Planetary Radio: Space Exploration, Astronomy and Science - More From JPL's Linda and Tom Spilker

Episode Date: February 25, 2008

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The Spilkers of JPL and Neptune, 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. Last week, Linda and Tom Spilker gave us an update on the Cassini-Huygens mission at Saturn. Our conversation with JPL's first couple of science takes us onward to Neptune this week as we hear about a proposed mission to that mysterious blue ball. We'll also hear how a new project like this is born. Bill Nye, the science guy Guy brings us back down to Earth

as he considers how satellites far out in space are helping us understand challenges we face here on the surface. Happily, Emily Lakdawalla joins us much more frequently than once in a blue moon, as she'll explain in Q&A. And Bruce Betts will join the stars on the red carpet. The planets, too. Who will win the coveted Planetary Radio t-shirt? Somebody named Oscar? Welcome home, Atlantis. Job well done delivering the Columbus lab to the International Space Station. Do you know that in 13 days, the shuttle traveled over 5 million miles, or about 10 round trips to the moon. Next up is Endeavour, with launch targeted for March 11. Atlantis won't fly again till August, when it will head out to repair the Hubble Space Telescope one last time. After 17 years in space, Ulysses is enjoying its last hurrah.

The joint NASA-ESA mission revealed the polar regions of our sun for the first time. It has been returning data almost continuously for nearly four times as long as was planned, but now with its radioisotope power source diminishing, Ulysses isn't expected to stay warm enough to keep its fuel from freezing as it swings out toward the orbit of Jupiter. The end is probably just weeks or months away. I promise we'll get someone from the mission team to help us mark the passing of this unique spacecraft. As always, there's more news at planetary.org, where you'll also find Emily's space blog. Check out those amazing white rocks on Mars. I'll be back in a couple of minutes with Linda and Tom Spilker.

Here's Bill. Bill Nye, the Planetary Guy here, Vice President of Planetary Society. This week, discoveries from outer space. And these discoveries affect the Atchafalaya River Delta, which is near New Orleans. The delta is sinking. The delta is flowing into the Gulf of Mexico, and the reason, among other things, we had an ice age 22,000 years ago. NASA scientists discovered this by using information from the global positioning system. With a proper analysis, we can understand that

the delta is sinking at least 0.1, a tenth of a centimeter a year. A tenth of a centimeter doesn't sound like much. But a very dear friend of mine from college had a house in Lafayette, Louisiana, right up the street, if you will, from New Orleans. And she remarked often to me that she was very fortunate that her house was six inches, 15 centimeters higher than the houses about a mile away, 1,500 meters away. And those 15 centimeters kept her house high and dry where the other houses were low and wet. So my fellow taxpayers and voters, with these discoveries made with information from outer space, tiny, tiny electromagnetic signals from these distant satellites,

do we as taxpayers and voters continue to build levees and pump out the river delta? Or do we decide it's time to abandon it at huge cost with huge loss of materials and infrastructure? It's up to us. Do we trust the numbers? Do we make decisions about the future? Or do we think something else? Well, we wouldn't be able to make these decisions without this information from space and that is part of space exploration being used to learn about our own planet, the Earth. Think it over and I'll talk to you next time

on Planetary Radio. Bill Nye, the Planetary Guy. We sat down last week with Linda and Tom Spilker to talk about the Cassini-Huygens mission. They are veteran staffers at the Jet Propulsion Lab near Pasadena, California, who've also been married for a lot of years. Linda is deputy project scientist for Cassini, while Tom is a principal member of the engineering staff. When we finished catching up

with the news from Saturn, we turned our gaze considerably farther out in our solar system. Tom, Linda, and a lot of other good people have proposed a mission to Neptune. As a JPL mission architect, I wanted to talk with Tom about how this kind of project gets underway and the challenges faced in a world of worthy mission proposals, but not nearly enough money to turn all of them to reality. Tom, Linda, welcome back. You're the first people who've made it through two of these, I think. Our little update on Cassini last week that, Linda, we've done with you several times.

But we're going to move on, first of all now, to this brand-new mission. And we've got a lot of very good people other than the two of you involved with this. I think in particular of Heidi Hamel, who cares very deeply about things like Uranus and Neptune. And so here we are considering a mission to Neptune, which I guess, when did you give this an official name? When did that actually get assigned? That was about two weeks ago, I believe. When did you give this an official name? When did that actually get assigned? That was about two weeks ago, I believe.

One of the people working with us, Nathan Strange, had been looking into Greek mythology and possible names and came across Argo and the mission of the Argo ship and its crew and thought, oh, this is so appropriate, suggested it, and it was an immediate hit with the entire team. You don't have anybody named Jason on the team, do you? Not yet. Good chance for later on, I hope. I know that that was a major consideration. Tom, you and I back during the holidays had a conversation about trying to come up with appropriate names, and I know there were a lot of things being considered there.

I was pulling for one in particular that would have been the third in a rather famous series of spacecraft that we won't even mention. But Argo seems to be a lovely name for a mission to the outer reaches of the solar system. Why don't you tell us a little bit about what this mission would hope to accomplish if it can find funding and make its way out there? Well, we've only been to Neptune once with a spacecraft. One of the Voyager spacecraft, Voyager 2, made a flyby of Neptune in 1989, flew by Neptune itself, flew by Triton, and then continued on from there out into the outer reaches of the solar system. We only got a snapshot of Neptune from that flyby. We did a few months of pre-encounter, very low resolution imaging and so on, just getting familiar with

the gross aspects of Neptune itself. And then for only a brief few days, were we able to very carefully track clouds and see features on the surface of Triton for just a few hours. Of course, it changed completely our views of what Neptune was and what Triton is. Many things that we learned about the system just from that snapshot, but we don't know a lot about how it changes with time. Are there seasons on Neptune? Are there seasons on Triton? Is there a long-term secular change that we weren't able to see in the brief exposure that we got with Voyager? We're hoping to go back with better instrumentation. Of course, Voyager had the Vidicon type of television tube in its camera. We're hoping to go back with a CCD-based orders of magnitude improvement in sensitivity and resolution.

Makes me think of our recent conversation with Sean Solomon about Messenger and comparing those incredible images to the ones that Mariner 10 picked up. Even in areas of Mercury that had been visited and imaged by Mariner 10, it was like seeing them brand new. And we hope to do the same kinds of things with Neptune, being able to see the smaller scale clouds, how they're moving, parts of their structure that give you an indication of how they're formed, how the winds are moving around them, and of course structure on the surface of Triton, what geologically is going on to cause this body to still be active. And don't forget the rings. We know from ground-based

observations that the ring arcs around Neptune have changed in the time since Voyager flew by. So there could be other changes in the Neptune system as well, and we'd like a chance to go and look. Well, speaking of change, I mean, I saw images. There was an image from Voyager of Neptune and another one taken by the great kekscopes in Hawaii that indicated that Neptune is a pretty dynamic place. Absolutely.

Yes, indeed. For instance, only five or six years after Voyager flew by Neptune, showing the Great Dark Spot, which captured everybody's imagination, the Great Dark Spot was gone. And within a year or two after that, there was a new Great Dark Spot in the other hemisphere. Large changes, things that if they happened on Jupiter, everybody would be saying, what is wrong with Jupiter? These things seem to be commonplace on Neptune.

So we'd really like to see it again and see how that atmosphere has changed, how big a difference has it made since we were there with Voyager, and what kind of planetary physics would explain that. And Neptune offers us another opportunity. Neptune is a big gravity source. We can use it to bend the trajectory of the Argo spacecraft and go on to visit an object in the Kuiper Belt. We think that Triton is a captured object.

It has a retrograde orbit, and we'd like to go out and look at some other additional objects in the Kuiper Belt. So Argo offers the opportunity to do that as well. In fact, you were just showing me, both of you, a slide from a presentation that I guess is part of the selling of the mission, if you will, that shows a comparison between this relatively narrow angle that New Horizons, the wonderful mission headed to Pluto right now, of course, it just, there isn't much, as you put it, delta V you can pick up from a little guy like Pluto. But with Neptune, you can really steer yourself toward a big swath of sky.

With the New Horizons mission, since Pluto is so small, it can only change the direction that the New Horizons spacecraft is heading by a small fraction of a degree. And even using its rocket engine, it can only change its direction by less than a degree. But using Neptune's gravity, we can change up to about 60 degrees. This makes about 4,000 times more volume of the Kuiper Belt accessible than it would be with New Horizons. And so we get to pick and choose among the objects that we might visit. I take it, Linda, also that within the right launch window anyway, Argo may be able to make some other, well, not stops, but some other flybys. Yeah, in fact, there's a possibility we could fly by both Jupiter and Saturn

and in a sense sort of recreate some of what Voyager did, a Voyager 3 perhaps. A grand tour. A visit of the outer solar system once again. Yeah, well, there's that series of spacecraft that I wouldn't name earlier. Of course, I happen to like that, but Argo is a lovely name too. Yes, indeed. That's Tom Spilker of JPL. He and Linda will rejoin us right after this break.

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The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. Our guests are Linda Spilker, Deputy Project Scientist at the Jet Propulsion Lab for the Cassini-Huygens mission to Saturn, and her husband Tom Spilker, a mission architect and principal member of the JPL engineering staff. They are part of a new team that has proposed the Argo mission to Neptune. Argo is still a long, long way from sitting on top of a rocket about to be launched, but all great missions and ideas start somewhere.

Tom, let's talk about what goes into somebody says, let's go back to Neptune. And if you're lucky, someday from that, as someone once said, let's send an orbiter to Saturn, and now we're there. We're talking about not just years, but I can't imagine the tens of thousands of hours that must go into planning a mission like this. Oh, certainly. Of course it all hinges on the science. It's not that somebody decides, let's go to Neptune. Somebody decides, and this is usually a group of people in the planetary science community, decide there are some science objectives that we need to accomplish

that will allow us to understand something about the creation of the solar system or the evolution of the solar system or the creation of gas giant planets, ice giant planets, whatever. The science objectives are agreed upon. Everybody decides that, yes, if you can do this, this is worth flying a mission. Well, deciding that you want to do certain science doesn't get it accomplished. Somebody needs to sit down and think about what do we need to do to do these science objectives that require certain kinds of instruments to be in certain places and operate it in certain ways, generate either some data or a giant load of data that has to be sent back down to Earth,

many different aspects of how do you accomplish this science that you have to work into a spaceflight mission that has to leave Earth, travel from Earth out to the destination, get to the destination and either stay there or fly by in such a way that the instruments get to where they need to be to make their measurements, can send all of the data from those instruments down to Earth in a way that scientists here on Earth can use the data. There are many, many aspects of what we call implementation that have to be taken into consideration before you can decide, yes indeed, we can fly a mission that will cost approximately

this that will indeed accomplish the science that we want to, and that science makes it worth that cost. Argo is still in the very earliest stages at the moment, right? Yes. What are the most significant challenges that you face as you look at another mission to the outer solar system? Well, certainly, if you're going to go out to the outer solar system, you need to be able to get there. So we need to be able to launch enough spacecraft to handle all of its tasks once it gets there with a launch vehicle that can send that much mass out to that distance. Now, most launch vehicles cannot send something directly from Earth to Neptune. The kind of mass that they could launch is just nowhere near

what we would need to do science in the Neptune system. And so we have to look at trajectories that use gravity assists in the inner solar system, gravity assists with Jupiter, maybe Saturn, and so on, to take a launch vehicle that we can afford, launch enough mass to go through this trajectory that builds its energy up enough to get out to Neptune. So that's a lot of what we're doing right now. How do we get out there? We also need to think about how are we going to power this spacecraft when you're so far from the sun? And maybe there are a couple of very simple missions that you can do at Saturn under solar power

with augmentation from batteries. But once you go past Saturn, our solar cell technology right now simply would not allow a mission to be viable out that far. And so we rely on what is essentially nuclear batteries, radioisotope thermoelectric generators, or RTGs. thermoelectric generators or RTGs. And we're looking at is NASA going to allow people to use RTGs for the announcement of opportunity that we expect to respond to. If they would not let us use RTGs, then we don't have a power source. We're also thinking about how much data do we need to send back. If we do have our nuclear batteries,

how much power will we have to devote to a telecom system, a telecommunication system, to send those data back to Earth? How long would it take us to send as much data as we think we would need? And is that commensurate with the amount of time that we're going to have to do it? So we're examining many different aspects of problems like that to try to make sure everything fits. It is exciting to be talking to you at this earliest stage of considering a mission. We only have about a minute or two left. I really cannot let this opportunity go by without talking to you about the more personal side of living with JPL as a longtime married couple. Your children are a little bit older now,

but you're still balancing a family life with very busy lives here at the lab. Linda, has it been a challenge? Yeah, it is a challenge indeed. And I think now that our children are older, they're 21, 23, and 26. We have three daughters that they're sort of off on their own. And so in a sense, we have even more time to think about ideas like Argo and what we're planning to do. But, of course, we're not completely narrow. We have lives outside of JPL. And there are things we have to do to make sure that we pay attention to those areas outside of JPL. we have to do to make sure that we pay attention to those areas outside of JPL.

For instance, we're somewhat familiar with good restaurants close to JPL in addition to good restaurants close to home. So if we happen to get an hour and a half after work here, we can hop over to a nice restaurant. We've looked at our commuting schedules and attempting to do carpooling and so on to help out with our schedules. And we've had some successes and some failures with that, which make us reexamine our tactics to make sure that we have enough time for both aspects of our lives. And we close with this. You were telling me something about on some of those trips to nearby restaurants about a lot of notes that end up on napkins. Right.

We use the napkins, and our daughters sometimes roll their eyes at this. We'll get to talking about some problem, and before you know it, there's a spacecraft and a little trajectory drawn, and we're talking about what the possibilities might be for future missions or even maybe something exciting that Cassini's doing, and use those napkins to draw pictures. But the daughter's friends, who aren't exposed to this so often, see us writing on a napkin and saying, this is the sun, this is Earth, and this is Neptune, say, wow. Well, you're spreading the good word then,

even if it's only at the table with your daughter's friends, as we, of course, hope to do with this radio show. Thank you so much for coming together for this and joining us for a couple of episodes of Planetary Radio. Thank you, Matt. Thank you, Matt. Linda Spilker is the Deputy Project Scientist for the Cassini-HHuygens mission headed right here at the Jet Propulsion Laboratory. Tom Spilker is a principal member of the engineering staff at JPL, but for our purposes, he is a mission architect, which is a little bit of what we've talked to him about today. We're going to keep talking, but it'll be with Bruce Betts for this week's edition of What's Up. That's after this week's Q&A from Emily.

Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, how come there are sometimes seven days and sometimes eight days between the phases of the moon? Those of you who are well-versed in how the sky works may be surprised to hear that most people aren't familiar enough with the sky to know that the moon takes more than four weeks, but less than one month to go through its regular cycle of phases. In fact, many people don't even realize that the moon is frequently visible during the day. Our moon takes a little more than 27 days to complete one elliptical orbit around Earth. However, because Earth advances in its own orbit around the sun during that time, it actually takes two more days for the lunar phases to catch up with Earth's orbital travel. So a full cycle of lunar phases is 29.5 days long, which is a bit longer than four

weeks. So if the full moon falls on a Monday, the next full moon will fall on a Wednesday or Thursday. But since 29.5 days is shorter than almost every month, each full moon usually falls one or two calendar days earlier than the full moon on the previous month. Once in a blue moon, there are two full moons per month. In fact, that's the definition of a blue moon. So blue moons always fall on the 30th or 31st day of a month. The full cycle of lunar phases actually measures one full lunar day from sunrise to sunrise. So for any point on the moon, the sun is above the horizon for nearly 15 days and below it for the next 15, meaning that the diurnal temperature range is 300 degrees Celsius.

You'd better have good heating and air conditioning if you plan to live on the moon. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. Got Bruce Betts on the Skype-o-phone once again, talking to each other across the miles here in Southern California. He is the director of projects for the Planetary Society. And Bruce, my friend, I'm so sorry to have come so close and missed out at the Oscars. Oh, it was brutal.

The hardest thing is trying to look like you don't care when the camera's on you and you just hear that thing. Got to keep smiling, I know. Best performance by a humorous astronomy segment. Damn that, Tom Hanks. My official platform, it was just nice to be nominated. All right, better luck next year, which begins right now. What's up? Oh, I better try hard.

Nothing. Darn it, if they're not going to give me an award, I'm just not going to work at this. No, a really great actor, you know, will make something of nothing. All right. I'm a professional. I'm moving on. In the evening sky, you can still check out Mars. It's faded quite a bit, but still looking like a kind of brightish-reddish beast fairly high in the sky in the evening.

Saturn coming up in the east in the early evening. You can check it out later in the evening, quite high up. It looks yellowish, and of course, try to check it out through a telescope, and you can check out those famous rings. Pre-dawn sky is still where it's at. That's where you've got both Venus and Jupiter extremely bright. Venus being the brighter of the two, but very low in the east. But if you can get a view low to the east, you can check out those two, the brightest of the planets. And Mercury is starting to work its way up a little bit from underneath them, but is extremely low in the eastern sky in the pre-dawn.

So that's what we've got going on. Did you check out the total lunar eclipse, Matt? I sure did. And I didn't think we were going to get a shot at it here, but it cleared just in time and it was really spectacular. It was indeed exactly how it went here. It was fabulous. But that's over.

So check out those planets for now and we'll keep you updated on other things coming up. Let's move on to this week in space history. In 2007, lo, an entire year ago, New Horizons flew past Jupiter on its way to Pluto. And do you know New Horizons is already at 9 AU, nine times the Earth-Sun distance, having just been launched two years ago? Wow, that is a fast little baby there, man. It is cooking. It is. It's the sports car spacecraft.

We've also got in space history 1982. Venera 13 returns the first color photos from the surface of Venus. Let us move on to Random Space Fact. 13 returns the first color photos from the surface of Venus. Let us move on to Random Space Fact. We got Earth observing NASA's, what they call the A-Train, the afternoon train, a series of right now five spacecraft. They all observe the same location as they pass over. They observe the same location within about 20 or 30 minutes of each other. And three of them, the three in the middle, are designed to actually observe the same

location within seconds of each other. So they can compare the different instruments for things like atmospheric phenomena that are changing all the time and really get a good handle that they're looking at the same stuff at the same time. So I thought that was kind of spiffy. That's very cool. Let's move on. Speaking of cool, let's go to the trivia contest. We asked you what work of literature out there actually discussed long before Mars's two moons, Phobos and Deimos, were discovered. Talked about the two moons of Mars. How'd we do, Matt? You know, we got some very interesting responses, as always, quite a few of them.

I don't know, this must have been a little bit difficult for people to Google, so maybe there are just a lot of fans of Jonathan Swift out there. Because, in fact, it was his Gulliver's Travels, actually known as Travels into Several Remote Nations of the World, by Lemuel Gulliver, published 1726, that's 150 years before the actual discovery of the two moons by our friend Asaph Hall. And sure enough, the scientists on Laputa, Laputa, the floating nation that Gulliver visited,

they talk about these two moons at Mars. That's kind of weird. I mean, it's even stranger that later they actually found that there were lilliputians amazing how many things in that book have come true in a floating city powered by a giant lodestone yes it's a good book uh you know who won hannah hannah beck probably our most faithful entrant in the uh trivia contest and it paid off. It's been about a year and a half, I think, since she's won,

but this is her fourth or fifth time winning, so I am deeply sorry to those of you out there who keep trying, but keep trying. As I recall, Hannah stuck with us for nearly the five years. Oh, man. Yeah, you're right. She has been there from the start in Ridgefield, Connecticut, and Hannah, that's another T-shirt you've chalked up. Excellent. Well, for all those who want to compete for their chance at a Planetary Radio T-shirt, or two or three or four of them, but only one at a time, we've got another trivia question for you. And that is, what was the first solar-powered spacecraft?

solar-powered spacecraft. First solar-powered spacecraft. Go to planetary.org slash radio. Find out how to enter, if you don't know already, and compete for that wonderful T-shirt. And you've got until Monday, March 3rd at 2 p.m. Pacific time, Monday the 3rd at 2 p.m. Pacific, to get us that entry. All right, we're done. All right, everybody, go out there, look up at the night sky,

and think about camellias, the beautiful flower. Don't you think? Thank you, we're done. All right, everybody, go out there, look up at the night sky, and think about camellias, the beautiful flower. Don't you think? Thank you, and good night. Sorry, I thought you were asking me. They're lovely. And here's a big bunch of them for you. He's Bruce Betts, the director of projects for the Planetary Society, and he does join us every week here for What's Up,

and next week, live and in person. How would you fly to and tag an asteroid that might someday collide with our planet? Join us next time as we meet the winners of the Apophis Mission Design Competition. Planetary Radio is produced by the Planetary Society in Pasadena, California. Have a great

week. Thank you.