space.com: Juno slipped into a highly elliptical, 53-Earth-day-long orbit around Jupiter when it arrived at the giant planet on July 4, 2016. by Mike Wall
'The probe was supposed to perform an engine burn in October to reduce its orbital period to 14 days, but an issue with two helium valves postponed that maneuver.
'The engine burn has now been canceled, meaning Juno will stay where it is through the end of its mission.
'"During a thorough review, we looked at multiple scenarios that would place Juno in a shorter-period orbit, but there was concern that another main engine burn could result in a less-than-desirable orbit," Rick Nybakken, Juno project manager at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, said in a statement. "The bottom line is, a burn represented a risk to completion of Juno's science objectives."'