CAPE CANAVERAL, Fla. -- The failure of an electronic unit for issuing critical flight commands forced an indefinite delay in the launching of the space shuttle Columbia yesterday on its often-postponed mission of scientific research.
NASA officials said that Saturday would be the earliest that Columbia could be ready again for launching. The malfunctioning master-event controller in the crew module must be replaced, the new unit must be tested, and other systems must be serviced and verified before the flight.
But officials are also reviewing alternative plans, including postponing Columbia's mission even longer and proceeding instead with preparations for launching the shuttle Atlantis on a flight to dock with the Russian space station Mir.
The Atlantis liftoff is scheduled for Nov. 1, and NASA is reluctant to disrupt that mission because of its international nature and its importance in developing the skills of assembling the U.S.-led space station toward the end of this decade.
If Columbia should be launched Saturday, it would not complete its planned 16-day mission until Oct. 30. Since ground shuttle technicians need at least four days between the landing of one vehicle and the liftoff of another, the Atlantis flight would be delayed several days. Officials gave no indication which way they were leaning.
"We're going to be talking about all the options," said Loren J. Schriver, chairman of the shuttle mission management team at the Kennedy Space Center, who added that a firm decision would probably not be reached until at least Tuesday.
The postponement of the Columbia liftoff yesterday was the fourth in 10 days. The mission was originally set to get under way Sept. 28. The first postponement was for a week because of a leaking fuel valve. Then it was bad weather. On Friday, a problem with hydraulics that operate the shuttle's nose wheel kept Columbia grounded.
The prospects were bright for a liftoff yesterday morning. Then, with 20 minutes to go, engineers detected trouble with one of the four channels in the shuttle's master-event controller. These units send the critical commands for separating the solid-fuel rocket boosters.