 Yn ystod, wrth gweithio, a ddod i chi'n gweithio'r ffordd o'r 11 o'r lefnod o'r 50 oed yn awgwrl. Mae'n gweithio'r 50 oed yn ymgyrch. I'n Josie Fraser, dyma'r dyma'r dyma'r dyma'r dyma'r dyma'r dyma'r dyma'r dyma'r dyma'r dyma'r 50 oed yn ymgyrch. Feut ai'n gweithio Llywodraeth Cymru ateb hwnnes yn fagorol hefyd elwed hyn yn datblygu unrhyw o'r lleol yn awgwrl. Ewa d refineid y peir arall, mae'r campattua leeaeth mae'r campattua adaptioddol iawn oha o hyn at yr carełemau decilio ac eich lleol, ac y lleol yn iawn y cyfnwn cyfl suiteb sy'n ymgylch yn gy statsiath flin喜b yn yr arwe 일ad. A dy Yn ymddangas gyda'r ysgol yma, rydym yn y gallu ddweud ychydig o'i leesio yn agorol, yn hynny'n ystod o'i cadwy acudwymiadau sy'n gofynu newydd a newydd. Yn ymddangos, dyma'r Dade Rothery, ymddangos ymddangos ymddangos ymddangos, mae'r puzzol ymddangos Mercury, ddiddorol yma, ac rydyn ni wedi bod yn gweld i'n gael Carol Haswell, ymddangos ymddangos ar gyfer astrofysic, i ymddiadau ymddiadau ymddiadau, a ymddiadau yn y Unifredig Starthrech. Felly, fyddwn ni'n gwneud i'r cyflwyno'r tîm yn y tîm. Felly, ymddiadau'n gweithio'r cyflwyno'r tîm yn ychydig ar gyfer gweld ymddiadau, oedd yw'r ideaen i ddweud ymddiadau, oedd yn gweithio'r cyflwyno, ymddiadau, ac mae'n ddweud o'r enthwynt yn ysgrifennu mewn gwirionedd, yn y cymuned o'r technolig gydyddwyd i ymgyrch o'r mifio, ymgyrch yn ymrydau cyffredigol. Mae David Carroll yw'n gweithio gyda llwyddiadau o'r ysgolig. Oeddem, mae'r unrhyw ymgyrch yn Professor Dave Rothery. yn ymwneud 2013, Dave wedi bod nhw'n unrhyw pethau o gyfnoddau geoscience ar y universityll yma. Mae'n cael ei ddefnyddio'r hynny, iawn i ddweud yng nghymru, ynghydfydd, ac y ddechrau'r ysgolodau ar gyfer geoscience. Yn yma 2006, mor ddweudio'r cyfnodd ynghylch gyda'r cyfnodd y Cymru o'r ddechrau'r cyfnodd ymddorol wedi ardal y dylau ymdraen, ond mor ddweudio'r cyfnodd ymdraen o'r cyfnodd ymdraen o'r cyfnodd o'r cyfnodd ymdraen o'r cyfnodd ymdraen. David research interest centre on the study of volcanic activity by means of remote sensing and generally volcanology and geoscience on other planets. I like to think of that as being an earth scientist for everywhere but earth. It gives me great pleasure to introduce Professor David Rothery. Thank you and good evening everybody. Posit of Planet Mercury, why go there? It's not exactly my title but I agree to go with it. It fits with the general theme and as this is my inaugural lecture I'm going to tell a little bit about the journey that's taken me to the position where I'm going to Mercury at least with the spacecraft on which I'm not actually a principal investigator. I'm a lead co-investigator for geology on this instrument but it's much the same kind of thing. But I didn't come here to work on other planets. I came here in 1978. This is my first concept with the Open University, a letter from Ian Gass in reply to one from me. Ian Gass was the founding professor of earth sciences here and I'd heard about a PhD here using satellites to do mapping in Arabia and the terrain that was being mapped was part of the ocean floor that had been thrust on top of the edge of the continent. It's called an ophiolite. Ophiolites were quite new and very exciting things to work on in those days. McBrown is here in the audience, started two years before me and ophiolites were really cool. It's a great thing to work on. This is a letter from Ian and here's my letter of appointment from the higher degrees office as it was then called saying you'll be starting on 1 September 1978 and current PhD students will be interested to note that this letter was sent to me on 2 October 1978. The higher degrees office has been rebranded multiple times since then but whatever it's called these days, it's always been like this, you get your letters too late. I started early because I was going to be sent off to the Oman in early November and I had to learn the drive before I got there. The very first thing I did, thanks to Ian Gas, in either July or August records have been lost, he got me weeks demonstrating at summer school. I went to summer school at Durham, met OU students and it was really that experience that showed me what a remarkable institution the Open University is, spending time with students, going out in the field with them, drinking with them in the evening and so on. I very much regret that so little of that happens these days because it did make us a community and students learned off each other and sparked off each other. I know you can do it remotely but it's better to meet people for real. Those summer schools were for me what showed me what OU students were like and really attracted me to the institution. I was going to summer school every year until they stopped a few years ago, very last if you still happen. What I did after that, I was able to get a postdoc and then lectureships here, I started getting PhD students of my own and at the first bunch, well Sasha on the left there was remote sensing of the Oman, doing a better job than I did because she had a better satellite. And the next three guys there were using satellites to monitor active volcanoes on the earth and that's what I did for a while. I wasn't headed towards planets like Mercury but that did come about a little while later. Let me just take you back to the Oman because there's a link between the Oman and what we're doing on Mercury. Here's me in my field area, that's something that's a sheeted diet complex in the background. It may not look like it but I am wearing shorts. It was a beautiful area, it was arid, the rocks were well exposed, perfect for remote sensing. Now the Oman is this region here, this is the straits of Hormuz and we're mapping this area here. This is Ian Gas supervising me in the field with a mug of tea in his hand. He was a Yorkshire man and this is my Land Rover. What a privilege to be given target of that Land Rover and told going to the mountains and make a map. I slept in that Land Rover, not with those goats. It was a great vehicle except when it broke down or got stuck. But I was in amongst the rocks trying to map them but my project was to see what remote sensing could do. Ian Gas was great at getting money from different sources and he got money to try out this new kind of Landsat technique. Here's a much better modern satellite image than we had in those days and the old Landsat images weren't a lot of use. What I used mostly was one to 60,000 scale RAF, black and white air photos flown in the 1950s. Just enlarge that one up. You can see, this is a watercourse here and you can probably make out individual acacia trees and you can see the fabric running through the terrain. That was great and we produced maps. Go back to this satellite view of my field area. Two winters mapping in the field, I turned it into a geological map. By forming the contacts in the field and learning what was what and how it looked in remote sense data. This is what we now do on other planets. Here's part of the planet Mercury. Jack Wright was in the audience, finished a PhD several months ago. This is a bigger area here than I mapped in Neoman and this is only part of Jack's area. He turned that into a geological map on another planet using very much the same techniques as I was using back from 1978 to 1982 during my PhD under Ian Gass's leadership. I've got quite a team doing planetary mapping here now. Here's my present team basically. If you're a little bit concerned about the gender imbalance there, it wasn't always like that. When I started mapping on Mercury, I started studying Mercury. I had three female students. The one who fancies herself as Cher Valentina was the one who spent time working on Photoshop rather than mapping. She produced that wonderful graphic. Mercury has been a very productive body to do research on. Our spacecraft, which you'll hear about shortly, is on its way there. We've been able to do so much because there's been a NASA mission called Messenger which provided wonderful data that we've been working on. Now where is Mercury? Here's the inner solar system as it is right now. Here's the Earth, and you can just about see its orbit. Here's Mercury on its orbit. Mercury is going clockwise round the sun, anti-clockwise round the sun. Just on Monday it passed exactly between the Earth and the sun. How many of you saw it? A lot of people who were here had a chance to see it. We had sunshine for most of the transit. A lot of people in the Mulberry lawn and somewhere, oh I've put a circle around it, there, just inside that little circle. Maybe you can see the tiny little dot of Mercury but it's just started transiting across the sun's disk. When Caroline Haswell gives her talk after me she'll be talking about planets transiting across their stars. Usually bigger planets and quite often smaller stars so they're easier to spot. This will be very hard to spot remotely. That is a planet transiting across the sun. It did dim the sunlight but the clouds that kept passing by were dimming the sunlight a lot more. But Mercury's a hard planet to study from the Earth because it is between the Earth and the sun. It never strays far from the sun in the sky. Here's a picture I took of it by leaning my iPhone on the wall of my house in Silverstone. That's Mercury, pale pink dot in the sky. You can see it if you look in the right place at the right time. So what's it like as a planet? OK, here's the Earth and Mercury to scale. Mercury at the top there, it's an airless body, fairly colourless. I'll be showing you images with exaggerated colour in a while but with the unaided eye it'll be pretty dark and grey. So it's a smaller body than the Earth. It's airless, it doesn't have enough gravity to hang on to an atmosphere, especially at the high temperatures by day that close to the sun. It's a weird world because it's very dense. It's got the same density as the Earth, which may not seem remarkable, but it's a much smaller body, much less gravity therefore, much less internal compression. So it's density relative to its size means it must have a very large core inside it. And here's what we think Mercury's internal structure is. This is the inner core which is solid. This is the outer core which is fluid. I was a big surprise when the Mariner 10 spacecraft got there and discovered that. And then this is the rocky mantle and this is the rocky crust. And that is a very small amount of rock enveloping a large amount of iron. You have to explain that if you want to understand how Mercury got to be like it is. If we show Earth and Mercury to the same size, Mercury here, Earth there, Mercury's core is much, much more massive, much more voluminous than the Earth's. And here they are at their actual size is Mercury's solid inner core. It's actually a little bit bigger than the Earth's solid inner core in absolute terms. Mercury, if it started out like the Earth with the same ingredients, which you broadly speaking expect, it's lost a lot of its rock. Well, how did that happen? I don't know how many of you watched the Planet series, the OU BBC co-production that I worked on as one of the two OU advisers. You saw graphics showing planetary embryos colliding with each other and ripping material away. It didn't really convey the story very well, I thought. But the point is, if this is Mercury, if it's just careened off a body that would later become the Earth or a body that would later become Venus and stripped away most of its rock, you're left with the core surviving that glancing blow, hit and run impact and a very small amount of rock surviving around it. And that's an easy way to explain big core, small amount of surrounding rock. But then when you find out what that rock is like and what it contains, it doesn't stack up very easily and I'll come on to that in a moment. So here's what we know about Mercury, some simple facts. These are the terrestrial planets at the correct relative scale. Mercury, Venus, Earth, I've put the moon there as well, and Mars. So you see Mercury is smaller than Mars but bigger than the moon. But it's relatively dense for its size. And it has a magnetic field which Marin the 10 discovered. So there's a magnetic field enveloping it. And that's a strange thing because the Earth has a magnetic field, but Venus doesn't, Mars doesn't, the moon doesn't. A magnetic field is telling you that you've got an electrical conducting fluid turning around inside. So that's why we think Mercury's outer core is fluid, like the Earth's outer core is. The cores of the other rocky bodies must be solid throughout. Okay, key facts about Mercury. I'll press the button again to make them play. Okay, there's a very large presumably iron rich core which we get from its density. But the surface is only 2% iron. That's a small amount of iron in the rock. All the iron's gone into the core. But there's a lot of sulfur, 2% to 5% sulfur wherever you look. Sulfur is what we call a volatile element. It's easily lost to space under conditions of high temperature. It's volatile. It doesn't stay at the surface. So how can a planet that's had this glancing impact with something else and stripped most of its rock still retain a lot of sulfur? There are other volatiles around on the surface. There's a lot of chlorine, potassium, sodium, various other substances, and some that we don't know what they are, but are clearly volatile. Mercury's a planet rich in volatiles, which is very hard to reconcile with his violent birth close to the sun. It's got gases surrounding it in space. This is a compositionally rich and variable exosphere. The exosphere changes from dawn to dusk and from poles to be equated. There's a lot going on. It's almost no atmosphere to speak of. The atmospheric pressure is a billion times less than the Earth, or less than that, but there are atoms around it. And some of these interact with the magnetic field and get ionised. And for me as a geologist, that's how I began, what particularly interests me apart from the volatile richness is the prolonged history of volcanism and tectonism, tectonism being fault movements. It's a geologically very complex world, which 20 odd years ago we wouldn't have expected. So, Bepe Colombo is the European mission that time involved in, and we launched it last year and it made it into the Sunday Telegraph quiz. So it was a quiz answer. Of course, if you fallish enough to believe what the Daily Telegraph reads, if you fallish enough to believe what the Daily Telegraph tells you, you would come away with the impression that Bepe Colombo is a British spacecraft heading to Mercury, but it's not. It's that European Space Agency spacecraft heading to Mercury with one British-led instrument on board, but it's certainly not Cristiano Ronaldo's yacht or a Chihuahua puppy belonging to the president of Colombia. Here's the spacecraft. Being launched from Peru in Guyana in the middle of a night out time in October last year, and on the left there is me standing beside a full-size replica of it, which you can see in the Science Museum. It's a big spacecraft. And how I got involved in it is like so. In 1994, I got a message. I'm not sure if it would have been an email in those days when we were a group of scientists proposing to the European Space Agency that it's time to send a spacecraft to Mercury, because there's only ever been one. It's high time to go again. John Guest, the guy pictured there, is our geologist, but he's ill. Can you go? Can you come with us to Paris? Cos we know about Manhit Filsman, about geology, and make the geological case for sending a spacecraft to Mercury. So I went and I said my piece, and it wasn't a very exciting planet in those days. I tried to big it up a bit. There were things we didn't know. I wanted to find out. But people would not have thought Mercury was as exciting as we now think it is. So I made my case to them, and I heard no more about it for the next decade, until it was approved by ESA in about the year 2000. And four years after that, I was asked to be on a panel reviewing the instruments to decide which instrument or instruments the UK could afford to buy into. And that's really when I got involved, apart from my cameo role in 1994. I got re-involved in 2004. And this is the spacecraft we have now, Bepe Colombo. This is its flight configuration. It would look now in space. It's powered by an iron drive. Flames here, not flames, but Xenon exhaust is what provides the drive. Powered by solar power from these panels here. And we're on a long cruise to get to Mercury. And on board is the British-led instrument, the one that I was lead scientist on for a while. Here, masterminded from Leicester University, which is where I'm posing here. It's an X-ray telescope. There's two instruments, but one on the left is a telescope. Here it is closer up. This is an X-ray lens to collect the X-rays, and they've collected the bottom. They're focused on for focal plane assembly. This is a device that collects more X-rays, but doesn't focus. It's a collimagor. We've got twin instruments collecting the X-rays that have come from Mercury. And it's capable of mapping the surface composition in all these elements here. The yellow ones, silicon, titanium, aluminium, iron, magnesium, calcium, and sulfur were mapped crudely by the X-ray spectrometer on messenger of a NASA mission. In red, a messenger couldn't see, but we will, and we'll do a better job on all those elements, because we've got a more modern X-ray spectrometer, basically. The principles behind it, I don't want to labour this point, are basically the sun. The sun is quite a bright X-ray source, and these X-rays hit Mercury's surface because there's no atmosphere to get in the way, and that causes fluorescence. The surface fluoresces, and what it detects is fluorescent X-rays whose exact energy is characteristic of whichever element they've come from. So by focusing an image of the fluorescent X-rays on the surface, you get a picture of the elemental abundances across Mercury's surface in a dozen or so of the most common elements. What the NASA mission messenger was able to do was produce crude X-ray maps like this, the bottom right ones are neutron images, but the others are X-rays, ratios between elements. We're looking obliquely down on the north pole. The southern hemisphere of Mercury was hardly seen in X-rays by a messenger because it was in an elliptical orbit, so it's got better resolution in the north than the south, and there are gaps in the coverage. We'll do this across the whole globe for more elements in better resolution. So here is our spacecraft. It's in four components. The bottoms of Mercury transfer module, that's the thing with the iron drive, which transports us to Mercury. The thing in the middle is the Mercury Planetary Orbiter. That's the ESA spacecraft, a European spacecraft that will do the science. The thing at the top called MEO is owned by the Japanese space agency, JAXA. When we get to Mercury, we'll be in orbits like this. The European orbiter will be in the blue orbit, almost circular, staying close to the planet. The red orbit is what MEO will do. It's more elliptical, has more or less four times the orbital period, goes further from the planet. It will study the magnetic field in great detail. We will also do the magnetic field at the same time from a different position, which is great. We will be looking down at the planet. And that's what the MIX instrument will do, as well as various optical cameras. Now, how are we going to get there? I'm going to show you where Bepe is now, I hope, just to open up this website. So, I'm heading back in towards the Earth's orbit. It's got to get into orbit around Mercury. So, I'm going to grab the slider. It's the cursor, there it is. So, grab this, take us back to launch. We launched in October last year. We set off inside the Earth's orbit. Then we went outside the Earth's orbit and we're coming back in. And next spring, we're going to swing by the Earth. And that will send us inwards and we'll swing past Venus twice. Having swung past Venus twice, we go in. And we'll have half a dozen encounters with Mercury each time using Mercury's gravity to slow us down a little bit. So, on the seventh time we approach the planet, we're going slowly enough to get into orbit. So, it's a seven and a half year cruise to get to Mercury. You can get to Mercury really quickly. It's not that far away, but you just sail past it and not stop. When you go to Mercury, the sun's gravity is accelerating you. That iron drive of ours is not to speed us on our way. It's to slow us down. It's firing in the direction of trouble to slow us down so we get there slowly. And even so, we have to use Mercury's gravity and Venus' to slow us down so we get there eventually going slowly enough to get into orbit. Seven and a half year cruise. I waited six years between getting my chair and being invited to do this in ordinary lecture. That's not so bad when you consider asking for a mission in 1994, it being approved in 2000, and then a seven and a half year cruise when you finally launch in 2018. So, that's our trajectory to Mercury. And the mission is healthy. Everything is looking quite optimistic now. We don't do any science, or much science at Venus and Mercury and all those flybys because the spacecraft's in this stacked configuration. When we finally get there, we jettison the iron drive. This thing is what gets into orbit about Mercury. We set Mio, the Japanese thing, spinning to keep it stable and set it into its elliptical orbit. Off it goes and start studying the magnetic field and the particles. And then we throw away the sun shield whose sole job has been to keep the sun off Mio and when we maneuver this into a lower, more circular orbit, and then we start doing our science looking down at the surface. And that's when the X-ray spectrometer mix will start doing its job. Now, why am I so confident that Mercury's going to be an interesting place to study? It's because we've had the messenger mission, the NASA mission, artist's impression of it there. It was launched, I forget, when about 2007, but it orbited Mercury from 2011 to 2015, produced a lot of great data. Not as good as we're going to get, but a lot better than the previous single flyby mission did Mariner 10. It mapped the entire globe, which would have been done before. It did it in colour. I've exaggerated the colour here because it's a fairly bland world. And let me show you the whole globe. This should rotate. Yeah. What can we see? Red areas and blue areas, a circular red area coming into view here, that feature there. It's the colourist base and the biggest impact base on Mercury. It's flooded by red lavers, as red lavers near the poles as well. Let's give it one more spin. It's the globe that's got variety. We think that the blue and the red areas are volcanic lavers. It's not like the moon, which has dark patches which are lava but rocks that have floated up from the mantle in a different way. Mercury's dark everywhere. It's lava flows as slightly different compositions coming out as blue and yellow, broadly speaking. The youngest lavers, including those red ones at the north, are up here. The colorist base is down there. How do we know these areas are lavers? Let me show you an image of part of the northern plains now known as Borealis Peninsula. It's a slightly coloured image here. On the left, or the west, I should say in the south, it's a more ancient terrain, more craters. Up here, the bulk of the image is less heavily created. The older the surface, the longer it's been there to collect impact craters hitting it and scarring the surface. That's a younger area centre and top right of that image. I'll exaggerate the colour for you. There is a colour contrast between those two which tells you the compositions are slightly different. We're confident it's all lava. It's easiest to see it's lava in the red northern plains. I'm going to show you detail inside that little box there. Here it is in black and white. Can you see the circular feature that's dominating that view? It's... I think it's all lava, but that's an impact crater that's been flooded by lava. We can still kind of see it through the lava that's flooded it. There are some craters, but they're much younger and they're on top of the lava. But what you're seeing there, that circular feature about 30km across, is a crater that was there on the previous surface that was flooded by lava. Let me show you a cross-sectional view of what that crater would look like. A 30km crater on Mercury has a raised rim and a central peak, which is much lower than the raised rim. If you flood it with lava of sufficient depth, you can completely hide it. It's going to contract firmly. It's also going to lose lots of void spaces that were filled with gas maybe. So it will sag down and do this. You can see that the rim of the crater is expressing itself topographically there. The central peak is too deep to see, but the rim of the crater is there. That's what we've got here. That's a flooded crater. We call it a ghost crater. We're actually several other ghost craters on this image. I'm perhaps too close to see them, but there's a flooded crater here and up here. Once you've seen one, they're all over the place. The only way, logically, for this to happen is big floods of volcanic lavas. Ghost craters. Here's the inside of the Chlorus Basin. It's the southern half of the basin. Chlorus Basin is filled with red lavas, but there are no ghost craters that the lava flooding there happens so soon after the basin formation. There hadn't been time for younger craters to be formed on the basin floor, or else they're flooded very, very deeply. I'm going to move on from looking at volcanic flooding to looking at explosive volcanism now. Patches like that one there, that one there, and particularly that one there. Brighter, redder material that's got diffuse edges and usually quite an interesting hole in the middle, such as here. This hole in the ground, in the middle here, there's a hole in the ground which is not circular. It's been described as kidney-shaped. I hope my kidney's not that shape. It's got this diffuse deposit around it. Here's a ring to show the edges. There's a similar deposit down here which we'll ignore, but this feature here, we think this is a volcanic explosion crater, and this is the stuff that's been flung out from it. If you're going to have an explosive volcanic eruption, that's telling you that the magma, the molten rock rising towards the surface has got volatiles dissolved in it which will come out of solution as the pressure drops and expand violently and throw out fragments. Or else maybe the volatiles have been incorporated from the adjacent rock near the surface. If you've got a volatile rich surface, the volatiles can get into the magma. Either way, you've got to have volatiles in sufficient abundance to give you these explosive eruptions. The kind of cartoon of an explosive eruption on the earth, the magma rises, bubbles form, if they grow big enough, you throw stuff out with violent force. On the earth, that would suck in the atmosphere and give you a big billowing convection column, but Mercury has no atmosphere, never has had. One place we can see eruptions into vacuum at the moment is Jupiter's moon Io. Here's a little video from the new horizon spacecraft going past, and you see that plume coming out. The stuff rises up and falls back to the ground on parabolic trajectories. Gives you a circular deposit with a diffuse outer edge, just like we see on Mercury. So this is what we've got going on on Mercury in the past. These violent explosive eruptions, which wouldn't happen if it was not a volatile rich place. Let's look inside that kidney shaped vent in more detail. Here's a high resolution view in black and white. That's the interior of the kidney shaped hole in the ground. It is a hole in the ground. It's not a mountain of a crater on top. It's basically a hole in the ground. What I see is that at the western end it's old enough that there's been time for quite a few small impact craters to form. Over here, there's one tiny impact crater just there maybe, but it's basically featureless, not old enough for impact craters to be formed in numbers, and in the middle it's very rugged, possibly an even younger surface. What I think is the first eruption happened there. Then there was one here, then the next one was maybe here, then here, then here, then here, and the youngest ones are here and here. There's a whole series. That's nine different explosions in the same region. On the earth you'd call this a compound volcano, where the the locus of activities migrated to and fro over time. I've seen these on the earth. On the left there's a volcano called Lasca, where I worked with Peter Francis and Clive Oppenheimen, overlapping craters. Here's the youngest one. Here's Messiah in Nicaragua, where I've worked with Hazel Reimer. Migrating eruption sites. If the eruptions are explosive, as they are on Mercury, it's not just telling you that magma keeps rising in almost the same spot. It's telling you that there are volatiles available there time after time after time, possibly over periods of billions of years. It's a volatile rich planet that keeps providing the volatiles. Very hard to explain. This is why we want to go to Mercury and suss out what's going on. Here's the biggest explosive deposit on Mercury, that big diffused yellow spot in the upper part of that image. It's 250 or so kilometres across. It's called Natère Facula. Here's an oblique view into that vent. It's 30 odd kilometres long and three kilometres deep and you can see some layering in the crust up through which it's blasted. It's being produced by a series of eruptions, we think, as well. It's not a single event to blast that out. Here's a really weird, but not the Mercury unusual shape. There's an impact crater trying to trace around the rim of the impact crater. Floor was possibly lava flooded, but this banana shaped hole in the ground with the brightest bit of deposit at the northern end, that's been ripped out, we think, by a series of eruptions. It's another compound volcano. It's in black and white, highest resolution view. Now, did it all go bang like that at once? I think unlikely. It's more likely to have started down there and worked its way up, but we need better detail in the images, which is what Bepicolumbur will give us to suss out the history of this. That's the volcanologist, the geologist, looking at the surface saying, this is weird. This ties in with the volatile richness we've got from our x-ray and other measurements, but we don't know what it is that's turning to gas here, but something sure as hell is. When magma arrives at the surface and blasphies holes in the ground, it's telling us it's a volatile rich planet. Completely different evidence for Mercury being volatile rich, which is a much more detailed image of which very few from messenger will get plenty from Bepicolumbur. On the Italian instrument called symbiosis we'll have really high resolution over a lot of the globe. That's a 1.5 kilometre wide area, about a mile wide. What we've got here, these are holes in the ground. They're called hollows. You've got steep sides and very flat featureless bottom. None of the bottoms of these hollows that we can see have any impact creators at all on them. They must be really young features. They're very young, younger than explosive volcanic features. We think these are growing even today. How the heck do you form these hollows? That's the word hollows for them. Let me show you a broader scale view. There's a big peak ring basin there. It's been flooded by lava, but hollows have developed upon it. In colour, the floors of them tend to be blue. The red material has been stripped away to expose the blue material as the hollows form. Steep sided flat bottom, they're only about 20 metres deep and it can be hundreds of metres to kilometres wide. How do they form? They're not being blown away by the wind. There's no wind. You don't see channels draining away from them. There's no conceivable liquid anywhere which could drain the stuff away. It's not falling into an underground cavern. The material must be being lost to space somehow. You're losing an at least moderately volatile substance. It's being removed without melting. No channels draining away. The candidate mechanism is a sublimation. That's like when dry ice, frozen CO2 turns from solid to vapour. You can't do that with silicate rock. Maybe a space weathering process attacking the rocky particles. Photons, UV photons, ultraviolet photons from the strong sunlight could break chemical bonds and stuff could escape away an atom at a time. Soul of the wind charge particles from the sun which will hit the surface during solar storms when the magnetic field no longer protects the surface could do it. Micrometeorites could hit the surface and break the bonds. But that's estimated to be too slow process to form hollows or maybe the planet's being stripped mined by aliens. I can't rule that out. Stripped mining by aliens doesn't require the surface to be rich in volatiles. All the other processes do. We don't know what the volatiles are but you're not going to lose them to space if they're not volatile. It's a volatile rich planet. Here's a cartoon about what's going on in cross-section, the red stuff at the top that's volatile rich, the blue stuff below. Strong sun shining at you. Mercury are three times closer to the sun than you are at the Earth. So the sun is nine times stronger. So whatever the sun is doing it's causing surface material to start being lost to space down to the bottom of the volatile rich layer then the hollows just get wider and wider. Sublimation, photon stimulated desorption, micrometriac sputtering which isn't the sun but whatever. Once they reach a certain depth they don't get any deeper, they just get wider. And all the ones we can see are young it's an active process today I'm sure they turn off eventually. So that's a mystery. We do not know what is being lost in these hollows. We want to measure this material and compare it with the exposed material at the floors of the hollows. We'll have the spatial resolution to do that with various Beppe Colombo instruments. There's some hints from messenger but they're not really convincing yet so we're working on that and I'm looking very much forward to getting there in 2026 when we start doing science with this wonderful spacecraft Beppe Colombo. In the meantime we are still busy doing geological maps. Here's a better view of Jack Wright's map of Mercury's whole quadrangle. Two versions of that map that's got the craters subdividing into three age-related classes and there are four age-related classes of the craters. You can see maybe up there this is the Hockerside quadrangle that Jack's worked on. In collaboration with colleagues across Europe we get a whole of this planet mapped before Beppe Colombo gets there so when we get our observations we know the geological context of what we're looking at. Now once the Beppe Colombo mission is finished our maps will be obsolete the whole planet will have to be remapped but these maps we hope are going to be very useful during the mission. So these were mapped in Italy this is Jack's my current two students who started three four years ago no three and two years ago are working here and student Ben who started just last month is going to map this quadrangle and we're not far off getting quadrangle maps for the whole planet that's what we're doing to get ready for Beppe Colombo's mission it is a pan-European effort we're receiving funding from the European Commission under the Horizon 2020 programme we're hoping to start a new student next year to do some mapping and get a consolidated grant to let us have a postdoctoral fellow to work on the South Pole and tying all that together in the meantime we're working as a group French, Italian, German essentially to get the whole down planet mapped and it's a great project to be involved in I'm finishing now I haven't had time to talk about the tectonics on Mercury but when what a wonderful planet the globe is contracting we've got a crater there and we've got weird terrains like this it's flooded by lava but I mean what the heck is happening here with these funny fracture patterns we don't know when Beppe Colombo gets there we will find out so doing Geologian of a Planet is what my career has turned into after starting doing it on the Earth and I think it's been a good thing to do we enjoy teaching it in S283 and I enjoy talking about it and I'm driving PhD students working with me on it so we'll leave you with these very profound thoughts and hand back over hand back over to Josie thank you for coming thanks very much Dave it now gives me great pleasure to introduce Professor Carol Haswell Professor of Astrophysics Carol is Head of Astronomy at the Open University her main research interest is exoplanets planets orbiting stars other than the Sun Carol works on transiting systems and hot planets which offer a unique opportunity to empirically determine the chemical composition and that places our solar system in context her accolades include the 2010 Royal Astronomical Society Group Achievement Award as a pioneering member of the Super WASP team I really need to ask her what that stands for and being named one of 20 women selected by the Royal Astronomical Society to appear in a portrait celebrating a century of female fellows Carol was appointed by the European Space Agency to the science advisory team overseeing the planned aerial mission which will perform spectroscopy of exoplanets and illuminate how planets form and evolve I'm delighted to hand over to Professor Carol Haswell Thank you very much Josie and thank you very much everybody for coming out tonight really appreciate you having interest in our subjects I'm going to tell you about some work that I've been doing over the last 15 years or so the main part of my talk is going to focus on a project that we've led here at the Open University which is why I've got that rogue capital you in the title it is our place in the universe the OU and I'm going to take you on this journey so it's a huge honour actually to be asked to give one of these inaugural lectures and particularly to be asked to give the final one in the series I feel very honoured by being asked to do that so I started off by reflecting a little bit on the 50 years that the OU has been in existence and just looking at what we've learned both about planets and more widely about the universe and our place as human beings within it so that's where I'll start with this lecture and then the bulk of what I'll talk about is going to be the research that I've been doing and what we've learned from the astrophysics research on exoplanets that I've been engaged in for about the last 15 years and then towards the end I'll talk about another project which has been a Europe-wide collaboration which has had some very very exciting results finding the very closest planets orbiting the sun's nearest neighbour stars and then I'll end by reflecting a little bit on the next 50 years and what that might bring both in terms of astrophysics and more broadly so I started just looking at the astrophysics of 50 years ago when the open university was formed so I had a look and it's very easy to do this now with all of the online databases and interfaces to actually find which astrophysics paper in 1969 was the most influential and it was this paper on pulsar electrodynamics so this is about the magnetic fields of a collapsed star which has collapsed to the density of an atomic nucleus and I was particularly chuffed to find that out because that paper has an open university connection so the picture on the right is a portrait of Dame Professor Jocelyn Bell Bernal who was actually the head of the department of physics and astronomy at the time that I was recruited to the open university and she was actually began her career as a PhD student in Cambridge and she actually discovered pulsars radio signals and she was the person who discovered pulsars so it's really nice that in the founding year of the open university we had that connection in what was to play out over the 50 years of the OU's life and I also thought it would be nice to sort of just have a quick look at what we knew about planets in 1969 and this was one of the most influential papers in 1969 on the planets of our own solar system and it turns out we didn't actually really know all that much about planets in 1969 which I found a bit surprising so the graph on the right here shows a number of lines on the horizontal axis is depth going down into the earth, into the interior of the earth and on the vertical axis is the temperature and if you look at those lines those are various people's idea of how the temperature varies as you drill down into the earth and you can see there's a factor of 3 disagreements in what the temperature of the centre of the earth was as state of the art knowledge in 1969 so we really didn't know all that much about planets 50 years ago and it's really quite astonishing how far we've come so the lecture we've just enjoyed from Dave showed us that we actually now really know rather a lot of detailed information about the other planets in our own solar system and I hope I'll convince you that we actually know quite a lot about planets that are orbiting other stars outside our own solar system so these are exciting times that we're living in we're on this epic journey of human discovery finding out about the universe and this is one of my earliest memories actually this is a picture that was taken by the first people who walked on the surface of the moon so the picture was actually taken by Neil Armstrong who you can see reflected in Buzz Aldrin's helmet faceplate and this is really exciting and it has a current open university connection as well because we enjoyed about a month ago a visit from space royalty Andy Aldrin who's the son of Buzz Aldrin visited us here at the open university he is sort of in a sense following in his father's footsteps he's very interested in space he's very interested in education and very interested in space entrepreneurship and all of those things link up with things that we're interested in doing here so we're living in very exciting times still now getting to exoplanets back in 1969 we really didn't know whether the planets in our solar system were completely unique in our galaxy we didn't know if generally stars are accompanied by planets and this was a viable theory for how the planets of the solar system were formed back in 1969 planet formation might have required a very rare and unusual event like two planets sorry two stars almost colliding and pulling material from the outer layers of the star which then coalesces to form the planets and if this was indeed the way planets were formed then our own solar system could have been completely unique the sun might have been the only star of the billions and billions of stars in the galaxy which actually had planets and this was actually a viable picture until quite recently until about the 1990s we now know that actually planets form with stars with no special requirements and in fact the laws of physics insist that angular momentum has to be conserved so as the star collapses you get this disk of material forming and the planets naturally form under their own self gravity out of that disk so we now know that planets form with stars with no special requirements so we expect when we look up into the night sky and we see stars each of those stars will actually have planets orbiting around it or there's a very good chance that it will do I should also say this is not an astronomical image this is an artist's impression of what a planetary system forming around another star may look like and we very rarely literally get pictures like this in astronomy we have to use indirect inferences to work out what's going on and then we talk to artists to make these beautiful pictures and there is a danger that when we just sort of send these to journalists they're presented as though this is actually what the telescope saw, it's not so it's quite important to bear that in mind and if you zip backwards and forwards there you can see as well as learning a lot about science our scientific visualisations are normally as well in the last 50 years and I think there's an awful lot of graphic artists doing really beautiful things that people 50 years ago would be very very impressed by so we know that there are lots of planets orbiting other stars in our galaxy and we know that because we've found about 4,000 of them and statistically by scaling up where we've got information having looked for stars in details we know that there are many many planets orbiting other stars in our galaxy and in fact the galaxy contains more planets than stars so that's a lot of planets the giant planets, planets like Jupiter are the easiest to find for obvious reasons they're bigger, they're brighter they have more of an influence on their surroundings but we do know that there are many many earth-sized planets in our galaxy so small presumably rocky planets like the earth are actually more common than giant planets so this is really quite exciting and this is where the Star Trek aspect of my title comes from as we find out more and more about the contents of our galaxy more and more it seems to resemble the galaxy that Captain Kirk went exploring on this TV series back in the 1960s which was another one of my earliest memories and myself and many people my age used to negotiate very hard with their parents to be allowed to stay up to the end of Star Trek which was it's sort of bordered bedtime so this is a picture of what the galaxy and human exploration of the galaxy might have looked like about 50 years ago and one of the things that I like about the lower picture is that even the alien kind of looks like a middle aged white guy which sort of was the world view back in the 1960s and more recently there's a little bit more diversity and a little bit more imagination so this is still from a recent film Star Wars, The Force Awakens and you can see here the two major characters included a different demographically women are allowed to take part in the adventures now and people of colour are allowed to take part in the adventures now and I think that's a good thing I think in the last 50 years I wouldn't say that's directly the influence of the OU but I think the OU has helped we're open to people of all kinds and that's good so I'm now going to move into sort of talking in a little bit more detail about stars and planets and as Dave foreshadowed I'm going to talk about transiting planets, planets that happen to be lined up so they pass between us and their host star from our point of view here on earth and those are special because we can learn more about those planets than we can about planets that are not lined up in that way so the first thing that I should say and probably everybody here knows this but I'll say it anyway just so we're all on the same page is that stars are much bigger and much brighter than planets and as an astronomer if you're working on planets that's a little bit of a nuisance because astronomers work with light and so it's very very difficult to detect planets because they always come with a star which outshines them so it's really hard to detect planets and Dave mentioned it's quite hard to see Mercury well it's much much harder to find an exoplanet because it's much much further away and from the distance we're viewing it it completely overlaps its host star in most cases so stars are easy to study planets are difficult to study and the graph sort of says the same thing as the words but it says says it in a more quantitative way so in the optical light that our eyes are sensitive to the sun is about ten billion times brighter than the earth so that's what we're up against as astronomers and in fact what we do is a very clever trick rather than looking for the light from the planet what we do is we indirectly detect and characterise the planet by looking at the effect that the planet has on the light from the star and the easiest way to do this is to use the transit method so if you simply collect the light from a star and measure its brightness what you will find is if that star happens to have planets that are oriented correctly so the planets pass in front of the star every time the planet comes around you'll see the star get slightly fainter as the planet gets in the way and blocks some of the starlight and you see this happen regularly and that immediately tells you how long the planet takes to complete one circuit around the star so it tells you what the planet's orbital period or equivalently what the length of a year is on that planet, how long it takes to go once around so this is really very simple and as a scientist it's always really nice to work on things that are very simple it gives you a bit more confidence that you're getting things right because you can actually understand what you're doing in detail so the planet detection by transits is a really lovely method and it also gives us a lot of information about the planet it's actually the only way we can directly measure the size of a planet outside our own solar system and you can do that simply by measuring how much light you've lost when the planet gets in the way of the star so it tells you the size of that black circle relative to the size of the white circle and we all know that the area of a circle is pi r squared so that tells you immediately how big your planet is so that's great and you can also learn other more detailed things like exactly how lined up is the orbit you can actually tell by the shape of the dip whether the planet is sort of going across the bottom of the stellar disc or whether it's going across the middle of the stellar disc and that would give you a different detailed shape of that dip so transiting planets are great they allow us to learn an awful lot about the star about the planet there's also another thing that we can do and this is a slide that I've pinched from one of our open university astronomy modules and if you want to learn more about stars and planets this is the very subtle sales message take an OU degree because we teach all of this and it's all great stuff one of the things that we can do with light as physicists is we can use it to learn about composition and Dave has already told us how you can do that with x-rays through x-ray fluorescence but the way that astronomers quite often use is if light is being filtered through a gas then the atoms in the gas will select out particular narrow colours of light and absorb them and so that's what's going on across the top of this slide the light is shining through a gas and the atoms in the gas are selecting out their own spectral lines each chemical element has its own sort of fingerprint of spectral lines so that's why astronomers by looking at light which has been filtered through a gas we can tell what the chemical composition of that gas is so without going there without taking a sample we can learn about the chemistry and this was actually how the chemical element helium was discovered it was discovered in the atmosphere of the sun by astronomers before anybody realised that helium was here and present on the earth so this is a really nice technique that astronomers use a lot to know what things are made of and you can apply this to transiting exoplanets so this is a zoom in again the black sort of segments of circles is the silhouette of a planet that's crossing its star and if that planet has an atmosphere that's translucent then actually at those exact colours of the light being absorbed by the chemicals in the atmosphere the planet will appear a bit bigger so by measuring a transiting exoplanet and spreading the light out into its component colours and measuring how deep it dips at each colour you can actually work out the composition of the atmosphere of the planet even though you can't directly see the planet and this is stuff I think is just really really exciting and I sort of learned quite a lot about my own psychology when exoplanets were discovered because until exoplanets were discovered which have so much scope for the imagination I thought planets were quite boring but now I think planets are absolutely fascinating so this is one of the things we can do and I'll come back to related things later in the lecture but there was a particular example of this in 2003 somebody pointed the Hubble space telescope at the exact wavelength of the strongest spectral line of hydrogen which is the most common chemical element in the universe and what they found was rather than about a 1% dip in the light from the star which is caused by the opaque planet itself getting in the way there was actually a 15% dip at this precise colour where hydrogen absorbs and that tells you that this planet is actually surrounded by a wacking great cloud of hydrogen and I saw this publication in nature and I just thought this is just too exciting to ignore so that was the point that I turned my back on my previous research field and decided exoplanets were for me and I've never looked back so what I did was I led the open university into the super wasp collaboration and since Josie wants to know what that is the super is just because it's really good and wasp stands for wide area search for planets and this was a large UK collaboration involving all of these institutions and dozens of people and it brought people together into an exciting new field and it was sort of a plucky UK low budget project and it's been immensely successful this is another view of one of our facilities and those lenses that what look like the little telescopes there those are actually Canon camera lenses that were designed for theatre photography and they'd all been discontinued by Canon with the onset of digital photography when they needed new lenses to work with CCDs rather than photographic films and they'd been remanded sent to Korea so as one of the few women who was involved in wasp in the early days I got the shopping mission and so I purchased most of those camera lenses on eBay using our grant funding which was a little bit nerve wracking because this was in the early days of e-commerce so I bought all of those lenses from a very nice man in South Korea who I never met up his side of the bargain and we sent him the money and wasp has been an incredibly successful collaboration it's still going it's discovered about 200 transiting exoplanets now and this is a family portrait album from the early days so you can see here our first 15 planet discoveries which are imaginatively named wasp 1 to wasp 15 and what you can see in these thumbnails is a cartoon which represents the size and the colour of the host star in colour and the size of the planet so the size of the planet you can see by the size of the black dot which indicates the planet is a transiting planet and then I hope you can also see the line which indicates the planet's orbit so of all of these planets one of the most extreme is wasp 12 which is third from the top on the right hand side and that is in a very very very short period orbit so it orbits round a very bright star with an orbital period of just over one day so it's extremely close it's extremely irradiated and it's sort of being baked alive and you can see that that black dot is actually bigger than the other black dots so this is one of the largest exoplanets that we've found so I'm now going to move into the main project that I'm going to tell you about which was inspired by work that I did on wasp 12b and this project is called the dispersed matter planet project and it's a project that I conceived and led and we've just got our first results and we're really really very excited and chuffed about the whole thing so this again is that thumbnail of wasp 12 so you can see there in the blue line just how tight that orbit is the planet is only about one stellar diameter away from the surface of the star it really is being baked alive and the graph on the right hand side on the x axis is irradiating flux so that's just how much light from the star is baking the planet and on the vertical axis is the size of the planet and in the open circles are plotted all of the exoplanets that we knew back in 2009 when we found wasp 12 using super wasp and you can see they all clustered together except there's one point in the top right hand corner and that's wasp 12 so you can see that's a bit extreme so I thought gosh that one's really interesting it's really being baked alive and it's much bigger than the other planets and those two facts are related the amount of heat it's collecting is causing it to expand and so it's a very large planet and since I'd done my shopping mission I was given the privilege of being able to lead the Hubble Space Telescope follow-up observations of this particular star planet system so we pointed the Hubble Space Telescope at wasp 12 in the ultraviolet and the graph on the left hand side shows a zoom in on what we saw when we spread out the ultraviolet light from wasp 12 into very fine wavelengths and then vertically is just telling us how much light we're getting at each of those very narrowly defined colours so wasp 12 is plotted in black and you'll see that the overall shape of what you can see in that graph there is like a W for wasp 12 the W, the two bottom bits of the W intersect zero so there are two narrow colours there that if we looked at that star we would see absolutely zero light even though there's a star there and every other star in the galaxy as far as we knew at that point had the sort of behaviour that you can see in the red, green and blue lines where instead of going down to zero at the bottom of the W you get a little peak and that's an inevitable consequence of the structure of a star like the sun which is burning hydrogen to helium at its core you always get that little emission peak at the bottom of that W and that was missing in wasp 12 making the star that hosts this very odd planet completely unique as far as we knew in 2012 so we developed a hypothesis to explain that and it seemed unlikely to me that the star would be unusual in its structure and also independently have this very unusual planet orbiting around it it seemed much more likely to me that those two very unusual properties were causally related one of them is causing the other and so I developed this picture that in fact what's going on is that the planet which is being baked alive and we know is very large is actually losing mass is forming a shroud of gas which completely surrounds the star so that when we're looking at the star we're actually looking through a gas shroud which consists of material that has been dispersed from the very hot mass losing planet and that absorbing gas imprints clues on the starlight and the first clue that we saw was that that graph goes down to zero at the bottom of the W so the absorbing gas imprints clues on the starlight and that absorbing gas clue indicates that the star hosts a mass losing planet the mass losing planet is feeding the gas shroud and we're looking through it and that imprints a clue on the starlight so this I thought could potentially give us a very quick and easy way of identifying those stars which are hosting these very extremely hot mass losing planets so I thought what we should do is look at all of the bright nearby stars to see which one have similar clues to WOS 12 so that's what we did now as I said earlier giant planets are quite easy to find and bright nearby stars are what astronomers like to study everything else being equal so I expected that all of the giant Jupiter-like planets around bright nearby stars would already have been discovered so I thought this clue would give us a shortcut to finding low mass, small rocky planets orbiting bright nearby stars and having watched Star Trek as a child I'm much more interested in those low mass rocky planets that we could potentially walk around on so this was my hypothesis that actually we could use this clue to find some really interesting objects and then the other thing just like when planets form angular momentum suggests that the gas that's being lost should stay in a disk that's concentrated in the orbit of the planet that's losing the mass which means that we should actually if we see that clue be looking at the system edge on so that we're likely actually to be finding planets that are transiting as I hope I convinced you earlier the transiting ones are special those are the ones that we really want to find so that was the hypothesis so now I'm going to tell you what happened when we tried to apply that so what we did was we first of all found a way of comparing the spectra of all of the bright nearby stars in a way that sort of tells us which one has the clue that there's absorbing gas so you don't really need to worry too much about the details but what's plotted on the y axis here is how much light there is that's sort of peeking up where that W went down to zero in WASP 12 the yellow squares on this graph are all stars that we already know that host transiting Jupiter sized planets and the very bottom yellow dot over towards the left hand side of that graph corresponds to WASP 12 which as you saw earlier is very extreme everything more than any other similar planet and the X axis I should probably say just spreads the stars out so you can see where they all are and they're all plotted on top of each other but the X axis is just how massive the star is or equivalently what colour it is the red line corresponds to what you would expect to a star like the sun which is very very magnetically quiet and there should be no main sequence stars like the sun burning hydrogen to helium at their core which lie below the red line intrinsically so WASP 12 and the other yellow dots we know host mass losing planets and we looked at about 3000 stars and those are all the blue dots and we plotted them on this graph and lo and behold 39 of them lie below that red line so those are showing the clue that there is a mass losing planet present orbiting around that star that we haven't detected yet and for the reasons that I told you my hypothesis was that these are actually low mass probably rocky probably transiting planets so these are potentially very very interesting objects to find so we found 39 targets and then we went to look for planets orbiting around them and this is the method that we used so just like the transiting method we're using the star light to find the planet and you may think that planets orbit around stars but actually from the point of view of physics the planet and the star are both masses and they both obey the laws of physics so the planet and the star actually are both in orbit around the common centre of mass of the system so as you can see there on the cartoon the star is doing a little orbit because it has almost all the mass while the planet does a big orbit and the rainbow coloured band at the bottom shows you how those spectral lines which arise because there are chemicals in the stellar atmosphere move backwards and forwards due to the Doppler shift as the star responds to the gravitational pull of the planet and goes around its orbit so this is the so-called radial velocity method of discovering planets so we're looking for very small motions of the star indicated by that Doppler shift which we can see in the star light so we try to apply this method to our 39 bright nearby stars to search for our low mass rocky planets that are very close into the stars and being heated to the point that they're losing their volatiles to form a circumstellar gashroud and this is where we did the work this is the European Southern Observatory in Chile it's a mountain top called La Silla in the Andes and on the left hand side there's a photograph I took at sunset so it gives you a snapshot of just how breathtakingly beautiful it is to be there and then the main picture is the control room which has actually been the place where most of the radial velocity planets that we know of has been discovered and you can see from the control room you get a lovely view of sunset which is invariably beautiful in the Andes but being a scientist isn't all fun and glamour so actually we spend most of our time with the blind shut staring at those two computer screens working very hard but we try to always enjoy the sunset before the night's work starts so just to remind you what we were doing was looking at those 39 blue dots that lie below the red line searching for low mass short period rocky planets in orbit around those stars and I hope this is probably not that much of a surprise since I'm showing off about it but we did actually find them which has been the most thrilling thing of my career actually so this is our poster child discovery so what is plotted along the x-axis here is time and days and all of the coloured points in the upper graph are our measurements so you can see we've been back to the telescope several times and our measurements span about 2.5 years and what we've discovered is four or five low mass rocky planets orbiting this particular star which we have renamed DMPP1 so we're staking our claim on it because we've done some original work to say this is a special system because it shows these clues and we found a system of four or five rocky planets which are causing a star to do quite a complicated orbit because there's several planets orbiting around it just as there are several planets orbiting around the sun so its motion is a superposition of its reaction to all of those different planets pull so you get this complicated jiggly shape due to the four or five planets that we've discovered and these are the people that did the work so here we are looking sort of quite geeky because we've found things so that's me in the middle John Barnes is a postdoc who's done a lot of the technical work and on the right hand side is Daniel Stab who was a PhD student working with us and he's now gone to work in industry and he's making plasma rockets to go exploring space more directly so we were the people that were responsible for most of this work and one thing that we like to show off about is that this was a very efficient way of finding planets because we knew exactly what we were looking for from the clue and the logic we applied we actually were about two and a half times more efficient than the nearest comparable discovery so this is quite nice it's always good to use telescope time efficiently because astronomers always have more things they want to learn about than there is telescope time available so this is again an artist's impression this is not what we saw but we have a system of four or five planets at least one of which is losing mass and forming a circumstellar gas shroud and if that disperse gases in the orbital plane then transits are likely and we'll be able to measure the size of those planets handily NASA has launched a really great space telescope called TESS for measuring transits and we do actually have a marginal detection of a transit in the system at a depth of less than a hundred parts per million so this is really high precision work and we're not completely ready to claim this but we think we might have found a transiting planet in this system meaning that it's exactly lined up so the planets cross in front of the star from our point of view this is our second discovery and this one was a little bit of a surprise as I said I thought that all of the giant planets would already be known orbiting these bright nearby stars and this is actually a giant planet about the mass of Saturn and as you can see here this isn't such a pretty graph as the first one that I showed you there's actually an enormous amount of scatter around this motion of the star in response to the gravitational pull of the planet and that's because this star is not well behaved for doing this very precise Doppler shift work and in fact what's going on is the star is pulsating so the star itself is wobbling which makes it more difficult to discover the planet but because we had the clue in the starlight we persisted and found this Saturn mass planet where other people had looked and then just given up so the nice thing about this one is because the star is pulsating we can get a lot of really precise knowledge about the structure and the composition of the star so we can actually learn more about the planet because we have very precise knowledge about the star so this again is a very very interesting system for further work and again if the dispersed gas is in the orbital plane then transits are likely so this again is likely to be a very very interesting system for follow up and then finally this is actually the most interesting of the systems we've discovered so far so as you can see on the video what we've got is two things one orbiting around the other in a very eccentric orbit and we were looking for very small motions due to low mass planets and what we found was a whacking great motion due to a low mass star so we found a previously unknown star in this eccentric orbit around our target which was a star that's about 90% of the mass of the sun and as far as we knew unremarkable apart from showing this particular absorption signature in the starlight that's right at the very threshold for sustaining nuclear fusion to power a star so the smaller of those two objects is what's called a red dwarf star right at the very bottom of the main sequence of stars only just able to sustain the temperatures and pressures to do nuclear fusion and shine like the sun does so that's an interesting object in its own right and worth further study however we did find what we were looking for too orbiting the sun like star there is a 2.6 mass planet in about a 7 day orbit and it's a challenge to see how this particular planetary system formed because if you've got a binary star where the stars coming very close into each other that will truncate and disrupt the disk that the planets are going to form from so this is a very unusual system and no other binary star system anywhere near this tight is known to host planets so this is probably of all of the things we've found so far the most interesting from the point of view of the astrophysics we can learn from it so I'm now going to tell you a little bit about the mass radius composition relationships for rocky planets picking up on another aspect of what Dave talked about so as we've already seen absorbing gas can reveal the composition of the material in the gas through those sort of chemical fingerprints that get imprinted on the starlight so that's again our OU level 2 astronomy module picture of how that works atoms pick out particular wavelengths of light and leave their chemical fingerprints so here is a graph on the x axis it shows you the mass of planets and on the y axis it shows you the radius of the planets and the lines which are drawn on the graph indicate what you would expect for the mass radius relationship for particular compositions so Dave already showed us mercury which has an unusually large fraction of its composition being composed of iron and the red line at the bottom shows you the mass radius relationship that you would expect if you built a planet completely from iron which is the densest material we know of and so you don't expect to ever find a planet more dense than that red line and plotted on the graph are the masses and radii of various planets all of which are less dense than iron so that's good in the bottom corner you can see venus and the earth and their masses and radii are known really rather accurately because obviously we can measure them quite easily and you can see for the earth and venus we can get a good idea of what the composition is from that mass and radius relationship whereas for the exoplanets because we're working with a very dim light from a star we have much less idea and much less precision on our mass and radius measurements so those measurements have big uncertainties attached to them and are consistent with a number of different composition models now the planets that we're finding we're measuring the mass using the Doppler shift of the starlight for those that transit we can measure the radius using the transit depth and by looking at the chemical fingerprints of the dispersed material we can actually measure the composition as well so these objects that we're finding in this OULed project are actually going to revolutionise our knowledge of the galaxy's rocky planet population and allow us to know the mass radius composition relationship for these planets directly just very quickly Dave told us that rock can't sublime in astrophysics we have much more scope for the imagination and I'm here to tell you that rock can sublime so this is a discovery from the Kepler mission and this is an object that's about the size and mass of Earth's moon in a 16 hour orbit around its host star so it's really really very very close to its star and it's really really being heated to a very high temperature and if you heat rock to about 2,000 degrees it does sublime and this particular planet is too small to detect as Dave said however its rocky surface is being turned into gas and leaving the planet and as the material leaves the planet dust condenses out of that metal rich vapour we see a transit of a dust cloud that's entrained in the orbit of the planet and this gives us some possibilities to actually start examining the mineralogy of this ablating surface I'm not going to go into the details however our discoveries might include some bright nearby examples of that so we might be able to do some really interesting exoplanet geology taking what Dave's doing and moving it beyond our own solar system so these allow detailed study and the more we find out about our galaxy the more it resembles the galaxy in Star Trek and I just find that really really very exciting and it gets me out of bed and into the office to sit in front of the computer every morning so finally I'm going to just quickly tell you a little bit about planets in the neighbourhood so this is a European project that I'm involved in involving collaborators mainly in Spain and Germany in 2016 John Barnes who worked with me was one of the discoveries of Proxima B which is the very very closest exoplanet to the solar system it orbits a very low mass star Proxima Centauri which you can see on the right hand side of the graphic about four light years away and then in 2018 we found a planet orbiting Barnard star which is the closest single star to the sun so it seems as soon as we start looking in detail at the sun's neighbour stars we're finding planets orbiting all of them so at the bottom there is the sun and there's an indication of the aught cloud and in fact the aught cloud goes actually half way to the nearest exoplanet and there's a reason for that the aught cloud is low mass bodies that are entrained by the sun's gravity and as all the stars orbit around the centre of the galaxy they each have this sort of large cloud of bodies that follow them around and sometimes I guess they probably swap but the aught cloud goes half way to it which I think actually offers some possibilities for exploration so rather than going on a generation ship to the nearby exoplanets we could possibly hop from rock to rock and get there more slowly and gradually that would be a long term project I think you would need tens of thousands of years to do that but perhaps we could do that and we do live in exciting times where we can actually think about things like this so I'm going to end by just quickly talking about what we might expect in the next 50 years I think what will happen in the next 50 years depends crucially on our collective decision making and I think you could say that over the last few years there have been some poor collective decisions made and I think the open university's mission is more important than ever I think it's really important particularly in democracies that as many people as possible are educated and are able to think for themselves and evaluate evidence and make good rational decisions and it's really really important that we get our act together and make good decisions to secure the future for the next generations and the university's mission is very very important both our education mission and our wider public understanding of science mission and then finally I'm going to end on a personal note so I'm in this picture which was taken about 50 years ago it was taken in an ordinary junior school on T side and there's a picture of all the girls in the class and we had a fabulous teacher called Mrs Mason who was extremely influential she was the first person who said to me you should go to university I'd never really heard of university I'm like what's that then and of that picture which is just an ordinary junior school class four of those girls became university academics which is really remarkable I think and I think what will happen in the next 50 years depends on each of us as individuals how we use our time and energy how we influence others and I think if only a handful of us are as influential and positive as Mrs Mason we've all got a good collective future thank you so my thanks to David and Carol for two fantastic lectures and it's now time for our Q&A so I'm going to ask Dave to come back up and join myself and Carol I'm going to ask a really dumb question so everyone else who has a question afterwards doesn't need to feel bad are the two areas that you're looking at related because you're talking about something maybe like sublimation of mercury and then you're talking about a huge amount of mass being exited from a rocky planet close to its sun could it be the same process it's just in a smaller scale possibly mercury is losing an infinitesimal amount of mass whereas Carol is looking at rather more extreme objects yeah though my objects are also not losing a lot of mass but the gas shroud gives us a very sensitive way of detecting it so I think they are related I think my objects are just more extreme and exciting than Dave's I think I maybe should have sat in the middle anyone else want to chime in with a question there's one here on the live stream so this is a question from Jack Parsons who's a nefar AS student here at the opening university my question is regarding exoplanets how far away are we from being able to send a probe to other solar systems and what experiments would be undertaken what do you want to find great question so we're really not far away at all so there is a project called breakthrough star shot which is aiming to use lasers to fire lots of little nano cameras and power them with light sails and send them to the proxima B system to beam back pictures so that's something that's actually being conceived and people are doing engineering work on it now and I think sending back a picture would probably be the first step I think it would be really lovely to go there but I think that's we need to go to Mars first I think it's a 50 year travel time of these light sails something about order isn't it well it depends how fast they go I don't know exactly it's decades it makes your 7 years look a bit better day is it a question here hi I'm Manjir and I'm from Milton Keynes and I'd like to ask Dave if the day David did today could go back with all the knowledge that you know now about mercury and volcanic behaviour all the things that you know now what would you say to yourself in the 1970s about earth geology knowing what you know now good question I don't know what it's taught me about earth geology it's earth geology that's taught me about other planets except you look at Mars not mercury or Venus and see the extremes of climate change that have gone on there it's made me realise that extreme climate changes can happen on a planet like ours as well probably not as extreme through natural processes but if we're not careful we're sending earth in the direction of Venus which we don't want so I think comparative planetology putting planets into context is important I love these pictures from rovers on Mars which roll along and see a little cross section through a layer of sedimentary rock and you can see but the grains are pebbles that must have been transported by water you can see the structures in them that show you flowing water or dried out lake beds and we can recognise the same processes on other planets that we can on the earth and it all begins to fit together into a picture of the variety of processes playing out in slightly different ways on different worlds I think if I could go back to my 1970 self I'd say what you're doing is going to turn out to be quite interesting not very interesting it's going to be super good you've got to work on the superlatives for the grand proposals it's a very academic thing to say can you do this, Carol? I just wonder I should have got Star Trek into my title there's one here and I think it was another one somewhere thank you Carol what do you hope that we might see or find on these exoplanets we haven't talked about mining we haven't talked about other life forms we haven't talked about anything like that really so what could we find what could we see? well I think initially we just need to try and understand planets in all their variety just to put our own solar system and our own earth in context and I think there has been talk about biomarkers and finding evidence for life on other planets but I think before we really start doing that we need to just understand better planets themselves and I think there's at least a couple of decades of careful work to do on that and there's a couple of really big missions that the European Space Agency is planning Plato and Ariel which will do some really important work in letting us understand the diversity of planets in the galaxy so those are going to launch in about 2026 and 2028 so I think that's going to be the big thing that people are working for towards for the next 10 years or so I don't think anybody would think about mining exoplanets the economics of going and bringing stuff back to earth doesn't make sense but going there and exploiting the resources so you can set up a self-sustaining base or a new civilisation that might be what you do but you've got to pick your exoplanet very carefully because not many of them will be habitable by humans could we build a megastructure from Mercury? You wouldn't want to build a megastructure that close to the sun because it's too hot there you want to be further out so you've got to haul your stuff out from the sun's gravitational well to a comfortable distance from the sun at a temperature wise a Dyson sphere encapsulates an entire star if you built it at Mercury's distance from the sun it would be too hot you'd have to build it at the Earth's distance from the sun so why go to Mercury and haul all that stuff all the way out it costs enormous energy cost I mean now we know that most stars have planets that don't we don't know any of it inhabited by technological civilisations yet to be a surprise if none of them are but we haven't seen any giant works of engineering in space nobody's built a Dyson sphere that we can see you should have an infrared signature shouldn't it Carol I'm not sure anybody's done a very careful search to eliminate that possibility Let me while I should have done what have you astronomers been playing at? Oh we've got more planets than you have Hello I'm Jonathan Clough from Cambridge and actually on the subject of finding planets a lot of the transiting exoplanets are not a lot but some have been found through citizen science because they've been so much data and I was wondering whether a similar approach could be taken with your your dissolving planet scenario could light curves or light signatures from lots of stars be put on to online and could you then get a lot more discoveries feeding into your project? I think I think the project that I'm working on that I described is probably not particularly amenable to citizen science because it's a fairly small number of targets and it was quite a lot of work actually to identify the targets and the measurements we need to make are very very precise so actually you need quite a lot of training to be able to do that very precisely there are other things that lend themselves to citizen science and there are other things that we're doing here at the Open University that lend themselves to citizen science so there's definitely stuff that can be done and if you're particularly interested in doing things then come and talk to us about the skills that you have that you can bring to the table because astrophysics there's always more things to do than we've got time to do Hello my name is Owen this question is for David you were talking about how Mercury's core is significantly larger in relation to it so do you know to what extent there's like more extreme magnetic fields in relation to the size of the planet to have influence over these metals and the atmosphere and going off of the surface? Okay it does have a metal to rock than we would expect its magnetic field is actually quite a lot weaker than the Earth's field but it is generating its own magnetic field of material that's being lost from the surface it doesn't sublim... if you've got the mineral olivine on the planet and you heat it up you don't get olivine you don't get it turning into olivine molecules you break it apart into silicon and oxygen and magnesium in atomic form if that goes on and you've got your atoms of silicon and oxygen they won't be affected by the magnetic field until they become charged if they get hit by a cosmic ray or photo ionized of illusial electrons then they can start interacting with a magnetic field and that's why the distribution of species around Mercury in space changes a lot but it's not an incredibly strong magnetic field it's small and compact and the dynamic things which go on in Mercury's magnetic field happen more quickly than they do in the Earth's magnetic field substorms and the like which is why my magnetospheric colleagues are very keen on seeing Mercury from two places at once when we have two satellites with magnetometers so it's a weird place we don't understand it but we'll understand it a lot better 10 years from now what you want to so we've got another online question first of all we've got a question from Bonnie on Twitter who asks is it possible to detect unbound or free-floating planets through transiting methods? I suppose hypothetically it's possible however if you just see a dip in the brightness from a star you have to do an awful lot of quality assurance before you can say it's a planet and one of the main things that tells you it's a planet is that it comes around regularly and so you know that it's a planet in orbit around a star if it was free-floating and just happened to get in the way then you would just put it down as a glitch in the data because there's no way to follow it up so there are ways to detect free-floating planets that actually have been detected but not through transits as far as I know Karen Martin on live stream is the proximity of the small red star to the near earth size star contributing gravitational heating to the small red star enabling it to sustain its nuclear fusion so that's a really good question and that is a question that we have sort of thought about at about that level of detail so as the star swings by the the sunlight star it will experience a lot of stress and the structure of the star will change in response to those stresses and it probably will actually change the amount of nuclear fusion that's going on at the centre because the star's structure is changing so this is something that we really want to look into but we haven't got very far along that route yet so it's a very good question and one that we'd like to one that we'd like to explore It's great getting online questions as well but it stops me paying attention to hands up in the room so I think we've got one back there Thank you Yeah, I'm Roger I live down in Henlo in fact I was one of David's students back in the early 90s thank you for that but my questions on exoplanets one of the main things for life is protection against solar winds and for that you need magnetic fields is there any way you can detect the magnetic fields on exoplanets? Well there's certainly been lots of papers written about detecting magnetic fields on exoplanets and in fact one of my papers on WASP 12 some of the things that we saw in the data people immediately said oh this is evidence for a magnetic field and there's gas entrained in the magnetic field of the planet and this is causing this particular signature in the transit light curve I was actually off on extended sick leave when all this was going on and I came back to work and thought oh is that really what you made of it all because I thought it was just noise in the data in fact it proved to be noise in the data so hypothetically you can detect the magnetic field through a number of ways and there have been detections of the magnetic field in the outer atmosphere of the star responding to a close-in planet orbiting around it but actually detecting the planet magnetic field I'm not convinced we've done that yet but there are various ways we could do it with bigger and better telescopes and more data But in terms of life we don't look necessarily for protection by a planet's magnetic field because in this solar system we're considering life below the ice inside icy bodies like Europa or Enceladus if you've got some warmth you can have life which depends on chemical energy not on sunlight so most of the habitable niches in the entire galaxy could be on icy worlds underneath the ice no we wouldn't maybe if the galaxy is full of microbes and not chatty people like Carol I do think that probably there is life on other planets but it probably is microbes rather than ladies with mini skirts that Captain Kirk Captain Kirk bumped into Captain Jackson I'd like to ask Carol with the discovery of water on exoplanets for the first time what's your take on it how much of your focus is going to be on that in the future so I think the discovery of water on exoplanets is a bit like the discovery of water on Mars it happens for the first time quite often I think water is actually a very very common molecule in the universe and I think water is obviously very interesting and very important for life so it is one of the molecules that the aerial mission which I'm very heavily involved in now will be looking for in a sample of about a thousand exoplanets but I wouldn't say that I'm particularly focusing on water at this point I'm kind of interested in the geology of these mass losing rocky bodies that's my current favourite geeky pastime so I'm leaving water to other people can I sell you a copy of Teach Yourself Geology Carol you could give me I'll give you one I was going to suggest you could give me tutorials and once you've got some water then you can call the biologists and we'll chip in as well I do love the fact that some of this science starts to really get interesting as all these boundaries intersect it's great having a STEM faculty that covers all bases here so this is probably one for Dave from Helen E. Campoy do you think AI advances will impact on astronomy and planetary science? Well it's one for both of us isn't it if we're sending probes out the more autonomous they can be in situ the better a job they will be I mean the argument for sending humans to Mars is fragile because it's very expensive and it's quite high risk but we don't mind robots dying when they go there but a human geologist can accomplish so much more in a half hour field excursion than a remote control rover can so I think AI in terms of planetary exploration in this solar system is going to be very important but surely AI is useful in astronomy as well for the analysis of data or something Yeah I mean astronomy almost by definition works with enormous amounts of data and in fact several of my last PhD students have gone on to become data scientists working in the commercial world and we've got big grants here at the Open University led by astrophysicists to do AI type applications so it's something that's already important and it's increasingly something that you see in results that are coming out in the astronomical literature that there's been an AI analysis component to it and we've got another online question as well Yeah so this one's coming from Zig on Twitter two for the price of one actually here and he congratulates you both on awesome presentations Firstly is there any way to search for exoplanets using amateur sized telescopes and also is it possible that Mercury could leave its orbit and would it change the other planets orbits as well Okay should I answer the first one So yes absolutely it is possible to find exoplanets using amateur sized telescopes so you know the whole WASP project is using you know camera lenses which are you know they're only about this much across so actually quite a lot of serious amateur astronomers have telescopes bigger than that and they can detect transiting exoplanets of the size of Jupiter and at slightly smaller One of the ways that amateurs can really contribute is on following up transiting exoplanets that we've already found because there's some interesting science in measuring the exact timing of the transits because a lot of these very close orbiting planets the orbit is actually decaying so if you can measure exactly when it comes round each time over a period of years to decades you can actually learn how the planets orbit is changing so there's a lot of work that amateur astronomers are doing and can do in that field Okay and could Mercury leave its orbit planetary orbits run almost but not quite like clockwork simulations show that orbits of the present planets are stable on timescales of hundreds of millions of years before chaos sets in that we're not looking at Mercury leaving its orbit but go back to the birth of the solar system when there was more gas around so gas drag and orbits have yet to settle down Mercury probably started further from the sun than it now is this is a possible solution to the enigma of how it can have lost a lot of rock and yet still be rich enough to volatiles to have explosive and these hollows forming it started further from the sun it would have had more volatiles to begin with it could have migrated inwards and on the way in collided with something which would later become beautiful Venus being stripped of its rock but the rock that survived still had a high volatile burden and then it settled into its present orbit which is now stable that's not going to fly out of that orbit and if it did it's quite a small body so it wouldn't perturb the other planets very much anyway but in the past orbital migration is very important it's probably how we get these hot Jupiters these close in easier to find exoplanets didn't begin there they started further out and work their way inwards almost certainly wouldn't you agree almost certainly that's like saying it's quite interesting is it that almost certainly I mean you both sounded pretty confident to me you were just prepared to be proved wrong that's why we're scientists absolutely well I happen to know that one of our colleagues in maths has written a paper about in situ formation of hot Jupiters okay there's room for other mechanisms interesting debate continues we've got yeah why not I apologise for being greedy and having a second question but it just occurred to me talking about the geology you're trying to detect I believe Bepi Colombo was due to when it was first formed to have a lander and that was cancelled presumably for costs is that for you a big loss or do you think it's not really necessary I don't regret Bepi Colombo not having a lander because it's a very well equipped pair of orbiters and that would do a good job Bepi Colombo was actually planned about the same time as Messenger NASA's mission was planned it would have been very premature to try and land on the planet which we'd only seen half of previously by the mariner flybys it was dropped because of cost but is now a proposal by a worldwide group of scientists suggesting that the next mission to Mercury should be a lander and that's the right time to try but where do you put down a lander that gives you wonderful measurements at one spot do you go on to the hollows if so do you land inside or outside do you go to the poles where there's water in the permanent shadow craters do you go to one of these volcanoes do you go to young volcanic plains where do you put your one lander down it's very tricky so there's a question back there and another one there that young lady there is waiting as well if you can get the mics in those directions thank you hi I was wondering whether the political event that shall not be named is going to have any impact on your funding and collaboration across Europe I think that scientists collaborate with each other largely because they've got interests in common so I'm sure the collaborations will continue however a lot of our potential funding routes are going to be curtailed and so that's obviously going to affect how much we can do if those funding routes are not replaced I would agree with that it's a worrying time good question so the young lady with the pink cardigan there is there a way to find out how hot the planets are do you say how hot how old how old yes there is the oldest bits of rock in the solar system are are meteorites the majority of meteorites have not been subject to any process since they formed and were condemned by radioactivity and they are about 4.56 they are an easy number to remember 4.56 billion years old so that's when we think the material the gas around the sun as it cooled down condensed to form these rocky minerals 4.56 billion years ago and the planets formed pretty quickly once it started the planetary formation process was over within 10 or 20 million years and then they just shuffled around in their orbits for a bit I love the geologist's concept of time 10 or 20 million years pretty quick so for exoplanets we just assume generally that the planet is as old as the star is and we can measure the ages of stars very accurately so a typical measurement might be something like 4 giga years that's 4 billion years plus or minus 2 billion years so we have quite large uncertainties on the ages of typical exoplanets but if you happen to find one that's very very young it actually shines because it's collapsing and releasing gravitational energy so if you catch one in these first few million years you can actually work out how old it is reasonably precisely to like a 10th of a million years great question there's a gentleman there at the back and then I think if we haven't got any more online it brings us to our close I've heard that life on Earth would be very different without the moon and I wondered if you'd found any moons around your exoplanets and whether their particular relationship with those planets might say something about their life there possibility of life so the planets I've been focusing on are all very very close to their stars and so they're quite hot and not really good prospects for life and they're also not good prospects for moons because you can't actually fit a moon in a stable orbit if the planet is very close to the star if I broaden my scope to the whole of what exoplanet astrophysics knows there has been one possible claim of an exo moon which is about the size of Neptune being a larger gas giant planet and that was discovered by the transit technique so there's a transit as the planet crosses the star and then there's another dip which is sort of following the orbit of the planet now it's a very long period planet so we need to go back and check to see if subsequent transits also show this additional signature due to the possible moon so there's a current controversy in the astronomical journals with some people saying I analysed this data and I found a moon and some other people saying I analysed the same data in a slightly different way and I don't think it is a moon so we have to wait to see but just as there are more planets than stars there are probably more moons than planets that's probably true almost certainly probably true very likely to be probably true and on that note thank you very much everybody thanks so much Carol and Dave