Navy divers have recovered what are believed to be some of the computers and flight recorders from the space shuttle Challenger, sources said tonight.

The instruments, described by one source as "badly mangled," could provide important clues into the final seconds of the shuttle's Jan. 28 flight, which ended in an explosive fireball that killed all seven crew members.

The instruments were brought ashore Wednesday night by a Navy salvage vessel that also carried some remains of the astronauts in what appeared to be a flag-draped coffin.

In a somber ceremony by the ship's crew, the coffin and body bags containing the remains were removed from the USS Preserver and placed in three ambulances.

Lt. James C. Devlin, the Preserver's commander, ordered an honor guard "to impress upon the crew . . . the solemnity of the occasion," a Navy spokeswoman said.

The Preserver's return was the latest sign that the recovery of the Challenger's crew cabin and the astronauts' remains was nearing completion.

Dr. Marvin Resnik, father of crew member Judith A. Resnik, said he was told by National Aeronautics and Space Administration officials that "some or most of the remains" had been recovered, but that no identifications have been made.

Resnik also said that the Preserver attempted to lift the crew cabin intact, but "they could not; it was just in pieces." He was told the cabin's flight deck where four of the crew sat was crushed, and that all the body parts were at the bottom of the hull, he said.

The computers, located in Challenger's crew cabin, would have recorded key data such as temperature and pressure within the orbiter. The cabin's recording system included an intercom system that could have picked up the final conversations of the astronauts, which could help investigators determine if death was instantaneous.

Even though the tapes have been under 100 feet of water for six weeks, a spokesman for 3M Co., which supplied the tape, said tonight that it might be possible to restore them, using special techniques that transfer magnetic impulses.

The Associated Press reported that the instruments were being kept in cool water until they could be cleaned and dried under controlled temperature and humidity conditions at a NASA tape-recorder facility.

NASA officials, citing family wishes, continued to refuse comment on the recovery. This has produced a flood of unconfirmed and often contradictory news reports about the operation.

Meanwhile, the three major television networks have gone to extraordinary lengths to follow the secretive operation, chartering boats and helicopters, monitoring ship-to-shore radio transmissions and staking out the Preserver as it returned to port.

One CBS crew followed the three ambulances that met the Preserver throughout a three-stop, late-night chase Wednesday only to discover upon arrival at Patrick Air Force Base that the contents had been removed.

However, NASA and Air Force officials did confirm today that the astronauts' remains had been transferred from the Patrick base morgue to a sophisticated medical laboratory adjacent to Kennedy Space Center here.

Medical tests, which could determine the precise cause of death, will be conducted at the NASA Life Science Facility at Cape Canaveral Air Force Station, a large lab that has been used in the past to monitor biomedical experiments in space.

Pathologists from the Armed Forces Institute of Pathology are on hand to conduct the tests.

The Challenger's crew cabin and the astronauts' remains have been the object of an intensive recovery operation since they were located in waters 100 feet deep about 15 miles off the Florida coast Friday night. Navy divers operating on the Preserver have tried all week to bring the remains to the surface.

But the divers have been thwarted at times by gusty winds and 6-foot waves. The rough seas continued today, forcing the Preserver to return to port after making a brief trip to the search area early in the morning.