Day by day, over the course of the week, the probe of the space shuttle Challenger disaster has taken on a decidedly different tone. Reports seeping out of the presidential commission investigating the accident -- and from engineers involved in the decision process prior to the Jan. 28 launch -- are pointing increasingly toward flaws in management of the shuttle launch, rather than technical flaws alone.
The first hint came last weekend, when commission chairman William Rogers stated that the launch decision ``may have been flawed,'' and asked that National Aeronautics and Space Administration (NASA) officials involved in the decision be taken off the investigation.
On Thursday, NASA announced that shuttle program director Jesse Moore would assume his new post as head of the Johnson Space Center in Houston a few months earlier than the original May date. Mr. Moore, whose job change was first announced prior to the accident, gave the go-ahead for Challenger's final launch and headed the space agency's internal probe into the explosion.
Rear Adm. Richard Truly, until now the head of the US Navy's Space Command and a former shuttle pilot, will replace Moore. He will also take charge of NASA's internal investigation.
In the meantime, a picture is forming of contentious debating between Morton Thiokol engineers and managers and NASA officials the day before Challenger's disastrous flight over the safety of the solid-rocket boosters in cold weather.
By Wednesday, Mr. Rogers had issued a statement that engineers at Morton Thiokol, the company that makes the shuttle's boosters, had ``strongly urged'' against launching Challenger because of cold weather. Further, according to the statement, at least three top NASA officials at the launch were never informed of Morton Thiokol's concerns.
The issue was whether the rubber O-rings that seal the joints between sections of the booster rockets would seat properly in subfreezing weather. If the O-rings were to leak, engineers believed, an explosion would result.
[According to the Associated Press, a Morton Thiokol engineer told Sen. Ernest F. Hollings (D) of South Carolina that the puff of smoke NASA uncovered on Challenger's right booster at launch has occurred before.
Senator Hollings, who sparred with NASA officials at Tuesday's Senate hearing, said Morton Thiokol engineer Allan J. McDonald told him the smoke indicates a broken seal. Mr. McDonald refused to back his company's decision to approve of the launch.
``He had observed, incidentally, in January, a year ago, this puff of . . . smoke . . . coming from the rocket booster, [and] knew it was trouble,'' Hollings said Thursday. ``He said he would never sign off on any kind of launch below 53 degrees. It was 53 degrees at that particular time'' in January of 1985.]
Infrared temperature readings suggest that the lower part of the right-hand booster, the prime suspect in the accident, may have been as cold as 7 degrees on the morning of the launch. The air temperature at launch time was 38 degrees.
This line of inquiry raises questions about the pressure shuttle managers were under to meet a heavy flight schedule. The credo at NASA has always been to put safety ahead of such considerations, and people who have worked in or around NASA generally believe that NASA has never let that standard slip.
But NASA was also under heavy pressure to meet its schedules, according to John Stewart, a member of the agency's independent safety advisory panel. The shuttles were expected to fly 15 missions this year, and to carry some planetary probes in May that would have to wait more than a year if they were delayed.
``NASA had a great deal to get done between now and May,'' says Mr. Stewart. The safety panel has been arguing for years against high flight rates and did not believe the shuttle program could meet its current schedule, he says. ``When that happens, you let the schedule slip and handle the safety questions,'' he says. ``That's how NASA has always worked.''
As the probe of the accident focuses on how decisions were made, the risks to the public perception of NASA grow greater. NASA's reputation has already been badly damaged, says John Logsden, director of science policy program at George Washington University.
The agency has been in some disarray for the past two or three years, Mr. Logsden believes, for lack of strong leadership at the top. ``The agency badly needs a white knight'' to put it in order, he says.
``The reputation of NASA as a highly competent agency is an important asset to the country,'' says Logsden. American competence in space is part of the message the US sends to the world and part of how the country sees itself, he explains.
The space program will survive the public scrutiny attending the Challenger disaster, according to Logsden. But the shuttle program will never again become routine, he says. Manned rockets are ``too sensitive and too dangerous'' to launch just to carry commercial satellites into space, he says.
Stewart agrees. The routine work of launching satellites may again fall to unmanned rockets, as it has in the past. And manned shuttles are likely to be launched less often than planned and with more attention spent on each launch.