When NASA sent a series of commands to the Juno spacecraft’s main engine last October, the spacecraft did not respond properly: two helium check valves that play an important role in its firing opened sluggishly. Those commands had been sent in preparation for a burn of the spacecraft’s Leros 1b engine, which would have brought Juno—a $1.1 billion mission to glean insights about Jupiter—into a significantly shorter orbital period around the gas giant.
Due to concerns about the engine, NASA held off on a “period reduction maneuver” that would shorten Juno’s orbital period from 53.4 to 14 days. When the next chance to do so came in December, again NASA held off. Now the space agency has made it official—Juno will remain in a longer, looping orbit around Jupiter for the extent of its lifetime observing the gas giant.
“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,” said Rick Nybakken, Juno project manager at NASA’s Jet Propulsion Laboratory in Pasadena, California. “The bottom line is a burn represented a risk to completion of Juno’s science objectives.”
In announcing the decision Friday, space agency scientists took pains to emphasize the benefits of a longer orbit around Jupiter. For example, the “bonus science” will allow Juno to further explore the outer reaches of the Jovian magnetosphere and better understand the interaction of these regions with the solar wind. Spending more time farther away from Jupiter will also lessen the spacecraft’s exposure to the gas giant’s harmful radiation, scientists said.
More:
https://arstechnica.co.uk/science/2017/02/due-to-concerns-about-engine-juno-to-remain-in-elongated-jupiter-orbit/
