 Hello everyone. My name is Simon Kelly. I'm the Associate Dean for Research and Scholarship in the Science Faculty. Now on to space. The reason why we're here this week. For most of human history, the question of whether the earth was the only host for life in the galaxy has been one for speculation. But now the Open University academics are investigating using robotic missions, using telescopes. So what you're going to hear this evening is about the search for life on comets, moons, extra solar planets. You're here for Professor Ian Wright about the possibility of life on comets. It's part of the remeseta mission. Professor David Rothery about the potential for life on moons around the gas giants of Saturn and Neptune and Jupiter, sorry. Finally, Carol Haswell will reveal a new population of potentially habitable planets and the possibility of life in our galaxy long after the earth is swallowed up by the sun. We'd like to hear your views too. After each of the talks, there'll be a few minutes for questions and then at the end we'll have a panel discussion and you can ask more questions and we'll be taking questions off Facebook that have come in this week and from Livestream. So let's move on. Can I introduce Professor Ian Wright? Ian has led the Open University's 20-year involvement in the reset mission. Ian. Welcome. Yes, my name's Ian Wright and I was going to tell you something about these things, these comets. You've already heard that the theme of this evening is about life and what I want to do is explain to you my interest in what we can understand about life from studying things like comets. I hope this almost doesn't need any introduction. This is a fairly iconic image of the comet 67P that we're going to as part of the reset mission and I think you can imagine that a bit of a scary-looking object really, not quite what we had in mind. I'll probably be referring it to as 67P but its full name is Juryumov Gerasimenko. I want you to just bear in mind the image of this thing, this object which we call the cometary nucleus because I'm sure if any of you have been lucky enough to see comets, we've seen pictures of them or whatever, you've seen something like this which is a body with a nice long tail that can be visible in the night sky. You'll never actually see one that looks like this with a naked eye, you need a long exposure on it but that's what they look like. I want to illustrate how long that tail is and to do that I'm going to take a geological map of the British Isles and I'm going to superimpose on that in inverted colours now, the comet's tail running from lands in to John O'Groats. I was a bit nervous when I first put this together because you know there was a fear that that bit at the top might belong to a different country by a time ago. Bear that in mind, imagine that comet tail goes all the way across the British Isles then the thing, the object that's making all that stuff is about that size, in fact that's an exaggeration, it's more like that size and that is a shape model there of 67p and if you're interested that's the the ESA project scientist and the land manager having some fun at the comet arrival press conference. So think about that, you've got something that big that's making that huge tail, the huge tail you can see from earth but in actual fact what we're interested in doing is going and finding out what it is that's making that tail and that is quite a small object that actually is about something like three or four kilometres across in actual size. As I say the theme is what is life, no no the theme is life and so I thought I'd introduce my talk by tackling the question what is life and I'll start by showing that some of you might recognise that this was a feature that was found in a Martian meteorite almost 20 years ago that was at the time interpreted as a biological fossil so this was evidence for life on Mars. 20 years later I can tell you that opinions of minds are very definitely made up but opinions are still divided so after all that time with the world's experts looking at this we still can't agree on exactly what that thing is so that shows that it's difficult mission but when I want to know about things like this I go back to basics and I went back to S104 it's our excellent introductory course to science, exploring science and in there it has some definitions of life and this is what you learn at level one university science level. So what is life? It's a state of being alive, yep I quite like that one. It's the sum of activities and some of activities of plants and animals yeah right whatever and it's the period between birth and death I mean that's got to be the best one hasn't it you know but in actual fact if you if you wait through it you'll eventually come to the definition that we use which kind of sets everything up you know living organisms are defined as those that have the attributes of reproduction growth and metabolism so that's what we mean by life that's what we're talking about in the context of of this evening and I want to just a step back and think about life a little bit and to do that I've taken these posters that are available through the Stargazing live websites these were done in conjunction with us and you can download them they come in two halves so there's part one and there's part two so they're quite big so I've stitched them together there and if we look at this graphic what we've got moving from left to right across the screen is a history of the universe so time is progressing as we go from left to right. Interesting when I was when I was pointing together I kind of remembered that actually there's a mistake on it or rather not a mistake there was a refinement in the measurement of the age of the universe that's appeared since we made the poster and I think that's a that's what science is all about it's things aren't necessarily cast in stone they're the best evidence and so on that we have at the time and they evolve and this is a great example of how things have evolved but if we think about well really anything to do with the universe but let's just concentrate on life they're at the start when we have the big bang when everything formed there wasn't any life there wasn't in anything if we look at present day we have the earth and I think we'll all agree does have some life on it but at some point in the past a few billion years ago that's when life actually began and so that's what we're interested in that interface between you know when there wasn't any life and there was some life and if we think about it in the context of the formation of the earth I mean this is the kind of place we know and love this is a fabulous Apollo 17 image of the earth taken 40 plus years ago now and I think for some of us it was the first color image that we saw of the earth that made us realise just exactly what a beautiful place it is and that's what it looks like but that's what it looked like four and a half billion years ago and in fact in it the geologists call this the Hadeian period after Hades now clearly you can't live on that earth absolutely impossible there was no life on the earth so in other words the solar system was formed four and a half billion years ago planets like the earth were formed and they look like this for a while but then things had to change so that life could ultimately get started and this is a kind of fairly romantic view about what the surface might look at at the interface in this time between the pre-life era and the life era and Dave's going to give a slightly different perspective on things in his talk so I just want to remind myself to say that what I'm interested in through the study of comments is that transition between the between an era when there was no life and then there was life and by looking at comments which are remnants of the solar system formation process we're looking back in time to that material that we no longer have on earth it's gone it's all gone to the reactions and the chemistry and the biology have gone to completion and we have what we have so we have to go out there and look at comments to see what existed before life got started but I will just mention Hoyl and Wick Ramasingh because they've taken their thinking to a much more extreme levels and they believe that actually comets brought life to the surface of the earth now I would say that there's aren't really any experiments on the Rosetta mission which are there to address this issue it's dare I say a fringe view but they would argue very passionately about it Fred Hoyl's dead now but Wick Ramasingh would argue passionately about it but most scientists believe that's just a complication too far so if you there are things on earth called carbonaceous condrites this is a meteorite that fell through the atmosphere and this is the all game meteorite we're celebrating its 150th year of its fall and most of the people in the community that study these things believe these actually came from comments so this is quite interesting if we can go to a comment and make that connection a bit more absolute then clearly we have the possibility to study these things in the in the laboratory and I was going to announce that my head of department had a sample with us for people to witness tonight but she's forgotten to bring it anyway so I a few weeks ago I gave a talk at a conference where we were talking about the connection between or gay and Rosetta and at the time this is kind of what things look like as far as the comet was concerned and so I was trolling through the web looking for pictures of or gay and I came across this guy's personal collection and on the right there is his sample of or gay and so I kind of inverted the image of the comet and put it next to or gay and yep I think that's proof that they must be related in in some way or another and so to to Rosetta the mission that I'm involved with it's a fabulous mission it's already arrived it's already starting to do scientific measurements it's a two part mission with an orbiter and a lander instruments on the orbiter audio acquiring data and I hope some of you have seen the images and so on that are coming back. We have an instrument on the lander the fill I lander and our instrument is designed to actually take samples of the cometary surface and analyse them and ultimately find out what the comet is made out of. Now you probably know that in the last few weeks what we've been doing is struggling over trying to find landing sites it's a you know I must say when we started practicing this process earlier in the year I kind of imagine the comet might look something like that so the challenges were there straight away so we have to consider sort of the shape the illumination the slopes the topography the fact that you've got to be able to communicate with the spacecraft and all the stuff it's a very complicated business but as things stand a landing site has been selected which glorifies in the name site J and that's where it is on the on the comet that the bit you can see sticking out that's the head of the duck if you like and then the body's behind it and actually the landing area is quite big and what I've done is just drawn on there a landing ellipse the kind of area we'd like to try and land in based on the cross that's put in the centre there and that is actually smaller than we think we can currently do but I think in order to avoid some of those features and so on on the surface that's what the engineers are struggling to try and do and to try and just give a bit of context to you to the instrument that we built here this is me in the lab a couple of weeks ago filming sky at night and I'm standing next to one of our laboratory instruments and that extends off two or three metres to the left of the slide it's that you know you can't send those up into space so I'm superimposed on that one of the members of our team roughly to scale there and in front of him is the shoebox sized instrument that we that we built here and that is going to do these kinds of measurements in the in space as the same kind of things that we would do in the lab with these huge great instrumentation and it's out there it's working I'm afraid this is kind of what we get we get excited by stuff like this but that proves that the instrument is working and I should say that at this very moment 300 million miles away we are running the instrument at this very point in time it's actually collecting samples of the Coma gases and it's going to analyse them and hopefully we'll get the data back tomorrow morning. Please follow us on Twitter. Fylo i Ptolymy and in case you're wondering why the instrument's called Ptolymy. Ptolymy was one of the words in the cartouche on the Rosetta stone that was instrumental in translating an understanding hieroglyphics and if you want to see that in a more local context this is the Philly obelisk here at Kingston Lacy house which is a national trust property in Dorset and actually if you go up to it it's got hieroglyphics on the side of it and if you look it's quite badly weathered but if you look quite carefully on this on one of the sides you can see the cartouche with Ptolymy on it and and and that's why we named our instrument Ptolymy and so I'll end there but in the spirit of a campaign we're doing for a promotional campaign for our first for students of the OU I mean there's a thank you and there's a landing on a comment thank you so so please follow that and I would also point to one more thing that we're doing as part of world space week we're doing a Twitter question and answer ask the expert session on Friday this week I think from two until three so if you've got extra questions or things you think about afterwards we're going to be online to to answer some of those then thank you so we're going to take a few questions now but we are very time bound so if people want to ask questions please wait for the mic ask any how much gravitational pull has the comet got to give you for for landing uh it's it's a tens of microgears so you know if you're standing on it and you're sneezed you you would probably never go back again um yes it's a very tricky engineering problem uh the the thing is about a comet there's hard bits and the soft bits and if you learn on a hard bit you're likely to bounce off and if you land on a soft bit you might sink um but the land that has been designed with all kinds of features to actually anchor itself down once it lands um you know it has explosive harpoons it's got screws in the feet and all this kind of stuff um but it it'll hit the surface hopefully at something like uh if you imagine a sheet of A4 paper landing on a on a desk that's kind of what the pressure what it will feel like so because I was thinking if you're going to start trying to push things down I think push the pro up we we we have thought about that we have worried about that um but uh you know we keep our fingers crossed you know in a in the best spirit of exploration yeah yeah it's rotating rotates about once every uh 12 hours or so and uh it's interesting when we when we're actually going to try and land on it uh we might be if we go to site jay we'll be ejected seven hours before landing so you can you can imagine the comet's actually rotated quite a long while you know you can't really see the landing site when you actually eject from the sizes you've suggested it sounds like that landing site is not much bigger than this building is that about right uh there's the circle well the the the certainly the ellipsoidro would be yeah that's it's a few hundred meters long but the actual official landing site is a circle of 500 meters radius um but I think it has to get down further than that so that sounds like a site about the same size as the OU campus uh yeah but I mean that was what we worked with during landing sites election because we wanted to look at bigger areas the plan was then to study the areas in great detail do the flight dynamics and whatever else and then to bring that down because across some of those areas that we looked at there are places you just wouldn't want to land in at all I guess this better be the last one yeah oh could could you tell us why this particular comet was selected for the mission don't want the short answer or the long answer the short answer is a really fabulous comet and we knew it wasn't the funny shape or anything like that uh it there's there's a historical aspect to this we designed everything for going to a different comet and unfortunately the launch before the one that we were due to go on had a failure and the Ariane program was put back a year and so of course the comet we were going to go to uh was long since not possible to get to so we had to rethink it through thanks very much Ian so the votes in the room are we leaving the comet model here or am I taking it away okay can I now introduce professor David Rothery David works on both terrestrial volcanoes and extraterrestrial uh planetary surfaces lunar surfaces and he will be talking on moons thank you Simon I was originally invited to come and talk about signs of life on the moon which would have been far too short a talk so I suggested this title instead very probably I've been thinking about moons since I remember it very clearly when the last when voyage had his last flyby of Neptune in 1989 I thought let's write a book about this so I did and then we had the chance to produce a moonsmook last year which was a lot of fun anybody here do the moonsmook it's running again in February it's it's um okay so search for life on moons you might not think of moons as being particularly habitable places when our moon isn't a good place for life which is why I changed my title but what does it take what do you need for a planetary body to be habitable to to be suitable for life I mean do you think you need an atmosphere do you have oxygen do you need liquid water do you need sunlight do you need a source of energy which of those do you think are essential requirements for life well here's what I think you don't need an atmosphere you don't need organisms breathing oxygen we do as far as we know need liquid water it's a wonderful solvent or cells depend on water and so on so you need temperature where liquid water is going to be available sunlight you know plants depend on sunlight no plants we'd starve or fine but there are ecosystems on the earth which don't need sunlight you do need an energy source some kind of chemical gradient that life can grab hold of and use for its metabolism that's all you need you need water and an energy source fundamentally for life and we do have water and we do have energy sources inside certain moons which is why moons are good candidates for life and here's an environment on earth um it's the floor of the deep ocean this column here being built up by chemicals precipitating is a meter or so long and this is the plume of turbid water with precipitates forming in it these are black smokers on the deep ocean floors and there are there's white scum round there which is bacteria there are a few shrimp and crabs and things scavenging around feeding on the bacteria there's a whole ecosystem down there that's independent of sunlight and um this is a favoured environment for where life on earth could have first began Ian showed a picture of kind of volcanic springs at the solid atmosphere interface but put an ocean in between you're protected from horrible ultraviolet sunlight or other kinds of harmful radiation and you can start forming life even when the earth is still being bombarded by quite a lot of meteorites if you're down the bottom of the ocean and if you look at the phylogenetics of life on earth the last common ancestor we can find is an organism that lives in hot environments like this and doesn't breathe oxygen either so this is a good setting for life to begin on the earth and we've got settings like that we think inside various icy bodies say if life could begin on the earth it could begin inside these icy bodies so these are called there's chemical energy there at the interface and these things are called hydrofermal vents last today bone dry with a few trickles of water coming out now and then but the surface is certainly pretty hostile for life it's bathed in UV radiation there might be things underground if you dig for them but you're not it's worth looking for life on Mars don't get me wrong but if we want to find a complex ecosystem we're far more likely to find one inside an icy moon i would argue than inside Mars icy moons have internal oceans here's a cross section for a ganymede this in the middle is meant to be its iron core there's the rock everything above where i've got my cursor is water some of it is solid water that's ice some of it is liquid water now inside the body with as much gravity as ganymede the ice can take various phases of different densities and on this model which only came out a year or so ago there are there are oceans at four different depths so in any of those you could have life especially the lowest one where the ice is sitting on top of the rock is more chemical rich so that you could have life inside a body like like ganymede here now that deepest ocean will be very hard to get down to so there are other moons which are much which have much more potentially accessible life but just for scale it's bigger than our moon slightly smaller than the planet Mercury this is a big body thank you so here's your ropa which is about the size of our moon we know from its density it's probably got an iron core then rock then 100 or so kilometers of water we don't know how much is solid that's to say ice and how much of it is liquid but we're sure that some of it most of it is liquid water but weight interferes interacts with Jupiter's magnetic field for example and we can see clues on the surface that the ice has broken apart so down here on the interface 100 kilometers below the surface we could have hydrofermal vents we can also get the surface like this why not hydrofermal vents like this on the floor of your oposition we know it's hot inside it's tightly heated we could have hydrofermal vents there supporting an ecosystem that doesn't need sunlight doesn't care whether there's an oxygen atmosphere above the icy surface i mean there isn't you don't need it it can breathe methane or whatever you just can metabolize without the use of oxygen so as well as the hydrofermal vents if life began there it could find its way to the surface in cracks the surface ice breaks apart now and then and life could have evolved into photosynthetic life forms inhabiting these cracks so you've got an ecosystem potential on the floor of the ocean and in these ephemeraly open cracks so it could be life in cracks so here's a view of Europa's surface seen from above it's 100 kilometers across and this is a crack which is opened and closed and every time it closes it squeezes some slush out and builds up a ridge either side go to one of those cracks when it's open you could find a life in the ocean go to a crack when it's squeezed shut and scrabble around in the slush that's refrozen you could find in tomed dead organisms so here's what could be inside one of these cracks some plants clinging to the walls some planktonic things which get sucked up when the crack opens push back down when the crack closes things which crawl so you could have photosynthetic life near the surface as well as chemo synthetic life at the vents deep down and we can tell that the ocean is dynamic because look at an area like this you can see places where you've got rafts of ice which have just barely broken apart but over here the the ice has been completely disrupted and has refrozen in between that ocean is occasionally exposed to space we think okay so Europa is a big one if you want to get down to the surface of Europa to look for life it's quite a challenge but i'll come to a possible solution at the end but Enceladus a satellite of Saturn nearly five and collision diameter it's a much easier target to go for because can you see these plumes here below the south pole water is being jetted to space not as liquid droplets it freezes straight away i mean the surface temperatures here are minus 160 centigrade so it's way too cold at the surface for life but once you can get warm water up there you're okay so we could have there's an ocean clearly inside Enceladus which is venting to space all he then have to do is fly a spacecraft through that plume and sample it and here's a wonderful close-up of these these vents jetting a couple of hundred kilometres into space from these cracks near Europa near Enceladus's south pole fly through very the right instruments you can find life because if there's life inside you should find it being jetted into space there's an the mission there called Cassini which is flown through the plumes but it wasn't equipped to look for life nobody suspected this when Cassini was designed so that's a kind of model through Enceladus a rocky core an ocean which may not be global just a sea over the south pole and tidal heat disturbing things keeping the water warm enough and venting to space um so just to look ahead to where we we hope to go in the future nearly two years ago now Issa announced an instrument sweet but it's Jupiter icy moons explorer a mission called juice which we hope to have open university involvement in it will orbit Jupiter it will study ganymedian detail have a few flybys through a flybys of Europa as well looking for life on Europa and this was going to be my last slide until last night when this news item came to my attention this is a massive proposal that's just received a hundred thousand dollars as a preliminary study to develop this concept further it's a cubesat it's three things as big as a packing case three or four things as packing case size bolted together which it would go to Jupiter map a go to Jupiter orbit Europa map its gravity field and then open up and just shower these things down onto Europa's surface these are called chipsats because they're they're pretty small things um give you an idea of scale they are not they're smaller than this wonderful book planets a very short introduction 799 from amazon which i but probably smaller than my iphone what they are like in size is a fitness of just a few individual moon trumps cards which you can get from the OU website and these things will be equipped with sensors just to do one or two specific tasks you could kit these out to sniff out molecules to do with life land them ideally some would land besides one of these recently closed cracks and look for the signs of organic processes having gone on on Europa when Europa's hard to land on because you can't it's got no answer for you can't parachute down share a few of these things down there robust some will survive landing on the surface maybe that's the way of the future shower a load of chipsats onto something like Europa to see if there's life i'll have retired by the time that happens but hopefully some of you won't have and i think let's go looking for this life out there because i want to know did life if life began on the earth did it begin anywhere else if we can find that life began independently of the earth on one other place in the solar system and hey all these exoplanets out there that's carol's going to talk about surely life has begun on suitable exoplanets as well at the moment all we've got to go on is one genesis on the earth if we can find a second genesis inside Encelerys inside Europa that's a fundamental change in our philosophy thank you sure any questions and please wait for the microphone any problem with like bacteria from our world you know being put onto a pristine environment very much so um it's very hard to get a lander on Mars clean a lander on Europa clean if you fill one of these things with chipsats look at all the surface area and all of these little things you've got to have them completely we can't have them completely devoid of life as devoid of life as you can before you launch and you've got to hope that most of things die on on routes but some will survive we know microbes can survive in space there are rules in place by an organisation called COS bar committee for peaceful use of outer space I forget what the acronym stands for and there are rules which say anywhere you send a spacecraft from earth there must be less than a one in a thousand chance or one in a hundred chance of contaminating it because it recognizes that ultimately we send something to another planet we're going to contaminate it now you may have ethical reservations about putting earth microbes in an environment where they might live it will certainly be harder to harder to study the your open biosphere if we've taken earthly organisms there as well but ultimately if we're going to explore space we we cannot avoid contaminating these other bodies but on the other hand nature might have done it already we've got as you heard in install we've got meter rights on the earth which have come from Mars will be bits of earth rock which have been knocked off the earth and found their way to Mars so earth and Mars have been exchanging bodily fluids for a past four and a half billion years so life on Mars could have come from earth or vice versa it's harder to get from earth to Europa so it's likely that life on Europa is independent of the earth but we need to check that it hasn't got there accidentally and we certainly don't want to deliberately not deliberately but accidentally contaminate Europa by sending a dirty spacecraft there as a question here if we've time you mentioned water and a source of energy yeah and saying well that's the prerequisite for life but we're carbon based life forms is there any chance that there's another element that life is based upon you say that you know when we've gone there we weren't looking for something is there a danger that we're not looking in the right place um there is a risk you're quite right but I think we have to deal with with with life as we know it because we know life based on carbon and using water can exist you can construct life based on silicon but it doesn't bond to as many elements or germanium as carbon does you can look for solvents other than water but they don't seem to be as good so let's begin at least by searching for things that we can recognise as life but I don't have a closed mind there could be other kinds of life but people who have looked at how life might work can't come up with anything better than complex carbon based molecules and anything better is a solvent than H2O so we're probably looking in the right places but possibly not the only places two minutes apparently yeah any more questions okay a little bit off the wall why would you not accept that we have already landed on mars or would I not accept that what hasn't already landed on mars life from earth yeah it could have it could have we could have terrestrial life on mars carry bear on our spacecraft which weren't clean enough or carried on meteorites from earth to mars now i'm talking about human life that have been sent up from this planet up onto the mars where there's underground cities and this is all done by USA and NASA that are we have actually been on mars since well before the second world war i really don't think there was the technological capability to do that or that any conspiracy like that could have been kept secret had it have happened i could go more but i'll leave it at that but it's quite deep we are actually on mars thank you do you want to take one more lady behind sorry i just have one question um the chips that they're thinking of sending out what are the chances of them actually landing without being smashed and being able to send back i think the idea is that they would be robust and that 50% would survive impact if you're sending out several dozens then you're going to get plenty of data back we can make bunker busting bombs which will go through several stories of underground bunkers and count how many floors they're going through before they explode to kill the bad guys so we can build technology it's the war-dividend we can build technology that will survive enormous decelerations and still work so it it can be done but my understanding of a chipsat concept is that they are sacrificial some will survive some won't okay thank you there is actually there is more research going on at the open university actually building mass spectrometers that go into artillery shells i've seen in the entrance to one of the buildings actually an artillery shell which has been hollowed out so there is research going on that i'm just going to rotate one to every 12 hours can i now introduce dr Carol Haswell Carol's an astronomer who works for telescope observations and she's going to talk about exoplanets i have to say it first i haven't brought any props with me so i'm very glad i've got Ian's duck to keep me company up here nor do i have anything to sell obviously i failed to prepare however in mitigation i think i do have the best topic because i think if we want to find life outside the earth the place to look is exoplanets exoplanets are planets which are orbiting around stars other than our own sun okay so i'm going to start by setting the scene and this is a an artist's impression of our own milky way galaxy and i'm an astronomer i work with light and so i'm just wondering so what we collect as astronomers is light using telescopes so if we were to observe a galaxy like the milky way what we would see is a lot of light and that light is coming from stars this is probably obvious but i thought i'd say it anyway stars are much bigger and much brighter than planets so as astronomers it's fairly easy to study stars studying planets which are not in our own solar system is rather troublesome because they're small and they're dim so they're difficult to study the difference in brightness between the earth and the sun is a factor of about 10 billion so you're looking for something very very faint next to something much brighter so that presents obvious problems so i'm going to tell you a little bit about stars that we're going to need later on so this is probably the most important diagram in astronomy this is the Hertzsprung-Russell diagram and it's a graph of on the y axis the brightness of stars on the x axis the color of stars and almost all the stars in our galaxy um that you create that beautiful pattern of light that you saw in the artist's impression fall along the diagonal stripe up the middle of that diagram and these are so called main sequence stars our sun is an example of a main sequence star and what all these stars have in common is that they're converting hydrogen to helium at their center and this creates the energy that produces the sunlight and the star light that creates light on the planet's orbiting around the star um our sun is about a third of the way up that stripe and there are actually more stars lower down that a smaller lower mass ffainter and redder and then as you go up towards the top of that stripe you've got more massive stars that are bluer and brighter okay one of the things that we've learned in the last 20 years which i think is really remarkable is that we now know that there are actually more planets than stars in our galaxy so when you look at the light in a galaxy you see the star like just because the stars are bright but we've now done enough work on nearby stars in our own galaxy to know that actually in general stars do have planets orbiting around them so there are lots and lots of planets in our galaxy um we don't know about all of them in detail the assertion that i just made that there are more planets than stars in the galaxy is based on statistics we know of about 2000 planets in detail and these have been studied by astronomers over the last 20 years or so we know of 1137 planetary systems or at least we did on the 9th of September so this these numbers are about a month out of date so we're probably up to about 2000 planets now because there's quite a large number of astronomers in the world who are constantly studying looking for new planets and there are new new announcements coming out every day so we know in detail of about 2000 exoplanets orbiting around stars other than the sun and so we now know that planets form with stars there's no special requirement at all 20 or well more than 20 years ago it was possible still that our own solar system was unique something special had happened to um the sun in its early history that created the the material that then formed planets but we now know that planets do generally form with stars there's no special requirements so we would expect the other stars like the sun to have planets also orbiting around them now i should probably just tell you a little bit about how we found these almost 2000 exoplanets that we know about because i've told you that it's very difficult to see planets because they're dim so both of the main ways that we've detected these planets depend on actually studying the light from the star and observing in the light from the star subtle effects due to the effect of the planet on the star so you can actually you think of planets orbiting around stars but in fact from the point of view of the laws of physics both the star and the planet have mass and they both orbit around their common centre of gravity which is much closer to the heavier star than it is to the light planet so the star itself has a little orbit which you can detect by looking at the light from the star and looking at the Doppler shift of that light and then there's another even more simple way of detecting a planet around a star which is if you happen to have a planetary system that's lined up so that the orbit of the planet happens to take the planet right in front of the star from our point of view then the planet gets in the way and blocks some of the light so you can actually see the star get dimmer every time a planet gets in front of it so these are the two main ways that we've detected the almost 2000 exoplanets that we know about okay so i'm now going to change gear a little bit and go back to a brief history of life on the earth so i'm revisiting some of the the points that Ian and Dave have already made so from about four billion to three point eight billion years ago the earth was being bombarded in a early period of its history called the late heavy bombardment so it was being bashed into by all sorts of stray bits of rock and asteroids that were chaotically orbiting around in the solar system so at this point the earth was probably not habitable but the interesting thing is rather promptly on astronomical timescales a mere 300 million years after the late heavy bombardment we can see evidence that photosynthesis was already happening on the earth so that implies that life got started really very quickly after the late heavy bombardment started so this means that probably you don't require very special circumstances for life now the the rather more pessimistic thing is that complex life of the sort of thing that that you and I trees cats and dogs that happened rather late and this is at the very other extreme of the history of life on earth so it was about 600 million years ago that the first very complex life happened so that may require rather special circumstances so from analogy with that it seems that probably life may be common on planets elsewhere in our galaxy but complex life may be rather rare okay so Dave told us that we need a source of energy and liquid water for life and I told you about the different kinds of stars where you would need to put a planet in order to have liquid life on its surface depends on the type of star you're orbiting around so the big hot blue stars have a habitable zone that's fairly large and fairly far away the the more plentiful cool red stars are dimmer and so you need a a planet to be closer in to have a temperature consistent with liquid water but it's more complicated than that you can't just put the planet in the habitable zone and say it's going to be a habitable planet it's much more complex than that and as we know from our own solar system the difference between earth and venus is dramatic and it depends a lot depends on the atmosphere and the clouds whether you have a dry and toxic environment like venus or a wet habitable environment like the earth so clouds can help as they do on earth but if you have too many clouds they can trap heat and cause a runaway greenhouse effect so it's really rather complicated to assess whether a planet is habitable or not in the future with more powerful telescopes we may be able to make observations which will allow us to identify individual chemicals in the atmosphere of planets and this gives us the potential to actually say is there life now on the surface of this planet that we're that we're observing so for example on the earth we have oxygen in our atmosphere oxygen is highly reactive and we only have oxygen in our atmosphere because it's been constantly replenished by the processes in plants on earth so if we were to be able to detect oxygen in the atmosphere of an exoplanet that would be a so-called biomarker and give us a strong steer that perhaps there is in fact life on that planet now finally i'm going to as as promise tell you a little bit about some work that we did here at the open university so i told you that most of the stars in the galaxy are along that diagonal in this diagram all of those stars will eventually run out of fuel and almost all of them will end their lives as white dwarf stars which are in the bottom corner of that diagram and those stars are no longer doing nuclear reactions they're just dying embers that are cooling like coals left over after a fire and it turns out that planets can survive around compact stellar remnants like that and surprisingly the way that white dwarf stars cool actually leads to conditions where you could have habitable temperatures on planets for up to eight billion years as the white dwarf is cooling so we did a little bit of work just examining this using the real spectrum that you would expect from a white dwarf star and we were able to calculate that if you put a planet in the right place you could have this persistent habitable zone in which you have photosynthetically useful light light that plants could use to generate energy while simultaneously not having too much damaging uv radiation so this is quite a sort of an optimistic sort of very long term picture that as all of the stars in the galaxy burn out we could nonetheless have a galaxy that's teeming with life on planets around white dwarf stars you know as we look sort of 10 billion 20 billion years into the future the prospects for life in the galaxy are actually rather promising so do we have questions if you have a question you need to wait for the microphone that's this one here the planets that you're finding on the stars how far away are the stars from us in light years ah right handily I happen to have a so this is a sort of schematic diagram of our Milky Way galaxy and there's a scale there in light years and the distance of our sun from the centre of the galaxy is indicated so the planets that we find their distance depends on the method used to find them so there's a little cloud of sort of greenish points there that are clustered quite close to the sun and those are the those are the ones that have been found by the Doppler technique where we're looking at the motion of the star caused by the larger motion of the less massive planet and to do that you need a fairly bright star because you have to spread the light out very very widely so you need a bright star to be able to do that then there's a sort of a slightly larger cloud of red points and those have been found by transit surveys so at the open university we were involved in what we are involved in the superwass project which has found quite a number of transiting planets I think we're up to almost 200 now and those planets are are around stars that are slightly more distant from the sun because you just have to collect all the light from the star to find them you don't have to do the very precise spectroscopy and then many more have been discovered by a satellite by a NASA satellite called Kepler which pointed in a particular direction and made very precise measurements again looking for planets that are getting in the way of the star and causing a transit signal where the light dims and because it's pointing in a particular direction it's actually on average looking at fainter stars as those are dimmer so I've sort of schematically indicated those with the with the blue dot and then there's another method I haven't told you about which uses gravitational lensing and that tends to find things just this side of the centre of the galaxy so that's probably a more detailed answer than you wanted yeah just wait for the microphone there'd be lots of planets going around every one star like how many on average would there be like eight or nine like in the solar system or would there be lots more that's a really good question and that's something that astronomers are working on so we we don't really know at this point because all of our techniques require certain things in order for us to be able to find the planet so for the the transit technique we need the planet to get in the way and if you were to look at our own solar system the the planets are aligned more or less in line with each other but not quite so there are quite a few systems where there's sort of up to about five or six transiting planets that have been found in the same system but you don't really know if there might be some that are just you know misaligned a little bit so they're just missing going in front of the star and similarly with the Doppler shift technique you can detect the very massive planets that cause a big wobble easily but there could be less massive planets in the same system that we're failing to to detect so we do know of of systems where there are five or more planets but we're not sure really what the typical number is yet but that's a very good question and you could probably still research on it you know when you're old enough to to do to do research at university. Hi your your research looking at the biomarkers for planets with life seems to be based around oxygen levels if obviously looked at the earth you wouldn't see oxygen levels as much with what we're looking at because it's nitrogen based so are you looking at it with different make-ups like nitrogen and carbon dioxide based as well? Yes so what you're doing is you're looking for something that's sort of out of equilibrium where you've got to have some sort of metabolic process and I should probably also say that that's not a particular thing that I've worked on but the things that I've worked on are the bits that I picked out but that's one of the most important general things that people are preparing to do in exoplanet astronomy in the next 10 years or so. Can I we're going to carry on questioning a little bit longer if we can get the speakers? Okay we've been taking questions on the Facebook page and some of them have come in through the live stream during the week so I've got a few here and I'm going to start off and then if there are more questions that that come out we'll take those from the room as well. First question now that a spacecraft is on the edge of the solar system could it be used to look at the types of particles, objects or space that is beyond our solar system and see if there's anything out there that looks like life? Dave do you want to start that one? This will be alluding to one of the voyages, is it voyager one or two that's left the solar system now that the probes that flew past Neptune in 2009 sent back wonderful bits of triton and so on is now beyond the solar system and it's still working but it wasn't equipped to do anything beyond the solar system it's detecting particle and magnetic fields and it's not really able to look outwards for distant signs of life it can look at its immediate environment and see the field strengths so it's a wonderful old spacecraft still doing stuff but it's not going to tell us anything about life beyond the solar system. It launched a long time ago wasn't it? There's a big gap between that and what you're looking at Carol is there a how do we look at something between the edge of our solar system and the distances that you're looking at? Well as an astronomer we need light and you know light by and large comes from stars so you can you can look at the what's called the interstellar medium the material between stars by seeing it absorbs some of the light from distant stars and certainly some of the molecules that are thought to be prerequisites for life have been detected in the interstellar medium but I don't think anybody would think that the interstellar medium was a particularly promising place for life because it's it's so low density I think you probably need a bit more a bit more stuff to get life going. Okay but I think what it shows that if for whatever reasons you wanted to do this it's going to take you 40 years to get there before we can start looking. Yeah so it's a it's a tricky thing to study if you by sending a spacecraft. Yeah and there's a lot of different ways we could do it. If people have a particular question that's coming out of discussion just stick your hand up and we'll try and pick it up. Another question that came from Facebook can people propose experiments that they would like be sent onto comments or into space you want to take that one in? Well that's an interesting one because the process that we went through was very formal and and it was the way things were done and the way things are likely to carry on being done if they're done through agencies and whatever else. I think just around the corner there's a new era of entrepreneurs or people who want to utilise space for their own probably commercial ends involving space tourism or whatever and we can see that's you know we're on the cusp of actually seeing some of these things now and I think that those will give the opportunities for people who want to do scientific research to piggyback onto these missions and I think it'll open up certainly great new possibilities for research projects. But if you want an instrument to do so and so on a spacecraft you probably have to be able to build that instrument yourself because you can't normally buy them off the shelf. We're pushing the edges of technology with these instruments. No okay. CubeSats now you can actually buy the bits and pieces just off the web and you can put them together yourself. No I think it's entirely possible it really is just around the corner. I think the question was particularly about landing on a comet or something like that that is a bit of a tough one for anyone to do and I think missions like that are going to remain the preserve of you know European agencies or whatever because they're just so challenging. Okay thanks. I'm going to take another question. We may have covered this one but let's just do it. Are viruses things that have developed on earth or do viruses come from space? It kind of goes back to your talk Dave. I didn't mention Fred Hoyle and Rick Rumerson. Sorry. I don't think so. Comets can deliver building blocks for life. We have no evidence that viruses which are sort of prebiotic things were on comets. So I think they probably began on earth but I can't prove it and it's one of the things we're trying to find out. I mean it almost gets a little bit philosophical that because I mean Dave did talk about the possibility of meteorites from earth going to other planets. Well if they do they will take stuff with them in a fairly sort of randomised way. I mean in the same way we probably somewhat paranoid about bringing samples back from Mars to earth which could have you know Martian life forms on them and we'd have all kinds of quarantine procedures and God knows what but meteorites from Mars arrive when they do and they come with whatever they've got so you know this is already happening it's already happened. I've got a question down here in the room. If comets and asteroids are deemed to be I don't know messengers carrying water or building blocks of life where did the building blocks of life originate from? What's the latest theories or speculations? Well interesting that probably is much more in Carol's domain than mine. They are made in stars, they are made in the interstellar medium by processes that are fairly well understood and it's the interesting aspect of how they get transformed from diffuse clouds of stuff, how they then aggregate into a solar system that has a central star and the planetary system. Now it's interesting I mean Carol was talking about exoplanets and whatever else we we tend to forget that actually this phenomenon was discovered in our lifetimes and most people here I guess you know several years ago there weren't any actually the only planets we knew about were in our own solar system. I mean now that we're finding them everywhere we look I mean it was kind of mad that we would have thought that perhaps our solar system was special. So I think I think that's the interesting part is how you convert from the stuff that you start with into what we've got and that's what people like me study but if you want an answer about how it's actually made then Carol's your person. I'm not sure I'm really your person but we do have quite a lot of astrochemists here at the Open University who in the lab will try and make a vacuum and then try and make some of the molecules that have been seen in the interstellar medium and they also do sort of analysis of the spectrum of those molecules so that they can identify them in the interstellar medium as I said before looking at the absorption of light from background stars. So there's a long list of I think dozens of molecules including sort of things that you need to build amino acids that have been detected in space and I think it's thought that a lot of them form on little dust grains so you know an atom will hit a dust grain and then sit there bored for a very long time and then another atom will come along and you maybe get a molecule forming very gradually in that way. But in principle what what we're made out of is stardust. All the elements in our bodies were made in stars. So far you've talked about fairly primitive life forms any thoughts about how we would detect whether this life form is in our sense intelligent and how would you know who it was? Ah well Carol touched on whether or not it's difficult to go from microbes to complex life. Are cells going to stick together give you multicellular organisms and if that happens is intelligence going to be a driver for evolution and will self-select and push life towards intelligence. People have famously argued that it only took a few billion years to get intelligent life on earth to our stage. We could be colonizing the galaxy in a thousand years time. You can build a ship that goes a tenth the speed of light that will take a thousand years to get to another star. Bootstrap a civilisation and then go on. You could colonize the whole galaxy in 10 million years. Why has nobody else done that? We see no signs of anybody having done this. This is the Fermi paradox Enrico Fermi articulated it. Where is everybody? If life is so common is intelligent life common and if it is why can't we see signs of it? It's a it's a big mystery. It could be pointing to the fact that life doesn't get started anywhere else or it could be that complex life is extremely rare or that intelligence rarely develops or that everybody who's intelligent is actually rather stupid and kills themselves before they can start colonizing space but it's a it's a big paradox. Is it also not possible that there could be some sort of cosmic cosbar agreement not to pollute pollute us culturally with superior knowledge? Okay let's take another one from the Facebook page. Are the signatures of life on Mars the same sort of bacteria that's found on ancient earth bacterial traces? I'm going to allow you to the plausible deniability of life on Mars there but is the signature or are the things on Mars like we see in ancient earth? Well I mean it's an active area of research and there are new missions going to Mars all the time some of which are going to try and address this this issue. It's been discussed already about the fact that it's a little bit tricky if you if you we can go to Mars and we can study it in a very kind of black and white sort of way we can find out what it's made of whether organic compounds whether there's a water cycle whatever. If you want to know about life you've either got to look for some indirect things or you've got to look for signs of biology signs of the kind of things that I talked about that define life on earth. The problem we're doing that on Mars is that we would tend to do that our thinking would be very what I call geocentric we think about how life on earth works and therefore we'd say oh this is how it has to work on Mars and of course there's no reason why it should do that so we could design an experiment on earth to go to Mars to detect life but completely misses it because it's looked for the wrong thing. So I think that it's a really tricky one it's really tricky to know the answer. I mean there are these rather fanciful ideas perhaps that actually life on earth started on Mars and was somehow or other transported to here during the history of the early solar system. It seems like I mean most of us would use Occam's razor here and say well I'm just just making it more complicated than it needs to be. There's need for more data I think. It's an active area of research yeah. There are no signatures of life on Mars at the moment that queer buggy thing in the electron microscope image of a Martian meteorite Ian showed has been largely discredited it's probably not organic. It's not proven. And the other possible signature of life on Mars was a methane signal in Mars's atmosphere. There's a gas out of equilibrium with the rest of the atmosphere and that is not widely credited anymore so we have no firm signatures of life on Mars at the moment. You're telling me that being in the meteorite is a real bug. As scientists we always have to be very careful about having a prejudged idea about what we're looking for. We have to be open to things. We have to set hypotheses and test them and all the rest of it. Certainly most scientists who've been engaged with the Martian meteorite and the life on Mars issue have come to the conclusion that it's not good evidence for that. That's not to say there aren't people that would argue passionately the other way. Okay thank you we're going to have one last question. Is there one in the audience? We've got one here. Looking at your saying about life on far distant planets we broadcast out to the universe on an ongoing basis right from when we had the first radio waves. If there was a life out there would it be picked up by our systems today because we still pick up the static from the birth of the universe? Would it will be pick up signals in any form? I think you could in principle detect those signals and there is in fact a project SETI which tries to look for radio signals that could be beam beams out by extraterrestrial civilizations. I think it's fair to say that they haven't found anything yet. The other interesting point is that our sort of radio noise which started I don't know 60 or 70 years ago is now quietening because of the way that we're changing the way television and radio signals are broadcast. So it may be a very brief interval in the history of the civilization where you do create a lot of radio noise. So certainly nothing's been found so far but there's no reason in principle why you couldn't if you made sensitive enough measurements. People have discussed what kind of a radio or a laser beaker would you construct if you want to draw attention to yourself and say hey we're here is anybody else listening? So deliberate attempts to signify your presence are different from the accidental ones like just your radio and TV transmissions leaking but people are looking for both and nothing has yet been found. This is part of the Fermi paradox again why can't we hear people chattering or why is nobody even if most civilizations in the galaxy want to be secretive you know there's 10 to the 10 stars in the galaxy similar number of planets how many of should have life on why is nobody saying hey we're here come and talk to us. Okay I'm going to finish on that note can we thank Dave and Carol and Ian again please. I know there were more questions coming in on Facebook and live stream and we will for those of you who are not in the room we'll try and answer those over the next few days. You can follow more events on in world space week on Twitter with the hashtag WSW 2014 and now if you'd like to join the stand stairs I think there might be some wine. Thank you.