centaur

This is the Centaur stage that was designed for use with the space shuttle. It was scheduled to launch the Galileo probe to Jupiter. In fact, in the upper left quadrant, the sign behind the viewing stand has a picture of Jupiter and Saturn. There were many risks involving having a liquid fueled rocket in the shuttle's cargo bay: in the case of an abort, the explosive liquid fuel of the Centaur would have to be jettisoned. Moreover, the increasing weight of the shuttle and the Centaur stage meant that the shuttle main engines would have to operate at 109% for part of the ascent phase. The increase in risk was significant, but engineers and astronauts had signed off on it. However, following the space shuttle Challenger explosion on January 28, 1986, the program was cancelled.

Here's a short video about choosing the boosters for the Galileo mission. It includes some musings on Congress' role in the process: vimeo.com/87712113

These are models of the two variants of Shuttle Centaur. On the right is Centaur G-prime, to be used for civilian (NASA) interplanetary probes launched from KSC, Florida. On the left is Centaur G, to be used for military (USAF) polar spy satellites to be launched from Vandenberg AFB, California, and GEO satellites to be launched from KSC. The Challenger disaster ended the Shuttle Centaur program: Centaur G-prime flight articles were built but never flew, and the launch complex at Vandenberg AFB was built but never used. N.B.: The Centaur G-prime model (right) is shown with its payload, an interplanetary probe (probably Galileo), whereas the Centaur G model (left) does not include a model of its payload, which would have been classified information.

Here's a link to a great article about Shuttle-Centaur: www.cleveland.com/science/index.ssf/2011/12/long-forgotte...

Model of the Centaur-G and the Galileo probe it was originally slated to propel to Jupiter after boosted into orbit aboard a Space Shuttle. After the explosion of Challenger (OV-099)in 1986, the risk of using the liquid fueled Centaur-G to boost payloads from the Shuttle's low Earth orbit were deemed to be too great, and Centaur-G was never used. However, a variant, the Centaur-T, would be used to boost payloads launched into orbit by the Titan IV rocket (itself used to launch payloads originally intended for the Shuttle prior to the Challenger's loss). See: en.wikipedia.org/wiki/Centaur_(rocket_stage)