The Galileo probe entered Jupiter’s atmosphere in 1995. It reached the planet on December 7, 1995, and plunged into the atmosphere while the Galileo orbiter positioned itself to receive the probe’s data.
The probe entered at approximately 22:04 UTC, traveling about 170,700 kilometers per hour relative to Jupiter. Its heat shield endured extreme aerodynamic heating and deceleration before the probe deployed a parachute and began transmitting measurements from beneath the cloud tops.
Galileo’s instruments measured temperature, pressure, wind, cloud particles, lightning, and the abundance of gases. The probe found stronger winds than expected, reaching roughly 530 km/h, and transmitted data for about 58 minutes before the increasing heat and pressure ended communications.
A common mix-up is confusing the probe’s atmospheric entry with the Galileo orbiter’s launch or arrival sequence. The spacecraft launched from Earth in 1989, but both the orbiter’s arrival at Jupiter and the atmospheric probe’s entry occurred in December 1995. The orbiter itself remained in service until 2003.