Rep. Sherwood Boehlert, a New York Republican and chairman of the House Science Committee, told Sean O'Keefe, head of the National Aeronautics and Space Administration, that the investigative board's charter must be rewritten to specify that it is not bound by NASA's policies and timetables and that it is not dependent on the agency's staff or cooperation.
But O'Keefe, appearing on Capitol Hill for the first time since the space shuttle disintegrated over Texas on Feb. 1, stopped short of promising changes to the investigative board, which is led by retired Navy Adm. Harold W. Gehman Jr.
"We will make changes in any way Admiral Gehman says is necessary," O'Keefe said under questioning.
O'Keefe has resisted calls for the creation of a presidential commission similar to the one that studied the explosion of the space shuttle Challenger in 1986.
O'Keefe said he had told Gehman that he could expand the board to include more outsiders if he saw fit, and he promised to consult with Gehman about potential changes to the board's charter.
"We need to go back and to soul-search on that to make sure that there is absolutely no way [the charter] can be misconstrued," O'Keefe said after the hearing, a joint session of the Senate Commerce, Science and Transportation Committee and the House Subcommittee on Space and Aeronautics.
Several Democrats from both chambers expressed concerns that NASA would exercise too much influence over the board's investigation.
"Mr. O'Keefe," said Rep. Bart Gordon of Tennessee, the senior Democrat on the subcommittee, "I'm afraid this won't pass anybody's smell test."
Sen. Byron L. Dorgan, a North Dakota Democrat, said a presidential commission should be convened, as in the case of the Challenger explosion.
"In almost any situation of this type," Dorgan said, "an agency can't effectively investigate itself."
Congressional aides said they have been talking to Gehman about amending the charter and expect revisions to ensure the panel's independence. Gehman and the other board members could not be reached for comment yesterday, a NASA spokesman said.
Speaking to reporters on Tuesday, Gehman sounded confident that his board is as independent as it needs to be.
"We're going to work just as hard, just as fast, put just as many days in. We're going to get just as much cooperation from everybody involved, no matter who signed our charter," he said.
Also at yesterday's hearing on Capitol Hill, O'Keefe defended NASA's conclusion during Columbia's 16-day mission that possible damage to the shuttle's thermal tiles had not harmed the orbiter in a way that would cause a catastrophe during re-entry.
The day after the launch, NASA engineers reviewing footage of the takeoff noted that a piece of insulating foam appeared to fall off the external fuel tank and strike the shuttle's left wing, possibly damaging protective tiles on the shuttle's underside.
NASA convened a panel to determine whether the incident could pose a risk to the shuttle; its members concluded that it would not. That conclusion has been called into question in light of Columbia's disintigration upon its descent.
"There were no abnormalities that would suggest that problem until 8:53 a.m. on Feb. 1," six minutes before NASA lost communications with Columbia, O'Keefe said. "All the information we have now ... suggests no abnormalities that would have pointed in that direction at all."