Tile Damage Seen As Key in Shuttle Breach / Columbia STS-107

Columbia accident investigators announced Tuesday they have concluded that damaged thermal tiles allowed superheated gases inside the space shuttle's left wing as it re-entered the atmosphere, leading to its destruction.

"We have a very good understanding of what happened," investigation board chairman Harold Gehman said at a news conference. "The orbiter (space shuttle) was returning with a pre-existing flaw in the wing.... The wing got heated from the inside."

However, Gehman said how the wing was damaged remains unproven, although a collision with foam insulation from the shuttle's external fuel tank during launch remains the most likely cause.

The shuttle came apart over Texas on Feb. 1 while streaking toward a planned landing at the Kennedy Space Center (news - web sites) in Florida. Seven astronauts were killed and the shuttle fleet was grounded while investigators looked for the cause of the accident.

The board for weeks was unwilling to take a firm position on what happened even as evidence mounted that a hole in the left wing was at the heart of the disaster. Even Tuesday, the board called its conclusions a "working scenario."

But Gehman said "we made sure that there were no facts that contradicted our scenario."

"We now know enough," he said. "We're at the point where we should focus our efforts."

He said the board will be able to make a broad range of recommendations this summer to make the shuttle program safer.

Gehman said the board may never be able to prove the wing was damaged by the foam insulation, though technicians next month will test that idea by firing chunks of the material at thermal tiles. But Gehman said NASA (news - web sites) already knows peeling insulation is a problem that must be fixed before the shuttle fleet flies again.

_As Columbia was launched Jan. 16, photos showed that the leading edge of the left wing was struck by a large piece of foam insulation. There was no indication while the craft was in orbit that the wing had sustained serious damage.

_On the shuttle's second day in orbit, Air Force radar detected an object drifting free of Columbia. Later analysis suggests, but does not prove, that the object was either a piece of reinforced carbon tile or a seal from the leading edge of the wing. It could have been broken by the foam during launch and then shaken free during a maneuver by Columbia.

_When Columbia re-entered the atmosphere on Feb. 1, gases heated to several thousand degrees entered a hole in the wing and melted metal struts and wiring.

_Sensors inside the wing detected rising temperatures within five minutes after the craft began its descent. Within six minutes, the sensors stopped sending data, suggesting wires were melting. In 15 minutes, all communication with Columbia ceased. Observers on the ground, from California to Texas, reported seeing burning debris falling.

_Reinforced carbon panels from the leading edge of left wing, numbers 8 and 9, were eroded by extreme heat. Other pieces from the wing were splashed with molten aluminum, copper, nickel and other metals, indicating extreme heat.

Gehman said there is a "high level of agreement" on the scenario among board members, but that "we reserve the right to change any part of it" if new facts surface.

Did PC Science Cause Shuttle Disaster?

Friday, February 07, 2003
By Steven Milloy

NASA is reconsidering whether tank foam debris caused the Columbia disaster. That’s quite a shift from days earlier when the foam was the "leading candidate" -- an explanation that quickly became embarrassing.

We may never know precisely what happened to Columbia, but one thing should be clear -- NASA should not be in charge of investigating itself.

A chunk of foam insulation broke off the external fuel tank during launch, perhaps damaging Columbia’s heat-protecting tiles. “We’re making the assumption that the external tank was the root cause of the accident,” said shuttle program manager Ron Dittemore in the immediate aftermath.

It seemed a very reasonable assumption based on Columbia’s history.

Until 1997, Columbia’s external fuel tanks were insulated with a Freon-based foam. Freon is a chlorofluorocarbon (CFC) supposedly linked with ozone depletion and phased out of widespread use under the international treaty known as the Montreal Protocol.

Despite that the Freon-based foam worked well and that an exemption from the CFC phase-out could have been obtained, NASA succumbed to political correctness. The agency substituted an allegedly more eco-friendly foam for the Freon-based foam.

PC-foam was an immediate problem.

The first mission with PC-foam resulted in 11 times more damaged thermal tiles on Columbia than the previous mission with the Freon-based foam.

A Dec. 23, 1997, diary entry on the NASA Web site reported: “308 hits were counted during the inspection, 132 were greater than 1-inch. Some of the hits measured 15 inches long, with depths measuring up to 1.5 inches. Considering that the depth of a tile is 2 inches, a 75 percent penetration depth had been reached.”

More than 100 tiles were damaged beyond repair, well over the normal count of 40. Flaking PC-foam was the chief suspect.

In 2001, the Environmental Protection Agency exempted NASA from the CFC phase-out. Even assuming for the sake of argument that widespread use of CFCs might significantly damage the ozone layer, the relatively small amount used by NASA would have no measurable impact. The bulk of CFC use, after all, was in consumer products such as air conditioners, refrigerators and aerosol cans.

But contrary to the exercise of common sense, NASA didn’t return to the safer Freon-based foam. Instead, NASA knowingly continued to risk tile damage -- and disaster -- with reformulated PC-foam.

This is obviously a potentially embarrassing situation for NASA.

In what smacks of an effort to avoid blame, NASA is now claiming the disintegration of Columbia has turned into a scientific mystery.

NASA says computer modeling fails to show how foam insulation striking the thermal tiles could do enough damage to cause catastrophe -- apparently ignoring that flaking foam substantially penetrated thermal tiles on an earlier flight.

NASA has even offered up the ultimate exculpatory theory -- that space junk or even a meteor could have hit the wing and damage the thermal tiles.

It’s certainly possible that a force majeure could have caused the disaster. But I’d like to see qualified independent experts come to that improbable conclusion.

Instead, NASA administrator Sean O’Keefe has activated the Space Shuttle Mishap Interagency Investigation Board. The board is a standing panel created by NASA in the mid-1990s. Its members are generals and other senior bureaucrats from the Department of Transportation -- except that no one from the National Transportation Safety Board is on the panel.

The appearance of independence is lacking. The board is a NASA creation. Its senior government bureaucrats may be reluctant to blame fellow senior bureaucrats. I also wonder whether the panel members personally possess the requisite technical expertise to investigate the accident.

The combination of NASA’s “lone meteor theory” and self-anointed commission strikes me as eerily similar to the Warren Commission and its controversial, if not dubious “lone gunman theory” for the assassination of President Kennedy.

Further, NASA previously dismantled its supposedly “independent” Aerospace Safety Advisory Panel after it questioned the agency’s long-term plans for safety.

NASA is not above pulling the wool over the public’s eyes for its own benefit.

Facing significant budget cuts in 1997, NASA produced the “Mars rock” -- a softball-sized meteorite found in Antarctica in 1984 containing complex organic molecules. Hoping to boost interest in the agency’s mission -- and its budget -- NASA boasted the rock was “evidence of primitive life on early Mars.”

Mars rock soon turned out to be Mars crock. Independent scientists arrived at a much more plausible Earth-bound explanation for the presence of the organic molecules.

NASA is an agency under pressure -- its mission is unclear and its budget demands are high. The last thing NASA needs is for its political correctness or other avoidable errors on the part of the agency to be the cause of the Columbia disaster.

The investigation into what happened to Columbia needs to be turned over to a truly independent and qualified commission -- and before the evidentiary trail starts to disappear.

Steven Milloy is the publisher of JunkScience.com, an adjunct scholar at the Cato Institute and the author of Junk Science Judo: Self-defense Against Health Scares and Scams (Cato Institute, 2001).

Some more from AP via Yahoo!

Shuttle Board Backing Tiles Theory

By JUAN A. LOZANO, Associated Press Writer

HOUSTON - Investigators have picked a leading theory to explain why the space shuttle Columbia broke apart on re-entry, proposing that superheated gases penetrated the spacecraft through damaged thermal tiles on its left wing.

Investigators were still hesitant to attribute a direct cause of the damage, even though evidence points to a collision with foam insulation from the shuttle's external fuel tank during launch as the likely culprit.

"We now know enough," retired Navy Adm. Harold Gehman Jr., the board's chair, said during the group's weekly news conference Tuesday. "We're at the point where we should focus our efforts."

But Gehman was quick to point out the board still needs more evidence to prove what damaged the left wing. The board was careful in discussing its theory, calling it a "working scenario."

The board did say Tuesday that photos showed a large piece of foam insulation struck the leading edge of the left wing as Columbia streaked skyward on Jan. 16.

"We were careful not to say the foam caused a hole in the shuttle. But that's not to say we don't believe that," Gehman said. "The board is certainly suspicious the foam had something to do with it."

For weeks now, evidence had mounted supporting the theory that a piece of fuel tank foam broke off, hitting and dislodging a fragment of an insulating panel or seal along the vulnerable leading edge of the shuttle's left wing.

Under its theory, the board believes that an object that drifted free of Columbia during its second day in orbit could either be an insulating panel or a seal. It could have been broken by the foam during launch and then shaken free during a maneuver by the shuttle.

The board's theory also states that sensors inside the wing detected rising temperatures within five minutes after the craft began its descent. Within six minutes, the sensors stopped sending data, suggesting wires were melting. In 15 minutes, all communication with Columbia ceased.

"We are very careful in our work not to have a scenario-dependent investigation, unless we can prove it," Gehman said. He said the board will be able to make a broad range of recommendations this summer to make the shuttle program safer.

Gehman said the board might never prove the wing was damaged by the foam insulation, though technicians next month will test that idea by firing chunks of the material at thermal tiles. But Gehman said NASA (news - web sites) already knows peeling insulation is a problem that must be fixed before the shuttle fleet flies again.

"The fact we (might not) have a single causal event doesn't bother me in the least," he said. "Our review of this program is so much wider than foam striking the leading edge. Therefore, we believe we will come up with recommendations that will make the shuttle safe to fly."

Board member Sheila Widnall, a former secretary of the Air Force, said the investigative group was in agreement about its working scenario. "This is obviously a first step," she said.

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