NASA wants to give astronauts on future flights a fighting chance if their space shuttles end up with damaged thermal tiles.
The Columbia crew of Columbia had no repair kit and no safe way of looking under the ship's left wing, which had been struck by insulating foam from the fuel tank shortly after liftoff.
NASA officials have said ever since Columbia disintegrated over Texas on Feb. 1 that even if they had known about severe tile damage to the wing, there was nothing the seven astronauts could have done about it.
Regardless of the outcome of the Columbia accident investigation, the space agency is already taking a much harder look at ways for astronauts to inspect and repair damaged tiles in orbit.
"When we looked at this early in the program, one of the major issues was, you don't have any stable platform to do any of these things," NASA spokesman James Hartsfield said Monday. "Now that most of the shuttle flights are for support of the international space station, one thing that will be looked at very closely is whether the station's robot arm can provide a stable platform."
Columbia did not fly to the space station, which has a 58-foot robot arm. Columbia did not even have its own mechanical arm; the usual 50-foot boom was removed to make room for the laboratory and other scientific payloads.
No matter what the board finds is the cause of the accident, the shuttle program also plans to eliminate foam from the so-called bipod area of the external fuel tank as a source of launch debris, Hartsfield said.
That is the area where foam broke off shortly after Columbia's liftoff on Jan. 16 - and also Atlantis' liftoff Oct. 7.
While Columbia was still in orbit, NASA and contractor engineers concluded that the tank debris posed no safety hazard, a finding that has since come under heavy criticism and is being reviewed.
The space agency and the investigation board, meanwhile, say an analysis of the final two seconds of data from Columbia's flight indicates a complete severance of the ship's hydraulics, yet the continued functioning of electrical, power and other systems in the fuselage.
The implication, according to experts, is that the fuselage, quite possibly including the crew cabin, remained intact until the shuttle started breaking apart over the Dallas and Fort Worth area, a full half-minute after Mission Control heard commander Rick Husband's last radioed words: "Roger, buh - ."
Given the information from those final seconds, "you would expect that the crew cabin is still more or less intact at this point," said Steven Schneider, a professor of aeronautics and astronautics at Purdue University. Once the shuttle began tumbling, however, the enormous gravity forces would have prevented the astronauts from staying conscious for long, he said.
NASA and the board have been reluctant to speculate on how much the astronauts knew about their fate, or how long they may have remained conscious.
Hartsfield said the final two seconds of data does not provide any information as to what the pilots may have been doing, if anything, to save themselves.
Four steering jets were fired to compensate for the increased left drag by the left wing in the final seconds. NASA knows the first two kicked in via autopilot, but is not certain whether the autopilot - or Husband and co-pilot William McCool - started the other two.
Of the 32 seconds of data transmitted from Columbia before its demise, only the first five and last two seconds have provided any insight. Experts have been unable to glean anything from the 25 seconds in between, but are still trying, said Laura Brown, a spokeswoman for the investigation board.
"I don't think they're real optimistic," she said Monday.
During those first five seconds of data, which begin at the moment of loss of signal between Columbia and Mission Control, the analyses indicate no new problems had surfaced during that time. Engineers already had detected a surge in temperatures in the left wing, and some sensors had stopped working.
After a 25-second gap, the final two-second burst of data indicates the pressure in all three hydraulic systems was zero and the quantity of hydraulic fluid in the reservoirs also was zero.
"That would indicate that all three systems were compromised at a common point" in the left wing, Hartsfield said.
One theory is the left wing may have come off at this point, but Schneider said he finds it hard to believe any data would still have been flowing.
"You lose the left wing, it's going to tumble," he said. "I would be real surprised if you could send a signal off this vehicle if it was tumbling."
Schneider said to get zero hydraulic readings, "all you would need is to cut the line. Think of this hot air coming in like a blowtorch, if it gets to one of the lines, it cuts it one way or another ... and the fluid just goes spilling out."
The 10-member investigation board, led by retired Navy Adm. Harold Gehman Jr., suspects a breach in the left wing allowed superheated gases to penetrate as Columbia descended through the atmosphere and aimed for a Florida landing. A central focus is whether any of the three pieces of foam debris identified in launch videos caused or contributed to that breach.
By Marcia Dunn