and actually this is a weather front. So this is up at about 60 degrees north, and this is a weather system going around a high and low pressure system. This is a low pressure system, just like we experience here. The physics is exactly the same. This is a modern map of Mars. This is actually maybe the laser altimeter. I don't have time to talk about all the features on it, but these are the volcanoes, these are the enormous volcanoes where you saw those clouds. Red colours on this map mean high, and blue colours mean low. White means very high. And this is the largest site of the mountains, the tallest mountain in the solar system. This is the Heleis Basin, as I mentioned earlier, you could see on Schiapparelli's map, and there's a smaller basin here called the Ajaya Basin which was also marked on his map. But I think the main points that I want to draw to your attention in this picture are that Mars is really made of two parts. There's a southern hemisphere, there's a kind of tennis ball shape between the two, flows in this ball and the southern hemisphere is high it is red colours and yellow colours it is cratered it is very old you are actually looking back at some of the oldest land you can see in the solar system some land this old would not still be on search for the Earth it would longer have been recycled in fact some of the land here is more than four billion years old and the Northern hemisphere , in contrast is low and it is very flat roedden nhw i fod ymlaenau, felly mae'n du peth o modd. Mae'n edrych o ddin sylweddol i rhaid ond, o'r môl yn cael nodd môl. Ac rwy'n mynd i bod maen nhw ba oedd oes oed yn rhaid o'r môl. Felly dŵr o'r gwriwn gweinau, gwybodaeth yn cael nodd ddangos. Mae'n gwirionedd, mae'n rhaid o'r peth o'ch dddangos a'r zaeth, mae'n gwirionedd o'r dda. Mae'n dod yn rhaid o'r môl, Mae'n gwybod o'n mynd i gyda'r Mars. Mae'n gwybod o'n 500m yn y ddweud o bob ystod yn y gymhyself. Ac mae'n gwybod o'r channelau o'r cyfle. Yn ymweld, mae'n cyfle o'r channelau sy'n gyflym yn ei gwybod o'r region fel y mawr oedd. Mars yn gwybod o'r mynd yn ei gwybod, ond mae'n gwybod i fi. Ar gwrthodd yma, nefnodd yn gwybod o'r llan dros y 4bllian o'r llan. Yr Mars i'n ei gwybod o'r llan dros 4.5bllian o'r llan o'r llan, Daeon loaders fyrdd d紹 і farcha nhw'n ffordd rhai. Mae'r ffordd voi buff yn hytrach y pwydd manner gliwn o'u lle. Mae'r ffordd 밥 ynrayl a bod rejo yn argynnu. Roedd mwyaf ni shade fan gol. Mae'r wych nawr yn leogotig ar fyf演id. if you strip the soil off the Amazon basin, it would not look unlike this. This is a river that was flowing four billion years ago. Back in mere three billion years, a Mars had changed. This was a period just called the Hesperian on Mars. And there was still flow though. This is a region, which you can just see on the bigger map. This is the height map with the same colour scheme as I showed you a while ago. And we cut across section through it and you can see these giant channels. So, two kilometre deep channels, 30 kilometres wide, this was a mega flood by any stretch of the imagination. It wasn't like a sort of channels carved by rain and a river. There's something, some vast amount of ice, probably, melted and collapsed and flooded out through these channels to the low northern plains. And in fact, you can see features like they saw over in North America. Nothing like this big, but much smaller. But there's evidence of mega floods in the past on Earth. Frenchman's Creek in North America, I believe, is one example. And even up to the modern day. So, the modern day on Mars and the dry cold Mars that we see now is called the Amazonian. But there's evidence that things are still happening. It's not a dead place. These are cliff sections. They're near both poles, so this is high here and that low here. And there's been some sort of land slip and that's a cliff face. And there's another cliff face. And in these cliff faces, you can see dark and light layers. And what you're actually looking at is ice. And it's either clean ice or dirty ice. And these layers are only maybe a few metres thick. But what we think is that these layers can be tied up with variations in Mars' wobble, in the wobble of its rotation axis, and it's all wet around the sun. And these layers may be formed over periods of 10,000 years, 20,000 years as the climate switched from a warmer, more active climate to a colder, clearer climate and back again. And now, right to the modern day, this will start to play in a second. So, this is some images taken very recently from two recent Mars years. There's just a cluster of images of the same place on Mars. We very rarely have images of the same place on Mars. And this shows a feature which we're called recurring slope lineae, or RSLs, in the scientific jargon. What they actually are is debris flow. They're debris flowed down channels. So, if you look at the images, you'll see that as the Mars goes into late winter, something happens and these black streaks here, over the course of, as the winter goes on, extend. So, what's happening is that debris is slipping down channels from the high ground here onto the flat ground. Now, why is that interesting? Because something must be lubricating this debris. And the chances are it's actually melting water ice, it's water ice that's melting in the present day. So, things are still changing. And then most recently, we've had some rather intriguing observations. This is actually a telescopic observation from the Earth, which is why it's low resolution compared to the spacecraft images I've shown you. But it suggests that we have found methane in the atmosphere of Mars. This is a very difficult observation to make. It's quite controversial still because you have to look through the Earth's atmosphere, which has lots of methane in it, and subtract that out. But the suggestion anyway is that the plumes of methane have been observed and several different observations seem to confirm this. Tiny amounts, 30 parts per billion, but it shouldn't be there because methane would only live for at most 300 years in the Martian atmosphere. So, something must be producing it if a plume of methane erupts one year and it's not there the next. And something must be destroying it as well, which we don't understand. So, this methane couldn't have been left over from the old days on Mars because it would have long ago been destroyed. So, something's making methane now, or releasing methane now. And there are many possibilities, which I don't have time to talk through, but there seem to be two fairly reasonable candidates, and the first one of which is a process called serpentisation, which is a geothermal process. So, it's when olivines are rocks that are rich in iron, react with water under high temperature and pressure, and they become layered, and this can release methane. It might be reached directly to the atmosphere or it might be stored in cages of water ice, but that's not so important. The point is that this process itself, we wouldn't expect to be happening on Mars because we think Mars is cooled down, it's smaller than the Earth, it's cooled down. We don't expect this sort of very active geothermal activity to be going on. So, that's quite exciting if that's happening. The other possibility is even more exciting, which is that the methane originates from simple life. Various sorts of microbial life will produce methane. So, how do we get to Mars? That's some of the reasons why we might find it an interesting place to go. How do we get there? This is a summary of all 42 space missions to Mars from the early 60s through to the modern day, and it's quite a complicated diagram. You needn't worry about trying to read all the details. The point is that if the cross ends here, the mission simply failed on Earth or on the way. If the mission gets to this circle, it means it was a flyby, and that's the easiest sort of space mission to do. You fly by the planet, take a photograph and disappear off. That's relatively easy. If we go to the next layer, the spacecraft got into an orbit around the planet. The next layer, it landed on the planet, and finally it delivered a rover which could drive around. And these are progressively harder. And the reason is because you have to go to Mars fast and you have to stop when you get there. And stopping when you get there is actually a lot of the problem. How do you get to Mars? Well, you can't just go when you like. This is one of the problems. You have to wait, and there's actually an opportunity every 27 months to go to Mars for a couple of weeks. So you have to wait until, roughly speaking, the Sun, Earth and Mars are all lined up. And that happened in March last year. At that time, you launch a rocket, but you don't fly out towards Mars. You fly off at a right angle, and you fly as fast as you can in this direction. And the rocket carries the angular momentum of the Earth, spins out and arrives over here six months later. And if you've done your calculations right, Mars also arrives there six months later. So that's how you get to Mars. And at that time, that's not free of problems because, of course, six months later, the Earth's round here and you're trying to talk to a rocket or a spacecraft up there, that's the light travel time from there to there is about 10 or 11 minutes. So the signals from the spacecraft take 10 minutes to reach us. We send some instruction back another 10 minutes to get back again. Now, if you did want to come back, it's even harder, unfortunately, you can't just mess around for a few days and come back. If you really wanted to come back, you have to wait for a year and a quarter on Mars. You have to wait until the Earth is now here, you don't have to wait for the Earth to go round once completely and once again to there. So one and three-quarter years after you started, at that point Mars is over there and you launch this way. If you launched when you were over here, you would never catch the Earth up because the Earth's going round quite fast and you'd be lost in space, you'd never catch up. So you wait until Mars is ahead of the Earth, you launch back in towards the Earth and six months later, if you've done your calculations right, the Earth's moved round from here to here and your rocket and the Earth arrive at this point at the same time. So you're going to Mars is challenging. You can't just go there and come back. You have to wait and you've only got a very limited window to come back in. So finally, I'm going to tell you a little bit about ExoMars itself. ExoMars is the ESA now, the ESA Roscosmos mission and the idea originally was to send this rover, which will be sent in 2020 now. I remember I told you there was an opportunity every two years, roughly. So the first part of the mission was to send this spacecraft, the Trace Gas Orbiter, as it's become known, which was originally a relay for this. It's just a communications relay for this, but it's going to do science now because it's a discovery of methane and the Sceparelli entry probe, and I'm going to tell you a little bit about how Sceparelli basically tested landing on Mars for us. So this is actually Trace Gas Orbiter, to give you a sense of scale. It's folded up, solid panels are folded up and there's Sceparelli being loaded at Bicolur in Kazakhstan for launch. And on the Trace Gas Orbiter, there are four instruments which I haven't got time to describe, but one of them, Nomad, had largely had its UV invisible channels built at the European University. So although the Belgians lead the infrared part, we lead the ultraviolet invisible part and we're involved in a lot of science that's going to come from this instrument over the next few years, the next four or five years. This shows you roughly what happens when you land on Mars. I'll just talk through some of the problems very quickly as it goes. So this is the spacecraft arriving on Mars, arriving about 120 kilometres above the surface. This is Sceparelli. At this stage, it's doing about Mach 35, about 21,000 kilometres an hour, which is the sort of speed you have to fly to Mars to get there in six months. At this point, it's inside a plasma sheath and you can't talk to it, which is another problem, because there's no radio communication possible. But this is one of the first part of the entry as a ballistic entry. We're flying through using the atmosphere to slow down from Mach 35 to about Mach 2. And to do that, you have to angle the spacecraft very carefully, but, of course, we can't drive it, because the landing had already happened by the time we got the communication back. It has to happen automatically. You have to fly through the thin atmosphere and wobble the spacecraft to slow it down and end up where you want to be. When you get to about Mach 2, you can throw out a parachute to slow down even further down to Mach 1, and this part also worked correctly. So the hypersonic entry worked well and this part worked well. The parachute slowed it down to about Mach 1 at about four kilometres above the surface, and then this happens. The shield comes off, that happened. We know the parachute will come out because we can see the bump on the spacecraft. And at this point, shortly, the retro rockets will fire to slow it down over the final part. Now, actually, what happened, of course, you know that Skeporelli crashed. What happened was at this point, this will work fine. The parachute will find it is attached. The rocket's fired. Unfortunately, what happened was that Skeporelli, at this point, believed it was on the ground through some error in the control system. And it said, oh, God, I'm on the ground. I'm going to turn off my rockets. That's a bad idea to have the rockets firing when I'm on the ground. It turned off the rockets. It started to work. It actually started to set up the weather station and all the time falling from four kilometres above the surface. So it was a very simple error, but actually most of the hardest parts of the entry ironically worked correctly. The hypersonic ballistic entry worked correctly. And it would have just fallen from about two metres onto the ground. That didn't work, unfortunately. So they're the most important parts which I've just talked through. And finally, just to show you the size of the thing we were landing, it was about a metric ton with a bloke there for scale. And you knew this is actually how exciting it gets flying a spacecraft. This was while it was doing that hypersonic entry. I was sitting in a small sweaty room in Germany looking at some numbers on a screen. Unfortunately, it has already crashed at that stage, but I didn't know it for a few minutes yet. And this is the remnants. Unfortunately, what happened was not only did it fall from four kilometres. Here is the parachute and the back shield, and here is the heat shield. They're in the right place. Everything worked correctly. That's the actual land or rather those bits of the land. That's the explosion because it's tanks were still full of fuel, hydrogen fuel. So not only did it fall, it crashed and blew up. So bad ending, but this is all about smoothing out the bugs for the landing rover. So most of the hardest parts worked. That's the good news. The really good news is that the orbiter, which is where 99% of the science is, is worked perfectly. So the orbiter is currently in a four-day orbit. We're not in the science orbit yet, but this just shows you. This is actually a picture from Casice, one of the four instruments which we also have an interest in. Casice is a camera, but it's a stereo camera. So this is a picture of a part of the Martian train as it flew past, and we don't get a two-dimensional picture, but we can turn it into a three-dimensional picture through using stereo imaging. And the Nomad. I haven't got you any Nomad data that I can show you, but I can promise you that it is working correctly as well. So it all seems to be good news, and over the next few years we'll get some science about the Martian atmosphere.