Galileo Entry Probe
NASA's Galileo Orbiter and Probe mission was launched from NASA's Space Shuttle while orbiting the Earth in October 1989, and arrived at Jupiter after getting gravity assists from a fly-by past Venus, then twice past Earth, and was inserted in an orbit around Jupiter in 1995. It carried the first entry Probe destined for an outer planet. The Galileo Probe was deployed six months before arrival at Jupiter and entered the atmosphere while the Orbiter went around Jupiter.
Galileo Probe explored the atmosphere of Jupiter below the clouds, sending data back to Earth from a depth where the atmosphereic pressure was 22 bars, about 156 km (97 miles) below the visible clouds. It found its environment different from what was expected – much less water than anticipated and led to new thinking about the formation of Jupiter.
