NASA Administrator Sean OKeefe repeatedly defended the boards independence from NASA while stressing that he is willing to comply with any changes that Gehman feels are necessary to ensure that the board can conduct its investigation without undue influence from NASA.

Rep. Bart Gordon (D-Tenn.), the ranking minority member of the House Science Committees space and aeronautics committee, said OKeefes recent moves to add new members to the board did not go far enough to allay his concerns about the boards independence.

Gordon has been out on point calling for an independent board more in the vein of the Rogers Commission that President Ronald Reagan appointed after the space shuttle Challenger disaster in 1986. While Gordon made one of the more impassioned pleas Wednesday for putting more distance between the Gehman board and NASA, he was not alone in calling for changes.

Gordon was joined by no fewer than a half dozen lawmakers from both sides of the aisle expressing concerns that the Gehman board could at least be perceived as being something less than entirely independent.

Among lawmakers urging changes to the boards charter or reporting relationship included Reps. Dana Rohrabacher (R-Calif.), Ken Calvert (R-Calif.) and Sens. Mary Cantwell (D-Wash.) and Byron Dorgan (D-N.D.).

Boehlert, who co-chaired the four-hour hearing with Sen. John McCain (R-Ariz.), concluded the hearing with a clear call for further changes to the boards charter in order to address the concerns expressed by lawmakers.

I hope you are hearing what we are saying, Boehlert said, We are the ones insisting on greater independence.

OKeefe told Boehlert and the remaining lawmakers that he would call Gehman that afternoon to convey to him the wishes of congress for further changes of the charter to ensure full independence.

OKeefe also told members of Congress that NASA had no indication that anything was wrong with Space Shuttle Columbia until the final minutes before the spacecraft was lost.

"During the 16-day mission, we had no indication that would suggest their was a compromise to flight safety," OKeefe said.

OKeefe said mission controllers at NASAs Johnson Space Center in Houston had only a few minutes between receiving the first abnormal temperatures readings from Columbias sensors and the loss of the shuttle high over the western United States.

Early speculation outside of NASA has focused on a piece of foam that broke away from the shuttles external fuel tank and struck the underside of the shuttle, possibly resulting in the loss of heat tiles under the shuttles left wing. The abnormal temperature readings came from the left wing, but NASA has publicly downplayed the foam as the root cause of the loss of Columbia.

During questioning by members of Congress, OKeefe repeated his assertion that NASA ground controllers received no abnormal temperature readings from the shuttle while it was in orbit during the 16-day mission.

"Were looking at sunset and sunrise every 90 minutes, with temperature variations by as much as 300 to 400 degrees," OKeefe said. "If there had been exposure, it almost certainly would have shown up during that. The fact remains, no abnormalities showed up until right before loss of Columbia."

OKeefe assured the senators and representatives that NASA places the safety of its astronauts before all other priorities and said he understood the publics expectations are very high. "When it comes to human space exploration, where margins are razor thin, we know we are graded on a very harsh curve," O'Keefe said. "For us, 96 percent to 99 percent is not an A. One hundred percent is the minimum passing grade."