Mushballs and a Great Blue Spot: What Lies Beneath Jupiter’s Pretty Clouds

NASA’s Juno probe is beginning an extended mission that may not have been possible if it hadn’t experienced engine trouble when it first arrived at the giant planet.

For something that was to have been done and thrown away three years ago, NASA’s Juno spacecraft has a busy schedule ahead exploring Jupiter and its big moons. The spacecraft entered orbit around Jupiter on July 4, 2016, and has survived bombardment from intense radiation at the largest of the solar system’s planets. It is now finishing its primary mission, but NASA has granted it a four-year extension and 42 more orbits. Last week, it zipped past Ganymede, Jupiter’s largest moon. “Basically, we designed and built an armored tank,” said Scott J. Bolton of the Southwest Research Institute in San Antonio, who is the mission’s principal investigator. “And it’s worked.”