NASA Cancels Jupiter, Sun Rocket : Modified Centaur Fails Safety Criteria for Shuttle Missions

The National Aeronautics and Space Administration Thursday canceled development of a modified Centaur rocket that it had planned to carry into orbit aboard the space shuttle and then use to fire scientific payloads to Jupiter and the sun.

NASA Administrator James C. Fletcher said the Centaur “would not meet safety criteria being applied to other cargo or elements of the space shuttle system.” His decision came after urgent NASA and congressional investigations of potential safety problems following the Jan. 28 destruction of the shuttle Challenger 73 seconds after launch.

The move was a stinging blow for the U.S. planetary exploration program. At the time of the Challenger disaster, the Centaur was to help launch spacecraft to Jupiter and the sun in May. Sources said those missions will now be delayed until at least 1990 or 1991.

Ulysses, Galileo

If the Centaur had been judged safe and the space shuttle had returned to flight status on the schedule currently anticipated by NASA, the space agency might have been able to launch the Ulysses spacecraft to the sun as early as July, 1988, and the Galileo spacecraft to Jupiter by December, 1988.

Fletcher, announcing the cancellation after daylong meetings with officials from the Jet Propulsion Laboratory and the Johnson Space Center, said: “Although the shuttle-Centaur decision was very difficult to make, it is the appropriate thing to do and this is the time to do it.”

Fletcher said a panel would be formed to study the history of the program and the events leading to Thursday’s cancellation. NASA said Richard Truly, chief of the space shuttle program, would study the options available for getting the U.S. planetary payloads into space.

Sources said there are now only two options. NASA could replace the Centaur by pushing ahead with development of a solid rocket--a two-stage version of the rocket now known as the “inertial upper stage”--that would be carried into orbit by the shuttle and then ignited to boost the Galileo and Ulysses probes on their way. Such a solid rocket might be deemed safer than the Centaur, though NASA sources estimated it would be 1990 before it could be available.

Modified Titan Rocket

NASA’s other option is to use a modified version of the Titan rocket now being developed for the Air Force, with a new liquid upper stage to launch the heavy planetary payloads on a direct ascent from Earth toward their destination. An expendable launch vehicle of this sort is at least five years away, sources said.

The hazards of hauling the 58-foot-long Centaur rocket loaded with liquid oxygen and liquid hydrogen propellant in the space shuttle cargo bay came under renewed scrutiny after the Challenger disaster. Moreover, the probes to be launched by the Centaur were to be powered by nuclear electric generators fueled with plutonium.

Extremely high pressures from certain kinds of shuttle accidents could conceivably rupture the generators’ protective shells, NASA studies have shown. Scientists agree that radioactive plutonium particles such an event might disperse would pose a serious cancer hazard to anyone who inhaled them.

Questions about the Centaur itself included its ability to safely vent the fuels overboard in case the rocket could not be unloaded from the shuttle bay in orbit. Officials also were concerned whether the shuttle could be safely landed with the rocket still aboard in the event of an aborted mission.

Even before Fletcher’s decision, Rep. Edward P. Boland (D-Mass.), chairman of the House appropriations subcommittee that handles the NASA budget, and Rep. Bill Green (R-N.Y.), the ranking minority member of the subcommittee, had advised him of their own conclusion that the program should be ended.

The cost of the cancellation to an agency already thrown into budgetary crisis by the shuttle accident will not be known until a decision is made on whether the Air Force can use the Centaurs that NASA had already ordered from General Dynamics.

Two of the rockets had already been delivered to the Kennedy Space Center and two more are nearing completion.