Juno Heads To Jupiter
JOE PALCA, host: This is SCIENCE FRIDAY, and I'm Joe Palca.
Up next, a trip to Jupiter. We're off to Jupiter. Well, you and I aren't, but Juno is. Juno is going to launch next week. And once underway, the solar-powered spacecraft will make two trips around the Earth, getting a gravity assist, and then it's on its way to Jupiter, our system's - Solar System's biggest planet. Juno's 11 different instruments will look for signs of water and ammonia and measure the planet's gravity. And there's a Juno cam, which scientists hope will send back the first-ever pictures of Jupiter's poles.
Joining me now to talk more about Juno and its mission is my guest, Scott Bolton, is principal investigator for the Juno mission to Jupiter. He's based at the Southwest Research Institute in San Antonio, Texas. Thanks for being with us today, Dr. Bolton.
Dr. SCOTT BOLTON: Well, thanks for having me. I'm - it's an exciting time. We're just days away from launching.
PALCA: Well, you have to describe that, but I want to invite our listeners also to ask questions. Our number is 800-989-8255. That's 800-989-TALK. And, yeah, so how does it feel? You're - it's next Friday. We probably wouldn't be able to get you on the show because you'll be down, I suppose, at the Kennedy Space Center.
BOLTON: I'm actually already down at Kennedy Space Center, working on all the final testing and preparations for the launch. It's been many years since we first put this whole mission together, so it's great to see everything coming together in one place. And we're so close to launch. It's just - it's like a dream come true.
PALCA: Well, I seem to - I think I heard you say earlier in the week, in a press conference, that this mission was conceived in - or approved in 2003. Is that right? Or competed in 2003?
BOLTON: It was competed back in 2003 and selected, I think, in 2005.
PALCA: And, you know, you were just describing, OK, there's a lot to prepare. What do you have to do to prepare a spacecraft for launch to another planet? I mean, are you just going through the software or making sure you pack your toothbrush? Or what do you have to do for a trip like this?
BOLTON: Well, you've got to make sure that all the science instruments are functioning and all the subsystems are working just the right way. And then after everything is loaded with fuel and - you have to mate it to the upper stage of the rocket. You put it inside of the payload fairing, which is the top part of the rocket.
And then that's shipped out to where they're building the rest of the rocket, which is, you know, has multiple stages. And then they lift it up and put it on top of that and do even more testing and final preparations. And then there's a series of reviews to make sure you've closed all your actions and left no unanswered questions about being ready. So there's quite a bit of work...
BOLTON: ...that gets going, even in the last few weeks.
PALCA: So you've got a little bit of time after it launches before you have to worry about getting data from Jupiter, anyway. How long is it going to take to get there?
BOLTON: It takes five years to get there. We get there in July of 2016.
PALCA: And do you do anything on the way, or are there any measurements that you can take as serendipity, as you pass by something?
BOLTON: There's probably quite a few. We haven't exhausted our search for those kinds of extra observations. What we do is, is when we launch - and we launch on an Atlas 551, so it's a pretty powerful rocket - it sends us into - gets us to escape Earth, but we're basically now in orbit around the Sun, like the Earth. And the first - we get an Earth gravity assist two years later, roughly. So we go around the Sun. We time it so that when we come back, Earth's here, Earth grabs us, slings us toward Jupiter even at a greater velocity so that we can reach out to Jupiter. And then we arrive at Jupiter three years later.
So we'll do calibrations, and we'll probably get some new science when we fly by the Earth, as well. And then on the way out to Jupiter, we'll take a look around to see if there's any closer asteroids that we could fly by and get some unique new science. There's a series of calibrations on the way out that we'll do to monitor the instruments' health and their ability to make the measurements. And we'll also look for other kinds of observations in the solar wind and the galactic plane and things like that that could be new and unique.
PALCA: OK. So why Jupiter? I mean, you got lots of planets in the solar system. Why is Jupiter this - your favorite at the moment?
BOLTON: Well, the driver to go to Jupiter is really because we're searching for the very earliest information, the earliest time when planets were first forming after the Sun formed. And Jupiter is the largest of all the planets and the most massive. In fact, if you take everything else in the Solar System, it fits inside Jupiter...
BOLTON: ...more than twice as much mass as everything else.
PALCA: So this is going to tell you about the early days of the Solar System before we were here, even.
BOLTON: That's right. So what happened is, you know - what people - what scientists believe is that you had a cloud, an interstellar cloud that collapses and forms a star, our Sun, and the - and then there's leftovers. And the solar system, basically, all the planets are made from the leftovers. Well, Jupiter got the majority of those leftovers. So what we want to understand is, you know, exactly what was in those leftovers? How did it eventually come to be that we have all of the planets in our solar system?
We're trying to discover this recipe for planet-making, and what Juno does is it goes after the ingredients. So we're at the ingredient list, first stage of that recipe, and we're also looking for keys to tell us the process and exactly how that planet got made. And it all stems from the fact that Jupiter is a little bit different in composition than the sun.
PALCA: Well, it's - I like the idea. It's sort of a humbling idea that we're all leftovers, but maybe we should learn to live with that. And let's take a call now, and go to Jim in Ocala, Florida. Jim, you're on SCIENCE FRIDAY. Welcome.
JIM: Thank you. I had a question about the radiation environment in Jupiter, what kind of hardening Juno has to have, and could a human actually be out there with the technology that we have? And thank you very much.
PALCA: You're welcome.
BOLTON: So that's a great question. Jupiter's radiation belts are probably the most hazardous region in the entire solar system other than going right to the sun itself. And so what Juno has is a vault, what we call a radiation vault. And it's basically a box made out of titanium. And we put all of our electronics in the middle of that that are sensitive to radiation.
And so we're very much like an armored tank going to Jupiter. And right now, I don't think we could construct something that would allow humans to survive for very long in that type of environment.
PALCA: No. I suppose not. That was a great call. Let's go now to Stephanie. Stephanie in Salt Lake City, Utah, welcome to SCIENCE FRIDAY. You're on the air.
STEPHANIE: Hey. Thanks for having me. I just had a question about the materials that the probe was going to be made out of to withstand the heat that is going to be going through, and like what the temperatures would be when it's going through the atmosphere.
BOLTON: Well, it doesn't go into Jupiter directly anyway, does it, Dr. Bolton?
No. In fact, we orbit Jupiter, and the closest we get is about four for five thousand kilometers above the cloud tops. So we're not experiencing the heat. There was a probe that went into Jupiter made out of - that was back on Galileo in 1995. We don't go into Jupiter.
At the end of our mission, we dispose of the spacecraft for planetary protection, basically, to make sure it doesn't accidentally crash into Europa. And it goes into the atmosphere then, but we don't operate during that period. That's just the getting rid of the spacecraft. So we don't have to worry about surviving the heat of going through the atmosphere.
PALCA: And Juno's in a different kind of orbit from Galileo, right?
BOLTON: Absolutely. We're in a polar orbit, so this is the first time that a spacecraft has gone into polar orbit of Jupiter. So not only are we going closer than (unintelligible) Galileo, but we're over the poles and Galileo was over the equator.
PALCA: All right. Is there something particularly of interest at the poles? I mean, there's nothing like a landing spot or anything like that.
BOLTON: No. There's no landing spot. It's all - it's giant ball of gas. It may have a core of heavy elements in the center of it, but it's nothing that you're going to land on.
(SOUNDBITE OF LAUGHTER)
BOLTON: No. The reason you go into polar orbit is we want to measure the magnetic and gravity fields, and they come out of the poles and drape around the planet. And so in order to make the precise measurements and understand the full field, we go over the poles so that we're measuring all latitudes, and then we have 30 orbits, each one is spaced evenly in longitude so we basically get a full map of the planet in both longitude and latitude. And that also serves our microwave experiment as well.
PALCA: But this is a map of the gravitational field, not the surface features if it's a gas planet.
BOLTON: Correct. We're getting a map of the gravity and magnetic fields. We also have a set of instruments that looks at the polar magnetosphere, so we - that polar orbit is used in order to look at Jupiter's aurora. Much like the Earth's aurora, it is concentrated at the poles.
PALCA: Let's take another call now and go to Janet in North Fort Myers, Florida. Welcome to SCIENCE FRIDAY, Janet.
JANET: Thank you very much. I'd like to know as an elementary school science lab teacher what Web-based resources are available for us to allow our students to track Juno's journey.
BOLTON: So we have two websites that you can go to and learn quite a bit about Juno. One is missionjuno.swri.edu, that SWRI stands for Southwest Research Institute, so missionjuno.swri.edu. And another one is NASA's, www.nasa.gov/juno. And at those two websites you can learn quite a bit about Juno. You can track our progress. You can watch the launch, in fact.
PALCA: Wow. And I suppose, yes, there's - I'm sure there's a lot of stuff describing the mission. But Janet, you're going to have to wait five years before you start getting data back, you understand. So all your elementary school kids will already be off to college.
JANET: That's right.
BOLTON: Not quite.
JANET: That's all right. We want to educate them along the journey also.
PALCA: All right. Well, that's cool. Thanks very much for your call. Let's take another call now, and go to Craig. Craig in Naples, Florida. We're in Florida this day. What - welcome to SCIENCE FRIDAY.
CRAIG: (Unintelligible) space shuttle launch (unintelligible) Saturn 5. But is that launch (unintelligible) is that open to the public and at what time? And also, in two years when it gets the slingshot effect from Earth's gravitation, will that be visible anywhere on Earth to see the thing rocket out? And I'll take my message off the air. Thank you very much for your time, gentlemen. Good luck.
PALCA: OK. Thanks, Craig. So when and where, the timing of the launch, and slingshot?
BOLTON: So the launch is set for August 5 around 11:30 a.m. Eastern time. To come onto the NASA property, you have to have some special NASA passes that some of them were open to the public. But I don't know if there's any - any of that is left. You'd have to contact Kennedy Space Center Visitor Center complex, and they may be able to get you some passes for the public to come in. But if you came down to Coco Beach or Cape Canaveral, you'd get a pretty close view no matter where you were in those towns. You could go right to the beach and get a great view of the launch.
And then as far as the Earth flyby, we go by pretty close, so I think it will be visible, although the exact time and location won't be finalized until we see exactly what day and time we launch. We have a three-week window. So August 5 represents the first day that we can launch, and of course we intend to launch that day. But if weather or some technical problem occurs, we could launch any day for the next three weeks. And so the Earth flyby moves around a little bit based on which day we go.
PALCA: We're talking with Scott Bolton. He is the principal investigator for the Juno mission to Jupiter, which is set to launch next week. I'm Joe Palca, and this is SCIENCE FRIDAY from NPR. So let's take another call now and go to Gordon(ph) from Dallas, Texas. Gordon, welcome to SCIENCE FRIDAY.
GORDON: Thank you very much for taking my call. I would like to know a bit about how long it takes for data to travel back to Earth from Jupiter, and if the gentleman could expand on us the type of technology that's used to transmit that information. And I'll take my answer off the air.
PALCA: OK. Thanks, Gordon.
BOLTON: OK. So Jupiter is five times the distance from the sun as the Earth is, and so it takes us about 50 minutes to send the data back from Jupiter to the Earth. That varies a little bit because the Earth is going around the sun, and so the distance between Earth and Jupiter varies a little bit during the year. And so it can be plus or minus 10 minutes or so. The technology that's used is basically microwave antennas. We have - we send data down in certain narrowband frequencies. We have what's called a high-gain antenna onboard our spacecraft.
The data is transmitted out of that high-gain antenna and received on the ground, at Earth, through the Deep Space Network, which is a set of antennas that NASA runs that are spaced around the whole world. There's one in California, one in Madrid, Spain, and one in Australia.
PALCA: All righty. I think we have time for one more question. And let's go to Bill in Charlottesville, Virginia. Bill, welcome to SCIENCE FRIDAY.
BILL: Hi. I love your show. OK. I'll try to make this quick. You're speaking English so I can ask this question. Why - if the solar system was formed by everything coming into a center and what's left outside is the leftovers, why isn't the solar system symmetrical?
PALCA: You mean were not perfect circle orbits as opposed to slightly...
BILL: No, no. No, no, the orbits, I understand, but why isn't the debris? Why aren't the planets? Why isn't everything symmetrical within the solar system?
PALCA: Oh. You mean why isn't it's just like a big fan of particles all over the place?
BILL: Yes, exactly.
PALCA: OK. I bet there's an answer. Let's see if Dr. Bolton can help us with that.
BOLTON: I can help you a little bit with that. But what, you know, the cloud that eventually forms you dictates a lot of what happens afterwards. So if there's a gravitational instability and I have this cloud of material that's mostly hydrogen, helium and a little tiny bit of the rest of all the other elements and it collapses down and forms the sun, that cloud may be rotating and have angular momentum before things start. And so once everything collapses down and starts to form the star, the debris and the sun that's formed also has that angular momentum. And things start to swirl around. And then each of the planets, as they start to form for whatever triggers their formation, grabs material.
Each time it does that, it's also incorporating that angular momentum and providing a little bit of asymmetry because it's taking material in one location as things are starting to go around. So most things, or most models have it so that when debris gets left, it's mostly in a flattened plane as opposed to a sphere. And that has to do with that angular momentum. And then each of the planets or objects that gets created also leaves a little plane of material that's left around it.
PALCA: I see. And once you get a little nucleus of planet forming, it starts to draw stuff in from its gravity, I presume.
BOLTON: Right. Many models have rocky substances or comet-like substances starting to get glued together from - and from crashes. And they start to gain enough of a critical mass that all of a sudden they have enough mass, and instability occurs and it grabs the rest of material that its gravity can dictate.
PALCA: All right. Well, Dr. Bolton, that was great. I wish you complete success on Friday, or whenever you actually launch. And we'll look forward to hearing more updates as the mission progresses.
BOLTON: Well, thank you very much. Thanks for having me.
PALCA: That's Scott Bolton. He's the principal investigator for the Juno mission to Jupiter. He is based in the Southwest Research Institute in San Antonio, Texas. He's down in Florida waiting for the launch of Juno that's taking off for Jupiter next Friday, if all goes well.
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