^M00:00:01 >> From the Library of Congress in Washington, D.C. ^M00:00:03 ^M00:00:23 >> Michelle Cadoree Bradley: Hello. I'm Michelle Cadoree Bradley. A Science Reference Specialist here in the Science, Technology, and Business Division of the Library of Congress. I'd like to welcome you to the 10th season of our collaboration with NASA Goddard and today is the third lecture of the eight that we have planned for this season. There's a list available outside of the theater -- of the room. And you can always check our website or subscribe to our blog to see what's coming up. Today, Dr. Jason Dworkin, Chief of the Astrochemistry laboratory at NASA's Goddard Space Flight Center in Greenbelt, Maryland will discuss the OSIRIS-REx -- I'm making lots of eye movements here. Cut that one out. Anyway, it is the first U.S. mission that will return samples from an asteroid to Earth. The findings will highlight the physical and chemical properties of material from asteroid Bennu. The Asteroid is a remnant of the early solar system and should contain clues to its formation. Online, I found a description that said it was "born from the rubble of a violent collision, hurled through space for millions of years and dismembered by the gravity of planets." Isn't it just thrilling to think of it. ^M00:01:44 [ Laughter ] ^M00:01:46 Dr. Dworkin has a Ph.D. in Biochemistry from the University of California - San Diego. And his research objective is to assess the organic species available for the origin and early evolution of life, with a focus on understanding the extraterrestrial input and origin of molecules relevant for life. Please join me in welcoming Dr. Dworkin. ^M00:02:13 [ Applause ] ^M00:02:19 >> Jason Dworkin: Thank you so much. What a great summary of the mission. I think I'm done. ^M00:02:25 [ Laughter ] ^M00:02:27 So, OSIRIS-REx is the first mission to return samples from an asteroid. It's also the largest sample return of any object since Apollo 17. I'll be happy to talk to you about that today. As you may know, planets and stars are born from nebula. And within those, protoplanetary disks form and out of which, planets condense. These are vast disks of gas and dust, ice and rocks and organic material that then coalesce into planets and leave behind rubble. ^M00:03:13 ^M00:03:15 Some of these rubble is large and which is responsible for the formation of the moon. Other bits are still there in the form of asteroids. This is the view that you've often seen of the solar system with the sun and the planets and the asteroid belts and the other planets and the Kuiper belt. And there was a presentation recently about the flyby Pluto. And even further away from that are the Oort cloud where some comets come from. Now this is not scale. On this scale -- this is a fun little website -- 1pixelmoon -- and this is the scale of that same solar system. You can see how far things are apart. And space is vast. ^M00:04:01 ^M00:04:03 Anyway, so planets accrete and life somehow forms. And from that, all life on the Earth is related. And so, you are here and your close ancestors are slime molds and fungus. ^M00:04:21 [ Laughter ] ^M00:04:22 And we're distant ancestors -- are bacteria and actinobacteria. But we all share the same fundamental biology. The same fundamental architecture of how life works. And that is all hidden somewhere in the ancient history of the Earth. ^M00:04:39 This is an excerpt from a -- [inaudible] cartoon from XKCD. It's a cartoon you should read. If you don't, you really should. Nearly four and a half billion years ago, Earth was -- had liquid water. All but the crust older than 3.5 billion years has been recycled into the mantle by subduction. A billion years of the stratigraphic record, the memory of the hills, is forever lost to us. What was it like four billion years ago? Earth, what secrets do you have? Come closer. I'll never tell. ^M00:05:07 [ Laughter ] ^M00:05:09 All we have are these stupid tantalizing zircons to tell us that the -- about four billion years ago, there was oceans on the Earth and scars on the face of the moon that tells me about the bombardment history of the ancient Earth. The Earth is mute on its early history so we have to look to asteroids and comets, meteorites which delivered water and organics. But the problem is -- I mean, you search for meteorites. You find them on the ground. In the dirt or on the ice. You don't know where they came from. And they become contaminated. So, if you're afraid of getting the rotten apple, don't go to the barrel. Go to the tree. From the Untouchables. And so, send a mission out to find a connection between the left-overs of the early formations of the solar system -- meteorites which are disconnected from their origins on the ground. You can send a robot. NASA is known for human exploration which is very exciting and very important. But robotic exploration is a little bit easier because robots don't insist on coming back home. ^M00:06:25 [ Laughter ] ^M00:06:26 And it's -- if a robot dies, it's sad but not tragic. And they are smaller, cheaper, and they don't require an annual salary when they're out exploring the cosmos. ^M00:06:39 And so, we know -- I showed you a little bit about how the clouds are formed from diffuse medium, condensed into planets. And from that you have information on the preserved in the form of asteroids and comets. And so, what we know about the [inaudible] medium from observations and simulations in the laboratory. We know about the ancient Earth -- we know from simulations because the Earth is mute on its early history. To get a real understanding about what was there, you have to have sample return from objects. And sample return are -- this is every sample return mission that has ever been flown. Starting in Apollo 11 up through OSIRIS-REx was launch just in September. And these are missions which bring back samples to the Earth to be studied for generations. So, for example, in my laboratory, I have a woman who recently published a paper on Apollo 16 and 17 samples. She was not yet born when the samples were collected using techniques that were not designed; asking questions thought unaskable when the missions were conceived of in the 1960s. ^M00:07:53 And so, that is the power of sample return. That you can interrogate samples using instruments that have either not yet been invented. And so, I ask young people where they -- what they will be doing when the sample comes back in seven years. Would they be making decisions that could set themselves in positions to analyze the sample? ^M00:08:15 ^M00:08:18 They can think about questions that we are not yet smart enough to ask right now. You can also fly instruments which cannot be miniaturized. ^M00:08:26 ^M00:08:29 Excuse me. So, for example, this is a synchrotron beam-line. And here is a scale bar. This is a car. And so, it's very hard to imagine how you can miniaturize something like that to fit into a five-meter ferrying -- to fly to space. Other instruments give you the analytical power that you can see tremendous detail that you can never see on an actual flight mission. Probably because once you design a mission, the instruments become static. You cannot change them as you come up with new ideas and new questions. You can if you bring a sample back and can interrogate it on Earth. So, we're going to an asteroid. This is every asteroid that's been visited by a spacecraft. Some are large like the dwarf planet series down to something very small like Bennu -- which is the one we're going -- which is half a kilometer across. ^M00:09:22 ^M00:09:25 And there are a lot of asteroids. ^M00:09:26 ^M00:09:29 This month, there have been 95 near Earth asteroids discovered. There are 714,000 asteroids known as of yesterday. And so, we can see that -- this is the main belt of asteroids. Here is Jupiter and there -- here's the Trojan asteroids. Mars. Earth. Venus. Mercury and the sun. ^M00:09:53 These red ones are Earth crossing asteroids. Again, the green ones. The main belt. And blue ones, Trojans. And then, of course, other objects further out. ^M00:10:02 How do you pick an asteroid to get to? Well, when we were conceiving of OSIRIS-REx, at the time there were only 500,000 asteroids. Not the 700,000 we have today. Of those, 7000 are near Earth crossing which means you have the chance of getting to and from the asteroid within the lifespan of a scientist or of a NASA program executive. Of those, 192, you can get there and back again with a rocket that we can conceivably build and fund. ^M00:10:36 Of those, 26 have diameters greater than 200 meters. That's important for two reasons. One is asteroids with diameters that are smaller than that. I've got a model out there you can play with. Smaller than that, they spin very fast. Up to one revolution per minute. And that has two problems. One is that the loose regolith on the surface get thrown off and lost which means it's very hard to sample the loose rock on the surface because it's not there. Even more important, it spins so fast that you can imagine the proximity operations of a spacecraft trying to match orbits -- match spin rate with an object spinning at one revolution per minute is challenging. Of those 26, five are carbon rich. We're interested in the origin of life. The early solar system. The organic inventory. And so, we need an object that is especially very dark and has evidence of organics and volatiles. Of those, Bennu is our choice. And that's because Bennu is a class B object which is similar to Themis which is a main belt asteroid that has ices and organics. [Inaudible] albedo, very low density. Lots of evidence of loose rocks. Very well understood orbital parameters. And, by the way, it is a potentially hazardous object with chance of hitting the late 22nd century. So, lots of time to prepare. Not to worry. ^M00:12:09 ^M00:12:11 But the most important reason is it's -- the most extensively characterized object that a spacecraft has never been to yet. We had a long campaign starting in 1999 when it was first discovered. And it was observed by numerous ground and space based telescopes so we have a very good understanding of what this object is so that, that was we can plan a mission that is low risk and has a high chance of success. The model that's out on the table, you can play with is from Arecibo data. That's the giant telescope in Puerto Rico. That generated the shape model and that's what the 3D printed model is, is this very shape. ^M00:12:54 ^M00:12:57 And in contrast, the Comet 67P/Churyumov-Gerasimenko -- the comet which the Rosetta mission is orbiting -- it was too far away to have radar imaging. So, it had -- light curves that could give a model -- turned out to be -- the shape was actually quite different from -- we could get from light curves. We'll know when we get there but we have high expectations that it will be basically round shaped. Very much like this. There could be some stretching in either direction but will not have these crazy lobes. So, it will be -- it should be a very safe object to orbit. And a very safe object to sample from within the usual risks of doing something in space which is hard. ^M00:13:45 ^M00:13:47 OSIRIS-REx is a large team. It's lead by PI Professor Dante Lauretta. Right here with mascot, Pen-REx. ^M00:13:55 [ Laughter ] ^M00:13:57 ^M00:13:59 This is just the science team. There's an even larger technical team of engineers and technicians who have built and designed the spacecraft. ^M00:14:07 ^M00:14:10 OSIRIS-REx -- the name is an acronym as most things in NASA are. It stands for Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer. This in animation -- which I pause for some -- of the sampling device and sampling action happening. The most important thing is to return a pristine sample which is extremely difficult because pristine is impossible. ^M00:14:39 ^M00:14:43 Totally clean is impossible. But you can focus on what matters to you and minimize contamination within a reasonable cost and not waste your time cleaning things that don't matter. And not waste your efforts by letting things become dirty that do matter. ^M00:15:01 Contamination studies start on day one. And so, from the start of the concept of the mission, we were concerned with making sure that we have a pristine sample. But, at the same time, the spacecraft has to work. I like to say that if the sample fell in the toilet, it wouldn't flush. ^M00:15:20 [ Laughter ] ^M00:15:22 So, having a contaminated sample is better than having no sample, but I really, really want a clean sample to understand the questions related to the origins of biology. So, I asked the science team. Give me a list of the elements that you really care about and we shouldn't get on the spacecraft. And they gave me these ones in red. ^M00:15:41 [ Laughter ] ^M00:15:43 So, I put this up and someone said, "Oh, actually, polonium is really cool too. So, don't put any polonium on there either." Like, okay. Come one. We're going to make the spacecraft out of neptunium and then, I'll violate our thermal requirements so we can't do that. Plus, it would be too expensive and dangerous and horrible in every way. Plus, you ask the organic people what do you want? Well, basically, anything that is an organic compound, we can't have. So, what we did is we took this and came up with representative species. Amino acids, limiting hydrazine, carbon, potassium, nickel, tin, nonindium, and lead as indicators of other [inaudible] elements for geological processes of our chemical processes. Came up with a limit that made sense to science based on meteorites and then turned that limit into engineering -- which makes sense -- people who actually built the spacecraft. ^M00:16:37 Beyond having a limit on contamination, we also have contamination control -- that lead to contamination knowledge. If you have a spacecraft that meets our control limits, you can still have some dirt. Understanding what that dirt is is important. And so, we have monitor in place that are on the spacecraft that we analyze when it comes back. And [inaudible] in the clean room that the science team is analyzing and [inaudible] the bill so we can understand the low levels of materials that are present and that being launched and sent back to Earth. We also have an archiving campaign of materials that are used in the production of the spacecraft so we can -- the science team can analyze it when it comes back in parallel with the samples. We can understand if they were an issue. So, for example, I worked on the Stardust mission. And turned out -- to the surprise of the science team -- that something called Synlube was used as a demolding agent in the aerogel. Stardust had these gelatin-like molds of aerogel that captured the comet dust. And to get out of the mold, they had to have an unmolding agent. Nobody mentioned that. And that turns out to be something like brake fluid which is this horrible mixture of organic compounds. It turned out that -- Synlube 100 was used on stardust. The company changed names. The records were lost to arson. Products rights were sold from the company. And the -- it was actually, I think, the owner's son was interviewed and suspected that Synlube 1000 was actually the same formulation as what was used on Stardust which was launched years before. So as a result, the science team spent six months studying Synlube instead of studying cometary material to understand what it was doing to our samples. And even so, there's still some uncertainty. And so, this is a mistake that we have learned from and so all of these, we have very tight controls over what is being used, good communication between the science team, the engineering team, and the technical team. And things like these that you have to have to make your spacecraft work -- we have an archive in Houston, the [inaudible] Harbor lab where -- so when you write a proposal to get some of the OSIRIS-REx sample, you get one milligram of OSIRIS-REx sample, and I would also like one milligram of [inaudible] to understand if that could have contributed to these things I'm seeing. So, we have all of that. It's being analyzed by the science team now. ^M00:19:16 And just like the sample, 75% is preserved for future generations. Anyway, enough on contamination. My pet little thing on the spacecraft. Our primary goal is to return and analyze a sample -- pristine sample. The sample comes back in a stardust like sample return capsule. Shown here. Returns in Utah September 24, 2023 at 8:53 a.m. -- in time for the Sunday morning talk shows. ^M00:19:46 [ Laughter ] ^M00:19:50 Actually, that time is dictated by orbital mechanics. We have nothing to do with that, but it just happens to work out that way. But anyway, set your [inaudible]. Number two is to understand how the sample fits in context. So, for that that, we'll be imaging and especially analyzing the sampling site down to the sub centimeter so we have a good idea of -- excuse me. ^M00:20:14 ^M00:20:17 Of how the sample that we got back to Earth compares with the immediate location and the context of that sample. Something that has not been done before on any sample return mission since Apollo. We will also understand Bennu as a geologic object by understanding the geology and dynamics and spectroscopy of the entire satellite. ^M00:20:41 ^M00:20:44 We also understand the interaction between the asteroid and thermal properties. And so, this is a light mill which you may have played with. I think they sell them in gift shops around here as well. This is like -- not quite the Yarkovsky Effect -- where light hits a dark surface. And in space, what happens is the light pressure hits, the dark surface is absorbed, the object is rotating, and the light is emitted on the night side and that acts as a low intensity thruster. And that changes the orbit of the object away from its Keplerian predicted orbits which is why we'll give impact probabilities for asteroids -- there's this error associated with it -- that's because of this extra term that's related to the color and topography of the asteroid. And light now is a little bit of a cheat because -- or radiometer -- because there's actually a rarified atmosphere so what's actually happening is the light is hitting the black surface, it's warming up the gas in front of it, and that acts as the thruster. ^M00:21:45 ^M00:21:47 Because otherwise, it wouldn't spin nearly as fast using just purely the Yarkovsky Effect. And finally, there are 700,000 asteroids -- NASA is not spending a billion dollars to go to every single one of them. We're going to go to one object and try and understand that from a point source down to the molecular level. And so, by using that information, we can then apply with what we can see with telescopes the other 700,000 objects and understand how they behave. ^M00:22:16 When the sample comes back, we'll be using a hypothesis based study to understand -- to try and pull back to the pre-solar history, protoplanetary disc, geologic activity, the evolution of Regolith as the object has moved through the solar system, through it's dynamical history and then finally, the impact that the spacecraft has had on the sample, including the contamination impact. ^M00:22:42 ^M00:22:45 We have a spacecraft. It's like most spacecraft, it has a science deck that has various cameras and spectrometers. We have solar arrays like most space crafts. What most spacecraft don't have is a sample return capsule and a three-meter long arm that collects the sample. ^M00:23:05 The payload contains a number of instruments that scan from the X-ray to the radar wavelengths. From the high-end antenna to the student built experiments. OVIRS is -- this is the image of the spacecraft. It is built, it is shipped to Kennedy Space Center. And this is -- the orientation of the flight deck here is OVIRS. It's a spectrometer. OTES is a different spectrometer. We have a camera suite that will give us -- from telescope image down to a microscopic imager. Well, almost microscopic. We have a light arm which would give us the topography. Student experiments for X-ray mapping -- to give us elemental composition. And the high gain antenna which will provide our gravity field mapping. ^M00:24:01 ^M00:24:03 The core of the mission is [inaudible] the sample. This is the sampling mechanism called TAGSAM. It is essentially like a car air filter. The initial design was actually called Muucav, which is vacuum spelled backwards. ^M00:24:18 [ Laughter ] ^M00:24:21 Us of the vacuum of space and blows a jet of nitrogen gas and instead of -- like in a vacuum cleaner, you have vacuum getting sucked -- vacuum sucks material out. You have the nitrous gas blowing into the [inaudible] it and getting sucked out into space through the air filter. It has been tested extensive -- this is fine -- extensively. From having a simulated spacecraft and an air bearing -- this is, kind of, like an air hockey table impacting surfaces at different slopes and thicknesses to see how the sampling occurs, to operating the sampling mechanism on a microgravity flight on the KC 165 vomit comet to make sure that the sampling works under microgravity, to using the same air bearing table to make sure that we can stow the sample head into the sample return capsule. And then there is a video of the sampling head being locked in the samples return capsule with three switches and then back off to make sure that it is in place. This will be a very similar image as we'll get from the cameras onboard the spacecraft to make sure that the head is actually locked in place because once we stow the head, we sever the joint, cutting it off so that when we close the sample return capsule up to bring it home, this is a one-time only action. ^M00:25:52 ^M00:25:53 Now we have nitrene bottles we can actually collect three times if we need to. We only want to collect once. But if there's an anomaly, we can go back and try again, and then again if we have to. But we want to collect once to get our 60 grams and as much as two kilograms. And these test flights, we've [inaudible] at least 150 grams. Usually, more like half a kilogram. And the two kilograms is based on packing the head entirely full. That's how much we can carry. And that's happened on occasion. ^M00:26:29 ^M00:26:32 The OSIRIS-REx has been through a lot of history. The first concept was in 2004. That's when I started working the project. And wrote a proposal, and was not selected. In fact, no one was selected that year. And then, we regrouped and wrote a better proposal with a better concept. And that went to a first cut-off selection, and then wrote up a more detailed proposal and then that was not selected. And then, we needed -- it became clear that a sample return mission requires more resources than was allowable in the discovery program. So, we went to the new frontiers program which is a larger cost gap -- PL admission. Wrote another proposal. Made it to Phase A which is -- this is Volume two of the phase A proposal. All 90 copies required by the review team. It's since gone digital but -- ^M00:27:24 [ Laughter ] ^M00:27:25 Way back in 2009, it was paper -- if you can imagine. Site visits; selections; lots and lots of meetings. And then, we actually [inaudible] implementation. And so, the ATLO which is the Assembly, test, and launch operations -- started March 23, 2015. This is the spacecraft being put into a thermovac chamber. That is a chamber to simulate the vacuum and coldness and heat of space to make sure that the systems function. More reviews, and then last week, the spacecraft was shipped to Kennedy Space Center and unloaded and is undergoing its final testing now until it's ready to launch. ^M00:28:10 And Atlas V 411. And that's code for 3-meter fairing, one solid rocket motor, and one single engine centaur stage. ^M00:28:19 The window opens at 7:05 p.m. eastern time, September 8, 2016. Come if you can. And because it's hurricane season, we have a 35-day launch window so that if something bad happens, we have lots of time to regroup and try again. ^M00:28:37 ^M00:28:40 So, after launch, we depart the Earth and then have -- Earth gravity assist one year later to change inclination. Get them on the same plane as Bennu. And then, we approach the asteroid initially as a point source and then it becomes more and more an actual geologic object. We enter an orbit which is a semi-stable orbit. I guess in this case, Bennu is so small that the pull of gravity is about equal to the pressure of the sun so you have to balance and, basically, surf in the gravity field and the solar field between the two which is why that it's very important that our center of mass and our center of area be coaligned in the spacecraft. ^M00:29:27 ^M00:29:29 Once we have understood the -- ^M00:29:31 ^M00:29:34 Let's try that again. ^M00:29:35 ^M00:29:36 The asteroid better, we'll be on detail survey to understand our favorite sampling sites. Down select to one sampling site. Do a rehearsal to make sure that we can do every single step of the operation of sampling. Because getting close to an asteroid is a little bit scary. You're only going to want to do it once -- the sampling. So, that means we have lots of margin for rehearsing it -- that it's matching the orbits, matching the heights. Getting very, very close. Everything but sampling until we're ready to sample. And then something happens where -- ^M00:30:10 ^M00:30:13 Because it's orbiting the sun, the asteroid gets very close to -- well, closer to the sun than we would like and so there's a risk of the sample will get hot after we collect it. We collect it in the sampling system, and then it's sitting outside in the spacecraft on the sampling arm for up to a month because as I mentioned, the stowing operation is a once-and-done operation. We want to make sure that we do it right. That means that it's sitting out in sunlight and that could get it too hot. So, we have this period here after the lying in the sand - LITS -- ^M00:30:48 [ Laughter ] ^M00:30:50 Where we will stand down and wait until it's cool enough to actually perform the sampling. If everything goes perfectly, we can sample earlier. But, there are things called safe modes that spacecraft go through where if you have, like, a computer glitch, the spacecraft goes to safe mode and resets itself. And this happens all the time. On average, about twice a year or so. Let's say, if the spacecraft is orbing Mars, that happens. And then, fine, you're still orbiting Mars. But we're near an object that has almost no gravity. And so, when we hit safe mode, our instructions are drive to the sun. Just burn away. So. that means that you're now -- you've gone from over here to over here. We have to approach the asteroid again and understand what's happening. And so, that takes extra time and so we've allocated lots of extra time margin to be able to reset ourselves and get the engineering team -- the navigation team to understand where the spacecraft is relative to the asteroid and become same. And then it will approach again. So, this could take as much as month after a safe mode, unlike a couple of days. And so, we have all that margin built in. And then -- let's see if we can get this to -- ^M00:32:07 [ Music ] ^M00:32:12 >> The milky way. Home to billions of starts rising and setting over billions of worlds including our own. In this vast expanse, how did our Sun, the Earth, and the planets come to be? In recent decades, our understanding of the solar system's evolution has greatly improved, but deep questions remain. ^M00:32:38 To answer those questions, astronomers are preparing to visit someplace very small. ^M00:32:44 Asteroid Bennu. A lump of rock and organic material, the early building blocks of the solar system, of Earth, of us. ^M00:32:57 Bennu is a time capsule, and its journey takes us way, way back...four and a half billion years. ^M00:33:04 ^M00:33:06 The raw ingredients of Bennu, and our solar system, originated in a stellar nursery: a vast cloud of hydrogen, helium, and dust. ^M00:33:17 Our own Sun doesn't yet exist. Nearby are hot stars like this one, quickly burning up its fuel... and destroying itself in a colossal explosion called a supernova. ^M00:33:30 ^M00:33:33 The explosion destabilizes our cloud, causing it to collapse. ^M00:33:39 In the geologic blink of an eye, a hundred thousand years, gravity, and angular momentum flatten the cloud into a swirling disc. In the center, where molecules crash together tightest, a proto-star revs up to incredible pressures and temperatures. Deep within the disc, clumps of dust not much larger than a grain of wheat are flash heated into droplets of molten rock, called chondrules. ^M00:34:10 The source of this heat remains a mystery. Chondrules are destined to become the building blocks of the solar system. Coaxed by gravity and turbulence, the chondrules clump. They grow into the first asteroids, into mountains, into planets. ^M00:34:32 The asteroids are rubble piles of rock, metal, ice, and organics. This large asteroid is the parent body of Bennu, a proto-planet whose size we can only guess. Closer to the proto-star, a planet begins to form. And then...dawn in the solar system. ^M00:34:57 ^M00:34:59 The proto-star undergoes fusion and ignites, revealing our Sun. But the solar system is far from finished. Jupiter most likely forms near its outer edge, but just 500 million years after the Sun ignites, some believe that it slowly moves inward. Its massive gravity ripples the asteroid belt, disrupting countless asteroids and comets, flinging them toward the Sun. ^M00:35:28 [ Music ] ^M00:35:31 They rain down on the inner planets, hammering and re-melting large portions of their crust. Did these impacts also deliver organics and water, key ingredients for life? Back in the asteroid belt, Bennu's parent body is lucky, it survives this period of heavy bombardment. The solar system cools and calms. Jupiter and its many moons assume the orbits that we see today. ^M00:35:59 Billions of years of quiet follow... ^M00:36:02 [ Impact ] ^M00:36:03 More or less. ^M00:36:04 ^M00:36:07 Then a billion years ago, one theory suggests a collision shatters the proto-planet. ^M00:36:13 [ Loud explosion ] ^M00:36:16 [ Music ] ^M00:36:18 Some of the debris loosely coalesces into a new, smaller body: Bennu. ^M00:36:24 But Bennu will not stay in place. Dull, non-reflective, it slowly migrates toward the Sun. Solar heating turns its warm side into a low-intensity thruster. Through millions of years, Bennu's orbit gradually tightens, until it interacts with Saturn's gravity, altering its trajectory, and hurling it into the inner solar system. ^M00:36:51 [ Music ] ^M00:36:53 Close encounters with Earth and Venus follow. Their gravitational tugs may have repeatedly stretched and reformed Bennu turning it inside out and pulling off loose material. As a result, it has no satellites of its own...until now. ^M00:37:12 ^M00:37:15 Today, NASA is sending a spacecraft called OSIRIS-REx to explore Bennu and retrieve a sample. Why? Bennu has survived its long journey and settled into a near-Earth orbit, bringing its secrets within our reach. Now it is ready to teach us more about the solar system's history, its formation, its evolution, and our own place among the stars. ^M00:37:42 [ Music fades ] ^M00:37:46 >> Jason Dworkin: Now, you should be very well armed to understand some of the deeper meanings of this presentation -- of this video. ^M00:37:53 [ Beeping ] ^M00:37:54 The video itself it -- it's very nicely done. It has, you'll notice scientists believe, one theory proposes -- these are all things that OSIRIS-REx will be testing. These are all testable hypothesis that are built into the mission summed up in this video. And now, you know what a low-intensity thruster is -- that's Yarkovsky Effect. You know about how the origin of the solar system could have indicated formation of organics delivered to the early Earth. How this asteroid can contain materials that we want to understand for generations to come. And how now you can become involved and learn more about OSIRIS-REx at our website. The PI's blog which has a lot of information, great pictures. And all kinds of other social media sites. And I thank you for your attention. ^M00:38:54 [ Applause ] ^M00:39:04 >> Michelle Cadoree Bradley: I just know that after that we have lots of questions so please feel free to ask your questions to Dr. Dworkin. Please repeat their questions as they come up. >> Jason Dworkin: Yes. >> Michelle Cadoree Bradley: Thank you. ii >> Jason Dworkin: Yes. >> Your collector. >> Jason Dworkin: Yes. >> It looked like you're blowing nitrogen gas and using the vacuum of outer space to make it a vacuum. >> Jason Dworkin: Mm-hmm. >> When you pull it off, how do you make sure the particles don't stay in the filter and not go back in -- out. >> Jason Dworkin: So, the question is how does the collector retain the material that gets inside? >> Yes. >> Jason Dworkin: There is a Mylar check valve that's where material comes in and it won't fall out of check valve when it gets trapped next to the filter. That's how. >> I have a second question. >> Jason Dworkin: Okay. >> In your picture of your spacecraft when it was orbiting, I didn't see a propulsion system to return [inaudible]. >> Jason Dworkin: We have a propulsion system. Here's the monoprop tank. You can see shaded by the solar rays, here are monoprop hydrogen thrusters. And this is how we do all of our transfers. This is our main engines. We have tiny little thrusters that help us to navigate around the asteroid. We have a main engine which will get us back to Earth. ^M00:40:35 What happens is when we get close to Earth, these sample return caps -- we divert towards the Earth. Release the sample return capsule. It spins up and so it's rotation stabilized and enters over Utah with less than 1:1,000,000 chance of damaging life or property because it lands in the Utah Test and Training Range outside Salt Lake City. And then, the spacecraft itself diverts away from Earth and goes into heliocentric orbit. So, the spacecraft has thrusters. Yes, sir. ^M00:41:07 >> Why are the asteroids located in this tiny belt around the sun -- ^M00:41:12 [Inaudible comment] ^M00:41:15 >> Jason Dworkin: So why are the asteroids located in the asteroid belt? It's really -- gravitational pull of Jupiter is the main source. A good question is why are there any planets at all? Why isn't it just gas and dust? Gravitationally, they tend to accrete and in the asteroid belt, there's enough gravitational disruption from Jupiter -- as I understand. Again, I'm a chemist so the orbital dynamics is a hobby, not a specialty. But it's too unstable there for a planet to actually form. And so, that's a belt that is retained by Jupiter and Solar interactions. >> Thank you. >> Jason Dworkin: Yes, sir. >> How do you [inaudible] be sure that the surface of the asteroid is dusty and would respond to the capture mechanism and not shiny and smooth? >> Jason Dworkin: All right, so how do we know that the asteroid has regolith on it? We have thermal inertia measurements taken from -- ^M00:42:11 ^M00:42:15 From the -- primarily, the Spitzer Space telescope, as well as some other telescopes, that give us a thermal inertia of the asteroid. Thermal inertia is how long it takes for a solid to cool off when it gets out of the sunlight. And so, compare the thermal inertia of beach sand versus rocks. And beach sand cools off faster because it's finer grain. And so, you can use that to tell the grain size. Average grain size is about two centimeters which is perfect for fitting inside of our sampling system. And there's bound to be dust. That's also why we have contact pads on the sampling system so that if the worst happens and we don't get rocks inside, we'll get dust on the surface collect. [Inaudible] indication of what, also, the surface is like. ^M00:43:10 [Inaudible comment] ^M00:43:16 >> Jason Dworkin: The question is, is the dust on the surface representative? Boy, if I knew that, we wouldn't have to go. ^M00:43:23 [ Laughter ] ^M00:43:25 And we actually have conversa-, it will be a very interesting day when we choose the sampling site. Let us imagine that you have the surface of Bennu when it's all black and there's one white rock. Do you want to sample the one white rock because it's weird or the black part because it's normal? Again, that will be an interesting conversation and that's a PI led mission and so there's a council that reports to the PI, who makes the decision, who then gets concurrence from the Associate Administrator of NASA. And so, there's a bureaucracy to make sure that we make a decision that is equally unpleasant to all. ^M00:44:07 [ Laughter ] ^M00:44:09 Yes. In the back. ^M00:44:11 >> How do you match the surface? I assume that you're going to have to be stationary over whatever the surface is that you're going to sample. How do you match its orbit? I assume you know which way the spin is, et cetera? ^M00:44:26 >> Jason Dworkin: The orbital parameters of Bennu was a 4.2-hour day. It's retrograde orbit. We know that already. When the spacecraft gets close, we'll be able to match it very precisely because it is such a small object, it's really, more like a docking maneuver than it is an orbiting maneuver. And so, we can use all of the tiny little thrusters all over the spacecraft to help us orient ourselves to match the orbital rotation when we go into our rehearsals -- to make sure that we can do that properly. And then, actually match the orientation on the surface. We'll be generating four maps to help us choose our sample. The first map is the safety map. Make sure we have a site that is actually -- will not endanger the spacecraft. The second map is the sampleability map to make sure that we have sample sizes at that location which can fit in our sampling system. Measuring again the thermal inertia and taking images. After that, we have the deliverability map to make sure that the navigators can get us to that spot. ^M00:45:36 Like it's not, say in the North Pole, where the rotation is such that you actually have to spin the space craft too fast. And then, after that is the science map that gives us the most exciting science. The black rock versus the white rock for example. And so, the addition of these four maps will help us decide the safest, most sampleable, most deliverable, most exciting site we can get. Yes, sir. ^M00:46:02 >> How do you discriminate between material that has accumulated on to this object over times [inaudible] and you're passing through the different medium as opposed to what real content of the rock represents? Is there a way of finding that or -- >> Jason Dworkin: So, the question is how do we differentiate between original Bennu material and material accreted from other objects? That will be looking at the minerology. Looking at the detailed elemental abundancies and I stop at distributions of the sample when we get back. ^M00:46:41 They're both very interesting stories. So, for example, the Almahata Sitta meteorite that landed, or well, crashed into Sudan in -- what was it? 2010 or so. No. 2008. 2008 -- TC3 was the asteroid and was the only time an asteroid was observed in space and [inaudible] characterized. And then hit the Earth and it was collected. So, it's both an asteroid and a meteorite. Almahata Sitta, 2008, TC3. ^M00:47:15 Anyway, that turns out to be a [inaudible] of a whole bunch of different kinds of meteorites thrown together in a really weird way. And what exciting science that will be if that's what Bennu is. But just as with Almahata Sitta, we'll be able to determine that by looking at the rocks. ^M00:47:32 Yes, sir? ^M00:47:33 >> If you were to hit the jackpot, get everything you want to know out of this, what would that be? >> Jason Dworkin: So, what is the ultimate success for this mission? Well, nothing less than original life, of course. ^M00:47:45 [ Laughter ] ^M00:47:48 It's to either prove or disprove theories on solar system formation, on are there [inaudible] that led to the timing of the proto-solar nebula. What organic compounds are present? Are there excess of left-handed amino acids? Something that I specialize in that led to, perhaps, the origin of life. Are there -- are those amino acids a biological type but not contamination? Are these -- the sugar contents -- nucleus basis. There's a wealth of chemistry that we cannot yet answer from rocks on the ground because of contamination that this will help us understand. ^M00:48:47 ^M00:48:50 [Inaudible comment] ^M00:48:57 >> Jason Dworkin: So, this is comparing OSIRIS-REx to ARM, the Asteroid Redirect Mission. OSIRIS-REx is a PI led mission that was -- getting there. ^M00:49:09 ^M00:49:15 That was selected on the New Frontiers line in 2009. It is a science driven mission to return a sample for purpose of science. ARM is very much like Gemini, it's a way to rehearse and practice having astronauts operate in space. ARM is an engineering exercise directed by the agency to understand how to work on objects in space to help up get closer to Mars. That is not science drive, that's technology driven. If there is a science pay off, then that's great. But science is not the driver of that mission. In the case of OSIRIS-REx, science is the driver. And there might be some technology pay offs in how to interact with small bodies, but the purpose is science. So, they have entirely different purposes. They're also at pretty different stages in their life cycle. The OSIRIS-REx is built and about to launch, ARM is still a concept. ^M00:50:17 ^M00:50:22 Anyone else? Yes, sir. ^M00:50:23 ^M00:50:26 >> If asteroid are formed from the same material as [inaudible], why would we have different -- ^M00:50:33 [Inaudible comment] ^M00:50:41 >> Jason Dworkin: So, it's -- if the Earth and the asteroids came from the same source, why are they different now? Well, for one thing, the Earth melted. And partly because of this gigantic -- I can't get back to it -- this gigantic impact that formed the moon, that totally melted the earth. After that, life will find a way. Life is pervasive. It has totally dominated the chemistry of the earth. Geologic processing like subduction has also dominated the crust of the earth. And so, between geology and life, the earth is a highly-evolved object. There's not much left of it that's primordial. And these asteroids have never melted. And they've never seen life. And they've never seen liquid water -- at least not that we know of. ^M00:51:38 And they've certainly never seen subduction. And so, they contain the untarnished history of the early solar system unlike the Earth which has been totally rearranged. And just has Mars has been rearranged by its geologic history. And Venus has been rearranged by its geologic history. Anyone else? ^M00:52:05 [Inaudible comment] ^M00:52:06 Pardon? ^M00:52:08 Oh, Bennu is an Egyptian bird god. And so, OSIRIS-REx is the acronym for the mission. Egypt is kind of cool and that's why we went with the Egyptology reference. And that was initially for the early OSIRIS concepts which were not funded. OSIRIS-REx was the big grander version. Started as a joke. The OSIRIS king. And I guess that's post-[inaudible] but whatever. ^M00:52:42 [ Laughter ] ^M00:52:45 And so, the joke stuck and we came up with a backronym for what REx stands for. Regolith explorer. And so, we had a contest to rename 101955 1999 RQ36 something a little bit more palatable. And a young man in North Carolina came up with the name and he's been given a ticket to the launch to see it. And so, he thought that the image of the spacecraft reminded him a bit of a bird which also led to a parody song, Bennu and the Rex. Which I will not sing here. ^M00:53:21 [ Laughter ] ^M00:53:24 >> Thank you. ^M00:53:25 [ Applause ] ^M00:53:29 >> This has been a presentation of the Library of Congress. Visit us at loc.gov. ^E00:53:36