The Galileo Probe–Jack Fisher

In 1978 I was stationed at KSC in Florida for the launch of the two Pioneer Venus missions. The Orbiter was launched on May 20 and the Multiprobe on August 8. I had been the Hughes systems engineering manager for these missions. The Multiprobe launch spelled the end of my duties in Florida and my family and I headed back to California vacationing on the way with stops in Washington DC and Chicago.

When I arrived back in California I was assigned to the Galileo Probe project as the systems engineering manager. The Galileo mission included a probe to enter the atmosphere of Jupiter and an orbiter to conduct long-term studies of the planet. The Orbiter would carry the probe to Jupiter, release it so that it would enter the Jovian atmosphere, and relay the probe radio signals back to Earth before insertion into orbit. The Galileo Orbiter was to be provided by JPL.

The NASA contract for the probe was awarded to Hughes in September, 1978. The probe contract with the NASA Ames Research Center included the probe, and the orbiter-mounted radio relay hardware required to receive the probe radio signals, and a heatshield provided by General Electric,. The NASA project manager at Ames was Joel Sperans and the Hughes project manager was Uldis Lapins.

With the completion of the initial design a preliminary design review was held in January, 1979. At this review Ames and Hughes were directed by John Casani, Galileo Orbiter project manager at JPL, to modify our probe design to provide redundancy. This had not previously been a requirement as Ames had based their requirements on their experience with the Pioneer Venus probes all of which were all single-string designs. There were four atmospheric probes, one large and three small, none of which were expected to survive landing. Of course, one could argue that the three small probes, in themselves, provided redundancy. The Galileo probe design was modified to include redundancy and several months later a follow-up review was satisfactorily conducted. There was a significant impact on a volume-constrained design that resulted in weight and cost increases.

During 1980, and earlier, there was considerable uncertainty regarding the launch of Galileo originally scheduled for 1982. The plan had been to carry Galileo and Inertial Upper Stage (IUS) into orbit with the Shuttle and boost the spacecraft towards Jupiter with the IUS. There was a pending delay due to Shuttle performance issues. Although I don’t recall all the details, I believe Boeing’s Inertial Upper Stage was canceled in 1980 due to cost overruns and Centaur was adopted as the means of launching Galileo towards Jupiter.

The original mission plan of separate probe and orbiter missions was readopted and NASA developed requirements for a probe carrier spacecraft that would carry the probe to Jupiter. Responsibility was assigned to the Ames Research Center who subsequently issued an RFP for this mission. Hughes developed a design and submitted a proposal in August, 1980. The proposal manager was Mal Meredith and I was asked to head the systems design effort for this activity and subsequently left the Galileo probe project. This vehicle was not allowed to carry any science payload other than the probe and was to serve as a relay to return probe data to the Earth. There was another competitor, possibly TRW, but Hughes was selected and was in the process of negotiating a contract with Ames when NASA’s launch plans changed again and the Galileo mission went back to the single Jupiter Orbiter/Probe spacecraft thus spelling the end of our probe carrier effort.

The probe carrier mission required RTGs as a power source which concerned me as Hughes did not have any experience with the integration of these devices into a spacecraft design. So I was greatly relieved as I thought Hughes had seriously underbid this proposal.

I did not return to the probe project after this episode and John Radecki became the systems engineering manager. Galileo was scheduled to be launched by the Shuttle in early 1986, but was delayed again by the Challenger tragedy. Galileo was finally launched in 1989 and reached Jupiter in 1995 after a complicated mission profile known as VEEGA that required flybys of Venus and Earth. The longer flight time and the revised thermal profile with the Venus encounter required meticulous probe engineering that was overseen by Bernie Dagarin with a great deal of care and dedication. For a description of the mission see Michael Meltzer’s book “Mission to Jupiter, NASA SP-4231.”


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About Jack Fisher

Jack was a systems engineer at Hughes from 1961 to 1992. He contributed to various programs including Surveyor, Pioneer Venus, Galileo, Intelsat VI and innumerable proposals. He was the manager of of the Spacecraft Systems Engineering Lab until his retirement. Upon retirement Jack taught systems engineering at a number of national and international venues.

1 thought on “The Galileo Probe–Jack Fisher

  1. The Jupiter and Venus probes were very successful and produced the desired science infomation. My only regret is that the current technology for imaging and data compression was not available for producing images during descent at the time of the Galileo and Pioneer Venus missions. The subsequent Titan probe had such a imaging system which made the mission that mouch more interesting to the general (taxpaying) public.

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