Galileo Crosses Boundary Into Jupiter's Environment . NASA's Galileo spacecraft radioed confirmation late this week that it has entered Jupiter's environment, crossing over the boundary from interplanetary space into the giant magnetic cocoon around Jupiter called the magnetosphere. ... On Thursday, December 7, Galileo's previously deployed atmospheric probe will plunge into Jupiter's cloud tops at 5:56 p.m. EST and descend into the giant planet on a parachute. ... Space History Galileo . ...