Shuttle Reaches Orbit With One Engine Dead : Emergency Landing Averted; Crew May Make Full 7-Day Flight Despite Craft’s Low Altitude

The space shuttle Challenger narrowly averted an emergency landing Monday when one of its main engines suddenly died about 5 minutes after liftoff. But the craft was able to achieve a low orbit, and space agency officials made a preliminary decision to keep the crew aloft for the planned stay of seven days.

It was the first time in 19 shuttle missions that an engine had failed after launching, and managers at the National Aeronautics and Space Administration said that an emergency landing would have been necessary if the failure had occurred 33 seconds earlier in the flight.

May Raise Orbit

Because of the lost engine, the officials said, the craft was in an orbit about 70 miles lower than planned but would attempt to lift itself to a slightly higher orbit early today, using its two smaller orbit-maneuvering engines.

Flight director Cleon Lacefield disclosed that, during the tense first minutes after launching, the crew was instructed to disconnect a temperature-reading sensor to prevent a second engine from shutting down before the ship could reach orbit.

Jesse M. Moore, director of the shuttle program, said at a press conference after the launching, “We are safely in orbit. The crew is doing fine. We are pretty optimistic about achieving essentially all the objectives of the mission.”

The engine was shut down by an on-board computer about three minutes before its scheduled burnout. The speed of the craft and the remaining two main engines carried the Challenger into orbit.

The engine that failed has no further purpose during the flight and would not have been used again in any case, according to officials. The shuttle uses the orbiting engines during its return to Earth.

Challenger, carrying $78 million in scientific instruments had rocketed into space at exactly 2 p.m. PDT, 97 minutes past its scheduled liftoff.

An earlier effort had aborted on the launching pad on July 12. In that incident, a computer sensed an engine valve failure and halted the launching three seconds before liftoff. Failure to lift off Monday would have forced NASA to cancel the flight for up to a year because of a crowded shuttle schedule.

Although officials later painted a picture of a mission only slightly handicapped, the first few moments after the engine shut down were harried at Kennedy.

In the control center “there was a buzz,” said Thomas Utsman, shuttle director at Kennedy. “Everyone was feeling good about getting that beast out of town, and then it happened.”

Lacefield said that the engine failure occured at a point just past the cutoff for an emergency landing.

Such a landing, known at the space agency as a transatlantic abort, would have required the shuttle to abandon its attempt to orbit and put down at a U.S. Air Force Base near Zaragoza, Spain.

Week of Experiments

Once orbit was achieved, NASA officials said, they quickly concluded that the shuttle probably could remain in space for its weeklong schedule of scientific experiments.

According to Moore, the sequence of events leading to the engine shutdown began about 3 1/2 minutes after launching.

A computer channel controlling the shuttle’s main engines began to indicate overheating in the pump feeding hydrogen fuel to one of the craft’s main engines. The computer then switched to an alternative channel to check the initial reading.

The second channel also indicated overheating, and the engine was automatically shut down at 5 minutes, 45 seconds into the flight.

Lacefield said that Mission Control then received indications of dangerously high readings on a second engine as well. If another engine had failed at that point, Lacefield said, “We would have been in the water.” He said there would have been a chance the shuttle could have landed in Crete.

Sensor Turned Off

Rather than risk losing the other engine after one sensor warning, the shuttle crew manually turned off the other sensor to avoid a computer-ordered shutdown of the second engine, Lacefield said.

The shuttle’s main engines are arranged in a triangle pattern at the rear of the craft and burn liquid fuel. The shuttle’s two huge booster rockets, which provide most of the thrust for ascent, fired successfully.

To ensure that the spacecraft achieved a stable orbit, the remaining two engines were burned almost a minute longer than planned, and some of the shuttle’s reserve fuel was jettisoned.

The smaller orbit-maneuvering engines were later fired briefly to stabilize the orbit, which ranged from 115 to 241 miles above Earth.

May Be Instrument Failure

Late Monday, NASA officials said that they still were not certain whether the fault lay in a true failure of the fuel pump or whether the instruments registered incorrectly. The answer probably will not be found until the shuttle returns, they said.

Monday’s launching was delayed initially beyond its scheduled time of 12:23 p.m. PDT by a problem with one of the three gyroscopes that are situated in each of two solid-fuel rocket boosters that help give the shuttle the thrust needed to reach orbit. The problem was fixed and the countdown was resumed.

Dr. Daniel Spicer, chief scientist for the mission, said that most of the scientific experiments scheduled for the weeklong tour probably would still be carried out. But he said that this assessment was “preliminary.”

Challenger is carrying an array of instruments and the crew includes five scientists who will work in two 12-hour shifts to conduct experiments around the clock.

The equipment, mounted on three pallets attached to the cargo bay, includes a $60-million German-made Instrument Pointing System designed to point telescopes precisely. NASA scientists are eager to test this system so it will be ready for another mission in March, when scientists hope to get a good look at Halley’s comet.

Other experiments will study the sun, the gas surrounding Earth, cosmic rays, infrared radiation, bone demineralization and mineral balance during space flight.