Planetary Radio: Space Exploration, Astronomy and Science - Opportunity Lands and Hope Builds for Spirit

Episode Date: January 26, 2004

We celebrate the perfect landing of Mars Exploration Rover Opportunity with special guest Rob Manning, plus lots more, including two more Student Astronauts, and a "name that outcropping" contest from Bruce Betts.Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

This is Planetary Radio. I'm astonished. I'm blown away. Opportunity has set down in a bizarre alien landscape. That was Mars Exploration Rover Principal Investigator Steve Squires on the astounding first images from the second spacecraft to land safely on Mars this month. Hello everyone, and congratulations. Our species has once again gone where no one has gone before. There was plenty of reason to celebrate Saturday evening and Sunday morning, January 24 and 25. Here's NASA Administrator Sean O'Keefe.

Certainly the imagination and the interest of, I would suggest, the world has been captured by this remarkable set of achievements, as hard as it is. Again, there are four billion hits to the Web site in the last 24 days. Probably by tomorrow morning. Probably by, yeah, another billion here in the last few hours, I'm sure. Is that right? But that's phenomenal. And that exceeds all of what we got on the NASA websites all of last year. That's testimonial to, I think, the remarkable interest that there is out there

and just absolute amazement at the capacity to do something like this. Head of JPL, Charles Elachi. I'm just speechless. So I'm going to be extremely brief. I was thinking I was coming here, a friend of mine told me, good things happen slowly but great things happen suddenly. Today I know exactly what they meant. Mars Exploration Rover Mission Manager Pete Tysinger had similar sentiments. We've done good. But no one at JPL was happier than Steve Squires in the wee hours of Sunday morning.

Right now, I'm just in awe of what this team has done and what Mars looks like. Dr. Squires, before you go on, I understand we've just received a very special gift for you from Dr. Jim Bell, and this one, we're not kidding. Yeah. And there was the first color image from Opportunity. Oh, look at that. Wow. We've got one up there. Wow. There you go. Meridiani Plata.

Oh, my God. Yeah! Well, come to think of it, our guest this week was at least as happy as Steve. Rob Manning and his entry, descent, and landing team had just witnessed another flawless performance of their spacecraft. In fact, this Caltech and Whitman College grad is now 3-4-3 with his airbag landings since he served as the flight system chief engineer for Pathfinder. Here's a bit of what he had to say in the first press briefing after Opportunity rolled to a stop on the Meridiani Plainham, beginning with his colleague's reaction to his introduction.

Thank you. Thank you very much. You know, I feel like, Richard, to thank everybody is just too hard because the amount of talent required to pull this off. I mean, the talent in this room is phenomenal. It's scary. And it represents a wonderful cross-section of our wonderful country, and I think that's something that most Americans really should be proud of, that there are people like this next door. They're all around us, and we shouldn't forget that,

because it's the kid who picks up a magazine early on and starts reading early. It's the young scientist. It's the people who have just an incredible curiosity about how the world works. Those are the people who do this, and that's what makes us special. And I think as human beings we should be very proud of our accomplishment because there are two exciting things that happened in our solar system tonight tonight one in mars and one right here in pasadena and i'm and i'm very pleased that uh i can report that it that we had a great night in the solar system of ours let me tell you some thank you

rob very graciously granted us more time than he could probably afford for a conversation last Friday afternoon. At that time, all looked great for opportunity, and hope was growing for the rover's twin, Spirit. Rob Banning, what is the latest from Spirit on this Friday afternoon, January 23? from Spirit on this Friday afternoon, January 23. It's actually good news. For the first time in days, we were able to get data back from the spacecraft that actually told us a little bit about what it was doing. And since we had this anomaly on Sol 18, we've gotten very little information. The spacecraft appears to have tried to speak with us, and then it's hung up the phone.

And so it's been very frustrating. We know it's been alive because we can hear the radio going on, but then it hasn't been saying anything. That is until today. And early this morning, Friday morning, we were able to get our first bit of ones and zeros from the spacecraft. And, boy, that really gives us all a big relief. Now, it's still, this vehicle is a long ways from being healthy.

And we can see in the data that there's strange things going on. The spacecraft appears to be going through these periodic computer resets. In addition, it looks like the computer has been awake a good fraction of the time when it should have been sleeping in these last two days. You've done a lot of design work for computers that have gone into space. You also worked for quite a while in, what do you call it, fault toleration and dealing with problems like this? Yes, fault tolerance. We write software, we put it on our vehicle, and I've done this for many years, that tries

to use the best resources, the minimum amount of resources required in order to get the vehicle to communicate back to Earth, or in some cases, to be able to complete the mission, even in the presence of broken equipment or broken software. And this has happened many times in JPL's history of requiring this need for this special software to come along and kind of take over the wheel of the vehicle, as it were, and make sure that it puts itself in a configuration where it actually can be saved by human beings. Well, we hope that this will be another one of those miracles that JPL pulls out of its bag of tricks.

I hope it won't even be at the level of a miracle. But does your past experience give you any unique insight into what might be wrong with Spirit? Well, it's actually not all that different in the kind of problems that people have with their own computers and their systems. I'm not at all convinced that this is a software problem. However, hardware and software are becoming much more complex as we get along in our technology. And just like the very complex hardware and software you have in your office or at home,

we have to do the same kinds of things. When things go astray, sometimes the best thing to do is to pull the plug back into the wall and reboot and see what happens. And we have not yet done that, as far as we can tell. The vehicle might, in fact, be able to do that in the next 24 hours. That's the Mars equivalent of control-alt-delete. Yes, exactly. The Mars equivalent of control-alt-delete. Yes, exactly.

No, not that that would solve all our problems, but it's certainly one possibility. And these complex systems, there's a lot of room for interactions to go astray. Now, I would have thought, maybe some other people might have thought, that your major involvement with the Spirit rover, the first of the Mars Exploration rovers, mostly came to an end after that incredible landing that so many of us were watching over at the Pasadena Convention Center, or watching you guys get the telemetry back anyway. But obviously that's not the case. You're still very busy.

No, in fact, one of the biggest things we had to do as soon as we landed Spirit, the first thing we had to do was figure out, well, is there anything about the entry-descent landing process, even though it might look superficially perfect, is there anything we can learn from that that we could figure out and apply to the opportunity entry-descent landing process in order to make sure that will go as reliably as we possibly can. And so we spent an incredibly intense two-week period going through every bit of data we can, carefully analyzing all this information to see what really happened.

Really, how close to the edge did we come? Did we get come close to the edge? Did the design work as we intended? Did the environment interact with our vehicle the way we actually modeled it to do beforehand? And so we went through all this analysis and all the studies, a lot of computer processing of the information, and lo and behold, we finished actually earlier than I even expected. And we were able to fold some of these lessons into the opportunity landing tomorrow night. I was going to say, with all this rush, one would think that maybe you had to do it all again in a little more than 24 hours.

Exactly. Well, fortunately, we finished all this work, and we have learned some very interesting things. Talk about that. Well, the first thing we learned, and we saw this coming before we actually arrived at Gusev, the atmosphere did not behave itself in the weeks before landing at Gusev. About the middle of December, we saw a dust storm which rose from the southern hemisphere

and on the other side of the planet from Gusev and gradually extended to a very large regional dust storm. Well, that's still a long ways from Gusev, but this dust, especially in the uppermost atmosphere, races around the globe. As it races around the globe and covers our landing site, Gusev, clear on the other side of the planet, what it does, it raises the temperature. The dust itself absorbs heat from the sun. It causes the neighboring molecules of carbon dioxide in the atmosphere to get warmer, and

it inflates the atmosphere, causing it to get less dense. And with less density, especially high up, that means that the vehicle is going faster lower. At the time you want the parachute to open, we're still going too fast. And the software did exactly what we told it to do. It said, hey, you know, I'm still going too fast. Even though I may be low to the ground, closer to the ground, we're still going too fast. Let's delay opening the parachute until we slow down enough

so that we don't overstress the parachute. And that's exactly the thing it did. Now, it turned out there was plenty of time to get to the ground at Gusev because by having less dense higher up, we also found it was more dense down below. So as we descended through the atmosphere, we found we were actually going slower down below. So that made up for some time. And we need all the time we can get, the time the parachute opens, the time we fire the rockets,

because there's a lot of things for the vehicle to do in that very short window. We talked a little bit about this with Mark Abler last week, and I mentioned that, as you seem to also be pointing out, it's a measure of how very intelligent this spacecraft is. Yes, we work very hard on a small number, actually quite a large number, of small programs that try to do the best they can at sort of optimizing something. In this particular case, there's a little software program that runs with the rest of the software whose job it is to assess how the vehicle is slowing down, and from that

make a best estimate of when to inflate the parachute. And it turns out that they can take a lot of software, but it is pretty smart for being so small. Likewise, there's a lot of intelligence in processing the radar altimeter data. By the way, all this has to happen automatically by the vehicle. We're just participants in the sense we're just watching this from a distance. Quite a distance, yeah. Quite a distance.

So the software, like the radar process, it has to look at this information from the radar and say, oh, my gosh, this is how fast I'm going. This is how high I'm going. For me to get this vehicle to stop at, say, 12 meters above the ground, which is our target, we find that the software has to make an estimate, look into the future and says, to do this right, I have to fire the rockets at this altitude and cut the bridle while the rockets are still firing at this time relative to rocket ignition so that I can get exactly to 12 meters above the ground. Well, that's what it tries to do.

Of course, because of all sorts of conditions, such as winds, that cause the system to tip, as it did with us, we know that the software won't be perfect at doing it. But it does a good enough job that, statistically speaking, we're always above the ground when we've cut the bridle, which is what we want. Yeah, good enough. Darn near perfect. Thank you very much.

It was very perfect. We were very thrilled, and that was a very exciting landing. It turns out we had a very, very large wind gust in the last 1,000 feet before getting to the ground, and that wind gust pushed the vehicle, not just accelerated it horizontally through the wind toward the east, but it also caused the whole vehicle to tip over eastward. And what that tilt does is because we use these rockets, these solid rocket motors, to slow us down vertically, that means they're not pointed straight up and down. If they're not pointed straight up and down, that means, although they'll do a pretty good job

of slowing you down vertically, that also means that they're going to straight up and down, that means, although they'll do a pretty good job of slowing you down vertically, that also means that they're going to cause you to keep going horizontally, and you actually give a kick in the very same direction that the wind is pushing you in. Oh, sure. And that's what happened. And, of course, we have good enough simulations, and this is a concern we even had back in the early 90s with Mars Pathfinder. What we did in this mission in order to mitigate that, we decided to put three little tiny rockets on the back shell, up with the three big rockets in the

middle between the parachute and the lander, the rover inside, way up high. There are three little rockets, and they're pulling it out the side. And they pushed the vehicle over under the control of more software that analyzes this horizontal motion. And sure enough, the combination of measuring the motion and taking pictures, the software then processes to figure out how fast we're moving. Those two things combined allowed us to correct for this very large speed we would have had had we not fired those little rockets horizontally.

And, in fact, we were able to reduce the speed by more than a factor of two, cut it in half. So we were very excited about that, that all the systems, all this kind of insurance policy we put into the design actually did its job. Very busy little spacecraft, and I want to thank you for taking a couple of minutes, more than a couple of minutes, to talk with us. Just as you were about to do this all over again, it must be another tense time up there. When we come back from a quick break, maybe we can talk a little bit about that

the next 30 hours or so. And again, we're speaking on Friday afternoon, the day before Spirit's twin, Opportunity, lands on Mars. Rob, we'll be right back. Thank you, Matt. This is Buzz Aldrin. When I walked on the moon, I knew it was just the beginning of humankind's great adventure in the solar system.

That's why I'm a member of the Planetary Society, the world's largest space interest group. The Planetary Society is helping to explore Mars. We're tracking near-Earth asteroids and comets. We sponsor the search for life on other worlds. And we're building the first ever solar sail. You can learn about these adventures and exciting new discoveries from space exploration in The Planetary Report. The Planetary Report is the Society's full-color magazine. It's just one of many member benefits.

You can learn more by calling 1-877-PLANETS. That's toll-free, 1-877-752-6387. And you can catch up on space exploration news and developments at our exciting and informative website, PlanetarySociety.org. The Planetary Society, exploring new worlds. Hi, I'm Abigail Freeman. I'm one of the student astronauts. I am from Maryland in the United States, and I'm 16 years old. During my time with the Mars Exploration Rovers, I got to witness Opportunity's landing,

which was an absolutely incredibly amazing experience. I was actually in the science assessment room with the entry, descent, and landing team during the landing, so it was really incredible to be with a group of people who had designed the landing system during the rovers landing when we first got here we were of course working with the spirit rover doing all the science we were there when the rover drove to Adirondack and employed the instrument arms we were also here when they started having the problems with spirit so we got to observe how they deal deal with serious problems like communications problems that they had with spirit. When I go home, I'm definitely going to keep up reading all the student astronaut journals.

I'm going to try and keep up with the news. And I really want to stay involved with planetary exploration and research. I can't wait to continue working on projects like the Mars Exploration River Project. Rob Manning is our guest on this week's Planetary Radio. He is the Entry, Descent, and Landing Development Manager for the Mars Exploration Rovers. He's pulled it off once, he and his amazing team. They're going to do it again as we're speaking.

Rob and I, Rob is sitting in a little conference room, found a quiet corner at JPL, which may be a little difficult right now, not too long before the landing of Opportunity. Rob, you've talked about how this very intelligent spacecraft, both of them actually, know how to compensate for things, mostly because of a lot of very smart software that you guys put together before they left Earth.

You must have also taken into account the landing sites themselves, because as we've heard from the science team, these landing sites, Gusev Crater and the Meridiani site, are very different. They are. In fact, our expectation at Gusev Crater and the Meridiani site, are very different. They are. In fact, our expectation at Gusev was, in fact, it was going to be even rockier and more slopes, more hills and bumps, than we actually see at our landing site. Now, it's not that they're not there. It's just that where we landed at Gusev was among the flattest parts of Gusev.

So when Steve Squire said we landed at the sweet spot, it was the sweet spot for both science and for engineering. So we were very, very happy to target very closely the center of the flattest part of the landing area. That made it very easy. But Meridiani, we've known for many years, actually for a year and a half now, it's actually a safer place and actually flatter. From the point of view of entry-descent landing, there are actually less hills and less bumps to consider ourselves with.

So we've always felt that Meridiani would be a safer place. The other thing about Meridiani, because it's not in a valley like Gusev is, it's actually in a wide, flat plain. Other than dust devils, like the dust devils you occasionally get at Gusev, the air is actually very stable, and we don't expect to see as much gusts and much winds as we saw in Gusev. So those two things make EDL a lot easier for us this time, but this is still a very scary thing to do. It's still...

We're still nervous. How much do you worry about an unexpectedly sharp rock that would be big enough maybe to penetrate one of those airbags? Well, we've done several things to mitigate that. First off, from Pathfinder, we went through and tried to make these airbags much more, even more robust than the Pathfinder airbags. We have six abrasion layers outside, and we have two interior bladders to protect us. So it's kind of like a bulletproof vest. If you take a knife and try to stab into it, you might get the first layers. You're very unlikely to get all the way through.

And even if we did, it turns out our gas generators are pretty good at replacing lost gas if the holes are small enough. So we continue to develop gas inside and keep the pressure going. So I'm really not that concerned about excessively sharp rocks getting us. It's mostly velocity, and if we can control the speed at the time of the first impact, that goes a long way to making a landing safe, no matter what the ground looks like. So I think we're okay in this department. So there are things, there are conditions and rocks and shapes, for example, tufa towers or funny-shaped, sharp rocks like the Devil's Postpile

or Hoi Hoi in Hawaii. That actually would be very bad for airbags, but we don't think any of those kinds of materials and processes were created there. All I can think is, wouldn't it be spectacular, though, if you got down on the surface and found some of those? Yes, it would be very interesting. But, again, I think even if we had some fairly rough terrain, I think the velocities will be under control.

And even with Gusev, with the big wind, we had a very easy landing. This was a much easier landing than even Mars Pathfinder landing. Even though the winds were there, the systems we put on board to fight the winds did their job. And so it was actually a pretty easy landing as far as landings go with airbags. Can you take a minute or so before we talk about what's going to be happening over the next few hours to review how you guys came up with this certainly unique but extremely successful so far way of landing a spacecraft on another planet, the airbag system. Well, in fact, this is an old idea.

The idea of using either some sort of compressible material or airbags for landing systems goes back to the 60s when people were trying to design low-cost or simple lunar landing systems. This was in a bag of tricks, even going back to the 60s, that we've had. It wasn't until about 1992, after a nearly 20-year hiatus from Mars after the successful Viking landers missions, that we actually said, well, how can we get to Mars without costing $3 billion? So the whole idea of a faster, better, cheaper mission was born in 1992 with the Mars Pathfinder mission. And at that time, it was much more like the Beagle system with a parachute and a very small lander and airbags without rockets or these other things.

Well, it turned out that we couldn't keep the mass under control. In order to talk directly back to Earth, everything had to get bigger. So we found that we just couldn't do it with airbags and a parachute and a heat shield alone. So we ended up adding these rockets and kind of stole ideas from the Army where they used actually rockets below parachutes to deliver large pieces of cargo to the ground. This is not an unusual terrestrial application. So we stole that idea. So we basically have been adding features to this landing system, adding it to the complexity

as we go, to try to make it more reliable. Our guest is Rob Manning. He can speak with authority about the Pathfinder mission as well. He served as the Flight System Chief Engineer for that very successful program. He is now the Entry, Descent, and Landing Development Manager for the Mars Exploration Rovers. Landing of Opportunity, as we speak, is, I don't have a clock around, but it can't be more than about 30 hours away. Are you going to be getting much sleep between now and then?

I intend to. I've been up a lot supporting the SPIRIT team. Those of us who are focused on Opportunity have really had to drag ourselves away and concentrate entirely on opportunity for the next day and a half. And I think opportunity is looking great. It's healthy. It's on target. We decided not to update the parameters just a couple of hours ago. Everything that's on board is probably going to be good enough to get us to Mars perfectly.

Without any further updates, our trajectory is right on, and we're going to get there, and we'll see how it goes when we hit the atmosphere. And a lot of us will be watching once again on NASA TV, as we'll be tense along with the rest of you standing there waiting for that telemany to come back to tell us that we now have two Mars exploration rovers on the surface of Mars. Rob Manning, we didn't have time to talk about much that's personal, but you started out a long time ago building models of rockets. I did the same thing.

My first was an Atlas Mercury, but now you get to build the real thing. It must be fun. It is a lot of fun. I have to admit, this is a childhood dream come true, a lot of work. have to admit, this is a childhood dream come true. A lot of work. And sometimes it's nice to be able to stand back and see what people, a large group of people with a lot of talent, can accomplish when they put their minds together. Thank you very much for taking this time during a very exciting and very busy period at the Jet Propulsion Laboratory, and I hope we can talk to you again soon.

Thank you, Matt. And best of luck. Thank you again. Before we go on, here's just a little more of Rob's eloquence in Sunday morning's JPL press briefing. Well, tonight is a very different circumstance. We didn't have as much wind, and we thought that earlier today that it would be less windy. But we did have some velocity.

It looks like we were, the Dimes camera, this camera that takes pictures on the way down, took pictures and the software used these three images to figure out how fast we're moving horizontally. It's a neat trick and it takes a little bit of computer processing and it's all done in real time by the little computer on board. And we estimated that we were going about 10 meters per second north and about 2.7 meters per second toward the west. And, well, interestingly enough, though,

the angles of the rocket were going in the opposite direction so that we were swinging a little bit, and the rockets induced a 7.7 meter per second velocity south, which countered the prevailing wind, the motion of the vehicle, and kind of canceling each other. So at the time we cut the bridle, we were going only 2.7 meter per second north and about 1.5 or so, 1.15 meters per second eastward. And that's, at least from a horizontal perspective,

that's not very fast going horizontally. So we cut the bridle. I don't know how high we were. We'll have to figure that out. And I don't know how many bounces yet or how hard we hit. I don't think we hit very hard, though. And we end up having a very kind of casual bounce for just a little while. And we'll have to see.

It turns out we did not fire the little rockets on top. We didn't need to. The software said we're going, everything is fine. Don't worry about it. Just leave it the way it is. So the big rockets fired, stopped us, and we'll see tomorrow just how far we fell and how far we bounced, and hopefully we'll actually have a nice view, provided all this stuff, these actions take place,

because the airbags have to be retracted, the pedal has to be righted, and very important, the solar rays have to be deployed, because we need power to get this vehicle healthy. And with some luck, that's happened, or just happened, on Mars, clear across our solar system. Thank you. Thank you. Thank you. Of course, you can learn much more and see much more on our website, planetary.org. I'll be right back with Bruce Betts after we hear from another of the student astronauts.

Good evening. My name is Shihan Chen. I'm from the UK and Taiwan. astronauts. landing. The experience is quite incredible as normally we watch it on TV so it's kind of weird to be there. It was an unusual experience because you know that it will land but you haven't got the complete confidence but then it turned out fine because Opportun opportunity landed absolutely flawlessly. So the kind of joy inside the mission operations was unexplainable. There was people hugging each other, shaking hands, congratulating each other. We were like immersed inside that happiness. Well, I would really like to explain this unusual experience to most people in the UK where I live and my school friends and teachers. I would say that this experience would probably last me for my lifetime because I'll probably remember when I'm 60 or something that once I was here in the Jet Propulsion Laboratory watching this live landing on Mars. Time for an abbreviated version of What's Up, because we are running a little bit long this week.

We welcome back Bruce Fetz, the Director of Projects for the Planetary Society. Bruce, another amazing couple of days. Truly amazing. Fabulous opportunity landing on the surface of Mars. Two successful rovers down there now and a truly spiffy landing site. What did you think? Oh, God, I was blown away.

The only thing that would have been better is if I had made it up to your house to watch it with other people. But I was here recording stuff and getting ready for today's show, which hopefully people have enjoyed this celebration of another successful landing on Mars. I want to mention that our trusty astronaut, Sandy Moondust, now on the surface joining Biff Starling. You can read her adventures. Biff and Sandy holding hands, well, half a planet apart. Half a planet apart.

But go read their adventures on planetary.org, the Astrobot Diaries. Sandy, you'll find out, but you'll be shocked to know it slipped into some surfer speak. She is so excited about the landing site. And there are plenty of new haikus from both Biff and Sandy describing their world. And we're going to have to get them on planetary radio here in the near future. Oh, yes, please. It's been way too long. And there is much else, as I've already said, on the site for people who want to know more

about what's going on with both Spirit and Opportunity. Yes, and Sandy's on the DVD carrying four million names to yet another place on the surface of Mars. You can learn more about that on our website, as well as try to crack the DVD codes. We've got this code up there now, and soon we'll have Sandy's for you to try to crack the codes, win some prizes, have some fun, get a neat certificate,

and good times. But I just keep thinking about that landing site. It's so amazing. There's nice outcropping of rocks, and you can see the bounce marks and roll marks from the airbags and the soils acting so much differently than we've seen at any other landing site. And it's going to be a neat place to find out about. Got to go ahead and get out there, start crawling around, and figure out what we're on. We'll come back to that outcropping in a moment, and we're going to also come back next week

to some of Bruce's other regular features, but because we are running late, we're going to jump right into last week's trivia contest. Bruce? Which was, what was the fourth country to launch its own satellite from its own territory? What did we find out, Matt? Well, Bruce, we found out that there's a lot of disagreement about which was the fourth country to do this wonderful feat. We got answers that said France.

We got some for Japan. We got some for China. I guess it depends on which authoritative source you consult. Our authoritative source, and a lot of other people who entered, indicated that it was Australia. And in fact, our winner, Michelle Arnett of Bullhead, Arizona, did say that Australia was the fourth nation from its own territory to launch a satellite into Earth orbit.

So congratulations, Michelle. You need to tell us what size T-shirt you want, and guess what? We do have mediums, so anything you want. Congratulations. For this week's Trivia Contest, we do what we do occasionally, and that's ask you for, instead of a factual answer,

we're going to ask you for something that, whichever one we think is the funniest, we will give you the Planetary Radio T-shirt. In this case, on the new opportunity images, there is a stunning outcrop of rock appearing basically right in front of the rover. It is already targeted as the most probable first place they're going to be going, at least after the soil in front. At these landing sites, rocks end up with all sorts of silly names the scientists give them. What do you think that outcrop of rocks should be called? Tell us.

Planetary.org slash radio. Give us an answer. What do you think the outcrop of rocks in front of the Opportunity Rover, what name should be given to that outcrop? This is going to be fun. Write to us at Planetary Radio at Planetary.org and please do so if you can by Thursday noon Pacific time.

Bruce, we're out of time. All right. Look up at the night sky, everyone, and think about the amazing fact that we have two rovers on Mars. Thank you. Good night. Bruce Betts, the director of projects for the Planetary Society, helping us to celebrate a wonderful weekend for our solar system and for humanity. We'll be with you again next week with our next regular installment of Planetary Radio.

Have a great week, everyone.