NASA promising July 4 big bang — and lots of science — when Juno probe reaches Jupiter

On Independence Day NASA’s Juno spacecraft reaches the largest planet in our solar system and is expected to transmit pictures the 1.8 billion miles back to Earth. But even more interesting than pictures, scientists hope to collect tons of data to help them understand Jupiter’s formation — and our own. Science correspondent Miles O’Brien joins William Brangham.

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    But, first: NASA is hoping for a big Fourth of July this year as it closes in on the planet Jupiter for an unprecedented look. The moment is arriving after a five-year-long journey of more than 1.8 billion miles.

    Scientists hope to gain new understandings about the largest planet in our system and the solar system itself.

    That is the focus of our weekly segment on the Leading Edge of science.

    William Brangham takes it from there.


    The holiday weekend is often a time for big blockbuster movies, and it's safe to say that concept has not been lost on NASA.

    The space agency has just released a kind of movie trailer about what it hopes will be a nail-biting night on the Fourth of July. That's when the Juno spacecraft, which is going to fly closer to Jupiter than any spacecraft has before, is supposed to reach its destination. But getting to Jupiter comes with its own risks.

    This is how NASA describes it in the trailer.

  • MAN:

    It's a monster. It's unforgiving. It's relentless. It's spinning around so fast its gravity is like a giant slingshot, slinging rocks, dust, electrons, whole comets. Anything that gets close to it becomes its weapon.


    OK, that got my attention.

    Our science correspondent Miles O'Brien is here to spell out some more.

  • MILES O’BRIEN, Science Correspondent:

    William, I should have brought the popcorn.




    We have been to Jupiter before. NASA's been there a couple of times. What's different this time?


    Well, depending on how you count, we have had about 10 missions to Jupiter.

    Most of them have been flybys, Voyager, Pioneer notable among them, New Horizons as well. We of course had the orbiting mission of Galileo, which began in the mid-'90s into the early 2000s, which did most science around Jupiter and its moons.

    And that's the big treasure trove of data. And all the while, the Hubble telescope has captured a lot of interesting data from Jupiter. And in particular, back in 1994, you may recall when the Shoemaker-Levy 9 comet, that fragment comet, struck Jupiter, Hubble got some amazing images of those impacts.

    But all off this is skin-deep.


    So what are we trying to learn this time?


    Well, there's a lot of things we can learn from Jupiter.

    Jupiter, of course, is the biggest plant in our solar system of eight planets. It's about two-and-a-half times the mass of all the rest of the solar system combined, of the planets, that is. And it's really like a big deep freeze for how our solar system began four billion years ago.

    It really hasn't changed very much. So scientists want to understand what's kind of beneath the surface there, how much hydrogen, how much water, what about the magnetic field, what about the gravitational pull, is there a solid core? All these are important clues and information for us to understand how our solar system progressed, how it developed and really how we came to be where we are today.

    The principal investigator of the mission is Scott Bolton, and he fills us in on some of the big questions.

  • SCOTT BOLTON, Principal Investigator, Juno Mission:

    The major science objectives of Juno are, one, to understand how Jupiter formed and what is it made out of. We want the recipe of solar systems, and we are at the ingredient list level.

    So we're gathering the ingredient list and understanding how Jupiter is structured. So the most important objectives are understanding Jupiter's formation and how that relates to the formation of other planets, including us


    So, if Juno isn't landing on Jupiter, how is it going to see beneath the surface?


    It's not so easy, is it? You're talking about, first of all, a very hazardous place to do business, if you will.

    But the key is, they to understand things about, for example, the magnetic fields. They're using things like magnetometers. They're using microwave detection capability which will be able to see beneath the clouds and sort of identify the composition of what lies beneath the clouds, spectrometers, a device which actually measure the gravitational pull from the planet itself on the spacecraft, and will be able to give scientists on the ground exactly how strong it is at any given point.

    Now, you can imagine, this is the closest orbit ever to Jupiter. This will be a 14-day orbit once it gets into its science mode, and building devices that are able to gather things on things like radiation, which are important, but which, of course, are very hazardous to the spacecraft itself, is difficult.

    So they built a titanium box with has just enough shielding to protect the instruments and yet allow the data to come in. One of the main people on the team is the deputy chief engineer, Tracy Drain.


    If you want to pick, aside from the sun, the scariest environments we know of to send a spacecraft to, Jupiter would be the place to go, because Jupiter has this gigantic magnetic field, which traps a lot of charged particles that get accelerated along the magnetic field lines.

    It builds up this huge radiation field. If we were to leave our spacecraft bathing in that radiation, it's just not designed to deal with that. So we are going to go through the radiation belts to get into orbit and then we will going in and out of the radiation belts as we do our science phase.


    So, Monday is the big day. What are we actually going to see? What's going to happen Monday?


    It's the denouement to a story which began five years ago with a launch.

    It launched in August of 2011, on its way, traveling more than a billion miles in space, making its way toward Jupiter, unfurling these giant solar arrays, the biggest arrays to ever to go on a deep space probe. There's only 4 percent of the sun's power at Jupiter relative to what we have here.


    It's that dim out there?


    It's that dim that they had to build these giant arrays. Those have been spread and they're operating just fine.

    And it's traveling now, as it speeds up toward Jupiter, being captured by the gravity, at more than 153,000 miles an hour, making it one of the fastest manmade objects ever. So, the trick will be reducing that speed enough so that it doesn't just whiz by the planet, like some of those other probes we talked about.

    So, it will turn its rocket in the opposite direction, sort of the reverse direction, fire it for about 35 minutes. And that should slow it down just enough for Jupiter to pull it into its grasp. And that will be a nail-biting moment for the folks at the Jet Propulsion Lab in Pasadena, California, as they wait to hear, subsequent to all that happening — this is all on autopilot.

    There's nothing they can do to make this happen or not happen. It will either happen or it won't. It's kind of the die is cast. They will get, like, a three-second beep, and that will be it. And that will be the best beep these guys have ever heard, hopefully.

    And then the mission begins. The scientific mission ultimately will begin toward the fall with 14-day orbits lasting for about 16 months. And then, when they're done with Juno, Juno will dive right into Jupiter and have a fiery conclusion.


    Are we going to see images coming back from Juno?


    It's not an imagery mission for the scientists, per se. All the data they want is more on the squiggly lines, if you will.

    However, there is a camera on board. It's designed primarily for public affairs. And the imagery should be interesting for us, because the orbit of Juno is polar. And we really haven't had a good look at the poles of Jupiter. And in particular, one of the scientific goals here is to understand their amazing auroras, which are much stronger than we have here on Earth.


    All right, we will be watching on the Fourth of July.

    Miles O'Brien, thank you so much.


    You're welcome, William.

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