Saturns Moon Titan: A World with Rivers,Lakes, and Possibly Even Life

good evening everyone my name is andrew frak noi i'm the astronomy instructor here at foothill college and it's a pleasure to welcome everyone in the Smithwick auditorium and everyone listening to us on the web to this very special lecture in the 12th annual Silicon Valley astronomy lecture series this series of public lectures completely free to the public is sponsored by NASA's Ames Research Center the Foothill College astronomy program the Astronomical Society of the Pacific and the SETI Institute and we're very grateful for their support tonight speaker is dr. Chris McKay of NASA Ames Research Center dr. McKay is a planetary scientist with NASA whose research focuses on the evolution of the solar system and the origin of life he's best known for his work on Mars he's been an investigator with several of the Mars project and he's actively involved in planning for future Mars missions including the Mars Science Laboratory mission that's coming up and also about thinking what might be needed for future human settlements on Mars he has been a leader in polar research since 1980 traveling through the dry valleys of the Antarctic and more recently to the Siberian Arctic to conduct research in these mars-like environments he's on the board of directors of the Planetary Society and one there Thomas owpain Memorial Award for the advancement of human exploration of Mars in 1994 um but the reason he's here tonight is because every once in a while he lets go of his passion for Mars and seeks understanding of other worlds and he's been very involved in the mission to explore the realm of Saturn and in particular Saturn's giant moon Titan um he was a co-investigator on the Huygens probe which landed on this moon Titan the first landing on a moon of a giant planet and so we've asked him here tonight to tell us about Titan an alien world with lakes rivers and intriguingly enough possibly life ladies and gentlemen it's a real pleasure for me to present to you one of the real explorers of the solar system dr. Chris McKay I want to start by thanking Andi for inviting me to give this talk and Foothill College for sponsoring it I've taken many classes here at Foothill so it's always a pleasure to come here as Andy mentioned I'm at NASA Ames just down the road and my main interest is exploring the solar system and searching for life searching for life in the solar system so I want to talk today about the prospects for understanding Titan the large moon of Saturn and the possibility that it might have life and so we know it's got rivers lakes and the possibility that intrigues us is that it has life it's the way I'm going to set this up is sort of a mystery and of course in a mystery story you first start off learning what the mystery is and then there's a lot of background information that you've got to trudge through before you get to the answer so here is the mystery in the beginning a few months ago there was a paper that pointed out that there was a flux of hydrogen down through Titans atmosphere into the ground so I call it the case of the missing hydrogen on Titan where is that hydrogen going and why am I so interested in why did that report really spark an interest in those of us that were speculating on the possibility of life so remember that I'll come back to it but of course this is the point in the story where you now flash back and you know well why are you here what's going on and you learn about all the characters and many many pages go by before you get back to the mystery at hand but it's the case of the missing hydrogen so what are we doing here why are we out looking for life I want to talk a little bit about what I research for life in the solar system or why in particular are we searching for what I call a second genesis of life because that's really what we're looking for why are we searching for second Genesis because we would then be able to compare the biochemistry of that life with our life all life on Earth we now know shares a common biochemistry a common genetics and a common phylogenetic history which is this tree of life all organisms on this planet that we know of map onto a single Tree of Life what we're interested in is finding another example we have one example on earth finding another example what I call life 2.0 we're looking for a second example because then instead of having a course called biochemistry you could have a course called biochemistry think how many more textbooks that would involve and the knowledge we have also if we were to find out that right here in our solar system life started twice once on earth once on Titan or once on earth once on Mars if we found out that life started twice then we would know that life is common in the universe it started twice right here just having one example it's very hard to extrapolate but having two would put us in a much much firmer position in understanding that life is common and I've added a little comment there yay it'd be great to know that there's life in the universe no at the scientific level and not in terms of rumors and so we we know what we're looking for we're looking for life that is not like life on Earth and we know what life on Earth is it's organisms that map on to our Tree of Life as it's called it's not really a tree some people say it's a bush or a ring or or mesh connecting life forms but the point is that all life forms on Earth have this shared biochemical history what we're looking for alien an alien is an organism that is not on this tree of life that's the operational definition and I show a picture of a possible halia taken from the NASA secret alien storage locker as people always ask me about and of course there is one and of course I would tell you about it and even show you a picture of aliens from the secret storage locker it's funny when I was a kid an alien was an organism from another planet so if you were from another planet you're an alien and if you're an alien you were from another planet but now we realize that that's inadequate definition and alien now is an organism that's different biochemically even if it comes from another planet we might go to Mars and find life there and it maps on our Tree of Life it's not an alien even though it comes from another planet on the other hand we might find something in the soil on earth that we never encountered before that is not on our tree of life and then it is an alien so we have a very the definition of alien has changed because of our understanding of biochemistry and so when we search for another type of life we're searching for a second Genesis well where how might we get information about another type of life there's really three programs directed towards searching for a second Genesis which I showed here one we're going to make it in the laboratory and that's getting closer and closer every day in a sense it's a race between these methods we're going to make it in the laboratory we're going to create synthetic life and then we'll be able to compare it to our life a hammer is not the tool they use to make synthetic life but it was what I could conveniently find as an icon so I put it in there the other is to go find it on another world and that's what I'm interested in go find it on the other world and since the shuttle is its last flight coming up I thought I'd put that icon there to commemorate the shuttle go search for it on the other worlds of our solar system those are the only worlds we can get to the search for an example of life that we can study biochemically we've discovered all sorts of planets around other world and Kepler that wonderful mission is discovering them faster than they can be numbered they've already got two numbers that exceed my ability to count and that's wonderful but we won't be able to go to those worlds and get an example of that life and map onto our Tree of Life the third approach of course is setting we listen for them to call well I'm doing this middle one because I'm not very good with in the lab and I'm not very good if the telephone my approach is go out and search for it so that's time to talk about how would we go search for life on another world what would we look for where would we look well ideally we would take a tricorder and just cruise by and detect alien life with the tricorder a wonderful device you all recognize of course the scene from episode 26 of the original series where with small adjustments of the tricorder Spock not only detects alien life but he detects silicon-based life wonderful tool we should have one unfortunately unfortunately science doesn't know how a tricorder works doesn't know the principle on which a tricorder detects life form even worse science fiction doesn't know the principle by which tricorder detects life-forms and I say that because if you go to Lawrence Krauss his wonderful book the physics of Star Trek in which he explains warp drive transporters force fields tricorders no not tricorder she explains everything but try quarters so even in the science fiction literature we don't have an explanation the other approach common approach to searching for life you can see the kind of literature I read Alvin and how we can't define it we don't know what it is but we'll know it when we see it you can think of this as the justice Potter Stewart approach to search for life and that's okay if the organisms are big and they're chasing us or we're chasing them but what we're likely to find we know already in our solar system is microscopic organisms and the sample that we're likely to have is likely to be dead so it's unlikely that we will be able to recognize microscopic life-forms that are dead either of these methods so what do we do the approach we're taking is to ask the question while what is life need and go look in those kind of environments so the approach is to say what is what is a list of things that life means and the list is pretty short it needs energy on earth there's only two types of energy that life uses sunlight and chemical energy particular type of chemical energy called redox chemical energy shown for example by this reaction so life needs energy it needs carbon it needs liquid water and it needs a few other elements nitrogen phosphorus and sulfur the key requirement for life in terms of its distribution on earth is liquid water so liquid water becomes the operational constraint that we use when we think about life on other worlds say what other worlds have liquid water those worlds usually have plenty of energy plenty of carbon and plenty of these other elements so liquid water is the restrictive requirement for life and that's why you often hear NASA's approach to search for life described as follow the water search for the water not that life equals water but that given all the things life needs water is the hardest to find so where are their worlds with water but in fact this slide is not worlds with water its worlds with liquids because you've got to argue that it's not water per se that life needs but it needs some kind of liquid medium in which to do it's chemistry life needs a liquid earth that liquid is water there is no other liquid that's occurs naturally on the surface of the earth Mars Europa Enceladus are all also water worlds they're worlds that had water or have water under ice in the case of your open and sellers so there we're searching for carbon-based life living in water just like we see here but it might be that on these worlds we find life indeed and they are related to us they're not alien Titan the world of interest tonight also has the liquid and that liquid is not water it's completely different so if we find life on Titan there's no chance at all that it is on our tree of life any life on Titan is sure to be alien because it's living in a fundamentally different liquid than life on earth is and that's why Titan is so fascinating to astrobiology because even though it's so strange it's very strange miss ensures us that whatever we find there will be interesting if it's life at all so that's why Titan is the focus so let's go to Titan so here is Titan as seen from space it looks just like an organic fuzz ball like a tennis ball because the atmosphere Titan has a thick atmosphere the atmosphere is rich with organics let me just do a quick comparison of Titan and Earth Titans got about the same size and gravity as the moon so think of it as a moon sized object but with an earth-like atmosphere it's the only world with an atmosphere that's roughly equal to ours in that it's pressure is only one and a half atmospheres so if you are standing on the surface of Titan it wouldn't feel that different than standing on the surface of Earth it would be the same pressure you'd experience under 15 feet of water swim to the bottom of a swimming pool and that's the pressure sensation you would feel on the surface of Titan it's also the only world with a nitrogen atmosphere of like Earth's so earth and tighten both have nitrogen atmospheres it also has rains and clouds in the act of hydrological cycle but instead of the liquid being water the liquid is methane it also has a strong greenhouse effect based on a different chemistry than the greenhouse effect on earth but the really big difference between Earth and Titan is on earth temperature is plus 15 centigrade on Titan it's minus 180 centigrade that's a big difference Titan is really cold it's like a it's like a mirror image of Earth where the mirror is a freezing-cold mirror everything that we see on earth all the processes that we see on earth we see cold counterparts on Titan now of course the folks on Titan are looking at earth and saying that world looks a lot like ours only it's really really hot much too hot to support life so so that's one reason why Titan is so interesting is this comparison to earth and part of this comparison is the organic chemistry as I said we see Titan's atmosphere it's rich with organics and we can simulate that in the laboratory this in fact is a photograph of an experiment that was done in our lab at Ames is actually done by a high school student it's part of what used to be called the Westinghouse science project and what what the student did is she hooked up a tank of nitrogen and methane flowing in and then Sparks in this chamber and over time there are sparks created a reaction in the methane to nitrogen and created this brown organic material and the spectral studies of this material show that it's the same as what we see on Titan from Earth and from spacecraft so we can simulate the organic processes that are making this haze on Titan in the laboratory we can study them and they don't have anything to do with biology this is just Sparks through a Titan like atmosphere and so it tightens atmosphere not surprising there's all sorts of organic molecules it's a real soup it's the most organic rich environment we know in the solar system if you like organics Titan is got lots of them they may not be very tasty but somewhere in the mix there's got to be things like chocolate and who knows what else so Titan is got organics and so searching for organic based life Titan is a place to go so that's where we went what we've learned about Titan is come from the fabulously successful Cassini mission and the Huygens probe the Cassini orbiter was built by NASA the Huygens probe through Titan was built by ISA so I call this picture the east sub view of the European view of the cassini-huygens mission seeing the probe up-close landing on Titan and it's interesting when we designed this mission many years ago we were sure that Titan was covered by an ocean so the probe was actually designed as a boat to float and even had sensors going through the bottom of the boat we thought we were going to land like this on an ocean or at least on the shore of a big giant equatorial sea we reason we thought that was because we saw methane in Titan's atmosphere and we knew that with time sunlight destroys that nothing and turns it into ethane and that would have happened in about 100 million years so the only way Titan could still have methane after being around the Sun for four billion years is if there was a huge supply of methane on the ground that was slowly being processed into FA so our concept when we built the probe was that we would land in an ocean of ethane and methane that would have been processed over time to produce to produce that ethane from an initial inventory ocean deep inventory of methane when we got there to our surprise what we found was essentially a desert world we land the probe landed on the equator not a drop to be seen and look dry look like scenes in deserts on earth go to the Mojave Desert and see scenes like this looks like rocks in the field and the entire equatorial region up to 50 degrees in both hemispheres was dry we didn't see any evidence of lakes or streams or ponds active at that time but there was some curious results one is that when the probe landed the accelerometer trace in the the ground was soft it landed with a splat not a splash or a thud these are highly technical terms a thud is what happens when you hit something that's really solid and a splash is when you go into a water in the pool and a splat this kind of something in between think of muddy ground so this was one indication that the ground that we landed on even though it looked dry and here are the black-and-white image showing the scale these rocks are about 15 centimeters in size that it looks dry but this is indicating that it's a little bit wet and sure enough one of the instruments on the probe detected vapor being released right after landing so this is the landing point splat we land and skiing starts coming up from the parts of the probe that are sticking into the ground the probe of course is much hotter and Titan because it's operating at electronics temperatures and the Titan is minus 180 centigrade so the probe is very hot it heats up the ground and we saw methane steam come out so the ground was wet which is it which is a puzzle we see what looks like a huge desert region in the equator of Titan but the ground is wet we did see clouds these were storms seen by the Cassini orbiter as it was flying by Titan these storms are at the polar regions there's cloud activity in the poles but the Equator was without clouds and seems to be without clouds or most of Titans year interestingly at the landing site we saw evidence of dried channels we saw evidence of rivers that were now dry and what looks like coastlines all now dry arguing that maybe in the past Titan may have had the global ocean or may have had large equatorial seas but now think of it as a desert world with mysteriously wet surfaces at the equator eventually we discovered that there were lakes in the polar engines this is Lake Ontario it was named that because it's about the size of Lake Ontario she only lake in the south polar region and in the north polar region many lakes were discovered here is different projections of that from Alex Hayes is PhD thesis and here is Lake Michigan for comparison so you can see these are Great Lakes so in summary Titan has lakes in the polar regions you can see that this is extending down to about 70 degrees north only so what we would call the Arctic and Antarctic regions on Titan have lakes but in the equatorial regions and the mid latitudes it's a desert with slightly damp soil so that's the world it's got liquid it's got liquid prevalent in lakes but also in terms of wet soil what does this mean so one of the questions is what is the possibility for life and to understand that I want to think about life on Earth viewed from space on earth we have carbon-based life it's made out of carbon it lives in liquid water and because it's carbon-based and because it lives in liquid water it's everywhere on this planet because water is everywhere on this planet so the life is widespread life on Earth is widespread it's in fact very hard to find a place on earth where there isn't life I spent decades trying to do it find a place on earth that's as lifeless as we can possibly find and in fact the most lifeless place we found is in the Atacama Desert in Chile the driest place on earth where we find the least level of life and still it's teeming with life compared to what we expect to find on Mars or anywhere else so even the most barren place on earth is rich on life and that's because carbon and water is prevalent on earth as a result of life being so prevalent it has a global effect it changes the world life has changed the world and it there's some obvious ways the oxygen in our atmosphere is made by life the fact that there's methane in the atmosphere at the same time as there's oxygen also is very odd and is due to life and the co2 that's my favorite example co2 has a very odd signature which is due to life here is that signature of co2 measured in Hawaii and you can see co2 in the atmosphere goes up and down up and down up and down up and down that is a signature of life well on Mars co2 also goes up and down but on Mars the co2 goes up in the summer and down in the winter on earth it's going up in the winter and down in the summer exactly the opposite and this of course is due to plants growing in the summer eating the co2 pulling it down and then in winter the plants die the leaves die the co2 goes back in the environment co2 goes up this is a direct signature of life now this increase with time could also be a signature of life but that scientific observation has been trumped by ideology so I don't want to discuss it tonight but let's go back to Titan where the science is still science observations are still interpreted free of ideology so back to Titan here we have plenty of carbon so we can postulate carbon-based life but if that life is to be widespread the liquid it's going to have to live in is liquid methane the liquid on Titan that's widespread is liquid methane so you can imagine well we should imagine life that's water-based on Titan but if it is we're not going to find it because there's no place on the surface of Titan where there's water wide search for water-based life there but we should search for is liquid methane base life well if there's carbon-based liquid methane based life on Titan then it should be widespread it should live in all these lakes it should live in the wet ground it should live everywhere on Titan just the way water-based life lives everywhere on earth you have a planet or a world it's not really a planet it's a world planet is not a scientifically useful term as we all know now given the sorry fate of poor Pluto but if there was life that could live in liquid methane it could be widespread and if it is widespread on Titan it should change the world that's the basic philosophy we're using a search for life on distant planets we look at a planet around another star we can't detect the life on that planet directly but if life is widespread it will change the world just like it is on earth it will create things like oxygen or methane or some global disequilibrium that we will recognize as a signature of life on other planets that are earth-like we've picked oxygen as the key indicator so when we see an earth-like world around a sun-like star we will look to see if it has oxygen and if it does that will be very very interesting but met but Titan is not an earth-like world life on Titan probably not making oxygen what is it making its living in liquid methane and that's the key point here so some of you may remember this famous cartoon ammonia ammonia but we want to change that liquid methane liquid methane what could live on liquid methane and what would it do how would life forms living in liquid methane alter their environment the way life on earth has altered our environment to create oxygen what would be the global change effects that we could see from Earth or see from a spacecraft flying and Titan so a couple years ago together with the graduate student who was Heather Smith who was then a graduate student who's now since graduated is working at the National Academies of science we did a study of what would organisms on Titan eat because if we go back to the things on earth that life has changed oxygen co2 methane they're all things that organisms consume or release as part of metabolism they're either food or waste product and in fact one organisms waste product is in other organisms food so when we breathe in oxygen we think oh this is all great fresh air that's just the waste product of other organisms algae and plants so we looked at what would organisms on Titan eat what would be their waste products so what they eat what an organism will lead is something that it can get energy from so here is the list that we came up with the sorts of things that would be edible on Titan in terms of the kind of reactions redox reactions that life on earth uses the most edible thing the tastiest thing on Titan Titan chocolate if you will is acetylene acetylene plus hydrogen makes methane produces a whopping 80 calories per mole so what does this mean it means that on earth what we do is we take in organic material and as you can probably tell preferably chocolate we take in our Danning material and we take in oxygen and we react that organic material with the oxygen to produce co2 and that gives us energy okay so we oxygenate organics untighten there is no oxygen but there's hydrogen in the atmosphere and it turns out that organisms can make energy by hydrogenating organics not oxygenating on earth we oxygenate organics because we live in an environment full of oxygen untighten the strategy would be to hydrogenate the organics so they react acetylene with hydrogen and that gives them energy and their waste product is methyl other things that organisms could eat would be attained or even the solid haze would be edible so if you're an organism on the surface of Titan food is coming down from the sky being produced by photochemistry producing these ethane and hydrogen which organisms can Veni so it's easy living if you can live in liquid methane easy living and you can get plenty of energy that way but if you say well what are the organ is was consuming they're consuming hydrogen they're consuming a settling and they're consuming FN so in the paper we wrote we pointed out which is hard to see but I'll read it to you that if there was life on Titan and it was widespread it would be it would reveal its presence by anomalous depletion of acetylene ethane and hydrogen at the surface so our prediction was the way life on Titan would change the world is not by making oxygen or seasonally varying co2 it would change the world by eating all the acetylene eating all the ethane and most importantly eating the hydrogen that's what life on Titan would do so this then takes us to the case of the missing hydrogen so we wrote this paper he submitted it the day the probe landed just because we were late I'm sure that had it done a few years earlier but we didn't we submitted it actually the day before the probe landed January 15 2005 the probe landed we submitted the papers the day before and we didn't really think much of it it was just sort of idle astrobiology speculation about the possibility of life on Titan and we went on to more serious things well then a few years later Daryl Strobel published his paper in which he concluded that the cassini-huygens measurement imply that something is eating hydrogen at the surface of Titan boy this got our attention right I went through and found that old paper and said wow that's exactly what we predicted right isn't that odd and it is odd and in fact when I went back and looked at the three things we predicted depletion of acetylene depletion of ethane and depletion of hydrogen all of them were being shown to be true so here's what we said we said the results would implicate the present life by anomalous depletions of acetylene ethane and hydrogen that's what we predicted would be gone and acetylene is expected but not the detected ethane is much more depleted than we originally thought it would be these are not very important constraints because there's other ways we could lose those molecules but the flex of hydrogen into the surface there's no way we could explain that without biology there's nothing eating hydrogen but organisms which is why we thought that was a particularly strong indication of something odd and maybe biological is the flux of the surface and so what we expected then is that the Huygens probe or any instrument would detect a depletion in hydrogen if there was no life we expected the concentration of hydrogen to be constant in the lower atmosphere if there was life we expected it to be to drop off we were thinking that the probe would detect this drop-off but there's confusing results when we look at the results from the probe which just came out a month and a half ago the hydrogen concentration looks straight all the way down I was like I would have been ecstatic if we saw a little drop here at the bottom hydrogen profile from the most recent analysis of the probe does not show any strong drop but nonetheless Darryl's model shows sorry Darryl's model go back to this shows that there's still a flux into the surface so in the case of the hydrogen depletion there's one bit of evidence that argues for it and one bit of evidence that seems to argue against it if we confirm that there really is hydrogen lost into the surface it's hard to explain that any other way but like so let's go back to life what would it be like to live on Titan would it be a difficult life challenges of life on type first as I said earlier food is easy it's falling from the sky the organic haze being produced by the sunlight is the food that the organisms would consume carbon is easy it's coming in those organic molecules nitrogen is easy it's being incorporated into the organics by photochemistry that's in contrast to earth on earth nitrogen is very hard biology has had to invent special tools to get nitrogen because the n2 in the atmosphere is so hard to break up your special nitrogen fixing enzymes to do it hydrogen is also easy what's hard on Titan is getting oxygen you can't imagine organic based life without oxygen it's needed in many different molecules it's not common on the surface of Titan it's all tied up in rocks otherwise known as water ice so there's going to be special enzymes for these organisms needed to pull the water ice out of the oxygen out of water to use it in their biochemistry the same way earth life has had to invent special enzymes to pull the nitrogen out of the air to use it in its chemistry on earth nitrogen is hard oxygen is easy on Titan oxygen is hard nitrogen is easy so let's imagine we did go to Titan this is not a real picture of Titan this is actually Lake Mead modified by computer graphics to look like Titan there's a film crew doing a special about tightening they sent me this image and said does this look realistic I was just amazed at how much it looked like what I would expect Titan to look like but suppose we did go to Titan we scooped up some stuff and we wanted to know is this gooey stuff from the bottom of the lake on Titan is it Titan life how would we tell it's going to be alien it's not going to be life like we know it but that's the whole point we want to find life like we don't know well what how would we detect it what would be in this liquid we don't we don't know yet we're just starting experiments to see what kind of organics could dissolve in a liquid like this could there would this soup be a thick soup or a thin soup well we already know that it's going to be a pretty thin soup but just how thin it is we don't really know yet we're just doing those experiments now but if we imagine that there is life on the shore of these legs how would we recognize it what would we look for so I want to make a suggestion that there is a way to tell the difference between organics that are produced in the atmosphere like in our Titan simulations that are just a biological organics and organics that are produced by a biological system biology is a lot more picky than chemistry shown by this schematic plot so I'm plotting concentration versus type of molecule a non-biological distribution has got all sorts of types of molecules more or less at the same amount everything is in there whereas biology pick certain molecules and uses only them for example biology uses L amino acids left-handed amino acids and not right-handed amino acids hooray for lefties that's the only kind of amino acid that biology uses whereas if we make amino acids in a chemical experiment we make both right and left-handed so biology chooses chemistry doesn't and we can see that by looking at the distribution organics now suppose and go to Titan and find some organic material and we find that it also has an unusual distribution but the distribution is different from the distribution of earth light that would be evidence that that organic material was produced biologically and it goes back to this example here about life choosing the L the left-handed amino acids and not the right-handed amino acid light biology chooses chemistry doesn't that is I think the most fundamental principle that we can generalize to searching for life that's not like us it wouldn't do us any good to search for DNA we know how to search for DNA but if there's life on Titan it's certainly not using DNA it's not using the same molecules that life on earth uses so we need a more general principle and that more general principle is life chooses but chemistry doesn't I want to end by going beyond our solar system there's a real excitement now in the planetary community the discovery of planets are on other stars our goal has been to search for earth-like planets that's cool I'm all for earth-like planets but we ought to also search for Titan light planets around other stars because Titan is so cold it doesn't have to be so close to the star to be habitable so we talk about liquid water habitable zones and unfortunately the most common type of star an M star red star all those you remember Superman comics know that he came from a red star of course because they're more red stars than any other type of stars but life in a water like world around an M star has to be uncomfortably close to the star so close that it's probably tidally locked but if you're living in a liquid methane world a Titan like world then you're much further from the M star so a Titan like world could be habitable around an M star at a much further distance and it wouldn't be titled why and Jonathon Looney no scientist involved in studies of Titan has suggested that there may be much more Titan like worlds in our galaxy than earth-like worlds because they could exist around these small dim very numerous stars and when we look at Titan we think boy it's going to be hard to live there but if we imagine the view from Titan just slide here that I call rare Titan and it's kind of a spoof on the book rare earth which some of you may be aware of in which the authors my good friends Don Brownlee and Peter Ward brilliant eyes and I like them but I don't like the conclusions of their book they said well earth is really unusual and really special and there's not going to be very many places like Earth I think well imagine there was a Don Brownlee and a Peter Ward of microscopic persons living on Titan writing a little book called rare Titan in which they point out that okay we've got this other world in which there's water but it can't hurry have life it's another world with liquid but that liquid water is extremely corrosive it dissolves organics it even dissolves in organics it's solution concentrations are so high as to be toxic the high temperatures would require organisms on that world to eat several times a day how could that possibly be and the solid phase would float over the liquid phase creating a temperature instability that could cause runaway glaciations and on and on their list would go proving that there couldn't be life on that water world and proving the suitability of the Titan environment and the intelligence of the design of the liquid methane environment suitable for life so it makes the point that maybe as we learn more about life will realize that its perspective on will get a different perspective and that this is the slide that tells me it's the end of the talk and time for questions thank start right here yes regarding flux of hydrogen done as I understand that means that hydrogen is moving down through the atmosphere toward the surface of Titan so wouldn't that also mean that there has to be hydrogen going back up again well that's that's exactly why it's a mystery is that there's a flux of hydrogen into the ground and that's it according to Darryl's study Darryl Strobel study there is a sink a loss of hydrogen so it's flowing into the ground and then something is consuming it and now that hydrogen may be reappearing as methane ch4 coming out but it's being changed it's not coming out as hydrogen and that's why it's a mystery something is consuming the hydrogen if he's right if Darryl is right and what could be consuming the hydrogen well my favorite answer is biology we can't there's no chemical process that we know of that would operate at these temperatures that would consume hydrogen so it's very curious question over here it has become apparent that per manned missions in space for longer than 90 days we need substantially more shielding against cosmic ray particles than is economical to launch and one solution that has been proposed as robots welding or faceting spherical asteroid components into a pole of sorts to shield and in order for robots to do that they would need a replenishable propellant the nuclear reactors could keep going for some time but the propellant would need to be replenished so the two alternatives are nitrogen from Titan's atmosphere in an ion engine or the ice and dry ice from comets and main main sequence comments in the asteroid belt which do you think would be the more economical and given the gravity well of Saturn and such which do you think would be the more economical source of propellants yeah that's a fundamental problem as long as you're using rockets you have to exhaust something out the back end and if you don't bring it from Earth you've got to find it in space I don't think either of those is going to prove the two methods you suggest we're using nitrogen on Titan or volatile from comets as the propellant in some sort of propulsion system I predict that neither of those will prove to be economical we need to invent a different type of space transportation than rockets now my personal favorite of course is warp drive but I'm willing to accept something intermediate but I don't think so I think it's a tough problem and I think the engineers ought to get working on it so if there's any engineers in the audience don't sit here go get working on it the rocket Rockets are just too too limited to get through the solar system it's a solar system is too big for Rockets we need a new technology and I don't know what that is question here since this talk was really more about life and I think a few days ago at Birth paper circus by Richard Harris in this so-called Journal of cosmology about ancient alien fossils in meteorites is this john courses science well that's a very timely question there was a big blurp in the internet over the weekend because of a paper in a sketchy online journal called the Journal of cosmology in which Richard Hoover is a friend of mine reported seeing structures that he identified as biological and origin not just biological in origin but a particular type of organism cyanobacteria and what's more identified heterocysts of cyanobacteria well cyanobacteria are photosynthetic they live in water with sunlight and heterocysts are structures at cyanobacteria make to protect their nitrogen fixing enzymes from oxygen so the presence of heterosis of cyanobacteria says that he is saying that these meteorites came from an environment with water sunlight and oxygen that is radical the alternative is that he's just seeing some bizarre shape that's got nothing to do with biology so you either have to accept that there's strange little shapes and meteorites or that meteorites come from a world that's strangely earth-like out of context of our understanding of meteorites now if I had to choose between those two I would choose it's just just a shape and that scale shapes don't tell you anything you think about it these shapes are micron in size you think of a meteorite that's say ten centimeters there's something like a hundred billion square microns in the cross-section of that so you're going to probably find something that looks like you know anything you want you know take a picture of one of your friends and search through and you'll find a picture of your friend in the meteorite where you then conclude that the meteorite came from a world that was populated by organisms that look like your friend I don't know you just include well isn't that curious that this shape had that odd proportions now I don't think it's it's contamination I don't think it's sloppy technique Richard Hoover is actually very good at microscopy but I just think that you can't unequivocally deduce biology from shape when you're looking at those kind of tiny shapes you'll see every type every structure you can imagine question over here regarding signatures of life in the chemistry of Titan have any researchers been modeling or simulating evolutionary pathways of organics into more and more complex molecules that got over you know simulated many large large intervals of time yeah that's that's a very important question and I carefully avoided talking about how life got started on Titan I only talked about the energetics and what the effect would be and I didn't say how could you get life started in such a cold organic pour mix as we see on the as we expect in the lakes there and part of the reason I avoid it is because we don't even know how life got started here and here we've got lots of scientists working on biology full time well at least part time so we don't understand how life got started here so we shouldn't expect to understand how it got started there but it is probably the most difficult part of postulating life on Titan is postulating how it could get started how the kind of self-organizing of organic molecules that we think leads to life could happen in a organic mixture at such low temperatures we're actually we're thinking I wouldn't say we're working on that because that would be a slight conceit in terms of the level of our understanding and effort but I'd say we are thinking about working on that thinking about what kind of experiments would we do to try to simulate organic prebiotic chemistry in a liquid methane light solution and the answer is we don't have any good ideas yet but we're still thinking that's what we get paid to do you know question here can here oh yeah you suggested that the probably the only way to get oxygen connected up with the chn would be some living process are there specific compounds that could be tected spectrographic lee from satellites or something probe that was with future missions be designed to look for something that had oxygen combined with that's a good point that's a very good point and that is if there's no life on Titan the oxygen content of the organics on the surface should be very low if there is life on Titan the oxygen content of the organics on the surface will be higher because those organisms will be scavenging oxygen and sticking it in to their biological molecules and that I don't know of any way to detect that from orbit or from Earth but we could detect it when we land and it's part of the whole idea that if we can land and scoop up some organics if there's life there we'll see it by the signature in the organics because it will look different than the stuff produced non-biologically and that will be a very good example of the kind of difference it will be enriched in oxygen the same way that on earth organic material is enriched in nitrogen compared to what you'd expect from non-biological processes on earth my earth life specifically collects nitrogen and phosphorus and so biological material of biological origin on earth is enriched in those elements nitrogen and phosphorus and nitrogen in particular people suggested that could be a way to detect life on Mars as look for nitrogen follow the nitrogen untighten it would be follow the oxygen good good point question here piggyback on that a little bit talking about signature signatures of organics is that something you can start doing now is that something Barney's and what does it take to think maybe a probe to the plant satellite orbiting or is it Hubble right Hubble in the oven are in spectrum I think to analyze the organics we've got to land and scoop up the organics we don't know of any way to make the analysis at the level of precision needed remotely we've got to scoop it up and then stick it in an instrument like very GCMs stick that in they stick the organics in there and then look at what we see we've flown those kind of instruments you've flown them on Viking you've flown them on the Huygens probe we've flown them on the mission that's going to Mars in November the Mars Science Laboratory is on its way to Mars it launches in November it will have a state-of-the-art GCMs with both liquid and pyrolysis extraction that instrument would be perfect to send a Titan the problem is getting it there it's a long way away and landing it safely and then getting the soil up from the ground and into the instrument but we have the instrument we just don't have the spacecraft to get there question here when one thing that fascinates me talking about the implications of life at such low temperatures and you've already indicated that life is slow temperatures will look at us they would be kind of God knowing got eighteen three times a day that's right how can you deliver them right sometimes I wonder myself well but when we look around the earth we see we've recently last 10 years 20 years discovered live in places we can expect whether it's in deep ocean vents and very high temperatures and aesthetic environments or what would we think of as poison glands but I'm not mistaken I recall to his life discovered a mile or two underground in rocks with presently slowly tab ilysm in that kind of environment where cell division might take a thousand years right and I'm just curious with mine laying those possibilities those things out what you have to say about what the implications be life taking places low temperatures I pursue motivated capitalism right but you're certainly correct that on earth we find organisms living very very slowly living at low temperatures metabolizing at a very slow rate or living in environments where they spend most of their time frozen or starved and hence are in a stasis and so their life cycle is stretched out over literally geological time scale so we even see that on earth so on Titan that could be taken to an extreme it could well be that the cycle time of an organism the metabolic lifetime could be thousands and tens of thousands of years but if you think what's the hurry if everybody is living at that same time scale if the organisms you're chasing and the ones that are chasing you are also moving at thousand-year paces you know everybody's going at the same pace who's to say that it that isn't fine so there's no intrinsic time scale that life must keep up with so I don't see any fundamental reason why it couldn't be true the life on Earth at very low temperatures and very long timescales is in a way a model but I think what if we do find life on Titan it'll be even slower still it will give a whole new meaning of life in the slowly okay on earth our water-loving life makes use of the fact that the water molecule has right whereas on the methane and ethane has no dipole moment I wonder if there's anything at all soluble in methane ethane it does have a like is ammonia at all soluble organic molecule the dipole moment that could be in there or you really have like operating during the kind of chemistry have you been listening in on our lab meetings because that's exactly this today at was the one o'clock or two o'clock one of those of clocks we were talking exactly about that okay methane isn't working very well nonpolar solvents are working well maybe a little bit of a polar solvent added in would spice up the mix and allow for enhanced solubility it's like you know just putting a little bit of alcohol in the water changes what the knees drop that's alright if you have any good ideas email them to me we need them really but it is a it is an interesting possibility because we have theories would suggest that there is ammonia on Titan it's going to be mostly frozen and solid but the literature suggests that there should be some small solubility of ammonia in the liquid methane and that could really change its solubility chemistry but the experiments are very hard to do I can't do them and the and the highly qualified technicians in the lab that are working on it can but it's still very hard working at very cold temperatures and the things you normally like to do like sonic ate a sample shake it up are very difficult to do if the samples at minus 200 centigrade so practical problems are preventing us but the line of thought I think is brilliant why'd you say so because we've been thinking the same thing which goes to show that great minds are all in the same rut question here so are there any more are there any more return trips to Titan plan say in the lifetime of any of the young people here are there any more trips to Titan plan in the lifetime of anybody here well trips to Titan take a long time when I started working on Titan on the mission because Huygens mission - when the data arrived was just two months short of 20 years so from start to data was 20 years so if we start again now would be another 20 years in 20 years you'll will all be 20 years older than we are now that's the way it works out so and we're not starting a Titan mission right now the Decatur survey just came out last week or yesterday Monday establishing the priorities for planetary science and Titan mission was about fourth so first was Mars sample return then was your Europa a pretty interesting world half as far away as Titan though Mars is really close you can get there in just six months we can do a Mars mission from start to finish in about four years tightening it's more like 20 years just because it's so far away so Titan is a few missions in down in the cube so maybe maybe it would get we'll start one in another 15 years and then it's another 20 years to get there so these predictions about life on Titan won't be disproved anytime soon so I'm I'm free to continue giving talks speculating about life on Titan who knows now on the other hand there's a bunch of clever engineers trying to come up with simple missions to Titan that might be able to sneak in like a mission that just lands on a lake and measures what's in the lake or an airplane mission that flies through the clouds those kind of missions are less expensive and could possibly get in as a faster near-term mission that might be only 15 or 20 years from the new start which could be in a couple years so maybe so if you want to see a Titan mission plan on living for quite some time don't smoke exercise regularly eat right get plenty of sleep and just think liquid methane I guess we're next question over here where's the end of last year there was some interesting publications about work at Mono Lake by I think it was Will Smith and her team looking at our sink as a life process and some potential bacteria that they bite down because that count is being off the tree and did it inform your work in any way yeah that's a good question and it's timely that what that work was there was a paper in science that reported an organism identified from Mono Lake a Californian that was able to utilize or survive I think technically survive very very high concentrations of arsenic our snake is poisoned the reason it's poison is because it's a lot like phosphorus phosphorus is an essential element our snake sneaks in and pretends like it's phosphorus and gums up the works because it's right below phosphorus in the periodic table so the idea of searching for phosphorus based life actually came out of a meeting at Arizona State a few years ago where we were trying to find trying to come up with ideas what can we look for on earth to find organisms not on our tree of life and one idea was well if we can find an organism that doesn't use phosphorus that uses arsenic instead that's pretty weird and maybe that won't be on our tree of life well it's kind of a success but not they found an organism that can survive extremely high concentrations of arsenic maybe even uses the arsenic as a replacement for phosphorous although that's not really anchored in the results and still controversial but it is not an alien organism it is a normal organism that normally likes to eat phosphorus but it will use arsenic if you or tolerate arsenic if the phosphorus is very low but it definitely is on our tree of life maps on to the bacterial Kingdom and it's got the same ribosomes and triplet code and all the things we know and love about life on Earth so it's one of us just strange one of us but this is California we accept all times they wouldn't allow it in New Jersey or New York or the East Coast or any of those red states but here we'll take it right hooray for diversity and life question here yeah that's a really good question the Drake Equation in fact most thinking about life beyond the earth and its distribution in the universe is based on our water life paradigm we say how many earth-like life worlds could there be what fraction of earth-like worlds could have life what fraction of earth-like worlds with life would have intelligence that's the basis of the Drake Equation is those estimation but it starts with an assumption that the life form is going to be like us living in water if we expand that to include liquid methane Jonathan Liu means point is there could be way more methane liquid methane world than water worlds and the reason is is the universe is a cold place it's hard to make it warm warm enough for water it's a lot easier to make it warm enough for liquid methane so there's a general scent a lot more phase space available for Coldplay Anacin for hot planets and so yeah it would affect our estimation now would that methane life have the possibility to develop intelligence and that's it you didn't ask that question but I'm asking it for you that's more problematic and maybe that the answer to that would be no that it's going to only be microbial but let me think about that maybe we should come up with some reason why methane-based life on Titan could develop multicellularity and hence intelligence on Earth multicellularity is rooted in oxygen metabolism we don't get multicellular life until we got oxygen and all complex large life forms use oxygen air there debride oxygen like humans do and so many people conclude that an oxygen-rich atmosphere is a prerequisite for multicellularity and a prerequisite for intelligence but they haven't really thought a lot about liquid methane life so maybe there's a way around that problem that's a good thought question here that's reasonable that regardless of the biochemistry you would expect life-forms to be organized into cells given that you focus mostly on biochemistry tonight efforts underway to deploy microscopes remotely-operated microscopes of sight commoners or other kinds of instruments for those small organized structures yeah that's a good point and it certainly would be true that if there was life on Titan it would compartmentalize itself and one of the questions we're asking is what kind of molecules would it used to compartmentalize itself life on Earth uses lipids lipids work because they have a hydrophilic and hydrophobic and so lipids work because they act against and with water on Titan you would need a different organizing principle to create compartmentalization maybe someday you could try to search for that with a microscope but that's not what I would send is a first instrument it's in something more general like a GCMs and just look for unusual patterns like high oxygen as we talked about earlier or chiral asymmetry all of certain left-handed or right-handed or some other signature in the organic that's a little more general and easier to spot whereas microscopes it goes back to the question about the meteorites if you look at something on a very very small scale you see all sorts of strange shapes and they no longer shape it no longer becomes characteristic of biology we're used to thinking of dinosaur fossils where just the shape of the fossil tells us that it was a lie but those are things that are large and you get to things that are micron big there's so many different shapes that shape is no longer a sign of function or sign of origin and so I would be very leery to argue for a microscope just as a way to search for life on an early mission once we detected life and we know it's there say with some biochemical approach then you might want to send a microscope to have a look at it because then you've got more of a context to put it in and that same logic I think applies to Mars microscope is powerful but it's only powerful when you know what you're looking at and that's the problem with the meteorite searches okay so three more questions on either side so that's good question here length of time to search porcelain robot foreign-based however I'm wondering instead of trying to land and drill or melt down through several honors vice what would you think about sending a spacecraft to the garage points around and itself because through the eruptions on themselves or impacts there should be a lot of stuff hanging out yeah and wouldn't that be a faster cheaper and perhaps better way of doing it flies through the fiscal novel Enceladus and gives you a very brief snapshot Horace shouldn't there be a lot of stuff that's been accumulated in the garage point yeah it's a good approach there's two parts the approach one is catch the stuff that's flying off and to catch it where it's accumulating now in the case of Enceladus it's definitely flying off we can fly through the plume it's also accumulating but not at a Lagrange point it's accumulating in the e-ring the entire earring of Saturn is Titan is from Enceladus so we could so when we were thinking of a sample return mission we're thinking of flying through the plume of Enceladus several times and then going through the e-ring and picking up some more stuff sort of catching the stuff that's been caught by Saturn because the stuff that leaves in Seles is still trapped caught by static Europa is a much harder case because we don't know for a fact that anything is jetting off there's one hint that there are eruptions from Europa and that was during the Galileo mission one of the flybys saw a very high increase in plasma density electron density factor of 10 over all the others and one interpretation of that is some sort of Plumer eruption so I've argued that if we do a Europa orbiter we ought to be watching for eruptions and just watch an orbit and catch it as it comes out and if it's coming from the ocean it should contain interesting things in it like argon dissolved in the water that we wouldn't see if it was just coming off the ice I'm not sure I haven't thought about the possibility that that stuff would be caught at a garage or in orbit around Jupiter I'd be more interested in catching it fresh which we could do with an orbiter so I'd argue that the way to do that is watch in an orbiter and if you see an increase in density there's something happening capture that and the Galileo data suggests that that pasta that's a plausible scenario question here if I recall your so your slides correctly the liquid methane lakes are concentrated one of the polar regions right presumably the solubility and diffusion rates of this molecular hydrogen within this kind of saucy solid surface of the equatorial regions and in the actual liquid methane lake or lakes is very different and presumably the magnitude of life would vary across the planet a question is is there any atmospheric model or any atmosphere tracer that might favor non-uniform distribution of life that one could pick up remotely auras are just too much atmospheric turbulence and smears are getting out no that's a good question and it's a good suggestion and it may even be happening the question is is there something we can see in the atmosphere that would vary with latitude that indicate that life is rich in the lakes and not so rich in the desert and in fact a couple years ago a friend of mine in Paris G Curtis sent me an email showing that his analysis of the Cassini data indicating variations in the hydrogen concentration from with latitude because hydrogen is the thing that the bugs are going to change that nothing else can change as easily and so I wrote him back and said well this is obviously signs of life not really but it but that's the answer is if the hydrogen really is if the organisms are really eating hydrogen and you have more organisms at the pole and less of the equator that you're going to get a latitudinal variation in hydrogen as well as a consumption going down so hydrogen is the molecule to track and that we can detect actually at some level from the Cassini orbiter and that orbiter of course is still going around Saturn we're still getting more data from Titan the mission continues more data comes in and the analysis of the hydrogen is still being done so the story may still be written its term in terms of what's happening with the Hydra you didn't even mention anything about the possibility of hot core of the planet is that the bet tribute to increase the chance of life by having you know localized hot spots to accelerate processing yeah we we think that Titan probably has some activity subsurface and we base that on the fact that since there was no ocean how is it getting methane we speculate that it must be coming out through volcanoes so there must be some sort of source we haven't seen any we have no evidence of volcanoes but we believe that they're there just from this theoretical argument so we believe that there must be a subsurface ocean and heating and a core so we have we have theoretical evidence if you will is that even a contradiction in terms you have theoretical indications that there is active interior whether that's going to be important biologically I don't see a connection the surface is so rich in energy and organic sources coming down from the atmosphere that organisms would not need to use any geothermal sources for geothermal energy there might be something to do just like on earth most life depends on sunlight but there are organisms nonetheless that depend on geothermal processes that may be also the case on Titan we have no way of knowing though question here excuse me but um if there is light evenly spread up in a vertical axis in the atmosphere which would explain the evenly spread hydrogen could volcanoes spread oxygen needed to the things to the life and to get you know frozen eyes could have used some sort of super powerful antifreeze and then we just couldn't use our modern cars yeah the the there's two questions there one is could there could there be life in the atmosphere itself it's a good question and I we haven't thought of it before there's a lot of organic material on the atmosphere and there's a lot of energy sources in the atmosphere there's even liquid methane in the atmosphere just like there's liquid water and clouds on earth and people find life and clouds on earth so maybe there could be light and clouds on nothing so it's something it's an interesting idea and it's worth thinking about could the life be in the atmosphere as well in terms of how would that life get oxygen if they're not decomposing rock we know that there's a very small flux of oxygen coming in in terms of meteorites burning up in the upper atmosphere very low levels producing a co level for example of about a part per million the organisms could be very efficient at scavenging that if they live in the atmosphere in terms of the antifreeze question now that's a different question on earth we look at Titan we see it's very cold we need antifreeze but to an organism that grew up in minus 190 Kelvin they would need antifreeze they would say this is just fine right so they probably have not invented antifreeze they just learn to live in that temperature that is the temperature that is the temperature of their environment to make water liquid at that low temperature you could put an antifreeze in it like ammonia and then you could have water at very very low temperatures but we don't see any evidence of that on the surface of Titan the liquids we see are liquid methane not ammonia water cold alum Ronia water mixtures question here as you know mike is a very simple selves a very intricate metric a very intricate intricate mechanisms which require a vast amount of information stored in the genetic material what do you postulate as the molecule capable of storing this kind of information in the very simple hydrocarbon chemistry of Titan right that's a good question I don't think you can with just simple hydrocarbons which is why you need oxygen and nitrogen you need the full complexity of all four molecules CH and and O to make the kind of complexity required for information storage and translation and expression all those things so I think you get to see for free you get the H for free and you get the end for free on Titan but you have to work to get the O so I think life will have to have solved that problem because I think from an information theory point of view you're going to need all four molecules now you say okay well what if what molecule does it actually use I have no idea but at a broad sort of theoretical level I think you're going to need the degrees of freedom that come with having more than just hydrocarbons you're going to need nitrogen you need more than that there in the oxygen so I can make a general argument that you need the complexity that comes from that diversity of molecules I can't make I can't answer you in specific what is the equivalent of DNA question here hey so on earth certain organisms take in oxygen and turn that into co2 in other organisms think that co2 in back and oxygen setting themselves on if on tightening organisms are taking in co2 and just putting out methane in order for that to be sustained doesn't mean that other doesn't have to dig another thing bringing back an ID yeah yeah that's a good point on Titan the settling and hydrogen is made by the Sun so the equivalent of what plants do which is to take sunlight and make food Titan that's occurring without plants without life in the atmosphere and we know that's happening so food is being made in the atmosphere and raining onto the ground so all we need is someone who's willing to eat it on earth there is no food being made in the atmosphere one theory for the origin of life is that's how like started with free food but now the atmosphere is oxygen-rich and there's nothing being made in the atmosphere so plants are making the food and then heterotrophs are eating the plants so that's the cycle you referred to on titan phototrophs don't exist it's just being made in the atmosphere so the simple cycle we imagine as sunlight makes acetylene and hydrogen by the photodissociation of methane that's food it comes to the surface organisms eat it making methane which goes back up and then gets hit by sunlight so it's it's a free lunch it's a very cold free lunch but it's a free lunch alright the last question is here right yep since that Titan has a gravity that means I hat that this atmosphere could be could be contained and have an orbit well Titan has a gravity about the same as the moon's the moon as you know doesn't have an atmosphere none of the other objects in our solar system that are the size of the Moon have an atmosphere but Titan which is also roughly the size of the moon does have an atmosphere and it's even thicker than Earth's atmosphere that is a mystery solve it and let me know what the answer is we don't know there's one theory by a colleague whose office is just down the halls of mine so I must believe this theory that it's got to do with the effects of Jupiter vs Saturn and on Saturn the impacts were so strong that they destroyed the atmosphere or Jupiter but on Saturn they were weaker but the real answer is we don't know so it is a little bit of a puzzle why such a small moon has an atmosphere and why that atmosphere isn't lost to orbit around Saturn the way the stuff coming off in sallet Asst is lost to orbit around Saturn so it's a puzzle but it's a fact that it does have an atmosphere in a very thick one and to me that raises the possibility that small world's around other stars could also have an atmosphere so yeah just because we can't explain it doesn't mean it doesn't exist

Channel: SVAstronomyLectures

Views: 132,434

Rating: 4.8201756 out of 5

Keywords: Astronomy, space, solar system, Saturn, Titan, planetary exploration, planetary probes, Cassini, Huygens, Cassini mission, Huygens probe, moons, space exploration, planetary science, atmosphere, methane, radar astronomy, infrared astronomy, planets, Chris McKay

Id: bbkTJeHoOKY

Length: 83min 33sec (5013 seconds)

Published: Mon Feb 25 2013