Planetary Radio: Space Exploration, Astronomy and Science - Dawn: Ten Years of Exploration

Episode Date: October 11, 2017

Dawn Mission Director and Chief Engineer Marc Rayman helps us salute the ion-engine powered spacecraft that first orbited asteroid Vesta in the main asteroid belt and then moved to dwarf planet Ceres, revealing two fascinating worlds.Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

Ten years in space, the Dawn Mission, 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. Dawn Mission Director and Chief Engineer Mark Raymond is back to celebrate the 10th anniversary of the only spacecraft that has orbited two solar system destinations. Bill Nye has also returned, sort of. I talked with him on the eve of his departure from Australia, where he delivered a keynote presentation at the International Astronautical Congress. And we've got more space art to give away on this week's What's Up segment with Bruce Betts. Last week was a big one for us space geeks.

It brought the 60th anniversary of Sputnik 1 and a meeting in Washington, D.C. that my colleague Casey Dreyer could not miss. Casey, great to get you on the regular edition of the show. And we will, right up front, let everybody know, make sure they know that the October edition of the Space Policy Edition is out and ready for people to listen to. It has this great interview that you did with Michael Neufeld of the Smithsonian Institution, a terrific conversation about the V-2 rocket. But we had to record it basically, what, a couple of days before something very important happened in Washington, D.C. Tell us about this meeting of the National Space Council. Well, as you said, it was the first meeting of the National Space Council. That is, the executive branch reconstituted this special group, which consists of the heads and leaders and cabinet members of various agencies that all have an interest in space. It's led by the vice president and the executive secretary of Scott Pace, who is the director of the Space Policy Institute, longtime, very well respected space policy mind. And they had their first public meeting. It was at the Smithsonian offsite secondary museum right in front of Space Shuttle Discovery.

secondary museum right in front of Space Shuttle Discovery. You had Secretary of State was there. You had the Deputy Secretary of Defense. You had Secretary of Transportation and Commerce, very high level folks, as well as the CEOs of basically every major aerospace company, including SpaceX, Lockheed, Boeing, all of them there, talking about what to do next in space. And there's also, I would say, a relatively important announcement of space policy, despite this being the first meeting of the Council. And that announcement has everything to do with where humans, at least American humans, are going to be going in space. It sure does.

So for all you keeping track, in the last 15 years, NASA was going to send humans to the moon, then to an asteroid, then to Mars. And now we are back to the moon, everybody. So, which is kind of what, and I like to emphasize this, kind of what NASA was already doing in the first place. It's just how much is going to be in orbit versus on the ground, and those types of questions we do not yet have answers to. It was a very interesting presentation, and they really were just, it appeared to me anyway, to be basically a series of presentations, mostly by these corporate executives that you mentioned. There was a big audience. The vice president, the chair, began it

with a statement that, at least to my ears, sounded like he was saying the United States lost its leadership in space. I don't know if you saw my Twitter post where I said Cassini, Hubble, Curiosity. What are these? Chopped liver? And not to mention, let's say, the largest orbiting space station in human history, the International Space Station. Yeah, and a thriving private commercial sector that launches rockets, a third of all the rockets in the world. Yeah, it's a very political statement. And as you saw, notably, none of the CEOs of any of the aerospace companies that were asked that question really agreed with the fact that we're not leading in space anymore, we being the United

States. Now, I think Brian Berger from Space News had a nice comment on that, which is maybe what they're really reacting to is we're not leading as much or the perception is the gap is narrowing. And that's true. But that's not really the fundamental problem. There's a lot of issues in space and the future in space. And human spaceflight takes up most of the attention because, as we talked about, it doesn't have this external driving force to create consensus about what should we do with humans in space. Space science at NASA, you have a bunch of scientists.

You have major questions of the scientific community. Scientists can get together. They can sit down and they can generally agree about what are the most important problems in their field. That's the whole process for this. and that's how they direct NASA. Here's what we think NASA should do, and that works really well. There is no equivalent process for human spaceflight because you can send humans to the moon for a certain reason. You can send humans to Mars for certain reasons. They're both totally legitimate reasons, and there's no one reason that's better than another reason.

If there was, we would have chosen a destination and stuck to it by now. It's very much a process of what do we do with this capability. And this is why we have this constant seesawing back and forth between where to send humans to. Again, we have more, as I said in my article, I wrote a big thing about this with Jason Davis at the Society. I have more questions than opinions at this point. Fine, if we want to go to the moon and onto Mars, okay, I need to be convinced. How does going to the moon in a big way help us get to Mars any faster? I have not yet seen that answered. We don't even know exactly, what does it mean by going to the moon? Are we going to make a moon base? We don't know. Are we

going to keep doing the deep space gateway, which NASA was already intending to do, which is a lunar space station, basically, which would also be, quote unquote, going back to the moon? Are we going to turn the surface over to private interests? Are we going to compete those contracts? None of these details are spelled out yet beyond the policy intention to go to the moon. And you even saw kind of a fascinating memorandum from Robert Lightfoot, the current acting administrator of NASA, which is another kind of interesting part. They had the first Space Council meeting without a seated NASA administrator in this new administration that really said, you know, we continue to talk to the White House and talk to them about the importance of the Deep Space Lunar Gateway,

which is, again, what they already wanted to do. But really clarifying that this new policy basically removes the go to the asteroid part of President Obama's previous national space policy, which had largely been forgotten by this point. But that may be the extent of this directive. So it's really still unclear on the implications of this statement. Casey, I'm willing to bet that you and Jason Callahan will have much more to say about this in the November Space Policy Edition of Planetary Radio, which will be available on the first Friday in November. Until then, I do encourage folks to read that piece that you and Jason Davis posted at Planetary.org on October 5th. It's called We Choose to Go to the Moon and Do the Other Things. And even more recently than that, Casey has posted,

on behalf of the Space Policy and Advocacy Area of the Planetary Society, a quarterly report, planetary.org as well. Casey, I'll see you next month and on the moon. Can't wait to talk about it, Matt. Casey Dreyer is the Director of space policy for the Planetary Society. Bill Nye is the CEO of the Planetary Society. At the moment, I am looking at him on Skype, literally halfway around the world, where he has just come down from climbing the bridge over Sydney Harbor.

I wish everyone could see your new hat. Yes, they issue you a hat, Matt, and the hat has a ring, a triangular-shaped ring that you clip to your jumpsuit. So if the hat blows off your head, it won't blow off the bridge. I thought maybe they clip it to a little guy wire so that if you fall, they can give the hat to someone else. If you fall, you're clipped to a guy wire. Do you know the story? It's quite a beautiful stainless steel mechanism that you're clipped to as you walk all over the bridge. It's very cool.

It's a thing to do. It's exciting. But, Matt, that's not why I was in Australia, as you may know. I was here for the International Astronautical Congress. The Planetary Society was well represented there. I was there along with our communications director, Aaron Greeson, social media guy, Andrew Pauly. And we had a great time meeting a lot of people, collecting a lot of business cards. We met a lot of people that want to be outreach coordinators around the world. So we're expanding our global reach a little bit, maybe more than a little bit.

And I did a talk about our beloved light sail. Which I hear went extremely well, I've heard from reliable sources. I also heard that from the head of the IAC, Brett Bennington, who was our guest on last week's show, the man who ran IAC. He said it was a very successful gathering. That was your impression? Oh, yeah, it was really good. This Astronautical Congress really features people from around the world.

I mean, the Planetary Society is based in Pasadena, California. When people from the U.S. think of space exploration, we generally think of NASA, National Aeronautics and Space Administration. But when you go to the Astronautical Congress, you meet people from the European Space Agency, from Japanese Aerospace Exploration Agency. And Roscosmos, the Russian space agency, and the head of the Mexican space agency. It was cool. It's much more international than I think U.S. listeners are used to. And you realize how much money is spent in space. Wait, all the money that's spent in space

is really spent on Earth. Cool. It was really good to be there for us. And we got everybody, many people excited again about the remarkable idea of solar sailing. I'm excited about getting on the Falcon Heavy second rocket and going into space. Elon Musk spoke about his very large rocket idea and he made extraordinary predictions. But his idea of using or their idea of using carbon dioxide from the atmosphere to make methane for rocket fuel is pretty cool. And the energy for that process would come from renewable sources. Mr. Musk left the Astronautical Congress to go to South Australia to what you might call the outback or the beginning of the outback, the end of the Outback, and set up the world's largest

lithium-ion battery array. And they're going to store energy from these enormous wind turbine areas or farms. And that way, they will have energy overnight. So after Elon Musk made this announcement about the world's largest lithium ion battery array. We went to the outback with a member of parliament of South Australia, a guy named Kai Marm. And he is a cool guy who really promotes renewable energy and sees South Australia as leading the world in this technology. And they have entire days where they run their base load, as we call it, and their peak load off wind and solar. So this can be done, and a lot of investment in space. It's really cool to be there as representing the Planetary Society. Before we wrap up, Bill, your thoughts about Australia announcing the formation of its

own national space agency? It was great. So during the opening ceremony of the Astronautical Congress, which was on a Monday, it was quite a moving ceremony. They had Aboriginal people lighting a fire on stage. They had a fabulous dance, this wonderful outer space style graphics. And then the Minister of Science and Industry comes out and announces that Australia has its own space agency. Now, many people thought Australia already had a space agency because of the important contribution of Canberra. But it was really a moving thing. It was fantastic.

And as I say all the time, NASA is the best brand the United States has. And I won't be surprised if the Australian Space Agency becomes the best brand Australia has. It was a great Congress. Sounds like you've had a wonderful stay and I know you're headed home tomorrow. Have a great trip and we'll see you back here in the Northern Hemisphere. Thank you, Matt. Carry on.

Bill Nye is the CEO of the Planetary Society wrapping up that trip to Australia and a keynote presentation at the International Astronautical Congress. If you missed it, listen to the show from last week with Brett Bennington. Now we head out to the largest asteroid by far in the asteroid belt with the Dawn spacecraft and Mark Raymond. Last week's 60th anniversary of the space age nearly coincided with the 10th anniversary of a mission that has gone where none has gone before, twice.

I've invited one of our favorite guests, Mark Raymond, to give us another update on the Dawn mission to Asteroids Vesta and Ceres. The spacecraft has achieved so much throughout its decade in space, it has now been orbiting and revealing dwarf planet Ceres for more than two and a half years. As you'll hear, it has answered some of the greatest mysteries about that world, even as it has posed new questions, such as science. Mark has been with the mission from its beginning. He is both chief engineer and mission director for NASA and the Jet Propulsion Laboratory. Mark Raymond, it has been too long.

Thank you for returning to Planetary Radio and for doing it here at Planetary Society headquarters. Well, it's always my pleasure to talk to you, Matt, but thank you not only for having me back, but for showing me around this wonderful facility. I think it's terrific. Well, as you could tell, I love giving tours of the place. It's really fun. As our audience hears this, you and the Dawn team will have just passed the 10th anniversary

of the launch of the spacecraft. Well, I will have passed it. The Dawn team will have passed it. But you left out two other important participants in this. The Dawn spacecraft will have passed it. The Dawn team will have passed it. But you left out two other important participants in this. The Dawn spacecraft will have passed it, and humankind will have. I mean, I always come back to the same point with Dawn and other missions like this. This isn't a mission of the Dawn team. It isn't a mission of the science community. It isn't a mission of NASA or engineering and science. These are missions of humankind, and that's what I think is so special about them. Well put. How is the spacecraft doing after 10 years tooling around the solar system? It's doing very well. We never expected that the mission would last this long, and it's surprising that it has, given the crucial components that have failed on the spacecraft. You probably remember that we have these devices called

reaction wheels that are disks that we spin electrically. And by changing the speed at which these wheels spin, we can make the spacecraft rotate or stop rotating, hold it stable. And we need three of them, of course, because we have three axes, X, Y, and Z, or pitch, roll, and yaw, or chocolate, vanilla, and strawberry, whatever you want to call them. We need three, so we carry four, and three have failed. And this could be truly dire for missions. But Dawn has now actually flown for more than half of its time in space with at least one of those wheels no longer operating.

You knew exactly where I was going to go without me telling you. And I want to find out how you've managed to do this with only one reaction wheel. But first of all, what's up with these things? They fail on spacecraft all the time. Is it just mechanical stuff in space? Well, mechanical stuff in space is always considered a risk because you can't fix it in general, and it has to work in a hostile environment after usually having a very rough ride from Earth into space.

So engineers prefer not to have devices that move, but in some cases you have to. But I should point out that there are many very reliable reaction wheels. Spacecraft have been using them for quite a long time, but there was just a run of wheels, a production of wheels that turned out not to perform very well. So missions both before and after this period of missions that have suffered problems with them really don't have too much to worry about. So I almost forgot to mention that there is such a great parallel right now. The fad is sort of dwindling, but do you know what I'm going to mention? The spinners that every kid in America was at least a month or two ago, you know, walking around and trying to use in the middle of class in school. Because you're

basically looking at just a gyroscope. That's right. But the wheels on satellites and spacecraft have to operate under even harsher conditions than they're subjected to by the youth of America. That's right. All right. So how have you gotten around this problem? I mean, as you said, you need three to work in three axes. Right.

And we launched in 2007. The first one that failed was in June of 2010, about a year before we began Vesta operations. Second one failed in August of 2012 as we were departing from Vesta. The third one failed in April of this year. And by the way, we don't have a one-wheel mode. So once the third failed, we operate without wheels at all. As for how we've managed, it's been through the usual amazing creativity that NASA brings to bear on the execution of its deep space missions. And the team at JPL, in collaboration with colleagues at Orbital ATK, really stepped up to this challenge. And well, let's see, when the

first one failed, the day after it failed, we got started on developing software to work with only two wheels so that if another wheel failed, we would be ready to switch over to using just two wheels in combination with the small supply of hydrazine, a conventional rocket propellant that's on the spacecraft. And it was not carried for the purpose of controlling the orientation of the spacecraft. The hydrazine was not. The hydrazine was not. So reaction wheels in space can gradually, through a complicated process that I could explain if we wanted to take the time, but maybe you can just take my word for it, that over time they will gradually speed up, go faster and faster and faster. And so we need a way to reduce the speed. And the hydrazine was carried for that. It's called desaturating the wheels because they get saturated with, actually with angular

momentum. Newton would be proud. He would. And we're proud that he's a member of our species. So the hydrazine was carried only for that purpose. But we adapted the hydrazine and modified the software so that we could operate with two wheels in combination with the hydrazine. And so when our second wheel failed, we were ready to go with that. But another thing we did is we needed to conserve hydrazine because we didn't have enough for these purposes.

So after the first one failed, again, that was June of 2010, in August of 2010, we powered all the wheels off, and we operated only with hydrazine control. We changed parameters on the spacecraft to make that more efficient than it otherwise would have been. But we wanted also to preserve the now recognized to be limited lifetime of these reaction wheels for when they would be most valuable, which was in orbit around Vesta and Ceres, not in orbit around the sun.

It's a long, complicated story, but the bottom line is that we came up with quite a few new methods of operating the spacecraft in order to extend the lifetime of the wheels and to preserve the hydrazine, to do these two things together. Will it be running out of hydrazine that will eventually end the Dawn mission just as it has ended the Cassini mission? The short answer is yes. The most likely reason for the Dawn mission to end is that we'll run out of hydrazine. The difference is that the fabulous Cassini mission,

which in my view is truly one of the best robotic missions NASA has ever undertaken. I'm not limiting that even just to planetary missions. I think Cassini is an underappreciated mission that is really, truly fabulous. But Cassini managed to stretch its hydrazine to last for many, many years beyond what anyone had ever anticipated. And it never needed to use the hydrazine in ways that were grossly different from what was anticipated when it launched. Dawn, however, is using the hydrazine at a much, much faster rate than we ever expected before we had wheel problems. And so it's going to lead now to an end of its life in the not-too-distant future. I should say that's fine because we completed our prime mission in 2016.

Yeah. We're wrapping up now our first extended mission. So even despite these failures, we're getting a fantastic return from the mission. And we're going to talk about some of that scientific return. return from the mission. And we're going to talk about some of that scientific return. After we talk a little bit more about the spacecraft, we've known from the start that only a spacecraft with solar electric propulsion, the ion engines that you've got on the rear end of Dawn, could have done what this mission has done, orbiting two different bodies. Still the only spacecraft ever to do it, right? That's right. It's the only spacecraft to orbit two different destinations.

Yes. For the space enthusiasts who listen to this, and that's quite a few people, I'm always careful to point out it's not the first spacecraft to orbit two solar system bodies. It's not the first spacecraft to orbit two objects, which is the description that many people use, because of course, spacecraft have orbited the Earth and the Sun. Spacecraft have orbited the Earth and the Moon. But it's the first spacecraft to have the capability to go to two extraterrestrial destinations. The Sun isn't the destination for most of those missions, nor of course is Earth. for most of those missions, nor, of course, is Earth.

But Dawn has the unique capability to leave Earth far behind, went to distant Vesta, orbited it, maneuvered extensively in orbit, and then left it, traveled for another 900 million miles in two and a half years to Ceres, which it now orbits and has maneuvered extensively there. Sorry for the aside. That's quite all right. It's very interesting. But what surprised me is what you told me just recently, which is that only a mission with solar electric propulsion

was really practical or affordable, as you put it, to reach either one of these destinations, Vesta or Ceres. That's exactly right. It's impressive, I think, that in 60 years of space exploration, this is the only spacecraft to orbit to deep space destinations. But as you're pointing out, NASA would not have been able to afford going to either Vesta or Ceres without ion propulsion within the Discovery Program, which is the fantastically successful and productive program of relatively low-cost planetary missions,

these destinations would have been too difficult to reach within that program without the ion propulsion. That is, either destination would have been too difficult to reach, yet we've managed to do both. I learned that Dawn has far exceeded the change in velocity achieved by any other spacecraft under its own power, and that over this period of years, those little ion engines have essentially equaled the output of those massive chemical rockets that got the spacecraft off the surface of Earth. It is pretty amazing. The Delta II rocket that we used with its nine solid strap-on external motors

and its first stage and its second stage and its third stage, all combined, imparted about the same velocity to the spacecraft that Dawn's gentle ion engines have accomplished, emitting this cool blue glow. It is cool. And as you know, thrusting with a force comparable to what you feel if you hold a single sheet of paper in your hand. So Dawn now changes velocity by in excess of 25,000 miles per hour. You will pardon, I hope, this inaccurate

description, but it does... I'll pardon anything for you, Matt. Thank you, Mark. Well, you haven't heard it yet. Oh, true. It does seem that Dawn has been flitting higher and lower ever since it got to Ceres. You know, it acts like a love-struck seagull. It sounds like a put-down. It's not. It's a wonderful capability. I mean, you've had how many different orbits just at Ceres? That's right. I think we're in our seventh different science orbit. And unlike spacecraft that orbit planets like Jupiter and Saturn,

where they have the gravitational effect of the moons to help modify the orbits, and unlike spacecraft that orbit Mars and Venus, where they have the atmosphere that they can use to modify the orbit, Dawn has to do it all by itself. And that's another one of the benefits of having the ion propulsion system. So we've maneuvered a great deal in orbit to optimize our scientific investigations. And so we've changed the altitude of the orbit, and we've changed the altitude of the orbit, and we've changed the orientation of the plane of the orbit. It's allowed us to conduct scientific investigations

that we would otherwise simply not have been able to do. And I should say, it's really fun to be flying a spacecraft around a dwarf planet. And we are piloting this thing extensively. And I think that's neat. So let's talk about a dwarf planet and we are piloting this thing extensively and I think that's neat. So let's talk about that dwarf planet. Is Ceres unique in our solar system? It is unique. It's unique in several ways. One of the ways is it's the only dwarf planet in the inner solar system. It's the only dwarf planet inside the orbit of Neptune. So Vesta doesn't count, not quite there. Vesta doesn't meet the criteria of a dwarf planet.

It's unique in some other interesting ways that maybe we can just dispense with briefly, just some sort of cool facts about Ceres. One is of the truly millions of objects orbiting the sun between Mars and Jupiter in what we, of course, call the main asteroid belt, about a third of that mass is in Ceres. I think that really is remarkable.

Yeah, it certainly is. It's also, by a substantial amount, the largest body. Vesta is the second largest and the second most massive. And as another just fun tidbit, Dawn has now single-handedly explored 40% of the mass of the main asteroid belt. So not to say 40% of the bodies in the belt, but 40% of the mass. 40% of the mass that's there. Key point. How well do we now know the surface of this world? Pretty well. We do. We certainly know what it looks like in great detail. We've fully mapped the surface

at 35 meters per pixel. That's about 120 feet per pixel. And for reference, Dawn's requirement, that is our objective when we built the spacecraft, launched it, and even as we flew to Ceres, was to map it at 200 meters per pixel, so about 660 feet. So we're about six times or so better than that. I think that's pretty good. We've mapped it in color. We've gotten visible and infrared spectra over much of the surface. We've acquired gamma-ray and neutron spectra and general nuclear spectra. So we not only know what it looks like, but we know a lot of what it's made of. We also know about the subsurface. And so now the planetary geology community is working on

putting all that together to understand how this alien world works. Where did it come from? How did it get to the state that it's in now? And what is the current geological activity occurring there. I've seen a very nice topographic map, too. That's right. We took pictures in stereo, and so that has allowed us to determine how high the mountains are and how deep the craters are. Let's talk about some of that stuff that is exciting scientists and that data that's going to live on much longer than the spacecraft, I'm sure.

You found water ice. That's sure, you found water ice. That's right, exposed water ice. Which can't have been there for very long, right? That's right. Ceres is close enough to the sun. It has a slightly elliptical orbit, not even as elliptical as Mars orbit, but it varies from a little over two and a half astronomical units, of course an astronomical unit being the average distance between the Earth and the Sun.

So it varies from a little more than two and a half astronomical units to a little less than three from the Sun. And at that distance, exposed ice is not stable. The Sun would warm it too much, and the ice would sublimate, that is, transform from being a solid to a gas. And yet Dawn has observed ice on the surface. So it can't have been there for long. It couldn't have been there for geological time scales. So there must be some process that exposes it. There are a number of candidates for that. Could be something as simple as landslides, for example. So that doesn't

necessarily require internal geological processes. That is, there could be ice under the surface, and an impactor comes, excavates a crater, imparts energy to Ceres, and so Ceres shakes, the ground shakes, and exposes ice. Landslides can occur for other reasons as well, including that there's an existing crater with a steep wall, and gradually over time that wall becomes unstable and collapses and exposes ice. So it could be something like that. But we have other reasons to believe that there is active geology going on on Ceres. And so it's possible that there are geological processes that are bringing ice up to the surface from below.

That's Dawn Mission Director and Chief Engineer Mark Raymond. He has much more to tell us about Dwarf Planet series when we return. This is Planetary Radio. Where did we come from? Are we alone in the cosmos? These are the questions at the core of our existence. And the secrets of the universe are out there, waiting to be discovered. But to find them, we have to go into space.

We have to explore. This endeavor unites us. Space exploration truly brings out the best in us, encouraging people from all walks of life to work together to achieve a common goal, to know the cosmos and our place within it. This is why the Planetary Society exists. Our mission is to give you the power to advance space science and exploration. With your support, we sponsor innovative space technologies, inspire curious minds, and advocate for our future in space. We are the Planetary Society. Join us. future in space. We are the Planetary Society. Join us. Welcome back to Planetary Radio. I'm Matt Kaplan. As we've heard from Mark Raymond, the Dawn mission is nearing its inevitable end,

but it's not there yet. The solar electric powered spacecraft is still investigating Ceres, the largest object in the main asteroid belt. Mark has more to share about what Don has taught us about this unique world and what Ceres has told us about the dawn of our solar system four and a half billion years ago. Did this dwarf planet once have an ocean? Or might it still have one hidden away? Yes to both. And I think that's really cool.

So there's growing evidence that at one time in the past, Ceres had a global ocean. And one of the reasons we believe that is because the minerals that are observed on the surface require the interaction of water and rock under pressure. of water and rock under pressure. So it couldn't be that these minerals formed from water that made its way to the surface, even if it could survive there for a short time, the pressure wouldn't have been high enough. It would have needed to be in an ocean. Because it's distributed globally, there's good reason to believe, that contributes to the reason to believe that it wasn't something that formed underground and then was pushed to the surface by convective processes that are driven by internal heat,

because those should differ in strength at the equator from at the poles, because it's colder at the poles than it is at the equator. But that's not what we observe in the distribution of this material. than it is at the equator. But that's not what we observe in the distribution of this material. This is the evidence, part of the evidence, that Ceres may have had a global ocean. But then that global ocean eventually would have frozen at the surface, so it would have been an ice shell with liquid underneath it.

And that ice, so this would have occurred, of course, because Ceres would have cooled off. It would have lost its radioactive heat as the material decayed. And then that ice would have sublimated, again, gone from the solid ice to a gas where the water molecules would have just dissipated into space. But it also would have been lost by the impact of debris in the asteroid belt. Ceres is the giant, but the little guys are always picking on him or her. And so the impact of these small asteroids would have chipped away at that ice

and over relatively short geological timescales could have removed many miles thick of ice. Just knocked it off into space. That's right. And so what's left is now the bottom of that past ocean. But you also asked about an ocean inside. The short answer is we don't know, but it's possible that there is liquid water under the surface of Ceres. The reason that can be is there still is internal heat at Ceres left over from its formation and the radioactive materials that were incorporated in it. Some of the minerals that have

been found on the surface make great antifreeze. And so they can change the freezing temperature of water. And so that mixed in with the H2O that's beneath the surface could cause some of it still to be liquid, which is a pretty intriguing possibility. It's mind-blowing, adding Ceres to this growing list of water worlds. Right, ocean worlds. Yeah, exactly. It's absolutely fascinating. Talk about the organics that you found on the surface, you and the team and the spacecraft. Right. Well, and it's in particular the infrared spectrometer. So infrared, of course, being wavelengths of light that we can't see but we know are there,

and the spectrometer breaking the light into its constituent colors, and then it shows the sort of the fingerprint of the material that reflected it. Then by looking in infrared, this device showed the signature of organic materials, mostly around one particular crater, but in another location as well, spread over a large area, and not exclusively inside this crater, not in another location as well, spread over a large area and not exclusively inside this crater, not exclusively outside it. So it's not as if somehow this is just limited to this one location. We've talked about water. We've talked about heat. I've referred generically to other chemicals being there. And now we're talking about organics.

So together, that's a recipe that's of great interest to astrobiologists. Or it's not the recipe, it's the ingredients, excuse me. Yeah. Well, and it's almost a cliche now. You find these three things anywhere on Earth, the only planet we've actually been able to sample adequately, and what do you find? You find life.

That's right. only planet we've actually been able to sample adequately. And what do you find? You find life. That's right. I mean, my goodness, to consider not just an ocean world, a water world, but another place where maybe we ought to be looking for critters someday. Well, and even if we're not finding, you said looking, and I agree with that, even if we're not finding critters, it's chemistry that's important for understanding what could happen, what are the conditions that might have been on early Earth or on other bodies, and under what circumstances does that lead to life, and under what circumstances does it not?

I mean, this is part of the bigger scientific process of understanding astrobiology. And this body series is as old as the Earth, right? That's right, yeah. There's a volcano, or more accurately a cryovolcano. That's right, yeah. Ahunamanz, it's the tallest mountain on Ceres, about 13,000 feet or so. We spotted it early on, not too surprising given that it's the tallest. And for a while, some people were calling it the Lonely Mountain because it's in an otherwise unremarkable area, large plains. There's a nearby crater, which is geologically unrelated to it. For a while, some people were calling it the conical mountain.

Some people also, for that matter, were calling it a pyramid, which always puzzled me because it doesn't even look like a pyramid, but that's okay. It's just a word, right? You have to squint and use your imagination, just like the face on Mars. Yeah, you have to squint, or maybe you have to just close your eyes. But the names aren't as important as what it is. And that is, as you said, a cryovolcano. So this is a structure that built up from cryomagma. So that is Ceres is colder than Earth. Everything there operates at a different temperature. And on Ceres, this cryomagma would have been composed of a mixture of salts and rock and water. So another name for that is mud.

But it would have been pushed up from beneath through, again, internal geological forces that built up this structure. And the estimate of its age is that it's relatively young in geological terms. So it's many millions of years old, but young enough that it was formed long after Ceres itself formed. If this could have formed some tens or perhaps a couple of hundred million years ago, something in that range, then the forces that were responsible for it could still be active on Ceres today. I think that's really neat. I think that's really neat. We cannot finish, as we near the end of our time, without hearing the latest about some of those sometimes almost blindingly bright spots. You knew I had to bring it up, right? They were such a mystery.

There was so much speculation. It sounds like we have a pretty good idea what's going on now. We do. You called them bright spots. I don't think of them as spots anymore. They were spots when Ceres was just a small object in our camera. Now, Ceres is a world. These things are miles across. And you and I are here in Pasadena. And if we thought of this area of Pasadena being covered in bright material, we wouldn't call

it a spot. The formal name for these things is facula, which are bright areas. Can't say bright spots, but bright areas on a planetary body. And we believe the origin of them is the brightest ones are in a crater called Akator. You'll often hear it pronounced Akator and other ways, but the correct pronunciation is Akator. This 57-mile diameter crater was excavated by an impactor perhaps 30 million years ago or so. There's still some fair amount of uncertainty on its age, but something of that scale, relatively recent in geological time. But as we've discussed, underground is saltwater, mostly frozen. So this frozen saltwater. After the impact, that made its way to the surface. Perhaps long after, there's some evidence that the central bright region in particular may be as young as just a few million

years, four million years or so. In other words, it formed tens of millions of years after the impact, or at least was replenished that recently. But this salt water made its way to the surface. That water would freeze on the surface of Ceres and then sublimate, so the water molecules would disperse. But the salts that were dissolved in the water would be left behind. These are salt flats. I just was going to say, the salt flats that you don't have to go far to see, not far from where we are in Pasadena. You don't have to if you live where we are, that's right.

Yeah, exactly. And they just reflect really well. That's right. They just reflect a lot more light. The Ceres itself, the sort of typical Syrian surface, reflects around 9 or 10 percent of the light that falls on it. But these salt flats reflect well over 50 percent of the light. So they simply are a lot brighter. Those are the brightest, the biggest, most salient ones. But there are hundreds of these bright features identified on Ceres. So this is something that's going on all over this alien world, not just in one location.

Obviously, still a dynamic place. You're up high enough now that you're monitoring cosmic rays. How is that going to help us understand what's happening on this dwarf planet? Yeah, that's surprising. So the spacecraft spent more than eight months orbiting closer to Ceres than the International Space Station does to Earth. So it was about 240 miles. And there weren't any tall trees, and so the spacecraft was fine.

We got a fabulous view there. And, in fact, when we arrived at that orbit in December of 2015, our goal was to get about six weeks' worth of data. And with our faltered reaction wheels, low on hydrazine, and nearing the end of the mission, we would have been delighted, truly, with six weeks of data there. We got eight months and recognized at that point that the spacecraft was not going to last much longer there. Everything was going very well.

The flight team was managing the spacecraft. It was cooperating. Things were going beautifully. But we were spending hydrazine at a very, very high rate. And this was just because of the increased gravity of that world, the unevenness of that gravity? That's right. It's a combination of the—well, the stronger gravity means that in order to keep pointing its sensors at the surface as dawn goes around it, it has to rotate faster. And dawn has very large solar arrays.

They're almost 65 feet wingtip to wingtip. Got to run those engines, yeah. That's right. This is the distance from a pitcher's mound to home plate in a professional baseball field. Each individual wing is the width of a singles tennis court. And so there's a phenomenon called gravity gradient torque. I won't go into it in detail, but in brief, it means the spacecraft tends to tip under the influence of the strong gravity from Ceres.

And so Dawn was constantly having to counter that. If it had had fully functional reaction wheels, it would have been able to do that much more effectively. But it didn't have fully functional reaction wheels, it would have been able to do that much more effectively. But it didn't have fully functional reaction wheels. And so that also was costing hydrazine at a very high rate, very high. And so we had collected these nuclear spectra, that is measuring this radiation emitted from Ceres, that provides insight into the elemental composition. What are the atoms that are in the material down to about a yard underground? But we couldn't do that for much

longer by August of 2016, August of last year. And we recognized a clever way to improve those measurements. We didn't need to do any more photography there. We'd already fully photographed the surface. But we could fly to higher altitude and measure cosmic rays because the cosmic rays are a source of noise in this measurement. Now, people listening on digital radio here maybe are unfamiliar with the concept of noise, but older people like us, who maybe remember AM radio, static, well, the cosmic rays contributed noise to Dawn's measurements. And you would be interested to hear how often I have to deal with that. I mean, if I'm in a noisy room, unlike the one we're in right now, if I can get a recording of that noise, that air conditioner noise, exactly, I can subtract it from the signal, which I suspect is where you're going.

That's exactly right. And I even wrote a Dawn Journal sometime last year. trying to pick out a singer amidst all the different instruments where the instruments are so loud they're interfering with your ability to hear the words in the song. But if you can separately record each one of those instruments, or you can separately record the background noise, or Dawn can separately record the background hiss from the cosmic rays, then we can mathematically subtract that from what we measured when we were near Ceres and improve the overall quality of the recording.

So that's exactly what Dawn has been doing. Now, when we flew up to higher altitude, we did other cool measurements as well. But that was, I think, perhaps the most counterintuitive of the objectives of flying up to high altitude. And because at high altitude, the spacecraft can operate for much longer, it could make a really, really good measurement of this cosmic ray background that is proving to be a better contribution to these nuclear spectra than the short time we would have had by staying at low altitude. For the real nerds

here, of whom you and I are two, I think of it actually as like gravitational time dilation. And everybody that saw the movie Interstellar understands this. At low altitude, a short time passes. That's equivalent to a long time at high altitude. So Dawn had the resources to live for a short time at low altitude. That's equivalent, those resources are equivalent to a long time at high altitude. And let us reassure the audience that there is no danger that Ceres will become a black hole.

Before we finish, what's next? We're working on that now, and this really is a testament to the longevity of the flight system and the flight team's capability to keep Dawn healthy. And so while we're in this high-altitude elliptical orbit now, we're looking forward to NASA headquarters making a decision on what the next objective should be for Dawn. But I think Ceres is such an interesting place that we won't run out of good measurements to make to learn more about how this alien world works and what it can tell us about the dawn and the present of the solar system. That aptly named mission to this world that shows us maybe what our solar system looked like

when it was in the process of birth, including our planet. Mark, thank you very much for this update. It won't be the last. I hope not. We'll take it out to the end of the Dawn mission and celebrate that as well because it will be worth celebrating just like the one we just celebrated at Saturn. Best of luck to you and the rest of the team. Thank you very much.

I always appreciate your interest. It's always fun to talk to you, and it's especially fun to do so here at the Planetary Society headquarters in Pasadena. This is really neat. That's Mark Raymond. He is the chief engineer and mission director for the Dawn mission at the Jet Propulsion Lab. He has received a whole bunch of awards, three exceptional achievement medals, two outstanding leadership medals from NASA.

He was named a JPL fellow. He's the only person, I assume this is still the case, to have received both the Exceptional Technical Excellence Award and the Exceptional Leadership Award, two of JPL's most prestigious honors. He also knows the history of space travel and exploration as well as anyone I know. Here's somebody else who's no slouch when it comes to knowing space exploration. Time to visit with Bruce Betts for this week's edition of What's Up. Bruce Betts is the Director of Science and Technology for the Planetary Society.

He joins us every week for What's Up and therefore has joined us right now to tell us about the night sky. and therefore has joined us right now to tell us about the night sky. And we've got all kinds of other great stuff to share with you, including a new space trivia contest. Welcome back. Thank you. Good to be back. Well, in the pre-dawn sky, we've got Venus and Mars nearby. Venus much, much brighter in the pre-dawn east. Mars above it, reddish, much dimmer.

And on October 17th, the crescent moon is in amongst them. In the evening sky, we've got Saturn shortly after sunset or in the early evening over in the southwest. And the moon joins it on October 24th. We move on to this week in space history. We've been talking a lot about it for some reason recently, 20 years since the Cassini-Huygens mission launched on its way to Saturn. It's an amazing anniversary, and it almost made it to a full 20 Earth years of duration. Not that that has any effect on the success, the grand success of that mission. Nope, but I thought I'd mention it so we could reflect once more on how awesome that mission was.

And thank you for that. We move on to a random space fact. I couldn't decide what I wanted to be. So the magnetic fields of both Uranus and Neptune, the dipole, essentially dipole magnetic fields, are both shifted. If you look at the center, they're shifted by one-third to one-half of planetary radii away from the center of the planets. So it would be like having your bar magnet not running through the center but running like half of radii outside. half of radii outside.

That probably has something to do with the convective currents that are creating the magnetic dynamo running possibly in some shell of liquid weirdness. That is weird. Why, thank you. We move on to the trivia contest, and I asked you, what is the definition of the metallicity of a star. Many people had great fun with this. We got an extensive response from Manuel Uribe in Mexico City. It's a delightful note to read.

He mentions how he listens to us on the National Science Foundation's Science 360 radio service or online radio service, which is a terrific service. It has all of the greatest science shows available online and through broadcast and us. You mean us at the top, right? Yes, of course. And it really is a terrific service. I listen to it now and then myself. Yes, of course. And it really is a terrific service. I listen to it now and then myself. Kudos to the NSF for that. The reason I mentioned Manuel is because he was chosen by Random.org for his answer. He says, and he goes on at some length, so I'll abbreviate this. The metallicity of a star is in one way an indication of how early it was born after the beginning of the universe.

one way an indication of how early it was born after the beginning of the universe. But really what you're after, he thinks, is that it's a measure of how much stuff other than hydrogen and helium a star has. Is that correct? That is correct. It's the fraction of mass of a star that is not hydrogen or helium. And so, yeah, astronomers get kind of sloppy with the whole metal term and just say, well, if it's not hydrogen and helium, it's a metal. Not quite the chemist or physicist definition. Yeah, well, and I have a response related to that from Sam Lipson of Martinez, California, who teaches an intro to a chemistry class. He says, you've really messed them up, their classical definition of metals and nonmetals.

He's miffed in a humorous way. I swear it wasn't me. But it does sound like Manuel has won. So congratulations, Manuel, in Mexico City. You are going to receive a Planetary Society T-shirt, very cool shirt, I love to wear mine, a 200-point itelescope.net astronomy account on that worldwide nonprofit network of telescopes. You can look at anything around the universe. And the first of these artworks, a beautifully mounted print by space artist Simon Krager. And you can see more of this stuff at simonkrager.com. It's an Apollo lunar module descending to the moon's surface. And I really, I cannot tell you how lovely this is.

It is an absolutely gorgeous, I'm sorry. Yes, it's about to set down. That is right. I thought for, I got confused for a moment. I thought maybe it was lifting off, but no, it's got the descent stage there. So it's about to set down on the surface of the moon. So congratulations, Manuel. Keith White in Ottawa, Ontario. so it's about to set down on the surface of the moon uh so congratulations uh manuel keith white in ottawa ontario he says he thinks he remembers you breathing helium on some previous show

inhaling some helium and he wants to know were you attempting to decrease your metallicity yes i'm sure that was why i was doing it. Always in the interest of science. Mark Little in Ireland. The metallicity of the star that is Dr. Bruce Betts is measured on a one to ten scale, where one is, turn that racket down to ten, which is, give me some more amps, baby. I blew out my microphone. Do you like that? I liked the comment, and I really enjoyed your voicing it. He wants to know where you come in on that scale. I told him an 11, of course. Of course.

The Bruce scale goes to 11. Dave Fairchild, our poet laureate in Shawnee, Kansas. If you take a star and suck the helium away, then blow off all the hydrogen like it was Judgment Day, whatever you have left, you know, is very sure to be the fragment of the star that is its metallicity. Oh. Another nice one. Thank you very much, Dave. We're ready to move on. On what body can you find a 92-kilometer diameter crater named Murray?

kilometer diameter crater named murray named after bruce c murray founder of the planetary society my phd thesis advisor that we are officially once again playing where in the solar system oh and it has been a while we love to play that game so go to planetary.org slash radio contest and get us your entry i think i'm going to have to wait to identify the specific artwork until we've said goodbye. But you will get yet another wonderful print from one of these top space artists, members of the International Association of Astronomical Artists, along with a Planetary Society t-shirt and a 200-point itelescope.net account. Better get it to us, by the way, by the 18th. That'd be Wednesday, October 18th at 8 a.m. Pacific time. All right, everybody, go out there, look up at the night sky, and think about what you would place on a tripod. Thank you, and good night. A giant Martian killing machine. That's what I would put on a tripod.

Thank you. He's Bruce Betts. He is the Director of Science and Technology for the Planetary Society, who joins us every week here for What's Up. Still fun, you know, after almost 15 years. It is indeed. Thank you. No thank you. Okay, here's the scoop on the artwork waiting for you in the new contest. It's Simon Kregar's beautiful portrait of Neil Armstrong in his Gemini 8 space helmet. You can see it at SimonKregar.com. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its ion-powered

members. Danielle Gunn is our associate producer. Josh Doyle composed our theme, which was arranged and performed by Peter Schlosser. I'm Matt Kaplan. Check out my rare but choice tweets at atplanrad. Clear skies.