NASA yesterday postponed the target date for launching the space shuttle by a week, to May 22, to enable engineers to complete the analysis and review of critical changes made to the orbiter in the aftermath of the Columbia disaster.
Space shuttle program manager Bill Parsons said he and senior planners began discussing the delay a week ago, and recommended it at a Kennedy Space Center meeting Tuesday with Administrator Michael Griffin and other top NASA officials.
"We are announcing [that the launch date] is no earlier than May 22," Parsons said during a telephone news conference. The shuttle team will present its formal recommendation at a "flight readiness review" May 10 and 11, but Parsons expressed confidence that "our recommendation would be May 22."
Space shuttle Discovery, undergoing flight preparations on its Kennedy Space Center launch pad, will be the first orbiter to fly since Columbia disintegrated during re-entry more than two years ago. The launch window will be from May 15 to June 3, leaving time for further postponements if the team needs them.
If the May 22 date holds, Parsons said, lift-off for the 12-day mission would occur between 1:03 p.m. and 1:08 p.m., allowing ground, air and shuttle-based cameras and sensors to check for damage during daylight while the choreography of Discovery's rendezvous with the international space station is executed.
Concerns about shuttle safety have been largely responsible for 22 major changes in the orbiter's design and as many as 40 more minor changes. "All of the redesign is complete," with a few exceptions, said Wayne Hale, deputy manager of the space shuttle program.
Hale said engineers still need to analyze how Discovery's new inspection boom will respond to the stresses of launch, and to complete an analysis of whether pieces of ice and foam insulation might break free from the external fuel tank and damage the orbiter's heat shielding. Columbia suffered fatal damage when a chunk of foam breached the shielding on the orbiter's left wing.
"I'm very comfortable and very confident in all the changes we made to the vehicle," Parsons said. The launch delay will allow engineers to finish writing up and reviewing their tests. "We just weren't ready for a flight-readiness review," he said. "It was the amount of open paper."
Until recently, the chief concern appeared to be the shuttle's ability to comply with 15 recommendations made by the Columbia Accident Investigation Board. Work on these matters has been monitored by a NASA-appointed Return to Flight Task Force, which Parsons said will meet -- perhaps for the last time -- during the first week of May.
Suspicion has grown in recent months that NASA's still experimental plans for the on-board repair of damaged heat-resistant tiles on the shuttle's underbelly will not pass muster with the task force, and that the final meeting, originally scheduled for the end of March, looms as a possible show-stopper.
But in confirmation hearings last week and at a news conference Monday, Griffin suggested that full compliance might not be possible, and that the shuttle launch "can't be go or no-go simply based on a tile-repair capability." And as the date of the final meeting has slipped, the task force's concerns have begun to fade.