NASA’s Juno Mission at Jupiter Goes Into Safe Mode –“Cause a Mystery”




NASA’s Juno Mission “went into safe mode Tuesday night while nearing the lowest point of its orbit around the gas giant, according to Scott Bolton, the mission’s principal investigator out of the Southwest Research Institute. “The spacecraft safe mode condition eliminated the science, but everything is okay and we retained the ability to do that rocket fire sometime in the future,” Bolton said. “Fortunately, the way we designed Juno and the orbit we went into is very flexible.”

“We’ve never been this close to Jupiter,” Bolton said. “We’re seeing things we didn’t expect, across the board. We haven’t really even started the main science, so there is a lot more to come,” Bolton said. NASA scientists have discovered Jupiter’s mysterious atmospheric features, described as bands, extend much deeper than originally thought.

The JunoCam, a public outreach camera on the spacecraft, has captured an image of a cyclone casting a shadow on what appears to be another layer of the atmosphere, believed to stretch nearly 4,500 miles — more than half the size of Earth – and stands about 60 miles tall. “Nobody had ever been able to see it before,” Bolton added.

Bolton said it was too soon to determine what triggered the safe mode. “It did happen pretty far away from Jupiter, so my instinct is that it may not have been tied to the intense radiation belts we’re so fearful of,” he said. “That doesn’t mean there isn’t something else in Jupiter’s environment that may have caused it.”

“We were still quite a ways from the planet’s more intense radiation belts and magnetic fields,” Rick Nybakken, Juno project manager at the Jet Propulsion Laboratory, said in a statement. “The spacecraft is healthy and we are working our standard recovery procedure.”

Bolton left open the possibility of keeping Juno in its current 53-day orbit, noting that the mission’s science is done primarily during each close approach to the planet. “We can obtain all of the science goals of Juno even if we stay in a 53-day orbit,” he said. “We were changing to 14 days primarily because we wanted the science faster.” Radiation would not be an issue for an extended mission, he added, because the spacecraft is exposed to intense radiation only during each close approach to Jupiter.

Keeping Juno in its current orbit, though, would stretch out the length of the mission. One issue Bolton raised is that Juno is currently in an orbit that keeps it illuminated by the sun at all times. By early 2019, he said, the orbit geometry would have shifted so that the Jupiter would eclipse the sun for several hours of each orbit. “If we were never going to change out of the 53-day orbit, we would have to go investigate how to get past an eclipse,” he said.

Bolton presented an update on the mission during a joint meeting of the Division for Planetary Sciences of the American Astronomical Society and the European Planetary Science Congress in Pasadena Wednesday. Bolton added that Juno can move into the 14-day orbit once the team believes it is safe. If NASA decides not to shift Juno’s orbit, the spacecraft will complete about 20 rotations of Jupiter before a potentially dangerous eclipse in 2019, Bolton said. “You can accomplish an incredible amount of science in 20 orbits,” he said. “The worst case scenario is I have to be patient and get the science slowly.”

The probe switched off most of its instruments, pointed itself toward the sun and waited for the team on Earth to investigate the problem. Out of caution, the team cancelled a planned maneuver to reduce the spacecraft’s orbit from a 53-day rotation to 14-days and left Juno’s scientific instruments off during a flyby roughly 3,100 miles above Jupiter’s clouds in its elliptical orbit around the planet.

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