WASHINGTON - Lawmakers increased their pressure yesterday on NASA's administrator for a more independent inquiry into the space shuttle disaster, saying the agency is too closely tied to the board it chose to investigate the accident.
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.
"The more I've read the board's charter, the more I've become convinced that it must be rewritten," Boehlert said as the committee began hearings into the Columbia disaster. "We all want the board to be independent not just in name but in fact."
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."
Space shuttles are typically exposed to sharp temperature fluctuations during orbit, O'Keefe said, suggesting that something "almost certainly would have shown up" on one of Columbia's 4,000 sensors during the flight if the orbiter's structure was under stress.
While the hearing was in progress yesterday, NASA released the contents of an e-mail message dated two days before the disaster in which a NASA engineer suggested that excessive heat exposure to the Columbia's wheel well could produce a "catastrophic" effect.
"It seems to me that with that much carnage in the wheel well, something could get screwed up enough to prevent deployment and then you are in a world of hurt," wrote Robert H. Daugherty, an engineer at NASA's Langley Research Center.
No lawmakers questioned O'Keefe about the message during the hearing, and he did not address it.
NASA engineers who evaluated the possible consequences of tile damage had been guided by past instances - "no more than a half a dozen," O'Keefe said - in which cracked thermal tiles were deemed not to be a safety risk.
"It was never determined to be significant in terms of a safety-of-flight consideration," O'Keefe said of previous cases in which insulating tiles fell off orbiters.
Under questioning by Sen. John B. Breaux, a Louisiana Democrat, O'Keefe agreed to provide Congress with a full account of all such incidents and to disclose how many tiles had sustained damage in the history of the shuttle program.
Without concrete evidence or conclusions about what caused Columbia's disintegration, lawmakers focused on budget cuts and policy decisions at NASA over the past decade, suggesting that they might have contributed to the accident.
"A comprehensive examination necessitates a review of our own actions and those of the administration to determine if the shuttle program was underfunded or managed in a manner that compromised safety," said Sen. John McCain, the Arizona Republican who is chairman of the Commerce Committee.
Several senior lawmakers pointed to cuts in the shuttle program's budget throughout the 1990s as a possible factor in the Columbia disaster. Both the amount of money NASA requested for the shuttle and the amount that Congress provided fell steadily during that period, according to an analysis by the Congressional Research Service.
Spending on the shuttle program fell from $4.8 billion in 1992 to about $3 billion in 1998. It has gradually risen since then to $3.3 billion in 2002.
O'Keefe - who attended the hearing armed with slides displaying photos, charts and graphs - attributed the spending decreases partly to the agency's finding "efficiencies," which he said cut costs even as shuttle performance and safety improved.
Many of the spending cuts, he said, occurred as NASA was planning to phase out the shuttle by 2012 in favor of a new launch vehicle. The space agency has since decided to keep flying the shuttle until 2015 or 2020, allowing more time to develop the new vehicle.
NASA fosters "a culture that is dedicated to ensuring safe flight operations, or else the flight does not occur," O'Keefe said.
In response to questioning by Rep. Zoe Lofgren, a California Democrat, O'Keefe agreed to review and report to Congress about whether any safety upgrades had been recommended to him - either as NASA chief or in his previous job as a top official in the White House budget office - that he did not support.
With the NASA investigation under way, aides said that Congress is likely to step back from investigative hearings or sessions about the future of the space agency until lawmakers learn more about the technical issues that led to the Columbia disaster.
"A big piece of the puzzle in terms of looking ahead for the policy questions is what went wrong technically," said Heidi Tringe, spokeswoman for the House Science Committee.