1975 NASA decides proposed Jupiter Orbiter Mission (JOM) will be first planetary spacecraft launched on Space Shuttle (The mission was later renamed to Galileo).
1977 Congress nearly cancels the Galileo program, but it survives and is approved for launch in 1982 and arrival in
1985. A new IUS (Interim
Upper Stage) is to be built that will propel Galileo directly to Jupiter.
1980 The Space Shuttle program falls far behind schedule and Galileo's launch is slipped to 1984 with arrival delayed until 1986. Since the 1984 trajectory is unfavorable NASA decides on a major engineering change. The spacecraft is split in two, and orbiter section and an atmospheric probe section, and are to be launched separately. The spacecraft and the mission are completely redesigned.
1981 The IUS (now cleverly renamed to Inertial Upper Stage) cannot meet its design specs and cannot propel Galileo directly to Jupiter. NASA opts for more powerful liquid fueled Centaur stage. The probe and orbiter are recombined for a single launch, and the spacecraft and mission are redesigned once again. The launch date is slipped to 1985.
1982 David Stockman cancels the Galileo program. The program is restored by Congress.
1984 Problems with the Space Shuttle and Centaur delay the Launch again to 1986 with arrival in 1988.
1986 Challenger explodes just 4 months before Galileo was to be launched.
Compiled from the JPL Space Calender located at http://newproducts.jpl.nasa.gov /calender
1987 The VEEGA trajectory is developed and can get Galileo to Jupiter using
the IUS. Galileo is scheduled again for launch in 1989. Cruise time to Jupiter
with the VEEGA trajectory is six years. Arrival time is late 1995, ten years
after the original arrival date.