NASA’s Juno orbiter set to arrive at Jupiter on Monday

Rachel Feltman

Washington Post

4th July 2016

Take a break from your cookout tonight to look up at the sky and think of Juno. On Monday, the spacecraft will zip into Jupiter’s orbit, allowing us to study the secrets of our solar system’s biggest, oldest planet for the first time. Other spacecraft have visited Jupiter before.

But Juno will orbit closer than any of them — within 2, 700 miles of the planet’s cloud cover — and allow scientists to probe for data from beneath the giant planet’s roiling, gassy surface. [How NASA’s Juno mission could help tell us where we came from] ”We’re barreling down on Jupiter really quick,” principal investigator Scott Bolton of the Southwest Research Institute said at a news briefing held at NASA’s Jet Propulsion Lab in California on Monday. ”It’s been an amazing journey.

” Around 1:30 p. m. Eastern, he said, Juno passed Europa — the Jovian moon that has subsurface oceans where future missions may look for signs of life.

Around half an hour later, it passed Io, the innermost moon. ”In one Jupiter rotation, we’ll be there,” said Jim Green, director of planetary science for NASA. ”What a wonderful day to celebrate.

It’s a milestone for our country, but also for planetary science.” Jupiter, a planet so huge that despite its gassy composition it has a mass greater than the rest of the objects in our solar system (save the sun) put together, is thought to hold some of the secrets of our own origins. Jupiter was formed from the sun’s leftovers, creating a planet that almost has its own mini solar system surrounding it.

The differences between Jupiter and the sun — and between Jupiter and the planets that followed it — could help scientists the conditions of our early solar system. [More signs that life could thrive on Jupiter’s moon Europa] ”This is the beast we’re after,” Bolton said after putting a new image of Jupiter — one taken just before Juno turned its science instruments off several days ago — up on the screen. ”And we’re going to conquer it tonight.

” ( ) Around midnight Eastern time, the spacecraft’s engine will fire, slowing it down by over 1, 700 feet per second. By slowing down at just the right spot — a target just a few miles wide — Juno will be set up to receive a gravitational hug that will tug it into the proper orbit. The spacecraft’s orbital path is designed to protect it from Jupiter’s incredibly strong radiation.

Jupiter has a magnetic field some 20, 000 times as powerful as the one surrounding Earth, and at its strongest points it hosts electrons that bounce back and forth at nearly the speed of light. [NASA’s Juno probe has entered Jupiter’s violent magnetosphere] ”Juno is going into the scariest part of the scariest place,” Heidi Becker, who leads Juno’s investigation at the Jet Propulsion Laboratory, said during Monday’s briefing. Its orbital path will keep it away from these danger zones most of the time, but it does have to pass through the most radioactive regions more than once during its insertion period.

When those electrons ricochet off Juno’s instruments, Becker explained, they create a spray of proton ”shrapnel” that could easily fry its computer systems. To protect the spacecraft during this period — and during its journey through the only quiet zones of Jupiter’s magnetic field — its important instruments are encased in a titanium vault. But those radioactive particles aren’t the only ones of concern.

Much larger particles — pieces of dust and rock — could sabotage the mission as well. Jupiter has a ring (like Saturn’s) and scientists aren’t sure how far it extends toward the planet’s surface. Juno is plowing through this ring of debris with its engine nozzle cap off in preparation for Monday’s burn.

It would be unlikely for the spacecraft to hit debris, the mission team says, but because of how little we know about the ring’s inner density, an unlucky encounter with a pesky piece of dust can’t be ruled out. At a maximum speed of 165, 000 miles per hour, Juno could theoretically be torn up by even a tiny speck of space dust if it were to hit the temporary breach in the spacecraft’s defenses. Caption New photos of Jupiter and Mars, the transit of Mercury and more images of space.

Auroras created by particles are seen on a pole of Jupiter in this NASA composite of two separate images taken by the Hubble Space Telescope. via Reuters .
 

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