It's been largely smooth sailing for NASA's Juno probe since it entered orbit around Jupiter a few months ago, but some minor hiccups are keeping mission operators on their toes. After being thrust into safe mode during its recent close flyby and foregoing a science collection opportunity, the spacecraft is now healthy and responsive. But the issue of some malfunctioning valves remains unresolved.
Juno has been circling Jupiter in a 53.5-day orbit since it arriving on the scene on July 4. Two weeks ago, as Juno approached its closest point to Jupiter on October 19, NASA was preparing to fire up the craft's main rocket to propel it into a tighter 14-day orbit, which will be the key science phase of the mission. But a pair of slowly opening valves in the lead up to the event prompted mission control to delay the move, which is known as a period reduction maneuver.
With no period reduction maneuver to worry about, the upside was that the team could use the opportunity to turn on all of Juno's science instruments for the October 19 flyby, rather than the three originally planned to be operational. But NASA was thrown another curveball on October 18 when a software performance monitor triggered a reset of the spacecraft's computer and placed Juno into safe mode, shutting down all of its science instruments in the process.
The team is still unsure of exactly what caused Juno to reboot, but has confirmed that it exited safe mode on Monday this week, is in good health and is responding to its commands. In preparation for its next close flyby on December 11, the team had Juno perform an orbital trim maneuver to adjust its velocity by around 5.8 mph (2.6 meters per second).
NASA is still investigating the possible reasons for the reboot and the misfiring valves, two issues which it says are unrelated. It says it expects to be switching on all of Juno's instruments in November in preparation for the December flyby, which also presents the spacecraft's next opportunity to conduct the period reduction maneuver and zero in for a closer look.