Planetary Radio: Space Exploration, Astronomy and Science - John Casani on NASA's Prometheus Project

Episode Date: February 28, 2005

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The Prometheus Project lights a fire under solar system exploration, 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. What would we do if we had 100 or 200 times as much power to move space vehicles among the planets? John Cassani runs a project with that goal in mind. We'll talk with him about nuclear electric ion propulsion.

And for all of you who were baffled by Bruce Betts' trivia question about the writing on spacesuits, relief is coming up in today's What's Up segment. Lots going on in our planetary neighborhood this week. The European Space Agency's Mars Express orbiter may have found evidence for a sea of ice on the red planet. And we're not talking about something that dried up a million years ago, but one that could be

there right now, a few meters under the surface. You can learn more at planetary.org. This has a lot to do with a new call by ESA scientists for a European mission to find life on Mars. Can't tell your craters without a program. Cassini is giving us our first close-up look at many of Saturn's moons. That means there are suddenly lots of surface features crying out for names. The Tale of Jason and the Argonauts is providing the handles for little pockmarked Phoebe. The cast of characters is listed at planetary.org. And Spaceship One is headed for the Smithsonian. The little vehicle that won the XPRIZE with its suborbital flights will be on display by the end of the year.

I'll be right back with John Cassani of the Prometheus Project. Here's Emily. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, If Mars was warm and wet once, would Mars and Earth have looked the same? Since the beginning of the space age, opinions have wavered back and forth between the idea that Mars was once warm and wet like Earth, and Mars was always cold and dry like the moon. Early spacecraft images showed evidence for both ideas. Scientists realized that a key test of the Mars climate

question would be the composition of rocks that formed on early Mars. If there was water on Mars for a long time, they thought, we should find rocks that look like those on Earth that form in watery environments. In particular, because Mars has an atmosphere rich in carbon dioxide, a warm, wet Mars should create carbonate rocks like the limestone we have all over the Earth. But in the 90s, Mars-orbiting spacecraft failed to find much evidence of carbonate minerals on Mars. Was Earth the only warm, wet place?

Stay tuned to Planetary Radio to find out. John Cassani heads the Prometheus Project, tasked with developing a revolutionary source of electric power and propulsion for interplanetary spacecraft. It's the latest in a long line of assignments John has worked on at the Jet Propulsion Lab outside Pasadena, California. The first probe to make use of nuclear electric propulsion was to have been the Jupiter-Icy Moon's orbiter. But JIMO, as it's called,

is an extremely challenging and expensive mission. So NASA has decided to postpone it in favor of a less ambitious so-called demonstration effort. And so that's what's been introduced into the budget. The GMO launch was baseline for 2015, and we're now being asked to consider a demo mission to be launched in 2014. Well, you know, I can't say I'm not disappointed, because like everybody, like you, I'm sure,

wouldn't it be great to get out there to Europa and spend some time for a while? You were project manager on the Voyager missions. Yes, I was. I was project manager on the Voyager missions. The original project manager was Bud Schirmeier, who started the project. And I worked for him for a while. And he left the project about two years before launch, and I took it over at that point in time. But you must have, or if not you, there must have been other people on your team who were thinking, as you got back all that incredible data and

images, boy, I wish we could hang around for a while, which is exactly what the Jimmo mission will do for us. Well, of course, that desire to hang around after the Jimmo, after the Voyager mission, excuse me, is what led to the Galileo mission. Yes. So now we're talking about going into orbit, not at Jupiter. But we'll start off by going into orbit at Jupiter. But then we'll go into orbit around each of the three outer Galilean satellites in order, Ganymede, rather be Callisto, then Ganymede, and then finally Europa. And orbiting Europa is really the challenge of this mission for a lot of reasons. Reasons that we've talked about frequently on this show, although not so much in connection with this mission. Obviously, the fact that we believe there's some liquid water underneath all that ice, and we'd love to know more about it.

Well, I would agree with that. I think most scientists would agree that the evidence from the Galileo mission is very, very compelling, and it's almost certain, if not absolutely certain, that there is water beneath the ice caps at Europa. And with less certainty, there's also a probability of water under the ice of the other two satellites, Ganymede and Callisto. So this ambitious mission may be postponed a little bit, So this ambitious mission may be postponed a little bit, but the technology that is the real point of the Prometheus project is, if anything, even more ambitious than any individual mission because it certainly appears to be the technology which,

if we want to really open up the solar system to exploration, I'm not sure there's an alternative with the possible exception of the solar sail, although when you get out toward Jupiter, that gets a little dicey. Yeah, it does, because for the same reason that solar panels do for solar electric energy. By the time you're out to Jupiter, the Jupiter radiation is down by a factor of 25, as you know, so nuclear electric propulsion using a reactor to generate heat, which is what reactors do, converting that heat to electric power, which we will do probably with Brayton engines, providing electrical power, mainly, mostly, I should say, for the ion engines.

Let me stop you. A Brayton engine, not a thermocouple in this case, but is that actually a mechanical heat engine? A Brayton cycle engine is a type of turbine. It's a thermodynamic cycle, and that's what we have in jet engines. Jet engines are Brayton cycle engines. Now, the only difference in our application will be that it'll be what we call a closed cycle Brayton engine, which means we take the exhaust that would come out of the back end of the

jet engine, so to speak, and turn it around and feed it in the front end. Now, the reason the jet engine works is that it burns gas or fuel, and that is used to heat and expand the gases before it goes through the turbine. In our case, what we'll do is take the gases that come out of the turbine and turn it around, run them through a heat exchanger, pick up heat from the reactor, and then reintroduce it into the front end of the engine. But other than that, it's very similar to a jet engine. Thermodynamically, it operates on the same principle. And then on the same shaft with the turbine and the compressor, we'll have an alternator that will generate electricity. and the compressor will have an alternator that will generate electricity.

So that's a fairly straightforward concept, but reducing it to practice for a space mission that has to operate unattended and flawlessly like ours do for more than 12 years. In the case of the Jupiter-IC moons orbiter mission, they're even longer for some of the other missions we're looking at for the other outer planets. And that electricity is used to accelerate ions, push them out the back incredibly fast. And this technology, the ion engine, pretty well proven out now in smaller applications, like with Deep Space One. That's exactly right.

We're talking about maybe 200 kilowatts of electric power, 150 kilowatts of electric power to 200 to these ion engines compared to one kilowatt or two kilowatts that have been used before. So we've scaled this up by a lot. And that means more thrust and higher efficiency. The other engines ran about 2,000 seconds or something like that, which is a measure of how efficiently the engine uses a propellant to generate thrust. And we're talking about something in the range of 7,000 seconds, plus or minus 1,000, maybe.

We're talking to John Cassani. He's the project manager for, well, you were listed as project manager for the JIMO, Jupiter Icy Moons Orbiter Mission. And I don't know if that title has changed now. Well, there's a little bit of confusion, I think. I'm the Prometheus project manager. And the goal of the Prometheus project is to develop this nuclear electric propulsion capability, which can be used for long-duration outer planet missions. And the first mission designated was the Jupiter-IC moons orbiter mission. And I am the leader of that because it comes part and parcel with being the Prometheus

project manager. And so we will talk when we come back about some of those other mission profiles that nuclear electric propulsion may open up to humanity. And we'll do that right after we come back from this quick break. Hope you'll stay with us. 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. Our guest this week is John Cassani. We are in his offices at the Jet Propulsion Laboratory near Pasadena, California. He is the project manager for the Prometheus Project,

also a member, I guess, of the executive committee here at JPL. That's right. I'm a member of the executive council at JPL. Executive council. Sorry. Right, right. We were talking about the technology that the Prometheus Project is all about and that even though the Jimmo or Gimo, you want to cue me on it. You're the boss of this.

Can you give me the correct pronunciation because I hear it four or five different ways. Well, whether it's GMO or GMO or GIMO is a matter of preference. It's either tomato or tomato or EO or IO. People are going to pronounce it the way they want to. As long as we don't call the whole thing off. We won't call the whole thing off. I'm happy to be the project manager. I don't need to branch into being the pronunciation Gestapo. I imagine you have enough to deal with. That's right. I looked at the team that you have brought together, the different agencies and institutions. Now, this is not out of the ordinary for a mission of this kind of scale.

But this list is truly amazing because it involves, for example, the Secretary of Energy and Naval Reactors Program, which tells me that your reactor technology, I suppose, is somewhat related to what the Navy has been successful with. Well, please don't suggest that the Secretary of Navy works on the project with me. The Secretary of Navy works on the project with me. It's true that we have a broad, broad spectrum of capability and talent across the country. Four or five NASA centers besides APL are involved in this. And Sean O'Keefe, when he was the administrator of NASA, he was really the father of this program.

It was his conviction that we needed this technology. He also was convinced that to build a reactor and put it in space was really very challenging. And it was his belief, and he's absolutely turned out to be absolutely correct, or he was absolutely correct from the beginning, that the best talent in the country for dealing with reactors have been the organization called Naval Reactors, which is the organization that Admiral Rickover founded. And we're really happy to have them part of this program. You also awarded a big contract about five months ago. Yes, we did. That was following a almost two-year study contract that we had let competitively to three of the almost two-year study contract that we had let competitively to three of the

aerospace industry contractors, and GST was selected. And they are now partners with us in developing the spacecraft. So the work goes on, and will go on for many years, because this really is groundbreaking technology, and you've got a lot of stuff that's never been worked out before. That's right. I think that the right way to characterize this or think about this, this is transforming technology. This is going to transform the way we go about solar system exploration in the years to come. This technology is going to open up capabilities that just heretofore have not been possible, couldn't even have been imagined or thought of. A good example of this, we spent several years here at JPL a few years back studying a Europa orbiter mission. I think we had a pretty good handle on

it. We were talking about carrying a science payload of about 30 kilograms into Europa orbit, operating it with maybe 50 watts of power that It would operate for three or four weeks. That was limited by the radiation exposure there, and basically maybe 100 kilobits per second data returned to the Earth. With the Jumo mission, we're planning to take 1,500 kilograms of science payload into orbit at Europa. We'll have 5 kilowatts, 10 kilowatts of power to energize those instruments and can return the data back from the Jupiter system at the rate of 10 or more megabits per second compared to 100 or 200 kilobits per second.

Wow. And we have the power to or the capability to maneuver around in that system, to go not just to Europa but to go to the other three moons. And you can think of other missions that are similar. We will probably go to a Neptune orbiter mission in the future with also orbiting Triton, the large moon there, a Titan orbiter, maybe carrying a rover, comet chasing missions, missions that can go from one asteroid to another, a series of them, and all with substantial science instruments, as much power, basically, as you can imagine.

We're going to see a lot of mission innovations that can be executed with this capability. The only one that I've heard talked about that you didn't just mention would be an asteroid mission. Well, we will have certainly an asteroid rendezvous where we can go and do science from one mission to another. But another very interesting capability that this system that we are building will be able to do, and that is what has been referred to as an asteroid tugboat mission. Russ D. Schweikert and the B612 people have been calling people's attention to the fact that there are a lot of near-Earth objects in the vicinity, in the solar system near Earth,

meaning that there are paths across the Earth's orbit or very close to it. And more and more of these are being discovered every day. And sooner or later, it's not if but when, one of these is going to recontact the Earth. One of them has our name on it. One of them has our name on it. So it would be nice if we had the capability to go out and intercept an asteroid that was headed for the Earth and nudge it out of the way. And that's what this technology can do for us. Yeah, in fact, Rusty Schweikert and the B612 team, they were smart. They took your basic design and show it nudging an asteroid. But we're almost out of time.

Let's talk about just the design of the spacecraft. And I realize these are just early artist's conceptions. But it happens to be, in my humble opinion, one of the coolest looking spacecraft ever. Partly because you have this big delta of what look like solar panels, but of course they're not solar panels. No, they're not solar panels. They're radiators. And here's the deal.

To convert heat from the reactor into electricity, we have to run through a power converter. We're looking at Brayton engines, as I mentioned, which can produce power at about 20 to 25 percent efficiency. So let's just say we wanted to have electrical power of 200 kilowatts, and the efficiency is, say, 20%. That means we'd have to generate a megawatt, 1,000 kilowatts, convert 200 kilowatts of that 1,000 to electricity, and then what do you do with the other 800 kilowatts?

If you don't get rid of it, the temperature of the spacecraft is going to go up. So the way we get rid of it is take that waste heat and circulate it through the radiator panels with liquid, be it sodium or potassium or even water conceivably, and take the heat away from the reactor and the power converter and run it down the boom and run it out on those large radiator panels. And they heat up and they're looking at the deep space temperature of about four degrees

Kelvin. And so that's how we get rid of the heat. And that's interesting because those panels dominate the configuration visually of the spacecraft. That's what you see when you look at it. Yeah, it makes it, as I said. It looks like a big sailing ship, right? It does, it does, which is a wonderful metaphor.

We're pretty much out of time. There's just one more question that I know we have to ask, and that is one you get hit with, I'm sure, often, the idea of putting a nuclear reactor into space and that there are some, I think, misconceptions about the safety of doing this because I think, for one thing, you don't turn it on until it's up there and far from Earth. That's right. We would not turn it on until it's well out of the Earth's influence and without any possibility of recontacting or reentering the Earth.

We are looking at some trajectories that start out at 1,000 kilometers altitude and fire the reactor up there and spiral out of the Earth's gravity well. And that's a very safe thing to do because even if the system would fail after it had been operating for a short while or a long while, that's such a high altitude for the spacecraft to decay from that altitude is several orders of magnitude of lifetime longer than the lifetime of the decay products that we'd be worried about. And we're looking at trajectories that go directly away from the Earth. But safety is paramount here, and we will design this and execute this in a way that is safe. John, we're out of time.

In fact, we've gone a little bit long here. I wish we had even more time, but I certainly hope that we can visit you again as this Prometheus project proceeds, progresses over the years. What did you call it? No, this is transforming technology. Transforming technology. This is the technology that really will open up

the new age of planetary exploration. John Cassani has been our guest. He's the project manager for NASA's, NASA JPL's, Prometheus project, primarily designed to make nuclear electric propulsion work in space, but almost as a byproduct to get us pretty much wherever we want to go and take a lot of stuff along with us in the solar system. We'll be back to learn more about this in coming shows. We'll be back here with Bruce Betts on What's Up in just a minute or so after this return visit from Emily.

I'm Emily Lakdawalla back with Q&A. In the 90s, it seemed that Mars's surface lacked any chemicals that could have formed in a warm, wet environment. But the Mars Exploration rovers have found wet chemistry, just not the kind that scientists were looking for. The rovers have found sulfate minerals, known on Earth as epsom salts. Scientists are now realizing that Mars may have had warm and wet environments, but with a fundamental difference from Earth's. The sulfate minerals suggest that Mars' rivers and lakes were acidic. Acid rain falling on acidic rocks making acidic rivers would have prevented limestone from forming. Any carbonate minerals on Mars would dissolve easily in the acid waters. Mars' carbon would have stayed up in the air as carbon dioxide, which is good news for the

proponents of a warm Mars because carbon dioxide is an excellent greenhouse gas. These acid waters don't sound much like Earth, but in fact there are many environments on Earth where volcanic activity creates acidic water. These places are often teeming with ancient primitive bacterial life, which makes scientists think that the early Earth may well have been covered with acidic waters and that a wet, acid early Mars promises the possibility that life could have begun there too. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio.

We've reached that hallowed time in Planetary Radio when we turn to Dr. Bruce Betts, the Director of Projects for the Planetary Society. By phone this week, we couldn't quite get together. Hi, Bruce. Welcome back. You refer to this as a hollow time, Matt? Hallowed. Hallowed. Oh, hallowed. Oh, that's much nicer. We leave it to the listeners to decide how hollow it is.

Well, I'm going to shove those hollow spaces with things to look for in the night sky. You can see on March 2nd and 3rd, the night of March 2nd, if you're in North or South America, you can probably see the star Antares being occulted by the moon. No, not joining the occult, but having the moon pass in front of Red and Terry's. And if you're in the right places, you can actually see it disappear early in the evening and then reappear late at night. If you want more details, go out there to the web and find a good astronomy site to show you some maps. That is on March 2nd and 3rd. While we're talking about weird events in the sky, I want to give a little preview a month ahead

so no one accuses me of missing it. Get ready for a weird solar eclipse happening on April 8th, and we'll give you more information about that. You're really psyched if you're in various parts of the southern hemisphere to see it, but it's also visible from some of the northern hemisphere as well. We'll give you more later.

My appetite is wetted. Excellent. Speaking of wet, Mars is up in the pre-dawn sky, and it was once wet. You can see Mars. It's right now in Sagittarius, and it will be near the moon, the crescent moon, on March 5th and March 6th. You see it in the pre-dawn sky, a little ways up in the southeast before dawn. If you look in the evening sky, you've got Jupiter rising in the early evening now, early to mid-evening, the brightest object in the sky in the east. Can't miss it.

You also have Saturn, which is up high by sunset early evening, still near Castor and Pollux, looking kind of yellowish, great object to look for in a small telescope. Cool stuff. Random Space Facts! Many features on Saturn's moon Phoebe have now had names applied to them after they were seen and detailed by the Cassini spacecraft. And the theme is the story of Jason and the Argonauts, the mythological story.

So another whole new set of fun features named things like Jason. Let's talk about that trivia question from a while back, which was on spacesuits, in particular the Space Shuttle EVA, Extravehicular Activity Suit. What is strange about the writing on the spacesuit? And how did we do, Matt? Not very well. What?

The listeners who we normally... You're not supposed to say that. I know. We normally praise listeners to high heaven because so many of them get it right. But boy, they were really challenged. And there was a lot of creative writing involved in this contest as people tried to figure out what you had in mind.

I mean, here's a guy who actually did figure it out. He's not our winner. in this contest as people tried to figure out what you had in mind. I mean, here's a guy who actually did figure it out. He's not our winner, Alex Chapman, who's a regular listener in Manchester, where they're hoping their soccer team doesn't get sold to a nasty American. But anyway, he said, now I have to say this week you have managed to come up with a really challenging question that I just can't Google my way out of, although Alex figured it out. So did our winner this week, Nathan Campanella of Denver, Colorado. Nathan said the writing on and the display from some spacesuits is presented backwards

so that the astronaut can read the information using a sleeve-mounted mirror. P.S. This is a total guess. Well, guess or not, that is absolutely correct. Not bad, Nathan. Good work. Yeah, so that's why if you see those pictures of astronauts in space, if you look carefully, a lot of the writing, especially anything giving them information about their system, is written backwards.

So they have not flipped the picture around. It is actually written backwards. So they've not flipped the picture around. It is actually written backwards. Planetary Radio T-shirt will go out to Nathan Campanella very soon. Bill Magnuson, longtime listener to the show, didn't get it right, couldn't figure it out, so he decided to entertain us instead. And if we had been going for funniest answer, he probably would have gotten it. Can I read you some of these? Sure.

He said that in case found by alien culture, a return to sender tag. And assembly instructions, and then printed across the butt in large letters, made in Taiwan. And anything in Klingon. And then here's my favorite. Done by smart aleck jealous spacesuit manufacturer on back of life support pack, kick me. So thank you, Bill.

That just seems so unlikely. Yes, well, in fact, yes. Anyway, Bill, thanks for entertaining us. But Nathan, you're the big winner this week. How about next time? It does actually say kick me, but it's written backwards. I guess that doesn't make any sense, as opposed to other things. If you want your chance at winning a Planetary Radio t-shirt, go to planetary.org

slash radio and answer the following question. Getting back to our friend Phoebe and Phoebe's new names, one of the creators on Phoebe has been named after the Argonaut that was referred to, at least in some mythology, as the Beekeeper. This amused me, so I'm asking you, what's the name of that crater? What's the name of the crater that corresponds in mythology to the Beekeeper? And since mythology can vary, I'll give you a little hint that at least on the Planetary Society website, that's how you'll find the description. I also enjoy the name itself. Go to planetary.org slash radio and enter.

And get it into us, get that entry into us, by noon Pacific time, March 7. That's Monday, March 7, noon Pacific time. And who knows, you might be the next Nathan Campanella winning that wonderful Planetary Radio t-shirt. Bruce, we're out of time. All right, look up in the night sky and think about whether the creatures around Red Antares are looking out and wondering what happened to parts of the Earth when the moon moves across.

Boy, that was complicated. Or just go up and go out there and think about cheese, whichever you want. Thank you. Good night. That's Bruce Betts, the director of Projects for the Planetary Society. He joins us each week here for What's Up. Planetary Radio gets personal next time when we'll talk with M.G. Lord, the author of Forever Barbie has just written AstroTurf, the private life of rocket science.

Have a great week, everyone.