Environment & Science

After 2 billion-mile journey, Juno's ready to get to work

This illustration show's NASA's Juno mission approaching Jupiter. Juno used distant stars to chart its course across the void.
This illustration show's NASA's Juno mission approaching Jupiter. Juno used distant stars to chart its course across the void.

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Last time we heard from JPL's intrepid Juno probe was July 4 when it finally reached Jupiter after a five year, 2 billion-mile trip. This Saturday, after taking a long, orbital lap around the gas giant, it'll finally open its eyes and take an up-close look at the planet — the first spacecraft to do so.

"Our mission is about figuring out the recipe for the solar system," said Steve Levin, the project scientist for JPL's Juno project. He and other scientists believe understanding more about Jupiter will help decipher that recipe. That's because Jupiter is believed to be the first planet that coalesced in our solar system, so it could have had an outsized impact on the formation of other planets as well.


Levin said the Juno team has four main goals for the mission:

To help answer these questions, the spacecraft on Saturday will turn on an array of high-tech equipment: a microwave radiometer, an ultraviolet imager, an infrared imager, a visible light camera and instruments to measure particles that hit the spacecraft. Researchers need these tools to see beyond Jupiter's tumultuous atmosphere, because it's what's underneath the clouds that counts. 

"We think, down in the center of Jupiter, beneath all of the gas, there should be a dense core somewhere between three and 20 times the mass of the Earth. We have no direct evidence that it’s even there, let alone how big it is. We expect to measure that with Juno," Levin explained. His team hopes to figure that out by measuring planetary traits, including its gravity and magnetic field.

The researchers also want to figure out what makes up Jupiter's atmosphere.

"The single most important number is how much water does Jupiter have," Levin explained. "And the reason that’s really important is, if Jupiter formed really far from the sun, where it’s very cold, then the amount of water you would see is different than if Jupiter formed closer to the sun, such as where it is now, where water is still frozen, but isn’t as cold."

"We’re going to look at the natural radio emission from Jupiter and use that to figure out how much water is in Jupiter’s atmosphere, and that will tell us a lot about how Jupiter formed and, therefore, how planets and solar systems formed," he said.

Juno will only orbit the planet for about a year-and-a-half before radiation from the planet starts to destroy its complicated electronics. After that, it will be lights out for Juno as JPL maneuvers it to crash into Jupiter's atmosphere.

"The reason for that is planetary protection," Levin said. "Jupiter’s moon, Europa, has a liquid-water ocean. We want to make sure that we won’t contaminate Europa. You’d hate to spend 50 years struggling to get a mission to Europa, dig beneath the ice, look in the liquid-water ocean, find life and then have to say, 'But I don’t know if it’s life from Europa or contamination from Juno 50 years ago.' "

Levin said he was excited about the mission,"We fully expect Jupiter to surprise us," he said, "we just don’t know what the surprise is going to be."