A frame from an animation showing the view from Juno as it approaches Jupiter with the Sun visible as a yellow speck just to the left of the giant planet. A 10.5-hour thruster firing changed Juno’s trajectory enough to keep the Sun in view of its solar panels, avoiding a mission-ending eclipse. Image: NASA/JPL-Caltech/SWRI
When NASA’s solar-powered Juno spacecraft was launched in 2011, engineers planned to put the spacecraft into a 14-day orbit around Jupiter, one that would allow scientists to meet all the mission’s objectives without having to worry about a fatal multi-hour trip through Jupiter’s shadow.
But after reaching an initial 53-day orbit around Jupiter in 2016, engineers encountered a possible problem with Juno’s main propulsion system and opted not to use the main engine to reduce the orbital period. All of the mission’s science goals could be met in the 53-day orbit, they decided, but it would take longer.
And it would eventually carry the spacecraft into Jupiter’s shadow during its next flyby on 3 November.
“Pre-launch mission planning did not anticipate a lengthy eclipse that would plunge our solar-powered spacecraft into darkness,” said Ed Hirst, Juno project manager at NASA’s Jet Propulsion Laboratory.
After a detailed ...