Copyright 1986 The New York Times Company
The New York Times
March 8, 1986, Saturday, Late City Final Edition
SECTION: Section 1; Page 11, Column 1; National Desk
LENGTH: 1108 words


BYLINE: By DAVID E. SANGER, Special to the New York Times


Testimony today before the inquiry into the explosion of the space shuttle Challenger highlighted a growing debate among space agency officials, who in recent days have suggested widely varying theories for the accident.

The new theories, which tend to shift blame to manufacturers and assemblers of key shuttle components, have emerged largely from officials of space agency's Marshall Space Flight Center in Huntsville, Ala. It was Marshall officials who were sharply criticized in hearings a week ago as failing to heed warnings that the cold weather could lead to a disaster. Almost all the new theories, which were partly disclosed in Huntsville earlier this week, exonerate both the cold and, by extension, Marshall officials.

In questioning today, members of the Presidential commission examining the accident made it clear that they regarded some of the new ideas as farfetched, based more on wishful thinking than hard evidence.

''I don't think there is anything malicious in what they are trying to do,'' one source familiar with the investigation said today at the end of the hearings. ''You can sort of understand why they are doing it. They want very much to prove they were right.''

Problem for Investigators

Indeed, the Marshall testimony today points to the growing difficulty of sifting through theories about the disaster developed by space agency officials who have a vested interest in where the commission ultimately places the blame.

In contrast to the Marshall engineers, technical experts at the Kennedy Space Center, who unlike their Marshall colleagues have no design responsibility for the solid-fuel booster rockets, have expressed few doubts that cold weather was the primary cause.

For their part, panel members involved in the questioning today made it clear that most of the new factors disclosed today probably only contributed to the disaster.

But they seem increasingly confident that the answer to the mystery lies in the freezing temperatures before the launching, which could have hardened the booster-rocket seals and caused them to lose flexibility. These theories were presented in a hearing at Spaceport U.S.A., the tourist center at the Kennedy Space Center here.

And the contrast was hardly lost on the National Aeronautics and Space Administration officials, whose Cape Canaveral showpiece was this week transformed into the current stage for the Rogers Commission inquest.

At recesses, the experts diagnosing the causes of the worst disaster in the history of space travel mixed with tourists gaping at the wonders of a moon lander and detailed exhibits of the shuttle's technology. And the auditorium where the panel held the hearing was occasionally shaken by a long, low rumble, the sound of a liftoff in ''The Dream is Alive,'' the upbeat space shuttle movie being shown in the adjacent theater.

Firmer Evidence Sought

But the panel members were clearly less enraptured by the testimony than the tourists were by the movie. Time and again, they pressed Marshall officials for evidence to support the new theories that they offered.

In a detailed presentation of possible ''accident scenarios,'' Marshall officials repeatedly implied that there was still a good chance that a pre-existing leak in the Challenger's external fuel tank was a major cause. Marshall is also responsible for the tank, but it would be up to the tank's manufacturer and Kennedy Space Center technicians to identify any flaws in the system.

At a Feb. 27 hearing, B.K Davis, a member of the NASA team that inspected the ill-fated shuttle three times the morning of the launching, said he and his colleagues would have almost certainly detected such a leak in a survey with infrared instruments. Asked whether he had any reason to suspect such a leak, Mr. Davis told the commission: ''No sir. I can't support even a consideration of it.''

Yet the Marshall officials offered no new evidence today to buttress their suspicions. And at one point the visibly annoyed chairman of the commission, William P. Rogers, said, ''Each time Marshall has testified, they have put the external tank as a prime suspect.''

"I Just Don't Understand"

''It seems to me,'' Mr. Rogers said of the area where the rocket seal is located, ''that the joint is the No. 1 one villain. I just don't understand.''

At that point Jack Lee, the deputy director of the Marshall Center, backtracked somewhat. Referring to the right-side solid-fuel booster rocket, he, acknowledged, ''We know the S.R.B. is the failure.'' But a leak, he said, could have sped along the explosion.

Similar doubts surrounded explanation of another theory: that a manufacturing flaw in the synthetic rubber O ring that seals the booster rocket might have let gas leak out.

The Marshall officials showed photographs of the seal, taken while the booster rocket was being assembled in December, that they said showed a possible flaw in the ring fifteen-one thousandth of an inch deep. The seal is usually a little more than a quarter of an inch thick.

''It looks anamolous to me,'' said Jerrol W. Littles, associate director for engineering at Marshall. The flaw, he said, was 90 degrees away from the area where black smoke appears just after the engine ignition.

However, Maj. Gen. Donald Kutyna of the Air Force, who is heading the commission's accident analysis subcommittee, quickly pointed out that minor flaws appeared all around the 12-foot diameter of the rocket. ''They're in a lot of areas,'' he said. ''It's tough to tell.''

Reconstructing Conditions

Marshall officials made it clear that they were still examining the effects of the cold, even conducting tests that, they said, showed the seals continued to work down to temperatures of 10 degrees below zero Fahrenheit. The effort now is to reconstruct the conditions of the accident, a task that experts say may prove impossible.

Possible or not, Mr. Rogers and other commission members seemed unhappy with the thought that the Marshall center and Morton Thiokol Inc., the manufacturer of the boosters, were the only ones conducting the tests. Both, he noted with considerable understatement, have vested interests in the outcome. At one point the chairman asked Mr. Littles whether he thought the tests could restore confidence in the design of the joint, allowing shuttle flights to resume with few design changes. He got no direct response.

''These tests are designed to determine the cause of the accident, is that correct?'' asked Joseph Sutter, a commission member, picking up on the same line of questioning.

''That is correct,'' Mr. Littles said in a quiet voice.''

GRAPHIC: Photo of debris recovered from the explosion of the Challenger laid out in a large grid at the Kennedy Space Center in Florida (NASA via AP)