Shuttle Launch Scrubbed Again; Computer Fails

A daring attempt to rescue a stranded satellite appeared to be in serious jeopardy Sunday after the launch of the space shuttle Discovery was scrubbed for the second day in a row.

A computer failure forced the National Aeronautics and Space Administration to cancel Sunday’s launch, and the back-to-back setbacks will require maintenance procedures that will delay the launch until Tuesday at the earliest.

But weather--the cause of the initial cancellation on Saturday--was deteriorating rapidly, and it is doubtful that Discovery will be able to keep Tuesday’s date either.

Correct Position Needed

If the shuttle is not launched by Thursday, it cannot be correctly positioned to attempt to rescue an $85-million Hughes satellite that failed to activate itself after it was released from the Discovery last April.

That would force postponement of the rescue attempt until a later mission, if ever. NASA’s busy launch schedule affords few opportunities to attempt the rescue because shuttle orbits and launch times are determined largely by commercial payloads, few of which would put the shuttle in the right place to rendezvous with the satellite, called Leasat 3.

With all of that in mind, NASA officials are keeping a wary eye on the weather, which would have been “marginal” for Sunday’s launch even if the computer had not failed, according to launch director Robert Sieck.

“A potential development of a tropical storm in the Gulf of Mexico” could wipe out any chances of launching the shuttle later in the week, Sieck said, which would add up to an exercise in frustration for Joe Engle and the other four members of his crew.

The Discovery had been set for launch Saturday, but a small storm moved over the launch pad at the last minute, precluding the blastoff during the 21-minute “launch window.” Shortly after the window closed, the skies cleared for several hours, although thunderstorms later drenched the area.

Sunday’s less-than-encouraging weather became a moot issue when the orbiter’s backup computer failed. The backup is designed to take over the crucial functions of any of the shuttle’s other computers should they fail during the critical moments of ascent. That computer is being replaced.

Today Skipped

NASA skipped today as a possible launch day to allow engineers to inspect the orbiter to be sure none of its systems deteriorated or sustained damage during the two false starts. There is always some concern that seals could have dried out or gaskets or electrical switches could have been damaged.

Inspectors will pay close attention to the ducts from the three main engines, which must be purged of potentially lethal gases by pumping supercooled nitrogen through the system.

Arnold Aldrich, the shuttle manager at the Johnson Space Center in Houston, said the great fluctuation in temperatures “could cause a break in the thermal insulation” around the ducts. He said failure of the insulation could cause the duct to deform, restricting the flow of hydrogen fuel after ignition.

That, in turn, could cause the engine to shut down during liftoff, he said.

Delaying the launch until Tuesday will give the “discouraged” launch team a chance to get a little rest, Sieck said.

Chance to Unwind

It will also give the five men in the crew a chance to unwind.

Engle, the 53-year-old commander of the Discovery and a former test pilot with more than 10,800 flight hours to his credit, took off in an astronaut training plane to fly a few acrobatic maneuvers off the Florida coast.

The other members of the crew are Richard O. Covey, 39, the pilot, and mission specialists James D. van Hoften, 41, John M. Lounge, 39, and William F. Fisher, 39.

Van Hoften and Fisher are scheduled to “hot wire” the disabled satellite so that ground controllers can crank it up and eventually fire its motor. That would be the first in-orbit repair of a commercial satellite by space-suited astronauts, but their chances of making the attempt are decreasing rapidly.

Opportunity Threatened

If the Discovery does not get off “by the end of the week, we run out of the opportunity for rendezvous,” Aldrich said. “After Thursday, we probably do not have that capability.”

Thursday will also be lost as a launch day if NASA tries unsuccessfully to launch on Tuesday and Wednesday. Thursday then would have to be used for maintenance.

Even if the chance for the rendezvous is lost, the mission will go on to permit the launching of three commercial satellites now in the Discovery’s cargo bay. That has always been listed as the primary objective of the flight.

The launch time Tuesday is set for 4:02 a.m. PDT, with landing at Edwards Air Force Base eight days later.