Juno probe has tech trouble, cancels orbital re-adjustment
Another 53-day loop needed while NASA sorts out helium check valve delay problem
The Juno probe orbiting Juipter has some trouble with its propulsion feed system and plans for the craft's stay at the gas giant are therefore being revisited.
"Telemetry indicates that two helium check valves that play an important role in the firing of the spacecraft's main engine did not operate as expected during a command sequence that was initiated yesterday," Rick Nybakken, Juno project manager at NASA's Jet Propulsion Laboratory in Pasadena, California, said last Friday. “"The valves should have opened in a few seconds, but it took several minutes. We need to better understand this issue before moving forward with a burn of the main engine."
The burn scheduled for October 19 was to have greatly shortened Juno's orbit from the current 53 terrestrial days to just 14 days. The shorter orbits would have been lower, affording us a fine look at Jupiter.
Now NASA has decided it will make at least one more long orbit before attempting the “period reduction manoeuvre” (PRM).
The news isn't all bad because during the October 19th manoeuvre Juno would have shut down all scientific instruments so it could concentrate on entering its new orbit. Now it will have its eyes wide open. NASA's not saying just what path the probe will take on this orbit, but its last visit to Jupiter saw it pass just 4,200 km above the gas giant's clouds.
Juno's next close approach to Jupiter will be on December 11, when it is hoped it will be possible to conduct the PRM. Even if it can't, mission bosses say they will still be able to collect plenty of useful data. ®