Planetary Radio: Space Exploration, Astronomy and Science - The End of Ulysses -- How Engineers Kept It Alive So Long

Episode Date: July 6, 2009

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I'm told, every week. Neil Gupta and Bailey Godowski, this one goes out to you. The end of Ulysses, this week on Planetary Radio. Hi, everyone. Welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. The Ulysses we have in mind was supposed to die months ago, but this pioneering spacecraft, the first to study the poles of our sun,

was only shut down last week following a heroic and ingenious effort by the European and American team behind it. In a couple of minutes, we'll welcome back Nigel Angold, the Mission Operations Manager for the European Space Agency. Bruce Betts is also back with a look at the night sky and a special contest that will begin our celebration of the Apollo 11 moon landing 40 years ago. Bill Nye the Planetary Guy is here to deliver this week's commentary. I'll be right back. Hey, Bill Nye the Planetary Guy here, Vice President of the Planetary Society. You know, in a couple of weeks, it's going to be the 40th anniversary of landing on the moon. And this will be a big deal. There'll be a lot discussed about it. It'll

be very exciting. But in the meantime, almost half a century later, we've be a lot discussed about it. It'll be very exciting. But in the meantime, almost half a century later, we've got a lot going on. People want to put spaceports in states like Wisconsin, let alone Florida, Virginia, Hawaii, California's Mojave Desert, Oklahoma, New Mexico. People are not just going to launch rockets. They want to have stuff come back down. It's going to be a place to come and go from all over the United States and maybe North America. There's big business out there. Big business. And NASA right now doesn't have an administrator. Maybe by the end of next two weeks, NASA will have an administrator and a deputy administrator, Lori Garber, who was the representative of the Planetary Society in Washington for a few years. And these people have got to make a bunch of decisions about whether or not NASA should be in the commercial space business,

providing rockets to carry communication satellites into orbit and so on, or should it be in the exploration business looking farther and farther out into space, taking perhaps people someday to Mars? And these decisions have got to be made pretty soon because there's just a lot of money involved. So while we're all celebrating and getting ready to celebrate this amazing adventure on the moon, we've got to start once again thinking to the future and how we're going to sort out how tax dollars are spent and how commercial dollars are spent to achieve goals like finding life on other worlds

and making sure our phones work any time of day and night. It's exciting, but you've got to think about it. Meanwhile, I've got to fly. Bill Nye the Planetary Guy. Bill Nye, the Planetary Guy. A nearly two-decade-long deep space mission ended last week with the transmission of a command. So that is the end of the Ulysses mission. The transmitter has been switched off. However, the receivers are still on, so should anybody wish to transmit commands to the spacecraft, it can still receive them.

However, that is unlikely to happen because there is minimal scientific gain to switch the spacecraft back on again. We wish a fond farewell to our friend that has kept us in fantastic data for the last 18 years, 8 months, and 24 days. That was Nigel Angold of the Ulysses mission hosting a live farewell webcast from the Ulysses Command Center at the Jet Propulsion Lab. By the way, we have a link to the webcast at planetary.org slash radio. No one believed the spacecraft would still be returning data well into 2009. That the Solar Explorer lasted so long is a testament to the ingenuity of engineers who kept finding solutions for problems that were never anticipated. It's a story that is repeated in mission after mission,

with Apollo 13 providing the most famous example. I asked Nigel to return to Planetary Radio, not just to mark the end of a magnificent mission of exploration, but to help us get a feel for the practical magic he and his colleagues around the world practice. Nigel, job well done. Congratulations. Thank you, Matt. It's good to be back, albeit at the end of a mission, which is rather a sad occasion. But I think we've done a pretty good job of keeping this mission going, the Ulysses mission going for 18 plus years. And it's good to be back talking with you. Yeah, pretty good. That's putting it mildly. You know, when we spoke almost a year ago now, I don't think you had any idea that you'd be able to sustain this spacecraft as long as you had.

Am I right? Yes, that's correct. We thought last year that we were probably going to be going maybe to the beginning of July 2008. Well, that was our aim, and that was what we broadcast. We had a press conference in Paris telling everybody this is when we were going to end the mission. We thought that was going to be about it. We thought we were going to either run out of fuel or we were going to freeze the fuel. However, we thought we would see if we could just get a little bit more out of it

by trying to make sure we didn't freeze the hydrazine on the spacecraft. And so we looked around for ways where we could do this and still get some data. One of the first things we looked at was trying to keep the internal temperature of the spacecraft as high as possible. If you recall, one of the reasons why it was getting colder was because our X-band transmitter had failed and we'd switched to an S-band transmitter, which is a lot lower power output. Because of that, we weren't dissipating as much heat inside the spacecraft and therefore the internal temperature of the spacecraft was dropping. Using the S-band transmitter was a way of getting the data back down, but the internal temperature

was getting cooler because of that. It's just interesting to me, once again, how a spacecraft has to be considered as a system as a whole because obviously you took this so-called waste heat from the X-band transmitter into account all along as part of what you needed to keep the spaceship healthy. That's exactly right. One of the really fun aspects about designing a satellite or a spacecraft and flying it is that it is always a compromise. There's always trade-offs

between power, thermal, mass, so many different things. Changing the power configuration also affects your thermal configuration. And so you have to juggle a lot of things all at once and and in fact in this last year this is exactly what we've been been doing i was i was getting to coming to say that okay we we've now got the s-band transmitter on and in switching the s-band transmitter on that takes away a certain amount of heat from the internal the internal part of the spacecraft as well. So we had to limit the amount of time we had the S-band transmitter switched on. So every time we were out of pass, we switched the transmitter off.

And we would take shorter DSN tracks rather than take 10 or 12 hours. Deep space network, of course. Yeah. We'd take four or five-hour passes instead of 10 or 12. And that obviously then means that you start to reduce your data return, which maybe we'll get into in a minute as well, because those are the kinds of things which have actually ultimately brought the mission to an end.

And you talked about needing to keep the hydrazine, which was the fuel that you were using to direct the spacecraft, right, powering your thrusters, that it was going to freeze in the lines because you couldn't run your heaters anymore, much less the X-band transmitter. Some of the pipework is wrapped with heaters, but even then, there are various cold spots. And the cold spot which we were really worried about actually was very close to the radiator plate of the X-band transmitter. And because now the X-band transmitter hasn't been on for 18 months, that suddenly became a very cold point in the spacecraft, which we had no control over, other than using secondary sources of heat such as the tape recorder which actually we kept moving backwards and forwards even though our data rates weren't high enough to be able to play back data anymore from the spacecraft another limiting

factor on our data return so we couldn't play back data from periods when we were no longer tracking the spacecraft. So we got much bigger gaps, which we couldn't record through. But we would still run the tape recorder in order to get just that little bit of extra heat from another unit close to this cold spot in the spacecraft. So that was another way of keeping things warm. And then

we looked and saw how much hydrazine we had left, which wasn't a lot. And of course, we need this hydrazine to point the high gain antenna every few days back towards the Earth in order to keep our data rate as high as possible and 512 bits per second for the most part. Let me stop you for a moment. 512, not 512 kilobits, 512 bits. That's right. Okay. In fact, the maximum data rate that we have on board the spacecraft in real time was only one kilobit. So in the recent months, that's been halved.

And like I said, at 512 bits per second, we can no longer get data back from a tape recorder on board because we'd need higher data rates than that. And very recently, in the last couple of weeks, we were dropping down to 256 bits per second. So again, another factor in determining when the mission was going to end. We looked at the amount of fuel that we had on board, and we decided that, okay, if the fuel is cold in just a couple of spots, and we were talking about maybe a couple of

centimeters of pipe work, which happened to be connected to a, what we call a standoff, how the pipe gets connected to a piece of structure on the spacecraft in order to hold it in place. You try and thermally isolate the pipework from its surroundings. There is some thermal drain through these standoffs. Oh, still like a heat sink. Exactly. It's just a little heat sink. And so there's a short piece of pipe which gets colder than the pieces of pipework either side of it. either side of it so we decided well what what if we just kept flowing hydrazine through these this cold spot and not letting it sit there and cool down for hours or days we just keep moving

the fuel through it maybe we can stop it from freezing prevent it from freezing so so we said okay well let's let's see what we might be able to do and so we actually started firing our spin up and spin down thruster every two hours just to move a little bit of fuel through the through the pipe work it didn't do anything didn't change the attitude didn't change the orbit and didn't really change the spin rate either i mean there was a very slight imbalance in the two thrusters which made made us have to do a small correction once in a while. But essentially, it was a do-nothing maneuver, just to flow fuel through the pipework in order to stop it from freezing.

And we were successful because even at the end of mission, we still had fuel on board, which kind of surprised us because we thought we were probably going to run out. But actually calculating how much fuel you have on board is not an exact science. You have to count pulses from the beginning of mission and hopefully know how much each pulse uses in terms of fuel. But we didn't run out and we didn't freeze the fuel. It couldn't have been very far away. I mean, this is one of the few regrets.

It would have been really nice to know exactly when we ran out of fuel or when it froze. We didn't get that opportunity because we actually ended up switching the transmitter off as opposed to letting the fuel run out or freeze. It would have been nice to know, but that wasn't a really big deal. We'll hear more from Nigel Angold of the Just Ended Ulysses Mission when Planetary Radio continues. Hi, I'm Lou Friedman, Executive Director of the Planetary Society. You've made Planetary Radio one of our most successful programs. Our valued listeners depend on it for weekly space-related news, entertainment, and inspiration.

However, today's economy is forcing the society to make tough choices. As a result, the future of Planetary Radio is now on the line. Transcription by CastingWords PlanetaryRadio.org. Tax-deductible donations of $50 or more will be rewarded with a Planetary Radio t-shirt. Our listeners are a thoughtful and committed team. I trust you will help sustain Planetary Radio so we can continue to explore new worlds. Please extend your lifeline of support at Planetary.org. And thank you. Welcome back to Planetary Radio. I'm Matt Kaplan. The Ulysses spacecraft ended its record-setting mission

of solar exploration just last week, long after anyone thought it would remain active. Nigel Angold is the European Space Agency's Mission Operations Manager. He is telling us how the Ulysses team managed to keep the spacecraft alive and kicking for so long. The tricks included the regular firing of thrusters to keep fuel from freezing. That would have ended the mission. Let me ask you before we move on to the significance of this last year that you managed to get

out of the spacecraft, those burns that you did, the firings of the thrusters every two hours, was that just set up automatically, or did somebody have to send the command to the spacecraft to do that every couple of hours? That's an interesting question. Well, we didn't have somebody there every two hours, and we didn't have a pass every two hours to do that, so we had to do something automatically on board.

It just so happened that we had something automatically on board now it just so happened that we had a program on board called conge it's short for conjunction what this was on board for was to ensure that we could maneuver the spacecraft at times of conjunction when when the sun the earth and the spacecraft are alignment, which happened a few times during the mission, not too much because we're typically out of ecliptic, and therefore you don't get this alignment. But nobody ever dreamt that it would be used for this purpose. Absolutely not, no.

And it involved a little bit of refinement in how we used it, but it was another unique way of using something on board the spacecraft which it wasn't designed to do. We had to get quite creative, and that's one of the reasons why, in actual fact, there's a number of the operations team have been on this project since launch, which is quite unusual when you think that we've been going for more than 18 years now. In fact, on Tuesday when we had our last pass, there were six or seven people in our mission support area

who were there for the first command. So amazing, really. But it's a testament to the fact that we've had a lot of different things go on and it's never been a stagnant, static mission. We've had to be creative right the way through, and there's always been engineering challenges to meet. Remind us, how long were you with the mission? I joined the mission in October 1989, so it's nearly 20 years now, just about a year before launch up until now. a year before launch up until now.

But having said that, I mean, I've been getting a lot of emails from people who've said that the majority of their career has been involved with Ulysses. Some people started their careers with Ulysses 30 years ago in the design of detectors. One of the things that I've really enjoyed is seeing the fact that there's so many careers have been dependent upon this mission, which makes me feel good that we've kept it going for so long. Also, one email that I got, which said that they have just got funding for a new postdoc to start working on Ulysses data. And that makes me very happy because it means that the Odyssey, the legacy continues after the mission has ended. So I'm very pleased to see that the data we've been gathering

will be used in years and decades to come. Yeah, that must be extremely satisfying. And you certainly have reason to be very proud. Where do you go from here? You personally. Matt, oh, I'm going to go to Disneyland. Oh. You could.

It's right down the road. You're right. Well, I don't know exactly what I'm going to do from here. I've got a number of months to think about it. think about it but in a couple of weeks time I actually will be going to do some teaching at a space camp in Germany with the European Space Agency. They run a space camp for their kids and I'm going to be having a lot of fun with about 120 children, actually learning about manned space flight. Obviously I've been involved for 18, 19 years with a mission which has got very little to do with manned spaceflight except for the launch, which is a whole other story. But it'll be fun trying to engage with these kids to show them what maybe is the future of human exploration.

Have a wonderful time there and during the summer. You certainly have earned it. And is there a chance we'll be able to hang on to you here, not just in the States, but hopefully here in Southern California, JPL? That's an interesting question. I think the last time you asked me a similar question and I said I wasn't quite sure where home is anymore. I'm going to go home, but I'm not sure where home is. There are possibilities. I could go back to Europe, but also staying in this area interests me. And JPL is obviously an inspiring place to work.

And there are a number of missions coming up and certainly some joint missions between ESA and NASA, ExoMars and some new Mars programs coming up. Herschel and Planck have obviously just been launched and there's both European and US involvement in those. So there's plenty of collaboration going on, which I'm very pleased to see, because Ulysses certainly wasn't the first for U.S. and Europeans to collaborate on, but it's definitely been a pioneer in that regard, and I'm so pleased to see that going on because it's the way we have to do business. Best of luck with those, Scott. I wouldn't be a bit surprised if many of those might not need another resourceful engineer

and mission manager. We knew we'd have you back on when the mission ended. We just didn't know it'd take this long for that to happen. Well, thank you. I'm very pleased it has taken that long. And maybe I'll be back on your show sometime talking about some completely different mission. I hope so. That'd be delightful. And we'll just finish with this as we get ready to head into this week's edition of What's Up with Bruce Betts. I have sitting next to me here, well, all I can say is stay tuned, folks, because it's special Ulysses prizes for the trivia contest coming up in just a few moments with Bruce. We've been talking with Nigel Angold, who, as you heard, has been with the Ulysses mission for nearly 20 years. He has been the mission operations manager of late for the European Space Agency,

which, of course, partnered with NASA and particularly JPL in this extremely successful mission that revealed so many previously unknown facts about the star at the center of everything in our solar system. We'll be right back with Bruce in just a couple of moments. It is time for What's Up on Planetary Radio. Here's Bruce Betts, the director of projects for the Planetary Society. Happy Fourth of July weekend, which is when we're recording this. And happy What's Up. Why, thank you.

As always, Matt, it's great to be here. You'd rather not be here because it's a holiday. I understand. But it's nice to be sitting across the table from you. Oh, and it's always with you, Matt. Let's talk about what's in the night sky, shall we? Please. We've got Saturn in the evening sky over in the west looking like a kind of bright star, kind of yellowish and hanging out below Leo.

Jupiter now rising in the middle of the night in the east and very high up in the south in the pre-dawn looking like an extremely bright star. Very high up in the south in the pre-dawn, looking like an extremely bright star. And we've got the brighter than anyone else Venus hanging out in the east in the pre-dawn with Mars looking much dimmer and reddish above it. That's what we've got cooking for the night sky. Let's go on to this week in space history. 1979. Two interesting things happened this week in 1979, 30 years ago. One, Voyager 2 made its flyby past Jupiter, turning all sorts of groovy data. And Skylab reentered the atmosphere.

Oh, is that right? Splattering Australia. It didn't hit a cow or anything, right? That was some meteorite I'm thinking of. You know, we've had a lot of good random space facts on Skyline. There were pieces that were displayed at the Miss Universe contest that year because it was in Australia. There was the guy who picked up a piece and ran back to win a $10,000 prize for the first piece brought back to a San Francisco newspaper. But no, I think cows were okay as far as we know.

Very nice. That's been a big week in space. I know what's next. So do I. On to Random Space Fact! It was tragic. It was absolute tragedy. It was tragic. It was absolute tragedy. It was.

But don't worry, the random space fact's not tragic. It has to do with the polar caps on Mars. The kind of random interesting thing is that during the balmy summer that you get in the Martian Arctic, the northern polar cap is the surface is water ice, but the southern polar cap, the surface is carbon dioxide ice, frozen dry ice. And that doesn't switch places ever?

That's just the way it is? I won't go with ever, but right now there's an asymmetry in the poles, particularly with altitude, but also wind and such like that. But the south polar cap is actually at a higher altitude, so it stays colder and you keep the carbon dioxide lit on things. And then, of course, in the winter, when it gets from cold to way butt cold, you are freezing out carbon dioxide ice straight out of the atmosphere and covering large regions. The polar cap getting bigger and smaller, like you can see on Earth, is primarily carbon dioxide ice.

Fascinating. I do want to assure people that way but cold is a scientific term. Oh, totally. Check any units book. Bigger than a bread box. Well, I mean, you got cold and you got butt cold, then you got way but cold. We have to get on to the trivia contest. All right.

Because you have something special planned. I do. I have specialness. But first, the just normal level of specialness. Our previous contest, we asked you, what was the first successful lunar orbiter? How did we do? Very interesting, actually. And it led me to looking up all the previous attempts because there were a bunch of attempts before the one that actually made it.

And we got lots of nice answers, accurate answers. The winning one, though, came from James Brown. Not that James Brown. It's been two and a half years. No, no. This is the James Brown in Rockwall. Well, maybe it is that James Brown. Rockwall, Texas, who it's been two and a half years since he last won the contest, according to my vast database.

Luna 10. Just in your head, isn't it? No, no. I make it up. So it is in my head. Luna 10 from the USSR. Back in the USSR, April 3rd, 1966, followed by the lunar orbiter put up by NASA. And as was pointed out, not by James, who will be getting a Planetary Radio t-shirt, of course,

but by Johann Peter Dahm, who's our friend in the Faroe Islands. He said that it was supposed to play back the notes of the Internationale, the communist theme song, and it didn't. It was missing one note. So the Soviet team faked it because they wanted to play it. The whole thing was to play it back for the 23rd meeting of the – I forget what it's called. But anyway, they faked it. They said, here's the song coming from Luna 10, and it wasn't. It was a cover tune.

Wow. It never ceases to amaze me, the depth of information. Yeah, I hope he didn't make it up, but I trust that that's the case. They don't lie on those islands. All right, for our next contest, winner will be revealed for our special Apollo 11 landing 40th anniversary show. Yep. With Ray Bradbury, I'm prepared

to say right now, he will be our special guest for that week of July 20th. For that show, here's your contest. If you had been Neil Armstrong, what would you have said when you first stepped out onto the surface of the moon? We will judge this using our skillful host-like judgments, ranging from the profound to the make us laugh.

What phrase would you think should have been uttered as, or if you did it, or your favorite dog, whatever, what should they have said? Go to planetary.org slash radio. Find out how to enter. And you have until Monday, 2 p.m., July 13. And then on the very day itself, that greatest of days in human history, many people think July 20th, will reveal the winner of this contest or possibly winners thanks to Nigel Angold. Now, you might think we'd give you some Apollo memorabilia.

No, we have Ulysses mission memorabilia thanks to Nigel who left us a bunch of shirts. You can hear the shirts in the plastic. Here they are. Here they are. And I would take out the tile. He left us a wonderful commemorative tile, which is right here. I'll just tap this on the table. There it is.

Wow. There's the radio. So special prizes for probably several of you if you manage to win this contest by impressing Bruce and me. And that's it. Should they give us their shirt size? Well, they could, but they're going to have to take what they can get. All right, never mind.

They're all a little large. We have two for women and three for men. OK, everyone. Is that it? Are we done? I think we are. All right, everybody, go out there all a little large. We have two for women and three for men. Okay, everyone. Is that it? Are we done? I think we are. All right, everybody, go out there, look up at the night sky, and think about snow globes. Ooh.

Thank you, and good night. You ever see Earthworm Jim, where they actually explain that the entire universe is in a snow globe? It's a really great episode of that classic show. He's Bruce Betts, the director of Projects for the Planetary Society, and he joins us every week here for What's Up. Next time, we'll begin our salute to the 40th anniversary of Apollo 11. Welcome back author Andrew Chaikin.

Then in two weeks, Ray Bradbury. Planetary Radio is produced by the Planetary Society in Pasadena, California. Have a great week.