The Galileo Probe became the first atmospheric probe to examine a gas giant on 7 December 1995. The key events which occurred were (all times are the time of the event at the spacecraft given in Eastern Standard Time):
Time Event ________ _____ 11:04 a.m. Coast timer initiates probe operation 12:46 p.m. Orbiter flyby of Io (~1000 km) (No imaging or spectral data collected) 2:04 p.m. Energetic Particles Investigation (EPI) begins measuring trapped radiation in a region previously unexplored. 4:54 p.m. Galileo Orbiter reaches closest point to Jupiter 5:04 p.m. Probe entry and data relay 5:05:52 p.m. Pilot parachute deployed 5:05:54 p.m. Main Parachute deployed 5:06:02 p.m. Deceleration module jettisoned 5:06:06 p.m. Direct scientific measurements begin 5:06:15 p.m. Radio transmission to orbiter begins ~5:08 p.m. Visible cloud tops of Jupiter reached 5:12 p.m. Atmospheric pressure the same as Earth's sea-level pressure 5:17 p.m. Second major cloud deck is encountered (uncertain) 5:28 p.m. Water clouds entered (uncertain) 5:34 p.m. Atmospheric temperature equal to room temperature on Earth 5:46 p.m. Probe enters twilight 6:04 p.m. End of baseline mission. Probe may cease to operate due to lack of battery power, attenuation of signal due to atmosphere, or being crushed. 6:19 p.m. Orbiter ceases to receive probe data (if still transmitting) 7:27 p.m. Ignition of Galileo main engine (49 minute duration) to insert into Jovian orbit
It is estimated that by 3:00 a.m. (EST) on 8 December 1995, the probe had been completely vaporized by the heat in Jupiter's atmosphere.
A more detailed version of this timeline is available from Ames Research Center
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