Planetary Radio: Space Exploration, Astronomy and Science - Return to Jupiter with the Juno Mission

Episode Date: January 26, 2009

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A return to Jupiter with Juno, 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. First Pioneer, then Voyager, and then Galileo. Get ready for the next robotic emissary to our solar system's largest planet. We'll talk with Scott Bolton, the principal investigator for the Juno mission, which will lift off for Jupiter in two and a half years. Juno may help us discover how our own planet came to be. Bill Nye, the science and planetary guy, is cooking with gas. Natural gas plumes on Mars. Emily Lakdawalla presents a

new Q&A segment about asteroids, iridium, and the death of the dinosaurs. And Bruce Betts will tell us about the night sky, just before we once again acknowledge the week in which all three of America's worst space disasters took place. Then we'll try to cheer you up with a new space trivia contest. We're glad so many of you enjoyed last week's celebration of the Mars Exploration Rovers. Emily's blog at planetary.org has more about Spirit and Opportunity's fifth anniversary on the Red Planet. has more about Spirit and Opportunity's fifth anniversary on the Red Planet. The entry includes an essay by Jim Bell, who heads the rover PANCAM team and is the president of the Planetary Society. You'll also find links in the blog to Jim's and Emily's podcasts about the rovers.

The 365 Days of Astronomy podcast series is part of the International Year of Astronomy. Here's Bill Nye. Hey, hey, Bill Nye, the planetary guy, vice president of the Planetary Society. And once again, it's a story about Mars this week that has me so excited. Michael Mumma, who's an investigator at the Goddard Space Flight Center, checked observations made back in 2003. Now, these observations in 2003 were made with the Mars Express spacecraft, and they thought that they detected methane. But get this, using telescopes here on Earth, Mama and his team have found sort of continent-sized methane outgassing from somewhere on the Martian surface. Now, there are many, many explanations,

perhaps, of methane, natural gas, methane, as we might say in the United Kingdom, in the atmosphere of Mars. But the methane in the atmosphere of the Earth comes from living things, comes from microbes. So are there microbes? Are there Mars-crobes on Mars and continent-sized subterranean deposits or colonies? And that makes it just that much more possible that there are living things on Mars. Not were, are living things on Mars. Oh, so there's a couple things. First of all, as we send more probes there, we got to be really careful. We don't want to be forward contaminating the Martian environment. But secondly, Mars Science Laboratory,

formerly Mars Smart Lander, got delayed. But maybe that's not such a bad thing. Because over the last few weeks, we've discovered what we believe are enormous glaciers on Mars, that's water, our enormous glaciers on Mars, that's water, and now enormous emitters of methane. So our choice of landing site can be that much better a few years from now. We can be that much more sophisticated about where we go next. Oh, my friends, as I so often say, if we discover life on Mars, it will change life on our planet because it will change the way we look at how living things come to be in the universe. It could, dare I say it, change the world. Well, thanks for listening. Please stay tuned to Planetary Radio. I gotta fly. Bill Nye, the Planetary Guy. When it leaves for Jupiter, Juno will be the first solar-powered spacecraft to head out that far.

All of its predecessors relied on the heat of decaying plutonium to generate the electricity they needed. It was thought that Jupiter was just too far from the sun for solar cells to do the trick. Principal investigator Scott Bolton and his team want to prove that thinking wrong by attaching four giant, super-efficient solar panels to their spacecraft and making sure it gets by on a power budget that makes your Energy Star appliances look like electron guzzlers. But there's so much more to this mission that will go into a polar orbit in 2016, passing just 3,000 miles above the mighty planet's clouds. Juno is being managed by the Jet Propulsion Lab, where Scott is spending a lot of his time. The spacecraft is being built by Lockheed Martin,

and there is substantial participation by the Italian Space Agency. We Skyped Scott at the Southwest Research Institute in San Antonio, Texas. That's where he heads the Space Science and Engineering Division. Scott, thank you for joining us on Planetary Radio. Let me start by asking you, what is Juno going to tell us that we didn't learn from Galileo? Well, Juno really picks up where Galileo left off. We're going after the piece of composition that the Galileo probe couldn't obtain. It didn't really make a measurement of the oxygen abundance or the water abundance, which is representative of the oxygen abundance in Jupiter.

And what Juno has on board is a set of micro-radiometers that look at the atmosphere and at different depths and measure the temperature or the brightness temperature of the atmosphere. And from that we can determine the water abundance, the global water abundance, the one down deep. We also see it as a function of longitude and latitude, so we'll see how it varies across the planet as well. Juno's in a close polar orbit, so we also study a piece of the magnetosphere that the Galileo orbiter was not able to do. The Galileo orbiter went around the equatorial bands of Jupiter near where the satellites are, and it buzzed around the Jupiter orbit near the equator, and Juno's polar.

So we go very close over the poles where the aurora are, and so we're able to really investigate the aurora in a way that Galileo couldn't do. And then we also, because we go in so close, we get a much better measurement of the magnetic field as well as the gravity field. When we talked the other day, you mentioned that this spacecraft, Juno, is sort of a radio astronomer's dream. What did you mean by that? Well, it's a radio astronomer's dream in the sense that we have so many kinds of antennas on board. Microwave radiometers are a passive radio astronomy instrument,

passive in the sense that it's a little bit like a radar instrument, but it's just listening. And then on top of that, we have a plasma wave instrument that also is looking at radio emissions, but at different frequencies and local plasma waves themselves. Galileo had one of those and so does Cassini, a plasma wave instrument. Of course, the magnetometer is another way to look at these kinds of waves that are very, very high frequency. And then we have an array, a large, not an array, but a large set of communication antennas. We have the high gain antenna. We have both X band and KA band in order to do gravity science. We also have all kinds of different toroidal and omni antennas to be able to stay in touch

with the Earth throughout the voyage out to Jupiter and while we're at Jupiter. And so altogether, we just have a huge number of radio antennas. I often observe Jupiter from the ground using the VLA or ground-based radio telescopes, and it's usually done at one or two frequencies. And we're carrying six frequencies just in the microwave system. So it's very rich in radio. You mentioned that you'll be able to investigate the gravity field surrounding this big planet.

What Juno is doing is using Doppler shifts in order to make a measurement of the gravity field. As the spacecraft comes by Jupiter, and it's going very, very close to Jupiter, the altitude of the perijoke passes about 5,000 kilometers above the cloud tops. And so Jupiter's enormous gravity field kind of pulls and tugs on that spacecraft. And that's picked up as changes in the Doppler shift

or changes in the frequency of the communication to the Earth. And we have a very sensitive gravity system, in the sense that we have both X and KA band, and they're both up and downlink. And so what's happening is that the Earth is sending a signal to the spacecraft, to DSN. The spacecraft is turning around, sending that signal back, and then the Earth, the DSN, sends that signal back to to the spacecraft again and so you have this two-way communication going and the fact that you have two different frequencies allows you to remove any small perturbations that would have happened

in the frequency due to the interplanetary plasma or effects from charged particles in the path of that radio signal and so it's a very, very sensitive system. And of course, because we're going polar, we sample the full gravity field of Jupiter. And we do this many times over and over again. And so in fact, we'll not only get a great measurement of the gravity field, but we'll be sensitive to the effects of the tides from Jupiter satellites even. Because each time we go around, those satellites will be in a slightly different orientation with respect to each other, and so we'll see that effect on Jupiter's gravity field. Voyager and then Galileo told us what an incredibly nasty place the environment around Jupiter is.

How are you building a spacecraft that will be able to withstand this and get so close to that radiation and electromagnetic radiation surrounded planet? That is one of the big challenges. There's no question. And that is what makes Juno very special in the sense of a spacecraft design. We're basically an armored tank going into Jupiter. And I mean, literally, what we have is we have what we call a vault in the middle of the spacecraft. And it's basically a box made out of, you know, radiation hardened material, you know, just shielding, like you would put lead, you know, like from Superman days. And we put all of this sensitive electronics inside of

this radiation vault. Now, of course, there's sensors and there's a few things that have to be outside that vault. But in general, everything is heavily, heavily shielded. And it's a little bit of an archaic system in the sense that it's like an armored tank. It's just mass. You just stick a lot of mass on board around this, all the electronics, and that stops these high-energy electrons and protons and ions from getting in and destroying your electronics. On the other hand, you've got these big solar wings, and in fact, you know, as we've said, first deep-space probe to be solar-powered.

Tell me, if you had a choice, wouldn't you have stuck one or two RTGs, radioisotope thermal generators, on there? Oh, that's an interesting question. If I had that choice, I might have gone that way. And in fact, when we were proposing it, we did have that choice. The way PI missions work is they put out an announcement of opportunity, NASA does, and they have certain ground rules that are in it. And in the announcement of opportunity that Juno responded to, they did offer RTGs. Now, the catch was is the RTGs weren't yet developed. And what they were

doing was saying, well, we're developing new ones, and we hope to have them ready by 2009. So when we looked at it, we knew there was a risk that maybe it wouldn't be ready in time for us to have it integrated. And so we looked at the option of could we do this with solar power? Turns out we're green, but we were green before it was in to be green. When I look back on it, I think I'm glad that we're solar powered. We're showing that you can do this at Jupiter, at least Juno can. And so there are certain mission architectures that would allow themselves to lend themselves to a solar powered mission. But, you know, in reality, if you had an RTG, it would be simpler

in a sense that I wouldn't have to worry about pointing the spacecraft at the sun in order to get power. And so solar power does complicate things in the sense of mission design and doing your pointing and downlinking and using up power and you're playing around with batteries and so forth. But at the same time, there's a simplicity in the sense that we did not have to wait for any new technology to be developed. That's Scott Bolton, principal investigator for the Juno mission to Jupiter. That's Scott Bolton, Principal Investigator for the Juno mission to Jupiter. More in a minute. This is Planetary Radio. I'm Sally Ride. After becoming the first American woman in space, I dedicated myself to supporting

space exploration and the education and inspiration of our youth. That's why I formed Sally Ride Science, and that's why I support the Planetary Society. The Society works with space agencies around the world and gets people directly involved with real space missions. It takes a lot to create exciting projects like the first solar sail, informative publications like an award-winning magazine, and many other outreach efforts like this radio show. Help make space exploration and inspiration happen. Here's how you can join us.

Help make space exploration and inspiration happen. Here's how you can join us. You can learn more about the Planetary Society at our website, planetary.org slash radio, or by calling 1-800-9-WORLDS. Planetary Radio listeners who aren't yet members can join and receive a Planetary Radio t-shirt. Members receive the internationally acclaimed Planetary Report magazine. That's planetary.org slash radio. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan.

The solar-powered Juno will arrive at Jupiter in 2016 after a five-year trip from Mother Earth. That means Principal Investigator Scott Bolton and his team have a bit more than two years to finish designing and building this medium-scale New Frontiers Program spacecraft. The only other New Frontiers probe is New Horizons, currently on its way to Pluto. How is progress on the spacecraft coming? I know it's being built by Lockheed Martin in Denver. Yes, we're progressing really well. We're in phase C, which means the critical design phase. And so engineering units are being built of different things and testing of some hardware is already being done. And we're getting ready for the final design to be kind of anchored down and then you'll start building the flight hardware. So we're making a lot of progress. And as you said, we have very large solar panels. And while I say there's not a lot of new technology in that, in fact, our solar cells are made to work at Jupiter. And so there are a little bit different than the normal solar cells that have been flown before. And they've been tested for low levels of light and low temperatures that will be experienced at Jupiter. And they have special cover glasses on them to protect them from the radiation. But in general, we're making a lot of progress on the spacecraft, and I'm very happy with our progress.

When you reach Jupiter, and I do say when, in 2016, after this five-year trip across the solar system, what are the questions that you hope this wonderful array of instruments is going to help us to answer? Well, the primary questions that we're after have to do with our origins and how the solar system was made and how planets are made in general. And so we're looking at Jupiter to look at the history, if you will, or the very early history of the solar system and what it's made of essentially is what the early solar system was made of so Galileo showed us another another NASA missions have showed us that our basic idea

that that planets are made after the sun formed the sun formed from a nebula a cloud that existed in our at the location of our solar system and then collapsed on itself and a star was born, our sun, and the material that was left over went into the planets. And one of the big questions, the planets are enriched in heavy elements. And how did that happen? Those heavy elements turn out to be very important to us. And what I mean by heavy elements is everything heavier than helium. So you've got all the oxygen, the nitrogen, the sulfur, the noble gases,

the krypton, argon, all these things. And Jupiter's enriched in these things, and we know that from Galileo Probe. And the question is, how did that enrichment occur? What happened in the early solar system that allowed all the planets to get enriched? And that's really what we're after, is how did Jupiter form? And how these elements were enriched in the planets is very important to us, in fact, because that's what we're made out of. That's what the Earth's made of. And in fact, that's what our life, you know, humans and all the animals and life that we have

on the planet is actually made of those. We can't look at the Earth to understand this question, because we've lost all of our history. We've outgassed the light elements of all of us. And then on top of that we have processes that go on inside the Earth where volcanoes and earthquakes and things get changed around, and so we've lost the history. We can't even really look down deep and see how our magnetic field was created. At Jupiter, that's not the case. It had enough mass to hold on to its original material, and when Galileo probe went in there, it went in to search for differences in those cosmic abundances of the,

or in fact, the heavy elements and the ratios of those, with the idea that that would give us clues as to how that enrichment occurred. Because it's often believed that it was brought in by ice, icy planetesimals. And as you know, hydrogen is the most abundant element in the universe with helium next and then comes oxygen. So the most abundant element or molecule is water. It's very important.

Somehow water is very good at trapping these heavy elements. So it's thought that things as the early solar system cooled it brought in these planetesimals and enriched Jupiter. But when Galileo probe went in they were all enriched about the same factor which meant that the volatility didn't really matter. That threw out basically

all the theories of how planets got made in one swoop. When Galileo went in and measured that and everything was sort of enriched the same, right away our theories of how Jupiter were made, and in fact all the planets were made, kind of went out the window. Either Jupiter was made in such a cold environment that the volatility of those elements didn't matter, or it didn't form where it is, and it moved in. Of course, we've now seen very close giant planets to other parent

stars, so the idea of planetary migration is fairly popular now. Juno's primary question is, that it's going to answer, is how did Jupiter get formed? We're going to address that by measuring the water abundance, the piece that Galileo probe missed. We're going to go after the gravity field that will tell us whether there's a core in the center of Jupiter that's missed, we're going to go after the gravity field that will tell us whether there's a core in the center of Jupiter that's solid, or is it just gas all the way down? And if it has a solid core, then that lays out groundwork that you had to form some solid chunks in the solar system that first came together before you formed Jupiter. So that lays out a certain kind of scenario for how, what the early

solar system had in it. On the other hand, if there is no core, or a very, very tiny one, then that says that Jupiter would have formed at a different time, possibly, with different processes. And then finally, we look at fundamental physics. We're looking at the magnetic field in a way that not only will tell us about the interior structure of Jupiter, but will really go in and understand planetary dynamos, which are not very well understood. And we can't really look at the Earth to understand this either, because the Earth has a permanent magnetized crust that blocks our view. And Jupiter will be able to see all the way down to where the magnetic field is created. So those are the three things that help us with the origin.

And then finally, our magnetosphere. We go over the magnetosphere and the poles so closely that we're outfitted with a very good payload of instruments in order to understand how the aurora are generated on Jupiter. It sounds like it's safe to say that we venture to Jupiter to learn about our own beginnings. I think that is very much capturing the essence of our proposal and what our project is about. Scott, we wish you the best of luck, continued luck. I hope we can talk again as you approach that launch in August of 2011.

Absolutely. I'd be honored to do that. Scott Bolton is the principal investigator for the Juno mission, leaving for the king of solar system planets in 2011, arriving there in 2016 to begin its close investigations of Jupiter. He is also the director of the Space Science and Engineering Division at the Southwest Research Institute in San Antonio, Texas, which is where we've been speaking to him today. We're going to be right back with

this week's edition of What's Up, and Bruce Betts, here's Emily. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, the smoking gun for the impact that killed the dinosaurs is a layer of iridium that formed in Earth's rocks at the time of the impact. Do all asteroids have large amounts of iridium? Why are they so different from Earth? On Earth, iridium is a rare chemical element, forming only 0.3 parts per billion of the mass of the crust. mass of the crust. The dark iridium band found in rocks around the world from the time of the deaths of the dinosaurs contains 6.3 parts per billion, a factor of 20 in Richmond. Telescopic studies of asteroids and chemical analysis of meteorites shows us that most contain much higher proportions of iridium, from the typical 500 parts per billion in

stony asteroids to much higher amounts in nickel-iron meteorites. So it's a good question. If they all formed from the same solar nebula, why should asteroids have gotten more iridium than Earth? The answer is that they didn't, on average, but the rocks we touch and feel on Earth are not really representative of Earth's chemical makeup as a whole. Earth's outermost layer, the crust, is made of rocks that have been chemically processed through billions of years of volcanism. Below the crust is a rocky mantle that has been less processed, and beneath that is a core made mostly of iron and nickel. Certain elements, such as iridium, have a higher chemical affinity for iron than they do for the

silicate minerals that make up rocks. So, long ago, when Earth differentiated into its metal core and rocky crust, the iridium and other iron-loving elements such as sulfur also preferentially went into the core, leaving the mantle and especially the crust depleted. There's plenty of iridium in Earth, it's just where we can't see or measure it. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. And by the way, Emily really means it when she asks for those questions.

We'd love to get some more of those from you, so do send them to planetaryary Radio at planetary.org and I will forward them to Ms. Laktawalla. And here is Dr. Betts, Bruce Betts, the Director of Projects for the Planetary Society, joining us once again for What's Up, and

happy birthday! Hey, thank you, on behalf of the Betts boys, signing you from Party Central. You're celebrating both birthdays? We are indeed. They're a week apart, so we do the big celebration on one big festive party day. So that's why we have you on the phone. But that's still a good way to tell us about the night sky.

You can hear balloons bouncing in the background. I hope so. They're singing, hollering, whooping. Craziness. So the night sky. We've got Venus in the early evening. You can still check it out looking like an extremely bright star-like object over there in the west. You can check out Saturn rising now in the early to mid-evening in the east.

And up high in the sky in the middle of the night, looking yellowish like a bright star. And let's go on to this week in space history. Unfortunately, we've reached anniversaries of Apollo 1 fire, the Challenger disaster, and the Columbia disaster, all falling within about a week in their respective years in the past. Weird, don't you think? Horrible and quite strange.

And let's hope that it stops right there with three. Yeah, and we remember all of them this week. We also had some positive things this week as well. Explorer 1 becoming the first successful U.S. satellite in orbit 51 years ago in 1958. One of our trivia contests, recent trivia contests, Ham the chimpanzee, first successful chimpanzee to space and back, flew back in 1961 this week. Everything worked out well for Ham.

Yeah, yeah. On to Random space facts! Just not the same on the phone. We haven't used the telephone in so long. But what do you got for us? The spirit. It's the spirit of it. If I do a quick, you know, basic thing, but people lose track. Phases of the moon, they have some kind of funny names. So you got the new moon, where the moon is in between the earth and the sun roughly so we're seeing the

dark side then we have the waxing crescent i always enjoy that terminology waxing crescent moves on to the waxing first quarter uh where we see half of the face facing us is called first quarter uh we never have half moons we don't know why we go on to the funny word gibbous waxing gibbous and then on to uh full moon and then we take it all back down again calling it waning waning gibbous waning or not wait last quarter and then waning crescent and back to new moon exciting huh i i do love gibbous. Gibbous. Gibbous. Gibbous. We're going to have to race through the trivia contest now. All right, trivia contest.

We asked you, it's hard to race through this one. What do you call it? What's the part of the shadow, for example, if you're watching an annular solar eclipse? That part that's not the umbra, not the penumbra. How do we do that? Well, I will just tell you that our lucky winner this week, and I think he is a first-time winner, is Craig Hutchinson. Craig Hutchinson of Suffolk, Virginia, who came up with it.

It's the ant umbra. It is. I had an ant umbra, actually. She was a lovely woman. Which means the unshadow or the anti-shadow. And you know what happens when you bring a shadow and an anti-shadow together. Oh, that's not good. Huge release of blackness.

Are we going to give Craig a year in space calendar? Yes, we are. And we'll also send him out a rewards card from Oceanside Photo and Telescope, optcorp.com. What do you got for next week? All right, everybody. Extra solar planets, planetary systems outside of our own. What's the maximum number of planets we know about anywhere, and what's the name of the system?

Keep updating. Go to planetary.org slash radio. Find out how to enter. Good one. I like that. We're going to get those answers from you, I hope, by Monday, 2 p.m., 2 p.m. Pacific time, on February 2nd, Monday the 2nd. All right, everybody, go out there, look up at the night sky, and think about kibble.

Thank you. Good night. I'd rather think about gibbous. And have a good closeout of the birthday party there. Thank you very much. Happy birthday and happy gibbous kibble. He's Bruce Betts, the director of projects for the Planetary Society. He joins us every week here for What's Up. Planetary Radio is produced by the Planetary Society in Pasadena, California.

Have a great week. And remember the fallen explorers of Columbia, Challenger, and Apollo 1. Thank you.