Titan Unveiled - Ralph Lorenz (SETI Talks)

welcome along ladies and gentlemen to your weekly City seminar series today we're fortunate enough to be joined by Ralph Lorenz who just come across the country just for this talk so we should feel honored for that today he's going to talk to us about his favorite planetary body and Titan and Ralph started his education in the UK he did a Bachelor of engineering in aerospace at the University of Southampton then he did a PhD in Space Sciences at the University of Kent where he was involved in the design of the penet rahmatu for the Huygens mission which travelled with Cassini and I'm sure we're going to hear about today after he finished his ph.d Ralph moved across the Atlantic and started work at LPL at university of arizona and just recently in 2006 he's moved from Arizona to Maryland and he's working at Johns Hopkins University Applied Physics Laboratory now Ralph is a Ultimate Frisbee enthusiast and he's written a book on the subject as well as several others including a couple and Titan unveiling Titan and sorry lifting Titans veil and the type the topic of his talk today which is tightened unveiled so if you'll join me in welcoming ruff well thank you Adrienne and thank you all for coming it's always a pleasure to to talk about Titan and thanks also to NASA's outer planets colloquium series which helped with the logistics of getting me here today or is the challenge with a talk like this is to sort of you know give something for everyone I'm sure it's a very diverse audience I will try as usual to hit a little bit on what's involved in implementing missions to the outer solar system you know some of the experience of working on Cassini and Huygens I'll talk about some of the things that I think are really cool about Titan the dunes and the Seas being as we're here at SETI at the Carl Sagan Center I'll touch on astrobiology I've also had a couple of special requests one to address the prospects of cryovolcanism on Titan which is intimately connected with prospects for astrobiology and also to try and work in Australia somehow so I've got an hour to try and do that so hold on to your hats this incidentally is a beautiful picture of Titan in the background taken by Cassini about a couple of years ago this is one of the small moons Epimetheus maybe maybe it's Pandora this picture is taken looking across Titans rings with sorry Saturn's rings with Titan in the background Cassini is just providing endless supplies of great great pictures that are not just in the textbooks now but even in the sort of coffee-table literature if any of what I talked about proves to be interesting if you want to follow up there's my website is was on the first slide if you google me I'm easy to find Kristof so time myself had a article that at least was very well illustrated by others if not well written in Scientific American earlier this year that's that's fairly up to date as as was just mentioned there are a couple of books one of which has the the title of this tall in fact the paperback edition of Titan unveiled just came out just a few weeks ago and actually has a an updated chapter to sort of bring us up to up to speed from the 2008 edition I venture that actually the first book lifting Titans veil which was pre Cassini is still of interest and one reason I didn't sort of just do a new edition is you know a lot of what we thought we knew about Titan has turned out to be wrong often wrong for very interesting reasons but science of course is a process it's not an ultimate destination so just having that record of why we thought what we did I think is is interesting and instructive so getting on to the talk itself the the caveat I must offer is that this is just going to scratch the surface there was a time back when I got involved in Cassini and Titan circa 1990 where you could sort of read just about everything that was known about Titan you know in in the course of a few weeks there was a few few dozen papers and as always cross referencing some duplications but you could basically read everything that was was written that is no longer the case driven largely by the data from the Cassini mission but also still excellent stuff coming out of ground-based telescopes and theoretical and laboratory work the the tiny literature is now up it's sort of a hundred papers a year so it's just hard to just read it all let alone do any new original work of your own just to put Titan in context here's a Hubble Space Telescope picture of Titan next to its parent planet Titan is the second largest only just the second largest satellite in the solar system but it is of course completely unique among the satellites in that it has a thick atmosphere an atmosphere predominantly of nitrogen like our own and in fact rather thicker than our own it's more I think useful actually to compare Titan to the terrestrial planets than it is to compare it to other icy satellites in some ways mass wise and radius wise it's not too different from Ganymede or Callisto or even to some extent Europa but many of the processes that shape the surface and the atmosphere of course are much more relevant to the terrestrial planets than to other icy satellite Titan's atmosphere is it's thick and optically thick most of the sunlight gets absorbed high up which is what happens at Venus and both bodies are fairly slowly rotating in an inertial sense and that slow rotation and optical thickness gives a sort of super rotating zonal wind system which is more or less common to the two bodies Titans pole is inclined by about 26 degrees much like the earth and Mars and so Titan has seasons much like Earth and Mars and a volatile transport that are rather reminiscent of those bodies and Titan has a hydrological cycle in fact Titan is - the Earth's hydrological cycle what Venus is - the Earth's greenhouse effect it's you know a terrestrial process stressful phenomenon but taken to an extreme seems the rainfall on Titan on average is very low but when it happens it happens in very violent outbursts punctuated by long droughts which in a way is what you get if you take the terrestrial hydrological cycle and warm the atmosphere so that it sort of takes longer to charge up with moisture so there's a lot to be learned by these interplanetary comparisons and it tightens a really interesting object in that sort of parameter space Titan takes twenty nine and a half years to go around the Sun obviously it's going around Saturn it's actually tidally locked to Saturn so it always shows the same face to Saturn just as our moon does to the earth Christian Huygens who discovered Titan in 1655 also remarked that the seasons on Titan would be sort of long and tedious because of this this long year it's it's worth pointing out also that Saturn's orbit around the Sun is not quite circular it's appreciably elliptical so it's about ten percent closer near perihelion which is near southern summer solstice than at aphelion and so there's a substantial modulation in the amount of sunlight just because of that changing distance so that means that southern summer at least a present is shorter but more intense than the northern summer that's also true for Mars for the same reason that the orbit around the Sun isn't his in circular and actually also for the earth of the effect on the earth is quite small and this 29 year timescale is actually kind of kind of interesting visits sort of rather commensurate with with human careers you can you can map out your life on Titan I was I was born in 69 just before southern summer solstice I you know went to went to grammar school in the UK in England and got a degree went to work for the European Space Agency this is me with the the project team just when the Cassini project started in 1990 I got a PhD he got married came to the US then the Huygens mission actually happened out here this is during the the encounter this is at the European Space Operations Center in Darmstadt in Germany you can see this of chaos is that the data were coming in and just earlier this year there was a sort of fifth anniversary of the Huygens descent celebration this telescope is an observatory in Barcelona overlooking the city was actually the telescope that a Catalan astronomer in 1908 Hosea comme Isola observed the Titans disk it's barely perceptible it's just an arc second across about the smallest thing you can see clearly through a telescope he could tell that the edges of the disc were darkened and he inferred that to mean the Titan had an atmosphere so the whole story of Titan history almost everything we know about Titan except for its discovery in 1655 has taken place over only 3 Titan years so I urge you all to you know sort of make versions of this plot with your own own sort of holiday snaps but it is a very sort of human time scale note also it was his 15 years from when Cassini was was the Cassini project started in earnest money was really starting to be spent to when it actually happened 15 years so that's a timescale of which you know people have to remember how everything worked and the documentation has to be tracked there was for example reprogramming of some instruments that had to happen to to fix a problem that was identified during cruise and some of the compilers were no longer supported you know people had to be brought out of retirement to do the fixes this kind of knowledge retention issue is is a real challenge for outer solar system exploration it's really somewhat analogous to to a crusade to almost you sort of sign up for a large part of your life to this kind of endeavor okay so going back to northern spring equinox in 1980 that was when the sort of modern era really starts with Titan studies and the encounter of Voyager 1 and Carl Sagan was very active in studying Titan it that this this time and if you're applying true geologists this was a very disappointing encounter and actually Voyager 1 was targeted to fly close to to Titan at the expense of any subsequent encounters with Uranus or Neptune because Titan was known to have an atmosphere was known to be interesting was known to have organics and so that made it a astrobiological interest and what was found was not much on the surface because it turns out this thick atmosphere is laden with a sort of organic smog basically there's methane in the atmosphere that is broken down by sunlight and the molecular fragments recombine to form a whole host of other compounds a bunch of which were identified here in this Voyager infrared spectrum so there's hydrogen cyanide acetylene ethane ethylene deuterated methane HC 3n I always forgets a de Crillon I trial or Souter nitrogen anyway there's a there's dozens of organic compounds and really that that atmospheric photo chemistry was what focus Titan science at the time because the geologists didn't have anything to work with and really the dominant paradigm was was that one of methane in the atmosphere being broken down it forms ethane which is a liquid at Titan surface temperatures and some other other compounds as you saw and those would presumably accumulate on the surface this cycle is irreversible because the hydrogen this release escapes to space and doesn't doesn't sort of restore the cycle so it was thought that maybe there was a lot of methane at the beginning of Titans history and progressively that was converted into into FA and maybe there would be enough ethane actually to to completely cover Titan surface that would be a global global ocean of hydrocarbons we didn't know any better at the time so this is the the sort of perspective that shaped the formulation of the Cassini mission which was originally formulated in in Europe in its ultimate form but is actually formerly an endeavor of NASA ISA the European Space Agency which is how I got into this business and the Italian space agency was sure provided the the high gain antenna here I'm going to be discussing a fair amount of geology in the rest of this talk and just in the interest of full disclosure I have never actually taken a geology class of any sort I sort of picked up a bit as I went along my formal training is as an aerospace engineer as you as you heard but this is you know this is what makes planetary science and astrobiology so stimulating that it's the intersection of many different fields of endeavor and there if you just restrict yourself to a narrow set of disciplines you'll you'll really miss out because it's all interesting anyway this is casillas is about the size of a bus it's the largest or most massive interplanetary spacecraft launched in the West it's two and a half tonnes dry at launch it was had about four tons of fuel on it almost all which has been used it gets electrical power remember we're ten times further from the Sun than is the earth so it's very little sunlight it's electrical power from these radioisotope thermoelectric generators there's a set of cameras bolted to the side of the spacecraft actually when Cassini was originally proposed like the Voyager spacecraft it had scan platforms articulated structures so you could point the cameras in one direction and point the high-gain antenna to the earth in 1992 the NASA budget crunch as there often is at the time involving their the space station and it's probably only the fact that Cassini was an international mission and the sort of you know shame that would result from pulling out that prevented its cancellation but as part of the slimming down that had to take place to retain the mission the scan platforms were delete it which you know saves you money gets you under the bar in in fiscal year 1992 but actually pushes out a lot of extra operations costs into into the present day because now all the different scientists you know some of us for example working on the radar instrument that uses the high-gain antenna you know we want to point the high-gain antenna at Titan and the cameras are out pointing here so every time flyby has to be choreographed like a Jackie Chan movie you know you want to point the cameras here on this moment and then turn around to point the radar but you've got to turn in such a way that you don't point the the sensitive radiators of the thermal instrument at the Sun while you do the turn and all that has to be figured out in excruciating detail also hiding at the back here is the the Huygens probe which was the the principal European contribution Cassini is a model of international collaboration there are contributions from Europe on many of the instruments on the orbiter and there are contributions from the u.s. to the main instruments on the on the Huygens probe were from the US so there's there's you know sort of complete cross fertilization and there are in fact instruments that flew to Titan that probably are only err on there as a result of this sort of broader a solicitation of ideas it's it's been very stimulating to me different people work in different ways and come up with different ideas and and everyone is enriched as a result I like to show this picture of the Huygens probe not because I'm particularly fond of you know shiny gold thermal blanketing but just to underscore you know why why exploring space is difficult why it takes money and effort to do all this and the reason is that you might see a space probe here and a heat shield but you've also got a structure that holds it up because somebody had to figure out that this backshell is going to have to attach to the front shell and we have to hold it up in such a way that that'll work and then you have to have a facility this is ier Begay in Germany where the doors are big enough for this this dolly to go through you know there are dozens and dozens of boxes inside here or which have literally hundreds of electrical connections those all have to match up the software in the camera experiment has to talk to the software on the spacecraft and all those interfaces the software the human interfaces the the bolts the electrical wires all have to match up and so there's this enormous coordination effort that has to take place and that's that's why it's difficult I'll point out this was all done and course is no nothing new in a way but this was all done before the World Wide Web we were doing this with faxed documents there wasn't Adobe PDFs at the time Microsoft Word hadn't established global hegemony at that at that point we the official word processor in ether at the time was IBM's display right for and I started out as a you know a junior engineer in the ISA project team and you know there's a 50 page fax coming through with an update to an experiment interface document and you know it was yours truly that had to you know phone phone aérospatiale in can and say can you send pages 23 and 27 again because they got smudged you know that that was how this is all done things are in a way a lot easier maybe it just means we just have to work harder and faster but but is this coordination that is really the the challenge it's interesting that ISA has a way of working for days just Rhetor which makes makes pork barreling look like in some ways a little opaque but in some ways easy ISA has to allocate the contracts on its big projects in the same proportion that it seems receives budget from the Member States I mean if you're a project manager in ISA and you just want to get something billed and it's going to and want it billed sorry for work you know just get the Germans to do the whole thing you know you'll be fine but what actually happens is to make the whole system work and get you know politically everyone behind it you know you have to give kind of 25% to France and 20-some percent to Germany and 15 to to Britain and you have to make sure that Belgium gets its 3% and Finland gets its one and a half percent so you know the technical solutions have to be modulated with this whole political story so you know the parachutes on Huygens came from the UK the software was done in the UK the thermal design in the testing was done in Germany the heat shield is made from French ballistic missile technology the structure was built in Spain the radio altimeter came from Finland it all all comes together in a really kind of opaque kind of sausage-making way but but come together it all did and it took roughly five years without maybe a little bit more for that whole project to to get to the the launch site obviously the probe built in Europe had to be delivered to the u.s. to be mated with the rest of Cassini at JPL before you know the whole state stack was assembled at the launch pad in Florida and it actually launched a couple of weeks late but that was actually all to the good meanwhile Titan was starting to get more and more interesting in 1993 the Hubble Space Telescope was was repaired and that gave HST the capability to image Titan and by looking instead of at the sort of orange wavelengths that the Voyager observed at was able to look in the in the near-infrared where Titans haze is less thick and it's actually brighter so it's like looking through thin fog instead of looking through thick smoke and that that wrote that imaging time was only you know 18 pixels across revealed this sort of leading-edge bright area called the Xanadu and we actually knew there was a reading edge bright area just by looking through ground-based telescopes at different times over Titans two-week orbital period because it's tightly locked then over over one orbit period it rotates under the telescope if you like and we saw in some near-infrared wavelengths that the leading face of Titan was appreciably brighter than the trailing side this kind of light curve this plot of brightness versus time or longitude is probably about the best data we will get for some considerable period of time on extrasolar planets in many ways that the study of Titan is kind of a prototype for extrasolar planet studies so we knew that bits of Titan were brighter than others which immediately begs the question well if Titan is being covered by stuff drizzling down from the atmosphere why are some areas bright and some dark you know what's keeping the muck from covering everything uniformly that all almost immediately suggests some sort of ongoing process where there geological or meteorology cool or what okay so Cassini was launched even on the the largest launch vehicle in the u.s. inventory the Titan for that vehicle isn't large enough to hurl five and a half tonnes straight to Saturn we actually had to fly by Venus once and Venus again and then get an earth flyby and even a little little boost from Jupiter and and even then it takes seven years to get out to Saturn that time actually proved to be very important we did a test the Huygens probe which parachuted down would relay its data via the Cassini orbiter so the signal would come up from Huygens be received by Cassini stored on board and then cusine would turn around and then send the data down to the earth we did a test during the earth flyby with the Goldstone dish in Southern California it's pretending to be Huygens so he was sending a signal like Huygens and would use their receivers and stuff on Cassini to check that it's received okay and in fact it wasn't and you know that was obviously a bit of a surprise and the immediate question is well what did we do the test wrong no we didn't do the test wrong as a whole set of investigations and we found in fact a design flaw in the the radio receiver which was built in built in Europe and bolted onto on to Cassini but because we had this time because we had three or four years to to analyze the problem understand the problem and develop a workaround we're to fix it had we been going to Mars you know or the moon and got there in two days or a month it would have been much more of a challenge so there's you know some lessons there about testing and buying radios from you but but the problem was identified and solved meanwhile Titan continues to to change as I said it had seasons he may have noted on the Voyager picture one hemisphere of Titan was slightly darker than the other that's the difference in the amount of haze in the atmosphere actually some of the haze gets blown from one hemisphere to another and in fact that one of the best records this is is by a 21 inch telescope at at Lowell Observatory in Flagstaff Wes Lockwood is patiently just measured how bright is Titan at a couple of wavelengths over more than a titin year I mean he's been doing this since 1970 and it shows incidentally that the the cycle doesn't repeat Titan is apparently changing from one year to the next one of the contributors this brightness is the haze asymmetry that the one one-half of Titan being darker than the other in that that changes over the course of a year but there's also this dark structure over the winter pole that that seems to form as a result of that area of being in winter shadow and in many ways there's some phenomenological similarities with the earth ozone hole I mean the chemistry is completely different and the temperatures are different than the length of the year is different and so on but fundamentally you've got an area of stratospheric downwelling bringing on in Titans case organic rich air you know from where all this chemistry happens down into the lower atmosphere where it can condense where it wouldn't otherwise condense there are compounds that would normally be destroyed by ultraviolet light that can build up during the winter because it's in shadow and the whole area sort of isolated from the rest of the atmosphere by a sort of circumpolar vortex near the polar winds the same sort of thing happens on the earth you've got the circum Antarctic current and the polar vortex that isolates polar stratospheric clouds actually of nitric acid that form in the stratosphere and those cloud services active catalytic surfaces in the destruction of ozone so again chemistry is different but the physic is the same that's really a theme that recurs on on Titan so I better keep that keep moving here also during the early part of this this decade or last decade telescopes the large telescopes that were built in the late 90s like the Keck were able to start seeing cloud systems on Titan your clouds like we know them methane cloud billowing up like cumulus cumulonimbus clouds probably with rain and hail underneath them clouds they'll evolve on just timescales of a few hours and they're concentrated around the South Pole remember this is during southern midsummer so this is where the surface is being most strongly heated so these are very much like the sort of summer afternoon clouds you get in the desert Southwest as Cassini has been there the cloud patterns have changed in fact we're starting to see more and more clouds in the North that's probably a trend that will continue as we move into northern summer so watch this space then Cassini arrived at Titan and has told us a enormous amount of things one of the big surprises was just how rich the the photochemistry was this is a mass spectrum taken by Cassini as it flew through the upper reaches of the atmosphere this is at an altitude of a thousand kilometers and if you did this experiment on the earth that'd be like three or four little Peaks you know oxygen and nitrogen atomic forms maybe some n o or something like that but there's literally dozens of compounds here it was a surprise that things even as high as benzene and toluene mass is seventy-two and higher up the instrument only went to a hundred so the chemistry is very very rich even well above the surface both iron chemistry and neutral chemistry for that matter and in fact there's some less direct ways of measuring that there are compounds with atomic mass of thousands literally thousands forming up there so it's a very rich chemical factory but from an astro biological point of view even though there's all these organics and compounds including nitrogen in them so nitriles and others there's very little oxygen in Titan's atmosphere because it's so cold the vapor pressure of oxygen bearing molecules is very low there's a few parts per billion I think of water vapor there's some Co it is a few parts per million or billion of co2 but they're really traces you know much as say CFCs are traces in the Earth's atmosphere and biological molecules have oxygen in them sugars and amino acids all have oxygen so that that synthesis can't go all the way to you know living things or whatever in the atmosphere alone but that's not where the story may stop and in fact Carl Sagan back in 1990 was really the first to point this this out that while you can have this photochemistry that gives you what of course what he called tollens after the Greek word for mud oligomers and polymers of hydrogen carbon and nitrogen that stuff will accumulate on the surface and if it gets exposed to water liquid water then a laboratory experiments have done among us elsewhere at Ames show you very quickly synthesize things like amino acids and Karima Dean's which Okonedo kind of one of the bases that encodes information in DNA you form this stuff in hours but geological structures where you might have liquid water as for example from a cryovolcano or from an impact melt sheet those structures will last for thousands or tens of thousands of years and that's not an experiment you can really do in the lab least not with current NASA funding cycles so we don't know how far down the chain of complexity that ultimately leads towards living things this kind of chemistry has occurred on Titan there may be functional systems like Auto catalysis information storage duplication that can happen in this sort of environment before it freezes that they may occur deep in Titans interior which we think is liquid but we just don't know until we kind of sample this material directly there's even the prospect admittedly a distant one that this kind of chemistry might be able to occur in a non-polar solvent and Titan has these lakes and seas of they could hydrocarbons but that recognized as speculative but you know one can never say never so this is the framework for a lot of the astrobiological interest on tiny juice you know just how far down the chain of complexity has the chemistry gone there and that's prompted a lot of debate in particularly because of this notion that if liquid water is erupting from Titans interior has a cryogenic equivalent of a volcano then there's all this interesting prebiotic synthesis that makes tightener a very interesting place to visit and there was a in the last few years there was a sort of choice NASA had to make between going to Europa first versus going to Titan first and I think this this debates about cryovolcanism figured into that this is a Cassini near-infrared map showing Titans surface there are dark areas which I'll come back to in bright areas and there are some areas that are distinct in composition this the red color in this part is at five microns there's a couple of particularly bright five micron areas and these when you look at them more closely seem to have them the evidence isn't great the resolution is not not not what we'd like they seem to have kind of you know low beta flows which are often associated with volcanic processes and that's been suggested as evidence for volcanism on tight so just the areas where this interesting prebiotic synthesis might take place there have been some Europa people if I can characterize them that way that have contended that the evidence for this is not great and they're of their right the evidence so far has not been terribly persuasive but the debates going on more data is coming in and negatives are very hard to maintain in the face of more and more data this is a radar image this is about 100 kilometers across of that red bright region hotel hotel Reggio and these sort of again lobate morphologies are very similar to those that are seen in radar in ages of volcanic volcanic flows on the earth so this is certainly a possibility it's been argued and I think Jeff Moore gave a talk here some months ago arguing that you can get lobate morphologies from landslides for example maybe flooville deposits and that's that that's true that needs to be looked at I think there needs to be a more systematic maybe quantitative evaluation of morphology because morphology is always one of these squirrely kind of disciplines where some people could say oh it looks like a frog and other people say no it looks like a whale and you know you kind of concretely argue it this area had been claimed to show photometric variability it was like brighter at some times than others and it been suggested that maybe this was some sort of the eruptive process that data has been disputed by members of the same team actually so I'm not sure that that evidence is terribly strong there is more and more topography data coming out of Cassini from principally the radar instrument both stereo and another technique showing that some of the structures advocated to be cryovolcanoes or maybe not as persuasive as they once were but there are others maybe that are looking quite compelling so you know stay tuned the debate is still ongoing as it should be that's what science is all about the the paradigm has been articulated that you know quite Titan doesn't have cryovolcanism it doesn't have tectonics it's dead there is I think relatively undisputed evidence of tectonic deformations now there's these mountain sets that seem to it seem to appear in sort of ridges of sets of three for some reason but they've looked very much like like tilted blocks many of these areas and on that leading edge bright areas an I do have a sort of rectilinear pattern and in fact there's River channels in them that similarly have a rectilinear pattern that suggests a tectonic control many of the mountains appear in these sort of belts in this sort of chevron pattern near Titans equator getting straight lines getting Chevron patterns might indicative of of tectonics I don't know how else to make mountains this way so you know again it's an ongoing debate but there's more and more data coming in so just to summarize this debate since it was was sought specifically I don't think there's unclad evidence of present-day volcanism there's this photometric variability is not a strong constraint there have been suggestions that some of titans clouds seem to appear in some places more than others and in fact meteor logically the atmosphere is is rather dry to expect clouds in the low latitudes so maybe there's some sort of methane venting the presence of argon-40 the radiogenic isotopes of argon in Titan's atmosphere does require that there's been this stuff was you know been brought to Titan's atmosphere from the interior because it's released from potassium which is in Titans interior and there's no reason Titan shouldn't have cryovolcanism you know if you just express the 10% of the geothermal heat flow we'd expect as the latent heat of of water magma you get many cubic kilometers per year it's perfectly viable and in fact the ammonia that may act as a sort of antifreeze in Titans interior makes cryo Magma's more buoyant than they would be with pure water and this this doesn't is it's irrelevant how thick the ice is above for this process above this this layer there are ways of getting liquids to the surface the morphological evidence is not evidently persuasive and it's not completely persuasive on an individual basis but there are enough different places on Titan that you know look like they could be that it's hard to argue that none of them are and what I find is a particularly compelling issue is the the spatial coincidence the fact that areas where we see in different datasets stuff that looks like flows are the same areas that have a distinct composition that Palmer suggests to me that something has come out from the inside is not just eroded down from the hills but whether that's cry of lava in this sort of sense people think of as water rapping from the interior is another story and Jeff Cargill has advocated you know keeping an open mind on all the different organics that could be in arthur c clarke s-- 1970s science fiction novel set on titan which I particularly like because it had Scots as the protagonist he was actually inspired by the latest information from Carl Sagan but he about Titan not what he talks about waxworms this kind of exotic land form that that sort of you know as stuff hosing out from the interior and then congealing in Titan's surface maybe we need to think about something like that and as a sort of cautionary example and I repeat I'm not a geologist I like this is this a lava flow or is it a flooville feature or a landslide feature I mean so it'll look slow bait to me when you show of hands for lava two three four not may show of hands for fluval one two three okay anything ever well it's if you speak Farsi then you'll know this means mountain of salt this is actually a salt glacier this area is saying southern Iran it's heavily Texan eyes there's a huge layer of salt formed but in the teeth of sea when it evaporated you know hundreds of millions of years ago the souls is being squeezed tectonic lee and actually hoses out of the ground and flows like a glacier it doesn't flow very fast salt is kind of a rock but it's actually a very soft rock so it does flow but you know if we were doing if this were on Titan and we were classifying it we might say it's a lava flow but it's not a lava flow so is there something like that on Titan that is fooling us don't know I think we need to keep an open mind okay I need to press on Huygens was released on Christmas Eve actually 2004 we actually on Cassini felt the reaction as the springs pushed Huygens away on some spiral rails through that spin state stabilization we could see that the reaction here we actually caught pictures of it as it sailed off in the distance this is from 52 kilometers away but a day after release really amazing picture I'll point out that a year before this a picture like that but actually rather better picture was the last that was ever seen of the Beagle 2 spacecraft so you know people were nervous but Huygens entered it was his largely successful barring another radio problem there was an interesting anomaly with the parachute descent in that there are these little wheel it's on the side of the probe that were supposed to spin the probe in a known way during the descent to pan the camera around the cameras looking down and out was the sight and in fact we think we understand why now but it turned out it spun the wrong way which meant the camera data took a lot longer to analyze I mean the data is still acquired fine but it took longer to analyze than it would have done but just to make the commercial break that that story is discussed in my book spinning flight and it's not another book on space distance failures more generally all available at your favorite online or real world bookstore anyway the Huygens probe landed we have no right to get this picture we have no right to expect to get this picture the Huygens probe was designed when we didn't know anything about the surface of Titan we didn't know if we're going to land another global ocean of liquid hydrocarbons we didn't ever going to land on a solid sheet of ice or a big pile of fufu dust that we just float through what didn't know we made sure the probe would have enough battery energy to last for three minutes after the longest possible descent we made sure the communication link would be open we made sure it would be warm enough as it turns out it landed on this outwash plain I mean these are rounded cobbles that have been tumbled in a methane stream and this picture is taken from about knee-high just that perspective it could have been that the the parachute would have fallen on the camera didn't happen happily we got this picture actually got like a hundred of this these pictures in one of those pictures there's kind of a blob in one corner that Kokoschka is modeled as a methane dew drop basically dripping off the camera baffle so that the surface was warmed a little bit by by the probe and in fact that heated Inlet of gas analyzer that term was on the bottom of the probe in that that heated Inlet volatilized some of the surface material and showed what might be benzene co2 ethane the ground was in fact seems to have been actually slightly damp and that's where my favorite 14 grams of the two hundred kilogram Huygens probe comes in as a graduate student in the UK I got to specify design build and test this thing called a penetrator is literally the size of my finger 14 millimeters in diameter it's a disk of a piezo electric ceramic so this material that generates a charge when it's squeezed so just like you know igniter for a gas fire squeeze it makes a charge so this thing sticking out to the bottom of the probe and you know if the probe is landing in sort of nearly vertical orientation this thing gets rammed into the ground and records a force profile and that that's what happened and during my PhD I tried it in dry sand and dry sand has this nice convex profile at you know when you when you squeeze dry sand the the grain sort of lock up so you get this increasing resistance with depth very characteristic of that kind of material wet clay deforms as a sort of plastic has a constant resistance and gravels have a spiky signature with the size and spacing of the spikes relating to the particle size all made sense to me then we've got the data from Titan and it looks like none of these which is great that's that's the way science is supposed to work and you know we have to make sense of this you know in this crowded room at about you know 9:00 p.m. on a Friday evening with the media watching closely I mean there were about 80 scientists from the Huygens teams at Darmstadt and about 200 journalists it was literally a siege mentality anyway we had to have get results for a versus 11:00 p.m. press briefing something crazy like that and we hadn't seen the pictures at this point right we were just interpreting little squiggles we had from our instrument and so he thought well okay this this is yeah I spent about three years designing and building this as a graduate student then it went in a closet got bolted onto the spacecraft got broke by a technician it's actually the flight spare that went to Titan so seven years later you know a billion miles from Earth 200 degrees Celsius below zero it worked for the one twentieth of a second that it was supposed to work so I was very pleased because you know my bid hadn't croaked so this bump actually is the back end of the mounting stalk hitting the ground so he can sort of dismiss that then it looks kind of flat a bit like the wet clay right and this this resistance is actually fairly weak so you could get something like you know packed snow or wet clay would have that sort of resistance maybe wet sand and then there was this spike at the beginning what was that spike could have been a like a spark jumped from Titan surface just when the probe arrived or was there a crust on top we thought that kind of wet clay with a crust kind of like creme brulee we sort of put that on the view graphing our our boss Sir John Czarnecki the principal investigator of the experiment actually yes you used that in the or hesitantly used it in their press conference the media loved that food analogies go really go really well apparently had the headline in nature magazine was Titan team gets his just desserts from creme brulee surface though we actually don't think now that it was creme brulee after all that actually the instrument may have hit one of these cobbles and that that's what gave the spike but anyway I was all all jolly good fun at the bottom is the the moment of impact at eight six nine point seven five nine eight seconds that was actually a very important number within our team because we had a sweepstake running on the duration of descent there was actually something like a 15-minute plus minus fifteen minute uncertainty and how long the descent would take because you never know quite the drag coefficient of the parachute we had uncertainties about the atmosphere we don't know the topography of Titan will be land in the valley would be land at the top of a mountain so there's a half an hour of uncertainty and we were actually right at the edge of that uncertainty band but john Czarnecki the the pie of the surface science package actually won the sweepstakes which was this bottle of like a ruling single malt you can see in the foreground I guess that's why they put him in charge so one thing that wasn't noted I mean everyone really focused on the the flu fuel channels in the foreground here in this mosaic the Huygens probe landed about here this bright triangle is about seven kilometers across and there are all these nice river channels that showed immediately Titan shaped by hydrologic processes off in the background there's these dark stripes and we didn't pay much attention to those at first when the area was observed by by radar not too long thereafter summer 2005 we got the sense of what those really were they this is a radar image about two hundred kilometers across and these are sand dunes not made of sand sand but made of something else and they're huge I mean they're tens to hundreds of kilometers long there are about a kilometer wide now that shows that in some cases they're about 150 meters high and they more less cover the equatorial regions morphologically and i didn't recognize this at the time they are very like these linear sand dunes seen in the Namib sand sea and there's a nice quote by hashed naught I was grave here as he saw them from the Space Shuttle this is actually a handheld digital camera picture out of the window of the Space Shuttle but these are about the biggest dunes on the earth but their same size same morphology and and really compelling analogues for for Titan it's a kind of June that actually forms in a wind regime that flips between two dominant directions which is unusually in the Americas which is why we don't don't have many of that kind of June here I'll go into that there is there are some nice analogues i'll see if anyone can guess where this is but looked at from from the air out of the airplane window there's some hills here and you can see the dunes sort of diverting around i mean this kind of linear dune that forms in this by directional wind regime the dunes sort of line up along the the sort of vector mean wind direction and it's interesting to see how sort of deviate around or break through these topographic obstacles so if you haven't figured out where they are maybe this picture will tell you this is Jamie radabaugh collaborator who works with me a lot on on these dunes you might be able to see some animal tracks here set of you know two prints with a sort of tail dragging between I see the Velociraptor or a kangaroo the these are dunes in the Simpson Desert about 50 kilometres south west of Alice Springs in Australia but you know as I say understanding how these dunes interact with the topographic obstacles is really helping us understand what we're seeing when we look at Tyson because we see this same sort of process this bright area here is elevated we think and the dunes are sort of deviating around it and when we do that analysis and Jani is mapped out something like 16,000 individual dunes and they cover all the dark areas around Titans equator and you can see them going around this crater ejecta blanket here they all point in this direction it'll go from west to east and that's interesting because all the modelers who build numerical models of titans winds say the wind should go the exact opposite direction and that's the great great you know tragedy of science and you know beautiful theory destroyed by an ugly fact but it's saying that this you know saying there's something in the models something needs to be in the models perhaps that is on Titan you know Titan is telling us something here and in fact this debate may have just been resolved actually there's a commentary piece published just last week in science magazine reporting on the work of Tetsu Takano very prolific modeler in Germany who indeed finds as everyone else has found that the low latitude low altitude winds should be predominantly from east to west I opposite to where the dunes go but for a brief period during spring equinox or fall equinoxes that matter there's more mixing as the Intertropical Convergence zone crosses the equator and the winds there actually for a brief period exceed the sort of average winds blowing in the other way so if the sand you know only responds to of say more than a meter a second then it's only going to see those eastwood wins during that brief period so it's only by looking at the statistics of the wins and the you know rare but stronger winds that blow towards the east that you can explain what we see so that's that's been reassuring because that was kind of a big puzzle for a while moving away from the equator into the poles are really the the most fun part of Titan and only the lakes this is again radar image about 200 kilometers across we see lakes of all such shapes and sizes these kind seems to be seated in pits several hundred meters deep a few tens of kilometers across often kind of more or less equipped more less sort of circular in platform without irregular they look a lot like dissolution features you know where the liquid is etched into the surface we should be kind of hard to understand what we know about the solubility of of ice is in liquid hydrocarbons there are other areas where they're in fact much larger seas this one Ligeia moiré is several hundred kilometers across that looked like what are called real coastlines where the liquid level is risen and sort of flooded valleys so it may be that there's you know change in the the amount or the distribution of liquid on the surface and once reminded here of Lake Mead which has the same sort of irregular outline because the liquid level has risen because we've built a dam there and I'm not a geologist but I occasionally play one on TV this is from a film shoot for a Discovery Channel thing last year missing me and a helicopter over Lake Mead you can see in fact that the door is opening through Apocalypse Now style I think this stripe is something to do with the the way the readout of the camera works with the chopping of the sunlight by the rotor blades but I'm sort of gesticulating about how cool Lake Mead is and how much it looks like Titan specifically the irregular flooded coastline which suggests that you know geologically the liquid level is risen but you can also see this sort of you know bar staggering this white layer where in recently the liquid level is dropped because of the drought and actually that same thing has been seen elsewhere on titan there's a lake in titan southern hemisphere called Marcus Ontario which seems to have a sort of bathtub ring as well suggesting it may have dried out more recently we've observed that with with radar and work by alex hayes and others has found first that the you know the there's an ultimate ultimate reproof i'll across the lake that shows indeed the lake is flat as we expect and the margins are very shallow the slopes here are very very gentle in fact rather similar to the slopes we see it at morphologically similar feature on earth this is racetrack tire in there Valley National Park and in fact the the margins of Ontario seem to have shrunk sorry this is about 200 kilometers across so it's about 50 times bigger than race track but you can see the shape is rather similar perhaps for similar reasons there's things that look like there might be sort of deltaic deposits here they connect to two river channels but the shoreline seems to have receded actually in the two or three years the Cassini has been observing suggesting that Ontario may be drying out and Alex phases as Matt there's a shoreline recession and the fact that the edge of the lake doesn't doesn't get totally radar dark just at the edge but it kind of fades off and if you look at the fading it's exponential as you might expect if the you know if the slope and the texture of the lake bed were the same you know on the dry side as on the wet side and you're just looking through an ever-increasing column of liquid and you can go to Gaz de France's one of our collaborators did and pour out some liquefied petroleum gas which is you know chemically the same as what's in this lake liquid ethane and methane and measure its microwave that absorptivity and the story hangs together and it looks like Ontario Marcus has dried out by about a meter or two a year over the last few years so it's a dynamic place just out of interest you can see racetrack fire off in the distance took this picture from the aeroplane yesterday our racetrack is is very flat but and for 350 plus days a year is bone-dry but occasionally it does flood and is the whole story of the moving rocks I won't go into but it is dead flatly can act as a perfect mirror as you see here even though it's outdoors and in fact wood will dry out in the course of just a few days so it's a very dynamic environment Ontario on titan seems to be dynamic similarly but it's you know on titan and things are a little bit slower but it's a good model and this is really a theme i want to reinforce is that we can really learn a lot about what we're seeing on titan by looking at places on the earth it's not only educational it's also kind of fun one of the big surprises actually with titan is that the distribution of lakes and the north polar regions in the south is quite different there's all these large sees like ligea and kraken in the north and it's just one very shallow and drying out Lake Ontario in the south and you know we don't think that's a seasonal effect because there's just so much liquid in here I'm in bed at about a hundred times all the liquefied natural gas and and oil that we have on the earth we think is found in these northern lakes there's no way you can perform a seasonal transport of all that volume of stuff on titan if we understand the meteorology correct means just basic energetics is not enough sunlight to do it but maybe there's something happening longer-term and when is reminded here of the difference between the North and South Poles of Mars which have very different polar caps both in extent and composition and that's forced by the in part by topography and in part by the seasonal asymmetry that the southern summer is shorter but more intense than in the north and Oded Aronson at Caltech has pointed out that this arrangement of the seasons on Titan would change over astronomical timescales just as the changing orbit of the earth gives us the Milankovitch or Crowell Milankovitch cycles that force the ice ages and similar cycles occur on Mars so on Titan the polar insulation varies on timescales of tens of thousands of years and that is enough perhaps to transport the liquids are out so we're seeing this very terrestrial kind of phenomenon one puzzle an outstanding puzzle about the lakes is so far they seem to be dead flat this is a plot actually by Lauren why who's here today from Stanford the this is a histogram of the amplitude of echoes from down-looking altimeter pulses and over land surfaces where you've got lots of different facets on lots of different places you get basically a Gaussian distribution because you're kind of randomly adding lots of little echoes together but the lakes don't look like that they have this very odd sort of saddle-shaped distribution basically you know if you're on a swing you spend more times at the end so it is with sampling that the little sinusoidal chirp from the altimeter and that's basically showing that the the lake surface is acting like a like a point source or even a perfect mirror of the the radio it's like putting this laser altimeter at the ground this shows that the lakes are Ontario at least on this day was dead flat and in fact Lauren put a an upper limit of three millimeters on the the surface roughness so that that observation isn't unique in the sense that last year there was an observation in the near infrared by the VINs instrument of the Sun glinting off the surface of what's actually gin pole arcus mirror lake near kraken so the northern hemisphere lakes at least on this one occasion are also dead smooth and that's a bit of a puzzle I did some experiments across the street at Ames a few years ago in this Mars wind tunnel which is this extraordinary building basically it's this you know huge former rocket testing facility where you can close the big door and pump all the air out and it's quite absurd but there's little wind tunnel in it which is used for our studies of Martian sand dunes and things like that and we put a tray of water in there and pump the air out and random winds at different speeds just to see how easy is it to make waves in thin atmosphere because it's believed that Mars once had sees these transient seas so why aren't there more wave-cut beaches wave generations has been throughout history and an empirical science the mathematics is very very challenging so the easiest thing to do is set up some buoys and measure the wind speed and measure how big the waves are get a big cloud of points and put a line through well that doesn't work if you're trying to predict what the wind speeds need to be on Titan for making waves because the gravity is different that liquid is different the air is different so you've got to somehow you know generate a more fundamental understanding of this very important process so we made some waves at different speeds in this train you know we've colored the water blue just to make it nice and easy to spot this is Aaron Crale who is a geology graduate student at UC Santa Cruz who helped me with this and in an idle moment we we also went and got some kerosene to kind of simulate Titan stuff and we found that for a given wind speed you get bigger waves in kerosene than you're doing water not an experiment anyone had bothered to do it to this point now the viscosity of kerosene is different from water the density is different and the surface tension is different so which of those factors matters most we don't know yet but you know notionally hydrocarbons look like they should be easier to make waves in so why don't we see waves on Titan yet well one possibility is that the stuff precipitating out of the atmosphere isn't pure ethane and isn't pure methane but there's propane and hydrogen cyanide and these things are all more viscous when dissolved in hydrocarbons so maybe the lake is kind of tari maybe that's why we're not seeing ways and there's this nice art exhibit in in London which is actually made with steel and used sump oil but you can see you can make it very good mirror out of tar or oil maybe maybe Titans legs like that the other possibility is that we just haven't been looking on windy days this is a plot of titans year 0 to 360 it's a standard measure of seasonal change Cassini's observations have been since it arrives in 2000 I've been out here and out here during which time this model by a Chicano shows that the winds at least near here that like year have been quite gentle probably less than the threshold required to make waves but in the next few years the winds will pick up and maybe we'll see waves in action that brings me to mention a proposal I've been busy working on with with others for a future mission to Titan a discovery mission to parachute a probe with a nuclear power source into my gmrs where it would float would analyze the composition of the liquid measure the waves measure the winds image the shoreline perhaps because now we know where the where the liquids are you know Huygens probe was was designed with this sort of scenario in mind but you know landed them at equatorial deserts could be you didn't know they were equatorial deserts at the time of course this isn't the only thing one can imagine doing airplanes have been proposed for Titan Rovers helicopters Landers even hovercraft in particular hot-air balloons in Titans thick cold atmosphere hot-air balloons work very well all but there's almost no vehicle that one can't imagine viably working on titan it's a wonderful place to to explore as a lot of possibilities you know who knows what will happen in Europe with NASA with regard to future programs as I say there's proposals in work for some some of these are probably ideas that are still you know a couple of decades away but whatever happens Cassini is still orbiting Saturn is still flying by Titan every few weeks there were 44 Titan flybys in the four-year nominal mission Cassini held up well its fuel supplies the last thing that way there's a radioisotope power of course continues to work so we had a a two-year extended mission with another 20-some flybys and NASA has approved pending you know continuing good results and performance to the spacecraft an extended mission the Solstice mission through to the summer solstice so we'll really see the seasonal change happening in the north as the Sun illuminates more and more of these large seas so another what is it 50 some Titan flybys over seven years there's a lot to look forward to and more flybys of Enceladus and pictures of the Rings and everything else so there's a lot to look forward to let me close with remark that you know some people have argued on the use of the words earth like to describe Titan and whatever there's differences of argued there are similarities there are enough similarities that at least for me it's been very useful to study the earth to see to try and understand what's going on at Titan so from a utilitarian perspective there's a lot of interesting analogies so let me stop there and take questions Thank You ruff could I get the first question in the Xanadu x' brighter albedo and the gyro for red yeah that's a long and disappointing story one of the challenges of trying to understand composition on Titan is that because of the thick atmosphere that's laden with methane methane absorbs light in in broad bands so there's only little bits of the spectrum that are accessible and the spectrum in those windows is at least open to enough interpretations that there hasn't really been a unique determination of what that is that might be generic to spectroscopy as a whole regardless to as to whether there's only obviously the spectrum available that you can't comment on that we do know that the material is bright at several wavelengths there's also radar data that suggests that Xanadu depolarizes radar echoes so it has some sort of funny texture to it we know on a macroscopic scale it's rough it's very mountainous and rugged it turns out it's not actually elevated which is what everyone thought before Cassini arrived but the radar topography shows that actually the whole area is actually somewhat depressed the mountains may poke up above the base there excuse me a base level so something has been going on there but we don't know what it what it is it doesn't appear to be pure water ice that much I think is is agreed upon there is a spectral signature that has been attributed to water ice in areas near the bright areas like Xanadu that suggests that maybe where you have fluvial erosion transporting material that somehow cleans some stuff off and exposes some water ice and that may be the strongest water I signature is actually in a crater ejecta blanket so yeah we're confronting very much kind of Martian issues of you know what's the dust or whatever crud that's covering everything and you know what's what's beneath but of course the amount of days we have is is very much less so I'm afraid I don't have a good answer for you probably organic but we don't know I will thanks for a great talk there was a commotion that I know you're familiar with a couple of months ago maybe it's a little bit more than that when a couple of papers were over interpreted by the media as indicating that maybe life had been discovered on Titan could you tell us what those two papers actually were about and how you're interpreting the results right it's like like dinosaurs and astronomy right there's this a couple of things that everyone wants to be the one to discover or predict which news volcanism or life in this case the debate which I think even was prompted by a press release rather than an actual new scientific work in the spirit of organic processes in exotic media Chris McKay here at Ames had published a paper some maybe 2005 several years ago just pointing out that a settling on Titan is potentially a viable energy source and if it were being used by a biological system or some other chemical process then that would lead I think to a depletion of hydrogen molecular hydrogen there had been an analysis of the measurements by the Huygens probe of molecular hydrogen in the atmosphere and I think when people have tried to fit there those measurements with models one you know little fudge you put in the computer program to make the data go through the curve go through the points was if you have a sink at the surface so you know somebody put two and two together and so on to think of the surface this paper says well if there's life it would use up hydrogen there for life on Titan so I think that's kind of the thought process if you look at each of the steps in in that you run into some big questions like well how good really are those hydrogen measurements how significant is the insertion of a sink term to make the fit better and well okay if you have hydrogen an acetylene how viable it is it really to have some sort of chemical process that uses about to your energy so that's that's the background storm in a teacup I really don't think we have the you know extraordinary evidence that Carl Sagan would require for an extraordinary claim what is the temperature and pressure or nominal ated temperatures and pressures on them on the surface you know I really should have stuffed it out where that shouldn't die I do apologize the surface pressure at sea level and we can actually use that word is one and a half bar one point four nine seven bar and get the Huygens landing site the Huygens the temperature of the atmosphere that wavings landing site was ninety three point six Kelvin we are pretty sure that the polls are about to Kelvin 3 Kelvin cooler than that maybe during the peak of summer they get a cup of Kelvin warmer than that the gravity on Titan is about the same as the Earth's moon one seventh of the earth or 1.3 meters per second squared so to get that one and a half bar which is just after although the weight of the column of air you actually have to have ten times that column so Titan's atmosphere is very very broadly extended into space I mean the Huygens probe throughout its parachute at an altitude of about 160 kilometers yeah which on earth is kind of you know in orbit the the density of the air at sea level and the air is 95% nitrogen and about 5% methane the methane humidity may vary a little bit much as more to humidity varies on the earth but the density of that that air because the low temperature is about four times that on earth so it's a very easy place to fly in any means and observing once calculated that you know human being could strap wings onto their arms and can flap and take off that that wouldn't be very clever the thing to do would be have a sort of you know bicycle kind of thing like a yeah gossamer albatross or whatever but heavier than air aviation works very well and actually there's a proposal that NASA Ames here is involved in fora for a Titan airplane in the upcoming discovery round as I say because the atmosphere is very cold a hot air balloon actually works very well and one reason that's been advocated is that you could use the waste heat from the radioisotope generator that you need to take anyway to have electrical power but the waste heat is enough to keep that thing warm of course there's just like many of these other sort of empirical things I've talked about on Titan hot-air ballooning has a long enough history that it's very empirical you know people just know because they do what everyone else has done for 50 years that you know two tanks of propane is about good for an hour but you know the actual fundamental calculation of how much mass can you carry in a hot air balloon of a given size with a given amount of heat you know there's no formula for that I had to work one out a couple of years ago because we are doing this mission studies but it's really fun and it's very much a recurring theme in Titan studies is is to be confronting these sort of empirical things and have to look at them anew and understand them in a more fundamental level you have both wind wave generation and hot air balloons and all these other things it's a really really kind of fun amusement pocket of science but just one one comment if anyone's looking for life there at ninety K the reactions are gonna be pretty slow and it's hard to imagine that metabolic absolutely and that's that's why these transient environments like cryovolcanoes are of particular interest I mean you would if you were doing the same sort of study on the earth you would say oh well the Earth's surface is too cold for molten rock and it is usually but that doesn't mean you can't form minerals you know hydrothermal that you can't get big thick bands of nickel like in the Sudbury impact structure in Canada so you're right Titan surface is too cold for metabolic processes of any sort to to take place quickly whether the rare environments I have to a near Titan surface that can allow things to happen very slowly you know that still needs some laboratory work that probably is going to be really challenging but but you're right one of the reasons Titan is interesting from this sort of prebiotic synthesis you is that unlike the earth not everything has been digested and modified this this prebiotic synthesis there's been frozen and the stuff is sitting there for us to to analyze yeah I think Titan is very much more a body where we can understand origins of life processes than it is a place where we are likely to find extend life do we know the thermal gradient as we go down the subsurface of Titan we can only estimate it and you know we we know how massive Titan is and so we know we think we know you know that is roughly half rock and a half ice and from the amount of rock you know if zooming its chondritic rock like like meteorites then we know how much radiogenic heat is being output it's probably not much tidal heating maybe about as much as there is radiogenic so that all amounts to five or ten milli watts per square meter of geothermal heat flow on the earth it's what 80 megawatts per square meter so if you know you take solid ice is the material then that means there's a subsurface gradient of about one Kelvin per kilometer but really I don't think that's a great number to work with in the sense that Titan is just as complicated as the earth I mean you can have there may be areas like the dunes where you've got dry sediments which are with that which have a low conductivity and the gradient will be higher but near the lakes there's probably hydrothermal circulation underneath and the gradients will be much lower so you know pick a number one at the back does Titan have any kind of a magnetic field a great question we we know it doesn't have a big one in fact the Voyager was able to place an upper limit on on an intrinsic field that isn't to say it doesn't have a you know an iron course or Missoni has a rock rock corn is partially differentiated the gravity information maybe suggests it hasn't completely differentiated of interest in this connection is induced fields which are what have told us for example that Europa has a liquid water layer as the applied field from the parent planet varies you get an induced field you know you get any currents induced in a conductive medium like a liquid water interior on on Titan that it's been very challenging to detect those induced fields for a couple of reasons one Saturn's magnetic field isn't strongly inclined as Jupiter's so that modulation is much weaker and second Titans got this thick atmosphere which has an ionosphere so there are currents flowing around in the ionosphere that you have to sort of subtract out to look for any induced signal now Cassini actually just just a few weeks ago made a special deeper than ever dip into Titan's atmosphere during a flyby flew past at 880 kilometers instead of the usual thousand to get beneath the peak in the ionosphere you know it probably looks a bit grimy after that encounter but you know there was a lot an awful lot of analysis went into making sure it would be would be safe I don't know if they if that encounter is revealed in an indication of an induced field or not but that's that's what we look for ideally on a future mission you know you'd have an orbiter to measure the applied field and a lander to measure the induced field you know can separate out the variables but it's quite a challenge with with Cassini but we know there's not a large you know residual or dynamo field we don't have any further questions Ralph we have a special City for welcome of course thank you for yeah well guide you through your future study sometime all right

Channel: SETI Institute

Views: 14,556

Rating: 4.7849464 out of 5

Keywords: saturn, titan, ralph lorenz, seti, astrobiology, cassini, titan unveiled, huygens

Id: cgyWaoaIW3Q

Length: 78min 1sec (4681 seconds)

Published: Tue Aug 31 2010