Planetary Radio: Space Exploration, Astronomy and Science - A Visit With Spirit Mission Manager Mark Adler

Episode Date: January 19, 2005

As the incredibly successful Mars Exploration Rover mission continues, Planetary Radio talks with Spirit's manager about what is being accomplished. We also hear from the second pair of Student Astronauts.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. Mars has the spirit and opportunity is knocking at the door. Hi everyone, I'm Matt Kaplan. This week we have a great conversation with Mark Adler, mission manager for the Mars Exploration Rover Spirit. Bruce Betts definitely has the spirit, along with this week's trivia contest, now awarding our stunningly beautiful Planetary Radio T-shirts. We'll also hear brief greetings from the current student astronauts.

Pairs of these lucky teens are coming from around the world each week, joining the rover science team at the Jet Propulsion Lab. Why, here's one of them now. I'll be right back with Mark Adler. Hello, I'm Thomas Kogan. I'm one of the student astronauts. I live in Spain. I'm 14 years old.

And, well, I really like space exploration and, well, Mars especially. So this is a great opportunity for me to see what JPL is like inside and to see how scientists work in mission operations. So I think the Planetary Society has given us a great opportunity. We're calibrating some sundial images. We're making like a movie of the time on Mars so we'll start like at 9 a.m. and you'll see the shadow moving until 5 or 7 p.m. or something like that. And then, well, we attended the meetings and wrote some journals about what happened today.

Mark Adler, thanks very much for taking a moment or two to talk to us at the beginning of your Martian day, Earth time, Pacific time. It's coming up on 7 p.m. on, I don't know, what sol do we correspond to on Mars? Right now we're sol 13 on Mars. Which, of course, is that day on Mars, which is about almost 40 minutes longer than ours. And you're wearing, you're the third person on the show who's wearing one of those wrist monitors to see how your body responds to this Martian daily cycle thing. Yeah, that's right.

They want to measure how poorly I adapt to Mars time. And I'm sure they're going to get a lot of good data from this one. Well, so you just had breakfast. You said you had boiled eggs. And you're here for the night. And it's going to be another big night for Spirit. Yeah, tonight is our first chance to actually use the arm, the robot arm on the front of the rover, to put out the instruments and touch the ground, put them on the dirt, and really just reach out and touch Mars for the first time. And you're going to do the first

microscopic examination of some of the soil? That's right. We have a little camera with a lens on the front that's kind of like a geologist's hand lens, and so that lets you look real close up at the soil and later on real close up at rocks to see what the grain structure is, what the pebble structure is, what the structure of the grain of the dirt is. And so with that, we're going to be able to tell how the dirt was made and try and learn more about what the site is like. We've also got a moss bower instrument on the arm, which tells us about the iron minerals in the rock.

And, of course, Mars is red. There's a lot of iron there. And so these iron minerals will tell us a lot about how the rocks were formed. That's going to be in place, I guess. Is that going to be tonight or is that going to be tomorrow, that the moss bower will start to do its work? Yeah, we're going to put the moss bower down tonight after the microscopic imager. And over the Martian night, which will be pretty much over the Earth day here in California,

it's going to be doing integration, which means it's going to be collecting more and more signal from the radiation that it sends into the rocks and into the dirt and gets back. And as it adds all that up, it gets enough signal above the noise to tell us what's in that rock or what kind of iron minerals are in that sand. And then the next night, I guess you'll want to use the APXS. See if I get it right.

Alpha particle X-ray spectrometer? You got it. I got it. Okay. Not proton, which was one of our trivia contest questions a couple of weeks ago. get it right. Alpha particle X-ray spectrometer? You got it. I got it. Okay. Not proton, which was one of our trivia contest questions a couple of weeks ago. That's right. On the Sojourner rover, it was called, it was the same acronym, APXS, but that instrument had also a proton detector.

And this one, we decided not to put the proton detector in. It really didn't add a whole lot to the instrument, so it's just the alpha and the X-ray. And that really tells us a lot about the elemental composition of the rock. It'll tell us how much silicon versus how much phosphorus versus how much oxygen is in the rocks. That one's going to take even longer, you were saying. It's got to be left there about 20 hours to get a really good reading? Yeah, quite a long time if you want to get all of the information you can out of it. Though it turns out for the APXS, we can put it down for just an hour and get a quick read,

sort of a quick look at the rock with the x-rays and be able to tell roughly what's in it. Exciting stuff, starting to do science, and you're talking about science, and yet you're the engineering guy or one of the amazing engineering guys behind the Spirit rover. Mission manager is how you're listed on the website. But I found it interesting how I can talk to those of you on the engineering side, and I can talk to people like Steve Squires, who are on the science side. And if you didn't know it up front, it would sometimes be hard to tell who was on which side of this mission.

Well, you know, I think that actually has a lot to do with the success we've had so far. It's a very complicated mission, and everybody really has to understand what's going on on all sides of the project. And so it's very important for the scientists, it's very important for Steve to understand what the engineering challenges are, And it's very important for the engineers, for people like me, to understand what we're trying to do. And that's the way we get our forces together. That's the way we get aligned. That's the way we understand what we're trying to do and get it done right. And I think we've done a great job so far. It's worked really well. And we'll see how well these instruments on this rover really figured out what's going on at this site. So you've got this

balance, this very dynamic tension relationship between the engineers and the scientists, because the scientists may want to go places that the engineers might fear to tread a little bit, because you want to protect that rover and keep it alive for as long as you can. Actually, you'd be surprised what the engineers want to do. I mean, these guys, you know, they worked on this thing for a couple years, and they've run this thing in the test bed, and they have some idea of what it really can do. I mean, these guys, they worked on this thing for a couple years, and they've run this thing in the test bed, and they have some idea of what it really can do.

And they like to take it for a little spin. Really? And so it is up to people like me, the mission managers and upper management, to maybe put a little bit of a throttle on that and to make sure we do the right things first. We're taking our time. We're being a little cautious with the arm today. We're going to put it down on a patch of dirt and maybe little pebbles that are right in front of us that we know is nice and flat and easy to operate on

to make sure that we don't run the arm into something or do some damage. So we're going to take it a step at a time. But as we gain confidence, as we learn how to use the arm, as we learn how to do traverses, we'll be a little more bold. And we'll try and do things. We'll try and get the arm in more difficult positions. We'll try and row for longer distances in a single saw. And after a while, I think, you know, we're all going to be very interested in trying to figure out what this vehicle can do and take it to its limits.

I talked to a couple of people over the last couple of weeks, well, week, who were saying, gee, you know, the thing can turn. Why don't they just get off of there and start rolling around? And I had to say, you know, it's not like they can call the auto club. That's right. You know, we had a very, very, very complicated unfolding act that we had to go through to get this rover set up. You know, it was all folded up in about ten different ways to fit inside this little lander. And now it has to expand. It had to get its solar panels out.

It had to get the high-gain antenna out. It had to stand up and deploy its wheels down. It had to get those wheels stuck out. It had to get the front wheels rotated out. There was like three different cables that we had to cut, big, big, fat cables. It had hundreds, thousands of wires in them running from the rover because the rover was the spacecraft. And all those wires had to control the lander, had to control the cruise stage, which flew us to Mars, had to fly the spacecraft.

And so we had to cut all those cables. And that's a tricky job. You have to do it at the right time and make sure that you don't lose some capability that you needed. All of these things were complicated. Every one of them required some verification on the ground to make sure that it worked right and that we're ready to go to the next step. And that kind of verification takes a while. We have to send this command to the spacecraft.

We have to get the data on Earth. It takes us a little while to look at it. We only have a certain number of communications sessions a day. And that really controls the pace of what we can do. And so we figured it would take about nine Sols, nine Martian days, about nine Earth days to get this thing off. We ended up futzing with airbags for a couple of days. And so that added a few days to it. And finally, we got off on Sol 12. But we've heard from a lot of people that while the expected life, sort of the warranty for this spacecraft, is three months, there's a good chance that you may get out beyond that.

I know you may be a little wary of making any predictions there. Yeah, well, we've done some analysis, and we know now today much better what the power situation is in the rover, how much power it takes to run the equipment. We now know better, now that it's on the surface of Mars, how well it retains heat overnight, and so we know how much energy it takes to stay warm at night. After a few weeks, we'll probably have a better idea of what the dust accumulation does on the solar panels to reduce our power. And all those factors combined, also with the weather at the site,

how cold it gets at night, will determine the lifetime. Right now, if we take the environmental models that we have for the site, and if we take our models for how the dust will accumulate on solar panels, and we take our measurements of how much power this thing takes and how warm it stays, we're predicting that it could last for maybe five months or six months, depending on the site. And in the Meridiani site, where Opportunity is going to land, it may last even longer since it's closer to the equator and the sun doesn't go as far north relative to the site.

I want to come back and talk a little bit about opportunity, but before we do, the decision has now been made. In fact, it was all over the media today, and we're speaking on Thursday the 15th. You've actually laid out where Spirit is going to go. So obviously, the scientists, the engineers have made their decision, and you're first headed over to that little interesting crater. Yeah, it's actually kind of a big crater. It's about 300 feet across. And so something made a big hole in the ground there. And the reason we're interested in a big hole in the ground is that that meteor dug into the ground for us. The rover can't dig very far. We have actually a trenching operation where we can run the wheels backwards against each other

and dig into the ground a little bit. But we can't get very far that way, obviously, and there's no drill on the rover. And we think that it's possible that the Martian environment may have buried some of the evidence at the site that we're looking for. Now, this lake was here a very, very long time ago. Since then, there's been dust storms, there's been lots of wind, all kinds of things that might have covered up what we're looking for. And so we're looking for those places where nature has dug a hole for us,

and this big crater is perfect. Is this another indication of how incredibly fortunate this spacecraft and all you guys have been? Yeah, it's really been surreal for me. I mean, when we did all the testing on the spacecraft, we found all kinds of problems with this thing or that thing. We fixed all the problems, you know, for the past three years, for the past three months, for the past three weeks, we found more and more problems. And we fixed them, we figured out how to go on.

But in all our testing, it's never, ever worked this well. three months, for the past three weeks, we found more and more problems. And we fix them. We figure out how to go on. But in all our testing, it's never, ever worked this well. I mean, this has been just an amazing experience to have everything just go click right off and have the landing go well, have the communication on the landing go well, have all the egress events work perfectly. Even if we did have to play with the airbags for a little bit, everything went exactly like we expected. We landed in a good place on the landing site, which was just really fortunate, in a place where it looks like the wind has scrubbed the for a little bit. Everything went exactly like we expected. We landed in a good place in the landing site, which was just really fortunate, in a place where it looks like the wind has scrubbed the ground a little bit.

We landed near this large crater, which there's probably a lot of craters there, so maybe that's not as lucky, but it was lucky that we're close enough to drive over to a large crater, which had a big excavation. And so, yeah, it's just been fantastic, and I can only hope that we haven't used up our luck and that we're going to keep going. We'll start using the arm today, and hopefully that will work, and we'll be able to do long traverses and get to the targets we want to get to. Well, you've got millions of us out here keeping our fingers crossed along with you.

We need to take a break. When we come back, if we can talk more about spirit and opportunity and about where we are. We happen to be speaking in Von Karman Auditorium, which is only odd at the moment because it's quiet here, where it has been one of the noisier, more exciting places in the world over the last week or two. We'll come back in just a minute, if that's okay. That's great. 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. Planetary Radio returns with our guest, Mark Adler, the mission manager for the Spirit Rover, now moving around on Mars and about to begin doing science with its arm, as we

were talking about just a few moments ago, and if we can continue with that for a second or two, Mark, I know this may be a question also for colleagues of yours like Rob Manning, but I wonder, Spirit didn't do everything exactly as was expected, and yet it did everything perfectly as it arrived at Mars. In part, that's evidence of how smart this spacecraft was, I believe. Yeah, it's able to really adjust to its environment, and it did a lot of that during the entry, descent, and landing.

It was designed to detect when it entered the atmosphere, what the right pressure was to deploy the parachute, when it got to the ground, when to fire the rockets. It did all of that great. It figured out what kind of wind it was going to encounter, what kind of tilt it had in the rockets that it was going to fire, and it compensated for all those things just beautifully. And the system did exactly what we designed it to do,

and it had a very light landing in a sense, I mean, compared to what the specifications were. You know, this thing dropped only about one and a half airbag heights from the cut height. It could have been much higher. It could have hit the ground much faster, but it didn't. And so it was a very good landing. From about, what, 28 feet high? Yeah, that's about right. What you have learned from Spirit, I'm assuming,

is also going to help out the folks who are about to arrive. Pacific time, it'll be on the 24th. Most of the rest of the world on the 25th of January. Opportunity, Spirit's twin. That's right. It's going to be landing at about 9.05 p.m., and it's getting all prepared right now. We're going to do a maneuver on Opportunity this Friday,

a small firing of the thrusters on the spacecraft to position it exactly to land where in the Meridiani site we want it to land. And we'll do a few more things on the spacecraft to get it primed, and I think that may be all we have to do to get it ready to land. Now, there will be some changes. We are thinking about changing things like the parachute deploy dynamic pressure, not so much because of the performance that we saw in Spirit, but more so because of weather changes that we've observed on Mars. We have seen, in fact, that there was a dust storm around

the Meridiani area several weeks ago, and it has changed the density of the atmosphere in the region where the parachute deploys. And so because of that, we'd like to make some fine-tuning, perhaps, to better prepare the system to deploy the parachute at a high enough altitude that it's got enough time to certainly complete all the events it has to complete before it gets to the ground. And this is an advantage, I suppose, of having a couple of eyes in the sky, really a couple of weather satellites circling Mars, although they do much more than that.

Yeah, we've got a great network now. I mean, it's actually incredible that we have two spacecraft that were already operating at Mars before these missions launched, the Mars Global Surveyor, which was launched in 1996, and the Mars Odyssey Orbiter, which was launched in 2001. Both are operating perfectly. The Mars Global Surveyor temperature instrument gives us very detailed information about the atmosphere, which we find important for our mission. Also, the Mars Global Surveyor plus the Odyssey orbiter gave us tremendous amounts of data about our landing sites that helped us pick our landing sites

and figure out where on Mars we wanted to go with these two rovers. And furthermore, those two orbiters are now helping out the missions directly by providing us with tremendous amounts of data through relay communications. We have small UHF radios, kind of like walkie-talkies, on each of the rovers that communicates directly to an orbiter as it flies maybe a few hundred miles overhead. And over that short distance, we can transmit a lot of data fast, even though it's only for six to eight to ten minutes. And over that time, we can blast a bunch of data up to the orbiter,

which the orbiter then holds in its memory and then sends back to Earth at a slower rate as it goes through its orbits. And we're able to get much more data than we're able to get through the high-gain antenna that we have on the rover that we use for direct communications and for commanding. When Spirit landed, I was at the Pasadena Convention Center for our Wild About Mars event, and you probably have heard that we had 2,200 people there jumping up and down and cheering just like all of you guys here at JPL. And it sounded like some of the first evidence you had that Spirit was okay came from Mike Malin,

who was monitoring the Mars Global Surveyor. That's right. Actually, well, our first information really was from the direct Earthlink. We did get tones from the direct Earthlink that said, yeah, the vehicle survived the first few bounces. And that was fantastic information. And then maybe 10 minutes later or 15 minutes later, we got information that said that the vehicle was on the ground and had survived. And that really was the key information.

At the same time, we also got data from Mars Global Surveyor that said that, yeah, Mars Global Surveyor was still receiving the UHF signal, which we really didn't expect, even after the landing. We did want to have and did expect to get Mars Global Surveyor relay data just before landing because one of the things we wanted to make sure is that if the landing didn't work, if we did have a problem and we're not able to communicate with the rover after the landing, we wanted to have enough data to piece together the picture and figure out what happened so that we could help opportunity and so that we could have lessons learned for future missions.

Which is why you put a lot of telemetry delivering equipment on these rovers that has not been there on some of the missions in the past. That's right. We have a lot more data through the interdescent landing event than we've had on any previous mission, and it's partly enabled because we have these orbiters already around Mars and also because we have a very capable deep space network that's able to pick up very faint signals from the vehicle as it bounces on the surface.

Before we run out of time, I want to switch gears a little bit. I said that we're sitting in von Kármán Auditorium, not exactly the most exciting place on Earth over the last couple of weeks, but only a few hundred feet from it, a place of enormous history. I mean, here next to us, a mock-up of the Voyager spacecraft. There has been a Viking spacecraft here in the past, your spacecraft. There has been a Viking spacecraft here in the past, your spacecraft. Do you ever think about how you are the descendant of incredible missions, and you're in the process of taking your place alongside them? No. Actually, we're so busy. We're so engaged with this mission.

I have things to do every day. I've got to come in. I've got to approve commands. We have to send them to the spacecraft. We have to figure out what we're going to do. We have to figure out what happened. And the planning that's gone up to this point has occupied all my time. And sometimes it's hard to sort of step back and think, well, what did we do? What is the significance of this? And it probably will hit me sometime later. Well, you've got a lifetime to think about that kind of stuff after those five months or however long with Spirit. You've also

spent some time with the student astronauts who are coming over, a pair at a time. They were featured on our show last week, Raphael and Courtney, the first pair. Now the others will be here. The second pair will be here with you tonight. I guess that's been kind of fun for you as well as for them.

I think it's great to have them really directly participating in the mission. They're actually getting data. They're analyzing the data. They're coming up with results. They're participating in the observation planning. And so that's a great experience for them, and I hope that they go out. We'd like them to be emissaries for other people, other students, other youth who are interested in this because they can say, what happens? What is it like to be in this kind of mission?, other youth who are interested in this,

because they can say, what happens? What is it like to be in this kind of mission? What is it like to work in this kind of thing? What is it like to explore other worlds? And I think it's just fantastic to have them here and get that experience and then relay that to others. You have had the chance with the rest of the team here to get very excited. This is even more fun than acting in Shakespeare, isn't it? Yeah.

I haven't done a lot of that in the past couple of years. I've been pretty busy. I used to do a little bit of amateur theater. But, no, this is fantastic. And this is not acting. This is reality. And sometimes it's hard to really connect with that. It's been so surreal that everything has worked so well.

But we are really on Mars and we're really exploring another world. And it's hard to beat this job. Well, we'll put a link to your personal website with a shot of you practicing for a sword fight in Henry V. But much more information about what you've been up to lately here at JPL. The world is watching. This truly is, I think, the most exciting place on this

planet. And we're monitoring a lot of exciting things happening on another planet. And it's going to be great fun to watch this happen. Almost as much fun as you're going to be having, I'm sure, making it happen. All right, yeah, it's going to be a fantastic adventure, and hopefully everybody can participate in it

and watch on our websites and see what's going on, see the pictures we take, see the science discoveries we make over the next several months. Thanks very much, Mark Adler, mission manager for the Spirit rover, now on Mars and about to start doing science, already taking some amazing photos, and about to start doing science.

Already taking some amazing photos, and we'll start delivering very soon some information about the geology of the red planet. All right, it's great to talk with you, Matt. And I'll be back with Bruce Betts and What's Up right after this. Hello, I'm Susanne De Silva. I'm from Sri Lanka. I'm one of the student astronauts chosen by the Pandora Society. I'm very glad to be here. This is an experience that I'll never have in my country. That's why it's so memorable and I value it so much.

We've been calibrating the mass dials. We put grid on them and then we can find time. Recently we've been making a movie out of them, how the shadow moves all throughout the sundial. And last night was the address and we've been We live in amazing times. We have a rover now crawling around on the surface of Mars, and a popular local hamburger chain in California now makes a burger without a bun. Bruce, it's a good time to be alive. It's a wonderful time to be alive. It makes me so happy. Oh, it's a good time to be alive. It's a wonderful time to be alive. It makes me so happy.

Oh, it's beautiful. Bruce is one of those low-carb guys, in addition to being a planetary scientist. But we digress. It's time for What's Up with Bruce Fetz. You know, it reminds me what the Spirit Rover said to the Opportunity Rover recently. And what was that? Catch up. Okay, so anyway, speaking of spirit and opportunity, spirit is happy on the surface,

has gotten off the rovers, starting to explore and party. This includes Biff Starling, astrobotic extraordinaire on the surface of Mars. You can read his diaries at planetary.org. You can also do other fun stuff tied to the mission, including, don't forget, you can come crack the secret codes in the picture

from Mars of our Planetary Society DVD, carrying four million names to the surface of Mars and a secret code. There'll be another one on opportunity. All found on beautifulplanetary.org. Good times. There's a wonderful photo, a huge panoramic photo, hanging in the Planetary Society office of a shot from Spirit just before it crawled off. And up in one corner is a little portrait of Biff.

Exactly. He's there. He's been appearing in a lot of the pictures, actually, as they rotated the rover, as you'll see in the Astro Bot Diaries. On to what's up in the night sky. Got all those pesky planets still up there. Fun to look at. Can't miss Venus at night.

That's the bright thing that you look over in the west and say, what the heck is that? That's Venus. Mars up above, basically almost straight up above, reddish, not that bright. Setting around midnight, Saturn rising at sunset. This is, again, like I mentioned last week, about as bright as Saturn gets. A good time overhead in the middle of the night. Jupiter rising in the late evening, extremely

bright. Mercury, tough to see now, but low on the horizon southeast before dawn. You can also look for those who dig things being next to each other. Venus and the crescent moon will make a striking pair on Saturday, January 24th. Go out, enjoy it. And while you're there, think about this week in space history. On January 24th, 1986, Voyager 2 flew past Uranus, giving us our first and only spacecraft view of Uranus. Random Space Fact! Kind of had to warm up to that one this time. On Mars, did you know that there are named geologic time frames, time scales? Just like on Earth, you have the famous Jurassic, Cretaceous, Tertiary.

On Mars, they are named Manny Moe and... No, that's not true. They are named Noachian, Hesperian, and Amazonian. Amazonian being the youngest. And if we had time, we'd find out why. Nutshell, they're... Oh, okay. We can save it for later.

No, you can... Go ahead. Nutshell, we've find out why. Nutshell, they're... Oh, okay. We can save it for later. No, you can... Go ahead. Nutshell, we've got a minute. They're named after terrains on Mars, areas of Mars that already correspond to those different time frames. So there's a Noacus, Hesperia, and Amazonas

that tie to those three time frames. On to our trivia contest. Last week, we asked you what was the first artificial object to hit Mars. And how'd we do? We did well, and so did the listeners, as always. Kind of cliche, because we always get all kinds of good answers. We rarely get a wrong one, which is why we have to rely on choosing the winner for each week randomly. Randomly!

It's also why... I'll put Echo behind that one, too. It's also why we often end up with past winners, because it's random. And we haven't yet said, okay, if you've won in the last three months, get lost. We might say that someday, but we aren't yet. Which is why our winner this week is Brian Morgan, who I'm fairly certain has won before. Brian, congratulations. He hails from Falls, Wisconsin. And like almost everybody else, he had the correct answer.

First artificial object to hit Mars was the Mars II, sent by the USSR. Back in the USSR, the lander arrived November 27, 1971. There was no useful data, and the lander was destroyed, although I did hear from some other contest entrants that, yes, the lander was destroyed, but that it had a rover if it had not smacked into Mars as hard as it did. Somebody said there was actually a rover that was tethered, and it could have crawled around within about a 15-foot radius. And someone else said that the orbiter actually did get back some photographs.

I don't know. Are you aware of any of that? There was only one person who mentioned all that. Why, no, I'm not. Well, check it out for us. Thanks for bringing it out during the show, but I know you can find out about it if you go to the Learning Center, part of the Planetary Society's website at planetary.org. We'll give you information on the Mars 2 probe. And basically, you should see the look he's giving me.

So anyway, on to our new trivia question. Who was, randomly chosen, the fourth country to launch its own satellite into space from its own territory? The fourth country to launch its own satellite into space from its own territory. In other words, it doesn't count if they built the satellite but asked somebody else to launch it for them. Correct. Okay. How do people enter? Go to planetary.org slash radio, and you'll find how you can enter our contest.

You can win the fabulous prize for Planetary Radio T-shirt. So make sure you send us your size. Thank you for mentioning that. I was going to say, we have to get your size, folks. And we should warn you that apparently we have no mediums left. So don't ask for mentioning that. I was going to say, we have to get your size, folks. And we should warn you that apparently we have no mediums left. So don't ask for a medium. Get a large or an extra large or even a double extra large or a small. And give it to a friend if you needed a medium.

Okay? Okay. And do try to get that entry into us by Thursday at noon Pacific time, if you don't mind. Anything else for us, Bruce? No, I'm tapped. Okay. Well, then, what should we do? We should look up in the night sky and think about T-shirt sizes.

Okay, we will. Thank you, good night. That's Bruce Betts. He's the Director of Projects for the Planetary Society, and he joins us each week here on Planetary Radio. He'll be back again. By this time next week, and if all goes well, we'll be celebrating the safe arrival of Spirit's twin Opportunity. And we hope to talk with another member of JPL's green team,

Entry, Descent, and Landing Development Manager, Rob Manning. I hope you'll join us. Take care, everyone.