Columbia had no equipment on board that would have permitted the crew to attempt a repair to its wing even if NASA had fully appreciated the danger the craft faced as a result of a foam debris strike that occurred shortly after liftoff of the ill-fated 16-day science mission.

Gehman said the 13-member board has been wrestling with just how prescriptive to be in recommending that NASA develop the means to attempt an on orbit repair should a shuttle ever again reach orbit with damage that would prevent its safe return to flight.

The board is also likely to recommend that NASA limit future flights, at least initially, to orbital inclinations that would permit a crippled shuttle to reach the space station.

NASA officials have already said that with the exception of a planned excursion to service and upgrade the Hubble Space Telescope, all other foreseeable shuttle flights will go to the space station, where cameras and other crewmembers with binoculars can inspect a shuttle's surface.

NASA's deputy associate administrator for the space shuttle and space station programs, Michael Kostelnik, said in a recent interview that a Hubble servicing mission is still on the table, but that priority will be given in the year ahead to getting space station assembly back on track.

Before the Columbia accident, NASA had planned to make a service call to Hubble in late 2004.

Board member Roger Tetrault, retired chairman of McDermott International Inc, offered one of the strongest indictments yet of the role insulating foam debris played in the Columbia disaster.

Forensic evidence collected from Columbia's wreckage and correlated with telemetry, sensor data, eyewitness accounts and other analysis points convincingly to the foam strike Columbia suffered about 81 seconds after liftoff.

"We believe the foam is the most probable cause," Tetrault told reporters. He said the evidence and analysis further suggests that Columbia's problems began at or near an area of its left wing known as Panel 8.

Debris recovery spanning several states efforts turned up the least amount of material from these sections of the wing, he said. "The fact that there is such a significant amount of material missing from this area is very telling," he said.

Tests recreating the foam strike on simulated and actual shuttle hardware are continuing at the Southwest Research Institute in San Antonio, Texas. Results to date continue to increase the probability there is a link between the foam strike and a breach in Columbia's heat shield on the left wing.

NASA has already taken steps to prevent a repeat of the foam strike. The so-called left bipod foam ramp, part of a fixture that attaches the space shuttle's giant orange external tank to the space shuttle orbiter, is being redesigned to eliminate the concern.

Other areas of the external tank have demonstrated a tendency to shed foam on liftoff, something the tanks were never supposed to do.

Gehman told reporters that the board would not require NASA to fix all known foam shedding problems before returning to flight. But Gehman stressed that that does not mean the board will sidestep other known foam concerns altogether.

Instead, the report will advise NASA to minimize and prevent foam loss as much as possible while at the same time strengthening the shuttle's ability to withstand such debris hits.

Gehman said NASA could strengthen the orbiter, but has been reluctant to do so in the past because of the added weight such a move would entail. He said strengthening the orbiter with tougher tiles and stronger leading edge materials, however, will not be required as a condition of returning to flight.

Should future shuttle flights suffer a potentially devastating debris strike, Gehman said, NASA will also have to be prepared to inspect for damage on orbit and ultimately repair that damage before bringing the orbiter back to Earth.

But as for crew escape systems and other matters pertaining to crew survivability, Gehman said the board would address it from a policy perspective but not deign to give NASA advice on something as nettlesome as redesigning the shuttle.