Planetary Radio: Space Exploration, Astronomy and Science - Asteroid Bennu’s Visitor From Earth

Episode Date: January 23, 2019

Spacecraft OSIRIS REx is now orbiting a 260-meter asteroid named Bennu.  Principal investigator Dante Lauretta returns to tell us what has already been learned, and to preview the excitement that is still to come, including the probe’s descent to the surface for collection of a pristine sample. Want one of five  Blu-ray copies of First Man, the movie about Neil Armstrong? Consider entering this week’s What’s Up space trivia contest that also offers Dante Lauretta’s two great board games about space exploration and astronomy. Learn more at:  http://www.planetary.org/multimedia/planetary-radio/show/2019/0123-2019-dante-lauretta-osiris-rex.htmlLearn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

The latest from Asteroid Bennu via OSIRIS-REx, this week on Planetary Radio. Welcome, I'm Matt Kaplan of the Planetary Society, with more of the human adventure across our solar system and beyond. A slightly abbreviated show this time, but we've still got great stuff for you, including a mission update from OSIRIS-REx Principal Investigator Dante Loretta. His spacecraft is now orbiting Bennu, where the search for a sample collection site is already underway. Now, I know you always stay for my What's Up conversations with Planetary Society Chief Scientist Bruce Betts. with Planetary Society Chief Scientist Bruce Betts. There's even more reason to do so today.

Five winners of the new space trivia contest are going to receive Blu-ray copies of First Man, starring Ryan Gosling as Neil Armstrong. And a couple of you are also going to receive either Extranaut or Constellations, the great space exploration and astronomy board games from our guest, Dante Loretta. Yes, he creates games that share the passion, beauty, and joy, but Dante is first and foremost a scientist.

He is a professor of planetary science and cosmochemistry at the University of Arizona's Lunar and Planetary Lab. That's also where he leads the OSIRIS-REx mission. Pay attention, because I'm only going to say this once. It stands for Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer. The spacecraft's main goal is to collect and return a sample of Bennu. Though, as you're about to hear, the mission has already begun sending home great images and data. the mission has already begun sending home great images and data.

Dante, welcome back to Planetary Radio, and congratulations on the enormous, exciting success of OSIRIS-REx. Thank you, Matt. It's great to be here. I was at the Applied Physics Lab waiting for New Horizons to pass a rock much farther out in our solar system on New Year's Eve. Something big was happening with your mission on that day. You successfully went into orbit? That's correct. On New Year's Eve of 2018, we set two world records by placing the OSIRIS-REx spacecraft

into orbit around the smallest body that has ever been orbited by a spacecraft from Earth, and also achieving the smallest radius orbit in spaceflight history. So congratulations on that as well. And I have to, in a somewhat embarrassed way, admit something to you. We mentioned this on the show a week or two ago. We had one of your team scientists on, and that person, as we have been at the Planetary Society, sort of used air quotes when we referred to your spacecraft orbiting Bennu. I got email from one of your navigators at that company, CanetX, that's one of your partners. And he said, no need for air quotes. You really are orbiting this small object.

That is true, Matt. We are in a true orbit around Bennu. It has a period of about 61 hours. We're moving at an orbital velocity on the order of 5 centimeters per second. I find this so charming in a way. And you are what? At most about 2 kilometers away from Bennu in this orbit? Yeah, we're ranging between 1.5 and two kilometers. It's a somewhat eccentric orbit.

Absolutely fascinating, and maybe eccentric in more ways than one. The science began even before you went into orbit, right? I mean, I saw this announcement that your team found water on Bennu. Yeah, we began observing Bennu in mid-August of 2018. That kicked off the approach phase science. So we started out two million kilometers away, and over the course between August and December, we closed into the 20-kilometer range, setting up preliminary survey flybys starting on December 3rd. So we had the spectrometers active. We have a visible and infrared spectrometer OVIIRS, and we have a thermal emission spectrometer OTES. Both of them were able to get Bennu in their field of view. They were challenging measurements because it didn't completely fill the field

of view, and these are instruments that are optimized for close-up spectral mapping, which will start later this year. But they both detected very convincing signs of hydrated clay-like minerals as the dominant material on the surface of the asteroid. And that's a really exciting result for us because the mission objective is to return pristine, carbonaceous, chondrite-like material from the asteroid, and those minerals are exactly the kind of material that we were hoping to find. Obviously not liquid water. It's not ice either. It's water, what, locked up in these clay compounds? That's correct. So we believe very early on in the history of the solar system, a much larger asteroid accreted both icy particles and rocky particles. And then that asteroid heated up and due to the decay of radioactive isotopes, the ice melted and reacted with the minerals to form clays.

And when you do that, the water actually becomes part of the crystal structure. do that, the water actually becomes part of the crystal structure. And so it gets preserved throughout the four and a half billion year history of the solar system inside those minerals. Remind us why, with all of the meteorites that have been found down here on the surface of Earth, why it is so important to pick up this pristine material and bring it back. There's really two compelling scientific reasons to go get a sample directly from the surface of an asteroid. The first is geologic context. When we find meteorites, we really have a tough time identifying where in the solar system they're coming from. We struggle to get their orbits, to trace them back to a region of the solar system where they're derived

from. And I think the best way to describe it is now for the very first time in history, the meteorite scientists are walking up to the outcrops to see where these rocks are actually coming from. Any field geologist knows you have to understand the geologic context in order to truly interpret the materials and the minerals in the sample that you're studying. The second reason is we are interested in the role these kinds of asteroids played in seeding the early Earth with the building blocks of life. And when you're trying to determine if those are present in meteorites, you have to overcome terrestrial contamination and also selection effects. Only the toughest material is going to make it through passage to the Earth's atmosphere.

And even when it lands on the ground, it's very quickly colonized and contaminated by terrestrial microbes and handling. I compare it to a forensic investigation. We're trying to lay out our case. And in order to make it as convincing as possible, we have to have control of the evidence from the moment it left the asteroid surface until it got into our analytical laboratories and those molecules were detected. That ultimate goal, of course, is that sample being recovered and brought to some very, very well-protected lab.

But the science, as you've said, has already begun. Now, even the best of this science, in-situ science, may still be ahead of us. But what else can you tell us at this point, if anything, about what you've discovered at Bennu? Yeah, so in addition to the approach phase, we executed the preliminary survey. That was a series of hyperbolic passes over the North Pole, the equator, and the South Pole. And so we got really good looks at the asteroid surface and some really high resolution imaging data with pixel scales of up to 33 centimeters per pixel. Wow. So we've done a really good job already characterizing the surface.

And there certainly have been some surprises. The ones that jump out at me right away is that there are a large number of impact craters on the surface of this asteroid. And we expected, since Bennu is a rubble pile asteroid, it's basically a loosely bound accumulation of boulders and gravel, that as it was in the inner solar system and it did close approaches to the terrestrial planets, and also as its rotation rate increased due to a phenomenon called the Yorpe effect, we expected that this would be a pretty active and dynamic surface, and we would see erasure of the older cratering record. But it looks like Bennu's surface age is anywhere from 100 million to a billion years old,

which really helps us understand its evolution and its geologic history. That said, there are a lot of processes going on on the surface. We do see mass wasting or material moving down slopes. There are a large number of boulders, I would say an uncomfortably large number of boulders, considering that we got to fly down to the surface and get a sample. So that definitely was a surprise to us as well. You know, that's a really important point that you've just made, the difficulties that are ahead as you collect this sample. We know that the Japanese spacecraft, Hayabusa 2, they're hoping to collect their sample from Ryugu possibly as soon as next month, but it's not going to be

easy. And do you face some of the same sorts of challenges with this rubble-strewn body that OSIRIS-REx has visited? Yeah, and we work very closely with the Hayabusa 2 team. They're great friends and colleagues of ours, and we have a lot of cross-pollination on the science team. So that's actually one of the best parts of the mission so far, is the ability to cross cultural boundaries and share information and data and build friendships and relationships to help each other out. Because we are both in a similar situation where we have a more challenging asteroid surface than we designed to.

And we're going to have to figure out how to overcome that challenge using our ingenuity and the capabilities of our spacecraft. And where and how are we going to go get that sample? That's our job over the next year on Osiris-Rex. Even though we got a lot of great data already, the science campaign hasn't truly begun. We're still in the preliminary assessment and setting up the detailed mapping phases. And we are seeing small patches of what look like fine grain material at our current imaging resolution. They're on the order of maybe 10 to 20 meters across, which is about half the size that we were expecting and what we designed our guidance systems to accommodate. What sort of resolution will you eventually have before you dive down to

scoop up that sample? We're looking at a global mapping resolution with a pixel scale of five centimeters per pixel. So that's going to be about a factor of six better than we have right now. So we're pretty excited about that. That's going to be unprecedented. That'll cover at least 80% of the surface of the asteroid. It gets more challenging as you try to image the polar regions because the lighting conditions are not as accommodating of good pictures being taken. Still pretty amazing, five centimeters per pixel. It is going to be an amazing data set. We're already having a field day with the science team here and the data that we've collected.

And every once in a while I stop and I remind them, I said, the best times are ahead of us, folks. We still got a lot of data to collect. What you're seeing now is kind of getting us thinking, but really this spring and summer are going to be the heyday for OSIRIS-REx and counter-science. Do you have a lot of confidence that your spectrometer, spectrometric instruments are going to be able to tell us a lot more as this continues, as you really get into the science campaign? Absolutely. As I mentioned

earlier, the spectrometers, the data that they're looking at now, the asteroid didn't even fill the field of view. It was about 40 percent of the field of view. So the signal to noise wasn't great and they were still able to make these amazing discoveries. We are going to get within a few kilometers of the asteroid surface. We're going to have resolutions of tens of meters. We're going to map out the entire asteroid surface with both spectrometers. meters. We're going to map out the entire asteroid surface with both spectrometers. And those instrument scientists can't wait because they've been working really hard to process the data. And I don't think the public usually appreciates how much work goes on to take

data from a spacecraft instrument and turn it into scientific quality information that can be analyzed. They're expecting their job to actually get a lot easier when we start making the observations that the instruments were actually designed and optimized for. What about images? I mean, you've mentioned the ones you've gotten already, and we will link to the mission website where people can see some of these really stunning photos of Bennu. When will we be seeing higher resolution images than you've already published? So right now, as you mentioned, we're in orbit, and the imaging conditions in orbit are actually kind of poor because we're constrained to orbiting in what we call the solar terminator plane, basically going over 6 a.m. and 6 p.m. of the asteroid surface every orbit. And that's because the gravity of the asteroid is so small that solar radiation pressure on the spacecraft is the same order of magnitude force. And so we got to keep that force constant. So we're not getting, we're getting images, but they're not better than what

we had before. Actually, the best data were taken on December 2nd as we were coming into the asteroid. We'll be leaving orbit at the end of February and going into the detailed survey phase. So that last week of February and then through March and early April, that's when those phenomenal new images will be coming in. Have you pinned down when OSIRIS-REx will descend to pick up that sample? Well, the nominal date on the schedule is July of 2020, but that was based on the plan that we had easily identifiable sample sites that met our design. Not being in that situation, we are gathering right now to determine what is the new requirement, what does that mean for our observation profile, maybe we have to write some new flight software,

mean for our observation profile? Maybe we have to write some new flight software. So that date may slip, but we're not ready to announce that yet. Can you say more about the actual engineering challenges that are now obvious as you see this object for what it is? We always knew the biggest challenge for OSIRIS-REx was accurate navigation in the microgravity environment. So that's going to come into play as we have to target a very tight region of the asteroid surface where we believe there'll be material that our TAGSAM device can collect. Now that said, the navigation team has beaten all expectations for the performance of the orbit phase. And we had expected that the orbit might be unstable and that we'd be doing a lot of maneuvering with the thrusters to maintain the orbit. But this group really nailed

it. And we have not had to have any trim maneuvers since we got into orbit over two weeks ago now. They are modeling the small forces on the spacecraft to unprecedented precision. And people didn't believe they could do it when we were going through the design of the mission way back in the design phases. There were a lot of skeptics on whether we could actually get into orbit around this asteroid and whether we could do the small force modeling that's necessary to maintain the orbit. And all of that's going really, really well. So that gives me a lot of confidence as we're looking at reducing the requirement for the navigation accuracy to the surface of the asteroid that this team's going to be able to

come through for us. Dante, it's been a pretty good season, hasn't it, for NASA's class of missions called New Frontiers? Absolutely. This is a great program. It's an honor to be part of it. We were, of course, thrilled to see the data coming in from Ultima Thule, the most distant world ever explored by a spacecraft and our interplanetary snowman. So that was just phenomenal work. And Alan Stern and that team have always been an inspiration and a great source, a resource for us as we've reached out to them. And I've personally reached out to Alan on many occasions as we've, as I've run into issues and I wanted a sounding board, somebody who maybe had had a similar experience. And of course, Juno in orbit around Jupiter continues to provide unprecedented information about the interior structure

and the cloud dynamics of the polar regions and overall the geophysical properties of the largest planet in our solar system. And, you know, there are two teams working right now on the final concepts for New Frontiers 4, and I'm excited about both of them. One is the CESAR comet sample return, which builds on the OSIRIS-REx legacy to go out to Comet 67P to get a sample from that surface. That was the target of the Rosetta mission.

And the other one is Dragonfly, which is a quadcopter to buzz around in the atmosphere of Titan, a very important and intriguing target in the solar system for understanding planetary evolution and even insights into the origin of life here on Earth. So we're really proud of all the accomplishments of the missions in the New Frontiers program, and we look forward to great things to come. Yeah, pretty good bang for the buck, I would say. And we still have to talk to people about the Caesar mission, but you may not know because it just went up as we speak.

We talked to Zivy Turtle about the Dragonfly proposal just last week on this program. So far, we've only talked to you in your role as a principal investigator for this great mission, OSIRIS-REx, but you are a dedicated science communicator as well, and I wonder if you want to tell us the current status of your activity there where you've developed not just one now, but I guess at least a couple of pretty successful games. Yeah, one of the other activities and organizations that I'm heavily involved in

is the Boys and Girls Clubs of America and locally the Boys and Girls Clubs of Tucson, which is a youth development organization that provides after-school care as well as summer care for students and kids from low socioeconomic status backgrounds. And one of the things that occurred as I was working with that group and doing STEM outreach in a weekly science club was that board games are a really great way to get concepts across to them and also have conversations and build relationships. I've always been a big board game player. And so that really got me thinking about using board games as a way to overcome some science phobias and get people excited about science concepts in a collegial and really dynamic and fun environment. So I have now three board

games to my credit. One, the first one's called Extranaut, the game of solar system exploration came out in 2015 and has done well. I think we've sold over 10,000 copies of that. I think I've told you that it's a pretty popular game at Planetary Society headquarters. That's great to hear. The second one is Constellations, which is about stargazing and stellar evolution and the patterns of stars in the sky. And then just last month on Kickstarter, we raised the funding to produce our third game called Downlink, the game of planetary discovery. I'm really excited about this one. Downlink is more for the hardcore gaming community, which is something that I enjoy.

A lot more strategy, resource management, longer gameplay, and decision-making, but it really is about putting science instruments on spacecraft and getting them out to all these different targets in the solar system and making scientific discoveries and scoring the most points along the way to win the game. So that is going to the factory for printing in the next month or so and should be available later on this year. Why is this side of what you do, communicating the science, not just communicating it, but making it really exciting and fun, why do you see this as such an important part of the job? Well, you know, I'm pretty fortunate to have the job that I do, and I never forget that. A lot of people believed in me and gave me an opportunity and really just taught me

what possibilities were out there. And, you know, I come from the Boys and Girls Clubs. I was a kid that went there. I was raised by a single mom and didn't really know what college was about. I was the first person in my family to go to college. I want to pay that forward. I think it's important to look to the next generation. You know, we have a lot of challenges on this planet, both politically and

scientifically, and we need well-educated, informed people, whether or not they go into a science career, we need them to understand the value that science plays in decision-making and the wonder of the universe that it reveals to us, because I think that just makes life so much more worth living. Well said, Dante. Thank you so much for that and for joining us once again on Planetary Radio. I hope we can talk again when that science campaign really gets underway and we'll keep following the mission right through the return of that pristine sample back here to Earth. Sounds great, Matt.

It's always a pleasure. Dante Loretta is a professor of planetary science and cosmochemistry at the University of Arizona's Lunar and Planetary Laboratory. And of course, he is the principal investigator on NASA's OSIRIS-REx mission, which is now orbiting a rock called Bennu. Time for What's Up on Planetary Radio with that pretty amazing prize package that I mentioned at the outset. Let's get underway. Tell us about the night sky. And I know what you're going to ask me.

Did I see the eclipse? Kind of. Kind of? It was cloudy. Oh, I thought you were in a delirious state and you just imagined it. Oh, I thought you were in a delirious state and you just imagined it. No, you could just barely see this smudge, a slightly reddish smudge up in the sky through the clouds that we had down here in San Diego. And that's the best I got.

How did you do? I did well, but it required staying outside and staring up pretty much the whole time because it was patchy clouds. So it would be gone for a few minutes and then it would be there for a little while. So it was cool. Of course, the following night, last night, as we speak, it was absolutely gorgeously clear. So, you know, just my luck. Well, sure. But there's all sorts of other good stuff you could look at in your clear skies, Matt. How's that for a segue? Are you serious? Tell me about it. Or them. Well, golly, if you're up in the pre-dawn morning, it is super-de-cool right now.

Yeah, that's a technical term. We've got Jupiter and Venus, the two brightest planets in the sky, hanging out near each other, very near each other in the pre-dawn east, fairly low down. Venus is the brighter of the two. Both of them are brighter than any star in the sky. And they're kind of lined up for the next few days with the reddish and dimmer, but bright star Antares in Scorpius. And so you can see a nice little line there, but wait, don't order yet. On January 31st, the crescent moon, I'll throw in the crescent moon. If you call in the next 15 minutes, no one way or the other, you will get the crescent moon hanging out right near Venus and do its upper left will be Jupiter and the upper, I'm sorry, upper right, upper right, is Jupiter, and to the

upper right of that is Antares. That's January 31st, and in the evening sky, we've still got reddish Mars hanging out in the southwest in the early evening. If you think that was exhausting, we've got this week in space history. This week had two of the large space disasters. 1967 was the Apollo 1 fire, killing three astronauts. And 1986, the Challenger disaster, killing seven astronauts. So we remember them this week. So it's that week again. Yeah, a good time to remember these explorers. It is. It is. And it just happens the way the weeks carve up. But also within that same week period, we have the Columbia disaster in 2003. Bad week for space. A couple other things. 30 years ago, Phobos 88 entered Mars orbit. Little known fact, but created a PhD thesis for me after

a lot of stress in the meantime. No kidding. Soviet mission, right? Yep. They launched two spacecraft headed to land on Phobos. One of them failed on the way to Mars. One failed after being in Mars orbit, but got some data about Mars. So the greatest success of that mission was your thesis. I don't think I'd quite claim that, but sure.

One of the greatest scientific successes, since there were so few, was my PhD thesis. And then 15 years ago, Opportunity landed on Mars and roved around for at least most of those 15 years. Still waiting for it to call home, I think. All right, we move on to a random space fai-yet. That was jaunty. Well, you know, I felt jaunty talking about nova.

That's right. Brightenings of stars in the sky during the 16th century. A little nova naming history. During the 16th century, a little nova naming history, during the 16th century, Tycho Brahe, observing what turned out to be a supernova, he described it in his book De Nova Stella, concerning the new star, which gave rise to the name Nu. Ironic, because most of the stars experiencing nova, or particularly supernovanova are at the end of their lives everything was called a nova until the 1930s when they started to sort out supernova from nova

and term those classical novae and they're dimmer and caused by a different way of doing things but uh yeah it's a whole new nova star convention. And that was a very nice little introduction. Learn more. All right, we move on to the trivia contest. And I asked you, relevant to what happened a few days ago now, when is the next total lunar eclipse as seen from the Earth's surface? How'd we do? I am going to open the responses this time with our poet laureate,

Dave Fairchild. A lunar eclipse is a proof that our world is circular to the observer, which dampens the hope of about 2% who claim to believe as flat earthers. So watch the penumbra and umbra advance because you aren't getting a rerun until the next time that a total arrives on May 26, 2021. That is correct. Thank you, Dave Fairchild. And here is our winner, Scott Borgsmiller. Scott Borgsmiller, longtime listener and last won the contest, get this, just over four years ago, according to my faulty records. But I think that's accurate.

He said May 26, 2021. So Scott in Ijamsville, Maryland, you are going to receive Rocket Men. That's Robert Curson's book about Apollo 8 that we were able to offer once again, because the previous winner, he went out and bought the book after we talked with Robert Kersen about it. That was a good move. Also, a complete set of those five great kick asteroid stickers from the Planetary Society Chop Shop store. That's chopshopstore.com to where you can find it. And a 200-point itelescope.net account for doing astronomy all over the world because they've got telescopes everywhere on that

great network, nonprofit network of telescopes. Nahari Rao, we hear from him now and then in Sugar Land, Texas. He says, with the moon moving away from Earth at about 3.8 centimeters per year, there will come a time when eclipses will vanish. Earth-moon will be tidally locked and the moon is so distant that it cannot block the sun entirely. No lunar or solar eclipses as we know them today. He made all that up, right? Yes, man. If it makes you feel better. Thank you. But we don't have to worry about it because those are really far off in the future. Yeah, but I don't want to wake up in a billion years and be told no more eclipses.

You missed the last one. It was cloudy. If you wake up in a billion years, I'm pretty sure you'll be able to go somewhere else to watch an eclipse. Thank you. That's a good thought. Nick Chury in Scotch Plains, New Jersey. He says that this month's total lunar eclipse is number 20 out of 85 that we will have this century. Does that sound about right? Sure. No, it sounds certainly in the right ballpark. I don't know if it includes

ones that are just penumbral eclipses, although it may not. Probably, sure, I'd buy that. But what happens in a billion years? Zoe Reinerts in Germany, one of our many listeners in Germany, sent a separate poem or a fragment of a poem, this from Thomas Hardy, from his poem, At a Lunar Eclipse. Thy shadow earth from pole to central sea now steals upon the moon's meek shine in even monochrome and curving line of imperturbable serenity. That is lovely. And with that, we're ready for another one. Here's your question. What was the last human mission to end with a splashdown in the Atlantic Ocean? Go to planetary.org slash radio contest. That's got to stretch pretty far back. You have until the 30th, January 30th. That's Wednesday at 8 a.m. Pacific time to get us the answer.

And here is that prize package. Five winners will receive the brand new Blu-ray release of First Man, starring Ryan Gosling as Neil Armstrong, because the studio has given us a bunch of these to give away. Two additional winners will receive either Extronaut or Constellations, those great space exploration and astronomy board games from Dante Loretto. So one person will get Extronaut, another will get Constellations, and wait, there's more. Someone else will get the full set of five kick asteroid

stickers from the Planetary Society Chop Shop store and a 200 point itelescope.net account. So eight winners in a couple of weeks when we answer this one. Matt, you're so generous. Thank you. This is a kind of an experiment. We've never done anything like this. So let's see what the response is. It's a pleasure talking with you and I think we're done. Alright everybody go out there, look up at the night sky and think not only about sunglasses but about

moon glasses. Thank you and good night. You know maybe that was the problem. Maybe I forgot to take mine off. Anyway, he's Bruce Betts, Chief Scientist of the Planetary Society who joins us every week here for What's Up. Planetary Radio isist of the Planetary Society, who joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made

possible by its steadfast members. Mary Liz Bender is our associate producer. Josh Doyle composed our theme, which was arranged and performed by Peter Schlosser. I'm Matt Kaplan, Ad Astra.