Washington ? NASA’s top administrator, Sean O’Keefe, said Friday he rejected the idea that nothing could have been done in orbit to help the crippled space shuttle Columbia and possibly save its seven astronauts.

Raising his voice, O’Keefe said NASA had a long history of responding to orbital emergencies and would have done so again had it been clear that Columbia was in trouble.

“To suggest that we would have done nothing is fallacious,” O’Keefe said. “If there had been a clear indication, there would have been no end to the efforts.”

O’Keefe was responding to a reporter who cited statements by Shuttle program director Ron Dittemore that nothing could have been done to help Columbia and its crew even if Mission Control had been certain that thermal protection tiles on the space shuttle had been damaged.

One theory of the cause of the accident is that tiles damaged during launch allowed the superheated gases of re-entry to penetrate and destroy the hollow wing.

“I completely reject the proposition that nothing could have been done,” O’Keefe said.

In remarks at a news conference on Feb. 1, the day of the Columbia disaster, Dittemore said there was no way to minimize the torrid heat of re-entry in order to allow for missing or damaged tiles.

“And so once you get to orbit, you’re there, and you have your tile insulation, and that’s all you have for protection on the way home from the extreme thermal heat heating during re-entry,” Dittemore said.

But on Friday O’Keefe heatedly dismissed the notion of doing nothing.

“I reject the premise that there was nothing that could have been done on orbit,” the administrator said.

O’Keefe cited the response of Mission Control engineers to the Apollo 13 accident in 1970. Engineers devised a way for that mission’s three astronauts to return safely to Earth after an oxygen tank exploded while the spacecraft was on its way to the moon.

The administrator acknowledged, however, that he knew of no formal, written contingency plan that would have covered the case of Columbia, in which a space shuttle in orbit was suspected to have damaged thermal protection tiles but there was no certainty of such damage.

He said trying to investigate the tiles using ground-based Department of Defense cameras was rejected because past efforts by the cameras had not produced useful images for objects as small as the tiles on Columbia’s underside.

Columbia broke up during the final minutes of re-entry, killing all seven of its astronauts. Engineers have said sensors in the shuttle’s left wing suggest that broken or damaged heat protection tiles allowed the 2,500-degree plasmas of re-entry to penetrate the wing’s interior. Films of the shuttle’s launch show insulation peeling from the craft’s external tank and smashing into tiles on the underside of the left wing.