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NASA’s Juno spacecraft is a trooper as it continues its 2-year-long mission.

Hosted by: Hank Green
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Hank: Earlier this year, NASA’s Juno spacecraft made it to Jupiter after years of hurtling through space – all ready to begin its 2-year-long mission. Juno settled into an orbit around the gas giant by the 4th of July, and on August 27th, its first flyby with all the scientific instruments on went without a hitch. But since that initial pass, things haven’t gone so smoothly.

Right before its second flyby, the spacecraft went into safe mode and couldn’t record any data. Plus, an engine-related issue caused the mission team to cancel an orbital maneuver two times, which has set back data collection too. But last week, the lead scientist on the mission announced that they can at least fix the safe mode issue.

Right now, Juno is in an elliptical orbit around Jupiter, passing close enough to the surface once every 53.4 days to take a peek under its outer cloak of clouds. During each pass, Juno gets as close as about 4,200 kilometers above the uppermost gases. Each of Juno’s eight scientific instruments is designed to help us learn what Jupiter’s made of and how it might have formed.

A lot of this involves collecting information about Jupiter’s atmospheric gases and auroras, which are light shows caused by energetic particles colliding with gas atoms. Originally, there were 36 data-collection flybys planned over the course of the mission. But, unfortunately, there have been some setbacks.

Right before Juno’s approach on October 19th, a problem sent the spacecraft into what’s called safe mode. Its computer rebooted, it reoriented to face the Sun to make sure its solar arrays got as much power as possible, and its instruments shut off so it couldn’t collect data during this prime time – until it exited safe mode again on October 24th.

The issue was a software problem with one of the instruments on board: the Jupiter Infrared Auroral Mapper, or JIRAM. Basically, it uses couple of sensors to study the composition and movement of Jupiter’s auroras – an infrared camera, which detects different levels of heat, and a spectrometer, which detects visible light.

The instrument itself wasn’t completely broken, but it was having trouble transferring data to Juno’s main computers and needed a software patch. NASA engineers are working on that, but for last week’s flyby, the mission team decided to go low-tech with their solution and just turn JIRAM off – and the data collection went just fine. They hope to have all instruments patched up and operational for the early February flyby.

But the other issue with Juno doesn’t have a fix yet. During the October approach, the spacecraft was supposed to do what’s called a period reduction maneuver, or PRM. It was supposed to ignite its main engine for a bit to get a little cozier with Jupiter, reducing the time it took to orbit from about 53 days to just 14.

But before executing the maneuver, the mission team discovered that two valves that control the helium supply to the engine were operating a lot slower than they should have – taking minutes to open instead of seconds. As of last week’s flyby, they still haven’t figured out how to improve the performance, so they haven’t done the PRM.

Despite these setbacks, the data and images we have collected so far are really useful. NASA engineers tend to be pretty good at solving tricky problems, so hopefully they can fix these ones soon and get Juno in tip-top shape for the rest of its mission.

A little closer to home in the asteroid belt, scientists are also making discoveries about the surface of the dwarf planet Ceres. Previous studies have found evidence of water on its surface, like water vapor clouds and some patches of water ice in certain places.

But two separate teams of researchers found a lot more ice on this dwarf plant, and reported their findings in Nature Astronomy and Science last week. Both of these teams used data from NASA’s Dawn spacecraft, which is currently in orbit around Ceres, to take images and send information back to scientists on Earth.

One team focused on images of the dwarf planet’s northern craters, to look for patches of ice lurking in the dark shadows. These kinds of craters are called cold traps, because they’re barely exposed to sunlight, and stay really chilly – I’m talking less than minus 160 degrees Celsius. We have not been having great weather here in Montana - but it’s preferable to that.

The researchers discovered bright spots in ten of these craters, which computer models suggest could be water ice reflecting light. And spectrometer data from Dawn have confirmed that at least one of them is water ice for sure. But they’re not sure where this water ice came from – whether it was from rocks crashing into the dwarf planet from space, or from Ceres’s crust.

Because it turns out that there’s a lot of ice everywhere on the rocky porous surface, according to the second team’s research. Based on data from the gamma ray and neutron detector, or GRaND, on the Dawn spacecraft, they found that there’s a lot of hydrogen on Ceres’s surface.

When neutrons interact with hydrogen atoms, they slow down, so GRaND detects fewer neutrons coming from those spots on the dwarf planet. And on Ceres, hydrogen is probably a sign of H2O, in the form of ice. So now we know: there’s water ice all over Ceres. And suddenly I’m in the mood to go ice skating. On a very low-gravity body in our asteroid belt.

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