Encounter with Ultima Thule: The Most Distant Object Humanity Has Ever Explored

good evening everyone my name is Andrew frack Noi I'm the emeritus chair of astronomy here at Foothill College and it's a great pleasure for me to welcome everyone here tonight in the Smithwick theater and everyone listening to us on the web to this first lecture in the 20th annual Silicon Valley astronomy lecture series this has been going on for twenty years and were delighted that it's continuing we thank the sponsoring organizations the Foothill College physical science math and engineering division NASA's Ames Research Center one of the premier NASA centers around the country the venerable Astronomical Society of the Pacific now celebrating its one hundred and thirtieth year and the SETI search for extraterrestrial intelligence Institute all these organizations have outreach programs in astronomy very much like the lecture series that this talk is part of so it's my pleasure tonight to introduce our distinguished speaker who returns to us having given earlier lectures and that's dr. Jeff Moore Jeff Moore is a research scientist in the space science division at NASA's Ames Research Center and a leader of the imaging team that explored both Pluto and Ultima Thule with the new Horizons spacecraft he's been a member or leader of several other space mission teams including the Galileo mission to Jupiter the Mars Exploration Rover and the Mars Reconnaissance Orbiter his research focuses on the nature and evolution of the surfaces of the planets and moons in our solar system including the role played by impacts quakes and volcanoes on other worlds he has also worked at the University of Oklahoma's national severe storms laboratory and at the SETI Institute and he has given talks a popular talks around the country on astronomical topics so tonight he will be speaking about a very fighting in current topic the exploration of the most distant object humanity has ever visited ladies and gentlemen please help me welcome dr. Jeff Moore you leave me everybody well thanks for inviting me back I was here about three years ago talking about the horizons encounter with the Pluto system I know that that's on their website so if you want to hear my rantings and ravings of three years ago you can find it on youtube ok so most of the stuff on this slide has already been discussed so let's just dive right in okay so the New Horizons mission was first funded in 2001 we built a spacecraft and got certifications to fly a spacecraft that uses two-tone IAM for it's ultimately it's electronic source and got it out to the pad and lot shipped in January 2006 the briefly discussed the the payload of the spacecraft now I'm a geologist so I can talk with some expertise on geological and geophysical matters but then there's some things which are not my field so you won't hear much about them so let's first talk about the things which I do know something about which of the the data collected by the Lorri high-resolution imaging system and then there's a combination instrument called the Ralph which is both a medium resolution but wide-angle color camera and the Lisa spectrometer as you can see they're described here and they all ride right here on on this pack you package there's also an ALICE instrument which is a UV spectrometer which I won't discuss much about and then there's two fields and particles instruments Pepsi and swap which I won't discuss at all and not my department and in the Rex instrument which is basically using our radio antenna as a passive radiometer for measuring temperatures and things like that ok so here is the historical journey to us you could rub as the the third zone of the solar system where conceptually the inner zone is the terrestrial planets the middle zone is where the gas giants in the and the ice giants live and then this zone which is not known as the Kuiper belt and we're currently in the extended mission we're exploring this region not here now three years ago four years ago we flew past the Pluto system and again as I said we've talked about that here in this auditorium a few years ago of course trying to be one of those remarkable places ever visited by spacecraft Pluto as it turns out is every bit as interesting as Mars is in many many ways and it has an equally interesting or I should say somewhat interesting moon of Charon plus some small irregular objects which themselves have quite the story to tell and I you may have already heard mark Showalter of the SETI Institute talk about them or if not you should invite him and ask him about them okay so this is the extended mission and we do several things we look at the distant large you know dwarf planets in the Kuiper belt - because we have a unique perspective to see them as we ourselves are out in the Kuiper belt to learn things about their face curves and which tells us things about the nature's of their surfaces and things like that but having flown past Pluto we the only target we have so far flown very closely to is mu 69 which is informally known as Ultima Thule okay so what kind of target did we go - we went to what's called a cold classical Kuiper belt object and I know this is a little bit of a geeky diagram about it what it's telling you is that the cold classical's have fairly circular orbits as these things go also their orbits are kind of down in the plane of the general solar system they're not at high inclinations of the sources of light for instance Pluto is and so we think for that reason they represent a an original undisturbed reservoir of the most primordial material still left in our solar system so what's ever there is the basic building blocks of the world where we currently live on we are part of as well as the rest of the solar system and it's probably the reservoir from any of the rest of these objects which have been disturbed by various types of gravitational actions with other planets that we think in early solar system that the gas giants might have moved around and that would have caused all kinds of health or skelter in the system and so you you would have gotten things like stop being scattered out as they say in dynamics parlance and you have gotten things transferred into it's called Jupiter family comets and for instance you have gotten things like CG which you know was visited by the rosetta spacecraft probably began life here but ended up getting roasted and toasted in the inner solar system okay now the ultimate tool a encounter was far more challenging than the Pluto flyby the target was 80 times smaller than the diameter of Pluto we had to do a four times closer flyby or crying a lot more navigational precision there was uncertain target location so as you'll see in a son up coming slide we had to actually image a belt of space hoping that our target would be inside the belt so we didn't miss the target entirely now as it turned out after all the gnashing of teeth and the pulling of hair explains my hair that we actually hit the target right on target having realized that it was right exactly where we thought it was to within five kilometers we would have had a completely different much more aggressive sequence of observations because we would have known could have gone right to it and taking a bunch of different pictures as we flew by but since we had to take pictures of a long belt we took fewer pictures to make sure that in case we were wrong about where it was we would capture it within you know the zone of uncertainty of these belts represent so if things weren't bad enough was also four times darker than Pluto and of course it's further out in the solar system so you know it receives you know v as much sunlight or a tenth this much sunlight and of course we were offering reduced spacecraft power and last but not least the two-way round-trip transmission time between us spacecraft and back was over 12 hours okay so here is a simplified version the flight sequence itself and it's more or less to scale and you can see as the top bullet says we flew past the target this new year day the encounter velocity was fourteen point four kilohertz a second which is about ten miles a second the heliocentric distance that's to say the distance of the target from the Sun is forty three point two three au which I think most of you know means it's forty three times further from the Sun than the earth is as we're coming in on the target we were still way back here on the left side we were approaching it at an angle about eleven point five degrees but and at the closest approach who flew about 3,500 kilometers from the target and as this bar suggests this is so we knew it would fall somewhere in this space and so we planned all these infrared observations color observations best resolution observations by imaging the entire bar and hoping that the target would fit right in the middle of it as I say by incredible good lucky fit in fact right in the middle of it okay so unlike the Pluto encounter Ultima Thule was basically unresolved pretty much until forty hours before the encounter so it was just basically a dot a pixel in our imaging system so the first images that reveal the shape indicated that it was oblong and that was a surprise because as we were looking at as unresolved dot the brightness never changed so people were really puzzled how it was possible the light was not changing if it's rotating especially if it's oblong why is it tumble end-over-end and can bright and dark and bright and darker hues and you see it in a distance well it turns out it's doing a pinwheel it's basically it's acts as more or less pointing at the spacecraft and it's spinning like this in front of you so it's brightness isn't changing even though it's quite elongated you could tell you for these pictures and to give you an example how things were going the very next day so this is now the New Year's Eve we've gotten this sort of a resolution image and to keep being begin to say things about its size it was about thirty three kilometres long or twenty-one miles and then on the very next day our first image radioed back to the ground you can actually resolve the thing showed that it was back made up of two joined objects which of course initially looked to us like this and so and you'll hear me refer to snow on several occasions in this talk and so the snowman model was held close to our hearts for for sometime during the first few days you were getting images down but as we began to get more images down Oh actually tell you some of the things that we before I jump to that let's talk about the things you can see at the highest resolution just briefly but we're gonna go over in detail about this here in addition upcoming slides but then so we named the the larger component ultima and the smaller component to lathe that needs since i've been coming up with a multiplet to lay before the encounter and this this is the best image taken it has a resolution of a little little better than about Oh 70 meters per pixel so in principle an individual picture element would be about this little a little smaller than a football feel so the very smallest things you can see like maybe the the craters over here or probably like maybe 200 meters across and early in the game we speculated it might be the formed by the merger of two planetesimals and we will go into a discussion of why we still think that and the implications for that okay as it was pin willing in front of us we finally in the last day of the encounter got enough information to actually determine its its rotation and it rotates slightly less than 16 hours now this image is interesting and I know that it run for a while on the right here is what it looks like as you're running up on the target but this is a version where we D rotated it and kept it all at the constant size so you see it's gets sharper and sharper if you approach but the cool thing about this it also gives you a sense of what it's actually it's real shape is like and so as you watch especially this portion the ultimate portion you can see it doesn't really look so much like a sphere or like the bottom part of a snowman after all it really looks very flattened and that's in fact what's going on as we'll see in the next few slides okay here is a fake stereo of you in the sense that we took two images which are in fact stereo pairs and simply did a little bit of CGI too to interpret lay between them to give the impression that's rotating back and forth but as you can see in that when the head goes all the way down the little craters become more noticeable and as the head goes back up and goes back it's blended back into the lower resolution and they're just the smallest craters disappear but again it gives you some sense of the overall shape and and an appearance of ultimate too late okay now for those of you in the audience you can cross your eyes and see stereo here's your chance now I can do that and i know i think i think they say statistically like the fifth of the audience can do that so for those of you can cross your eyes and see in stereo don't need your GF viewmaster or anything like that this is this is your chance okay and and and we he'll you see somebody's out there can do it I knew that I always get the WoW for the people who can do it and just for the record this is the highest resolution view and then this is the next highest resolution view and they're obviously taken at different times during the near flyby so you get a different perspective and that's get parallax and be able to see stereo okay this is the latest and greatest shape modeling so I'm going to show this to you first for truth and advertising so you can see that they're both flattened and ultimate is still flatter than to layer though I'm going to show you an animation in a moment where última seems thinner because it was an earlier version of what we thought it's real shape was like but but this is the version that we're currently talking to the public based upon a lot of very hard work and the part of several different people using several different techniques they come up with an understanding of the the shape of these objects so it's a it's really quite remarkable that they turn out to have this sort of flattened appearance and they're not simply spherical and we're still trying to understand what's that mean about how the individual components form okay here is the animation it was made about four four months ago when we still thought let's see there we go we're the ultimate component was a little flatter than it is now but but it most still communicates the idea we're dealing with a relatively flat a flat object set of objects okay so as you probably have already noticed just looking at the pictures that that ultima is different than Thule this is a geologic map that my colleague Oliver white put together and for instance it's clear that Ultima it has much blander surface or seems to be kind of less going on in some sense and there is on Thule so we'll we'll talk about both pieces in turn first of all I would talk about the crater accounting that has been done and we've had several groups of people do crater counting and as you can simply see about looking at the pictures that simply aren't many craters this is a typical crater count for places in the outer solar system this is in particular Pluto and you can see Ultima Ultima two ladies craters are way the heck out here so this crater slope basically represents the crater production function on an object which has still records in production the earliest moments of solid surfaces in our solar system and what's amazing is this region the cold classical Kuiper belt is so unpopulated after it was first formed that essentially nothing has happened out there it's you know except for the single event which formed this large crater which we informally named Maryland that don't ask me was it my choice that that you really know almost nothing has taken place and it's really quite remarkable that something like this could survive and and preserved and represent the basic blocks of our solar system okay let's talk a little about the apparent paucity of craters relative the inner solar system now I this is a picture of Mars's moon Phobos and before the encounter we took this image which originally taken by high-rise on reconnaissance orbiter and down resident and added additional smear and reduced its signal-to-noise and did all those things so that it would represent an image which was identical in quality to this image of Ultima Thule and so had Phobos spinning our camera instead of Ultima too late the motor closest approach this is exactly what you would have gotten back to the ground and this is informative because you can see there's far more kilometer and multi kilometer size craters on Phobos and there is an ultimate thule and ultimate Uli obviously just seems generally smoother as you can see the undulator II landscape of Phobos those are also Phobos and Ultima Thule are lit similarly by the Sun in these examples so literally you can compare and contrast what something orbiting Mars looks like versus an object and this object is in fact bigger than Phobos because he's also scaled to the same size to emphasize this point about how those you know these two different locations of the solar system are really radically different okay let's talk about some possible rules of collisions on Tulia and how that might affect their tectonics okay there's a plateau region right here it's marked here as p.m. on this map that it sticks up high and we introduce your asking ourselves is this an uplifted block and it's an uplifted block caused by either the impact of Maryland or is it uplifted block caused by the merger of ultima thule we don't know but it's something we're thinking about trying to consider what it might possibly be and we also see there's these grooves here and here they are shown in the map as well as the neck itself and we're wondering if it's one of two things either the these grooves and the other features such as the plateau or a consequence of the two lobes simply coming together or are they in fact post-merger stresses on the neck that are expressing themselves in the form of fractures so the fact that the two objects can retain their shape and some simple calculations about the tectonics of the two objects we're able to do certain things such as determine the minimum mechanical strength of Ultima Thule and so for instance we know that it takes at least several hundred Pascal's which I don't expect you to carry in there hey what a Pascal is so I picked a common material most people had a chance of walking on which is fresh snow so it's at least as strong as fresh snow or stronger and it also probably has a density on order of half a gram per cubic centimeter which is half the density of water and that seems to be typical for the density of comments as well including comments we've investigated in the inner solar system so those things all are consistent with the idea that Ultima Thule is a comet-like body also there are some retreating scarfs we think are these putative retreating scarfs these features I've marked out these black arrows and here you can see them there with this hat you're marking here here's an example of retreating scarfs in the south polar region of Mars where solid carbon dioxide is subliming away in the spring as the Sun comes back out and causes these interesting cusps eight scarfs and we think that these features resemble that we think that if in fact it is due to sublimation erosion that the likely volatiles are either nitrogen or carbon monoxide or else methane all three of those have we have good reason to believe or abundant at least in the primordial texture outer surface of of Ultima Thule and they are all even though Ultima Thule is way the heck out there and it's really really cold it's more that it's less than 40 degrees absolutely of absolute zero so it's like 35 degrees absolutely zero or that general vicinity that even still at those extremely low temperatures that in timescales of a few hundred million years all these volatiles I just mentioned was sublimated away so these scarps are not still growing they are basically stalled out that probably that refractory material by refractory and stuff it isn't volatile at those distances and and almost everything else is is involved at distance such as water ice and carbon dioxide and so on so so a lag formed and has prevented further erosion and the last but not least the the possibility that the real corporate and all this was methane it's the fact it's dark because methane unlike the other gases when they're exposed to radiation the methane molecules recombine themselves into larger and darker and more refractory compounds and so as these darker less volatile compounds build up on the surface it's just the system down and last but not least if in fact it turns out to be and due to sublimation erosion it also implies that at least Thule is probably onion layered and we've seen examples of onion layering in the commets we've exploited the inner solar system now the reality is rat the wait till someone flies out to ultimate tule again with rendezvous mission or an or another object like it to see if in fact these things are really onion layer but at least there's 10 funny penalizing evidence that's that's the case and also there's the whole story of what are the bright deposits you know the the neck region itself is especially bright and and all the depressions in fact seem to be bright and there's kind of two possibilities you've explored there's always that'll be something you can see something else that you're probably thought of one is that simply downslope movement of fines and the fines that is to say finely ground material is simply brighter than coarse material and that's what makes it brighter the other possibility is that there is a Balto migration of the most volatile ices it might still be outgassing and they collect in the local coal traps and to test those ideas here is a model done by my colleague or Khan Imran who I work with at Ames showing how stuff in fact does go poke downslope or downhill and collect in the neck and this is the model done by James King at Caltech which shows the regions which over eight Ultima Thule year we're the coolest places are and once again these parts of the neck qualify as being cool net over the year okay there's also on Ultima aligned pits and here the arrows are pointing to a few of them including some bright patches coming out of them and we ask ourselves are these class pits formed under a fissure perhaps they're associated with some kind of outgassing or even smiled explosions we're not sure the people who did the crater counting counted bees as if they were craters and even adding them into the crater cat still didn't have any appreciable effect on the extremely old age of Ultima Thule and of course you know as I said before Thule simply isn't like Ultima Ultima it's not like too late so Ultima as you can see is made of what seems to be a series of discreetly bordered similar-sized lo mounds we're not sure what it means maybe it represents some process and how finally flattened or it represents the that the penultimate state of the subcomponents which made up Ultima for themselves similar size and came together one idea which people thought were crazy but not so crazy didn't at least do a quick model was that there is a short-lived highly energetic radioisotope of Elune on the loom 26 which only exists for the few first few million years after its solar system formation so it was entertained the idea if you use aluminum-26 to heat up the interior of Ultima and cause it took in fact and that's what caused the lumps similar to the lumpy surface you see on Sputnik Lanisha on on a Pluto but as it turns out it doesn't work that if realistic parameters ain't happening but as usual once again we will invoke some of the process as well maybe we'll be the real explanation okay also Ultima Thule is is really dark this image the color coding represents the albedo or the brightness and so something that has an albedo of point 0.15 it means it has 15% the brightness it reflects 50% of the light it gets and so as you can see from the color scale that the ultimate to label on average reflects a little more than about 10% of the light it receives and as I said you can calculate for yourself but you know 40 to 1 or 42 square it is how much sunlight it's receiving and realize that it was quite the technical challenge to get good images of such a dim object under such low lighting okay also Ultima Thule is really red but it has a slightly less red deck and being raised in Oklahoma I can speak with authority on the subject of rednecks and so and it's amongst the reddest objects that they are it's in keeping with the redness we see of other cold classical Kuiper belt objects and they are and it is amongst the reddest objects in the solar system okay we have some composition results some preliminary results are the ones which the spectroscopists are comfortable talking about is they have a possible detection of water ice they also have a possible detection of methanol and methanol is basically rubbing alcohol it's the stuff they tell you don't drink as a cause you to go blind and like ethanol which is a different story entirely and again as I stated earlier it's a red classical it's got the right color and so on and it has a spectrum similar to several other objects which we think come from the cold festival Kuiper belt but because Again's of the Tirpitz as i discussed at the beginning of this lecture have been scattered inward and form so-called center objects and so some of these things are probably cool classical significant parts of the Centaur population okay so one of the methods we use to get a final handled on the shape was we turned the spacecraft around after closest approach and let the but ultimate tool a fly in front of us and as Ultima Thule swept across the star field you could see where it was blotting out stars and used that to figure out the unseen shape so this was yet another component of our work to try to get a handle on its actual shape and here's a montage of the last nine and a half hours of observation for closest approach and I can tell you now the data playback still is ongoing I've gotten most of our data on the ground we certainly got notes but in NASA mission parlance is served to is all the class 1 or class a objectives data sets are down that's one of the reasons why I can sit and talk to you about this is because we have it and it's been analyzed to the point it's no longer embargoed so we can have a public lecture on the subject but as you can see the data well some of the day will continue to come down well into next year ok so let's talk a little bit about the origins of the binary so you heard me suggest these are probably two objects which merged together but the question is is how fast could they merge and still retain their original shape so some of our colleagues who are not on the mission but very capable of modelers of something called s pH Co which stands for spherical particle Hydra code and all that translates into is they have computers which can calculate the gravitational attraction between or amongst many many particles you collect your many many particles into initial shapes and you send one of these shapes against the other and you see how the particles interact with each other mostly influenced by either the velocity that you can part on them or their gravitational interactions so first we'll see what happens if you do at a 10 meter per second collision and it's the course of glancing collision but you can see there's not much hope that they would stay together so the next thing done was to do a five meter per second collision and it's as you can see a little more promising it's you know but the smaller target gets fairly messed up at least in this particular simulation was it one more time okay so having them several these runs what becomes apparent is that collision velocities at least in this particular model have to be on order around three meters per second in order for the two objects to retain they're more or less original shape and so to give you a sense of what encountering something at three meters per second is like would be if you get up and stand in a chair and jump to the floor you will land on the floor at about roughly speaking briefly speaking about three meters per second so that we gave you a sense of how fast these things had come together did they go any faster you see they have problems so the next question is how do you form these in the first place well other modeling by other people suggest you start off with with you know particle clouds and you again play the same game at letting the particles interact of each other and collapse on each other you can see that you'll fairly quickly generate various components which is just this one and this one either coalesce or they will they will orbit each other and still fling off and here's a snapshot from different parts of this where you can see that you can get you know a central object of a number of smaller satellites which are bound to it you can get spheres which will come together and disappear and you'll also throw a bunch of stuff out so probably this mechanism it originally set up the arrangement where you would have at least a few large objects altima and Thule and other things and then how does it work out from there well one hypothesis is that these things came together like you saw in the last slide until you had this basically two big objects left and it was the ejection reputationally ejection of the last few smaller things which basically robbed orbital momentum from the two large objects and then they finally came together and that's how you see them as they are today but there are other hypotheses and currently the one that's most favorite leased by all the cool kids in astrodynamics is this one which is gas dragon here they think that in the early source system there is a maybe lot of day blur gas still out in the region of the Kuiper belt and as these objects are initially orbiting Co orbiting each other that is a plow through this this breeze of extremely rarefied gas on timescales of a few million years it robs the orbital momentum in the system and it brings them together and thus may be a surprisingly effective way of what's called hardening the cold classical Kuiper belt binaries and hardening is the word they dynamicists have come up with for getting into dock of each other okay evidence that this fact takes place fairly common is here is Ultima Thule and here is CG which was visited by B it was that a mission and here's some other examples of comets in the inner solar system which you've had spacecraft flyby and you can see that most of them that have a well ultimately of course has been roasted and toasted but you could imagine these guys are simply roasted and toasted versions of binaries that came from from the Kuiper belt and but the show that there are of course a few objects which are also we believe originally Kuiper belt objects just these two comets they can also not show up in the non binary form but it's the binary nosov comet's comets is common and so so we think what our process brought ultimately together probably explains the common binary nature of any other comets and in Kuiper belt objects ok the extended mission continues can we find out other Kuiper belt to fly by target well we hope so we have enough power to last for the 15 years at that point we'll be approaching a hundred times further from the Sun than the earth is we're using our own camera our own high-resolution camera to image in front of us taking long exposures and we think we could find things as small as comet CG which was this guy which is only about three kilometres across and a tenth of the size of Ultima Thule maybe as much as two months before we might run up on it and if it's accessible we can use the fuel is still aboard the spacecraft to fly closer to it and we have a can sequence aboard the spacecraft which will try to collect data so with a little luck we'll get maybe at least one more probably smaller object so I'll conclude the for all part of this talk by asking you simply to think of New Horizons is a time machine that has transported us to the very beginning of solar system history to place where we could observe the primordial building blocks of the planets and with that I'll take questions you're probably one of the world's experts of a very esoteric thing and that is cold objects way out of and fart spotted solar system we now have what seems to be a real interstellar comet coming in from the far outer part of some other solar system any comments on that no it's just it's interesting that is the second one we see now in a couple years when we had never seen any before I don't know that's a consequence of a much higher quality ability to detect such things or are we simply being showered by them that they're all coming from some same source I don't know they so far don't seem to have compositions that are very different than our comets from what I understand it Cressona spectroscopy so I'm not really the right person to answer the the first one that flew by was an extremely elongate object-- so much so that people wonder if it might actually be artificial as in an Arthur Clark science fiction trilogy that run did with Rama so the interesting idea was so and of course in run Dave of Rolla T they all flew in threes is those he who read those novels recall so Gordon now we're seeing the second month so who knows yeah sir yeah one of the things that I've read about or heard about is the meteor barrier and planetesimals formation so does this tell us anything more about that problem and what a solution might be to it time it's the the operative down yeah so the metre barrier is the meter barrier yes oh boy okay now you're really getting to something which I'm not an expert on which which is how may be other stuff forms small objects and I do know a person you could certainly invite to talk about that at length that's my colleague or con mehran who I mentioned earlier who did the modeling of local slopes on Ultima Thule it's really an Astrophysical problem as I said I'm a poor done geologist so I can kind of only wave my hands about how it all comes about but it and it's entertaining to listen to the astrophysicist talk about it because they use help so called pebble accretion the word pebble means something completely different to geologists and it means to astrophysicists apparently so that being the case I'm going to defer until Andy or Jeff invite or con to explain everything okay thank you oh yes I'm sorry good why is alternately you've read it's probably read because uh it was once covered or had mixed in the soil a lot of methane methane is the gas that comes out of your stove and you have a gas stove but of course in the outer solar system it's so cold methane forms in ice but as solar radiation and cosmic radiation bombard the methane molecules the molecules turn into bigger and darker and redder molecules and so it's slowly darkens and Redden's as the methane is converted to larger molecules that are built up of the irradiated methane molecules that help one of those that well what's it made of two things that we know and we could detect spectral spectroscopically was water ice and methanol which they say it's like rubbing alcohol in both cases it's so cold out there they those are both extremely cold and might as well be rocks at those temperatures it's very likely that when Ultima Thule was formed there was a significant amount of nitrogen which you probably notice the gas which makes it most of our atmosphere but again you get up to the to the Kuiper belt dr. Chynn turns into an ice and in fact on Pluto there are whole glaciers and huge huge basins filled with slowly moving soft nitrogen ice so you think probably nitrogen ice was an original constituent Ultima Thule and likewise carbon monoxide which is a poisonous gas to us but it freezes and forms an eye similar to methane at these temperatures these extremely low temperatures that exist in the outer solar system and you could imagine other things like maybe some ammonia maybe carbon monoxide carbon dioxide might be there dry ice those things right there ammonia and certainly and dioxide would be basically like rocks because it's so cold so I've seen the so you had that series of images as the as the new horizon probe is getting closer to Ultima Thor I noticed that as it was getting closer at the beginning it was getting closer at large intervals and then it completely almost completely stopped getting bigger the image right so what caused that well that's actually for the cadence in which the pictures were taken and because the spacecraft all the instruments are bolted onto the spacecraft the spacecraft has to physically physically move to point different instruments at different targets or different things or you want to take a pic color picture then take a you know black-and-white picture and so on you have to you know a lot of those interested those pictures to be taken kind of one at a time so there's a whole bunch of different observations which are kind of mixed in remember that one timeline I showed we had the little bar and had a bunch of arrows or lines pointing to taking a picture of the bars you flew past it well because also the different imaging systems and spectrometers require longer or shorter times to take pictures the interval breaks it all up so the long story stored is is that it represented the unevenness in which we took pictures in order to accommodate all the other instruments on the spacecraft to collect data and of course we focused on trying to get you know good pictures during the basically hour we're close to Ultima Thule because you know and that was some things are changing the most quickly for us too is just there within that one hour before that it was kind of often a distance and it wasn't changing a lot we had time to take more pictures thank you sure hi you may have touched on it in the beginning but as far as the trajectory of the satellite new horizons satellite how are you determining where its next location will be is that is that done with earth-based imaging telescopes or can the can the 10 New Horizons itself kind of survey it's its environment its future environment in do both and then the broader question is is there any science you can do with New Horizons while it's not looking at absolutely as I alluded to the beginning of the talk we can look at Kuiper belt objects which are further away you can't resolve them you see there's dots but because we have a unique perspective on seeing them we can see them you know essentially at large phase angles from the view you get from the earth and what that means is that from the earth all the objects in the Kuiper belt are essentially viewed the same way the full moon is the signs right behind you in your looking at the the entirely illuminated face but if you could fly past an object so you can see it half lumen ated you would see how they light behaves differently as you move past the object not just because you're seeing more and more dark you know dark side of the object but it would also tell you about some of the physical properties of the surface so we're making those sorts of observations as we fly past these things even you can't resolve them but you can see the way the light changes in dims and and also we're close enough to see we can detect rotation and things like that or see you they might be also other binaries so we're doing observations of objects that are distant to us well actually distance both us here on the earth and they're just to us from the spacecraft the spacecraft is much closer to them then we are on the earth and to your first question will we in fact found Ultima Thule first using Hubble images which was the only telescope that was near the earth or on the earth this case near the earth that could go dark enough and see things faint enough to find Ultima Thule and we finally it and one other object Ultima Thule sized that we had enough fuel on the spacecraft to fly to but once we knew where it was then we used a combination a day that we collected from our own cameras and additional information that we collected from very fancy star catalogs to ascertained its exact location and at the end of the day we actually had it pinned down with a few kilometers which is really quite remarkable even I was surprised we could get it so well but we did and in the future since we've now our inner reign a realm where probably there aren't any objects brought it up to be seen even by Hubble but we suspect there are smaller objects out there and we ourselves can see those objects a you know a couple of months before we come up on the target of our own cameras and if they are accessible we have enough fuel board to fly near them and we have a canned sequence to operate and try to take some pictures of these these smaller objects so if you might find on our own this is sort of a follow up on what you were just saying has the New Horizons probe added anything to our understanding of the density of the Kuiper belt or the number of objects out there and do expect it to before it runs out of power well absolutely and the most important thing we did was look at the crater surfaces that the cratered surfaces count the craters on first Pluto and its moon Charon now Charon unlike Pluto hasn't been acted for four billion years so even the youngest portions of share on the the smooth plains you saw in part of the pictures are still very older than the the Mari are the the smooth you know frozen lava surfaces on the Earth's moon by several hundred million years or even a billion years and even there we you know see a real dearth of small craters relative to large craters impacts in the inner solar system are dominated by what's called a collisional impact population isn't just there impacting of us but they've been impacting of each other and this impact of each other operates to basically very roughly produce 10 times as many things half the size as objects that is the next object up in a category so you get what's called a power law of to distribution of fragments and that expresses itself in the in the many many more smaller craters you see relative to large craters for instance on the Moon or Mars or on the earth in the case of the Pluto system we see far less small craters relative to large craters there that we do here in the inner solar system and we think that indicates that the Kuiper belt really doesn't have a lot of inter collisional destruction of particles you know causing the population density to rise and so they're far enough and few and few between so that that they don't interact and when they do occasionally strike something at all they just kind of leave this record of the of their in frequency and probably that's what's coming to make it for us surprisingly difficult relative to what we thought would be the case when we built the spacecraft now almost 20 years ago is we anticipated we actually find more small Kuiper belt objects to fly past than we have and that and and the search for other objects to fly by is itself a further indication of the relatively few number of small objects relative to large objects in comparison to say the the asteroid belt okay thank you already estimated um when both craters will merge out we think they'll never merge out we thinks now that the two bodies have come together they will stay together to the end of the lifetime of the solar system okay thank you you're welcome hi thanks for the talk thanks for the second talk and my question is related to hoping that you'll be back here to make it a trilogy so in regards to looking for an object I am assuming that's happening concurrently with getting the data back and we don't have to wait 20 months and also is the mission fully funded to do this search for the next few years and ideally if we find something out there what's your hope that we would find okay so let me take those several questions we are currently funded to continue to look for objects until the middle of 2021 and we're not waiting until all the data are down before we start looking we're already looking so in case we run into some find something soon of Vecna ours we think statistically based a lot of people think is the distribution objects in the Kuiper belt room or at least the cold classical Kuiper belt it's better looking now than later so so we are engaging in examining the sky in front of us inaccessible space to see if you can find something while inner spacing those data coming to the ground with the data you stored on our recorders and things that grounded from the ultimate thule encounter we're going to have to write what's called an admission proposal to NASA next year and if it is funded we will probably get something in order of another four to five years to conduct scientific investigations including continuing to look for new target targets who can do a close-up flyby of but that's going to be in the hands of whether we write a really good proposal and whether the review boards and the NASA bureaucracy believe the story we tell them thank you sir Thanks as I look at the bottom object there it it reminds me of when I was a child and I would take some lumps of clay separate lumps clays and kind of press them together it looks like the bottom objects comprised of a lot of different objects that have been gradually merged together so first of all is that conclusion correct and second of all why wouldn't the top object eventually merge in the same way and become part of a single body well your description is one that came to our minds right away for the same reasons we also played with clay like everybody else now if you go back to the slides I showed a few slides ago about stuff coming together different collisional speeds you notice the stuff that comes together faster also tends to not retain as much of a shape so in this scenario you would imagine that the individual components which make up the larger body which we informally calling Ultima came together at higher velocities and the final merger of this amalgamated shape which is Ultima with the final feature which is too late so again in this scenario you could imagine this lower portion being built up from similar sized material coming together at 10 or 15 meters per second something like that or 20 whereas the to the final merger of the Ultima with Thule again the models are telling us anything or at very low velocities on order of 3 meters per second or something like that doesn't correlate with demonstration showed at 10 meters per second and the two objects hit kind of sprayed out into space well yes but let's go back to get this one to work oh there's a cooperate with you when you've so we can make air I'm able get get this work we're doing it isn't like going backwards sorry it's good to catch up oh here we go and now can we make this work oh there we go right but if you have it of course that was also a glancing view and there's a bunch of other simulations which I'm not showing what you get actually it hit head-on you could have ended up a situation we kind of look like the lumpy snowman which might be two of the blobs which make up Ultima and certainly you get to you know five meters per second you can imagine that these kinds of collisions as they evolve into ping upon the real mechanical strength of the material as opposed the merely the model mechanical strength that this feature when it finally settled down could also look very lumpy so velocities that are several times faster than the velocity we think was responsible for merging Ultima with tool a could have been the velocities in which the individual lumps came together to form Ultima and does it heat the objects and that's how they merged I'm sorry does it heat the objects are not being heated they're emerging just because of their relatively low mechanical strength and just the interaction of their relative velocities and their self gravitation the individual particles thank you you're welcome all right [Applause]

Channel: SVAstronomyLectures

Views: 60,351

Keywords: astronomy, science, science news, Kuiper Belt, Ultima Thule, planetary science, Jeff Moore, solar system, New Horizons, space missions, space, NASA, planetary exploration, space images, comets, astronomy news

Id: i5P_6huIJm0

Length: 55min 29sec (3329 seconds)

Published: Tue Nov 05 2019