Breach in Shuttle Suspected

A breach in Columbia’s skin allowed glowing, superheated air to penetrate the shuttle -- possibly in its left wheel well -- seconds before the craft broke apart over Texas, killing its seven-member crew, investigators said Thursday.

In its first key finding, the independent board of investigators said the shuttle fuselage sustained a significant rupture, rather than simply incurring damage from the loss of a few heat-resistant tiles or another internal malfunction.

NASA officials now suspect that plasma -- air heated to temperatures exceeding 2,000 degrees Fahrenheit -- penetrated the shuttle’s armor either through the leading edge of its left wing or through a 300-pound landing gear door. Either way, one NASA consultant said Thursday night, “that’s death.”

The finding supports a scenario that NASA was warned about in a 1994 report by two researchers at Carnegie Mellon and Stanford universities, who said that debris on launch could cause enough damage to tiles to cause a loss of the orbiter on reentry.

Charles Bolden, a former shuttle astronaut, said NASA’s finding was significant because it was the first time that engineers have determined that a breach of the wing occurred.

“It is an important finding, but it still doesn’t tell you how the hole occurred,” he said. “They still do not know the sequence of events that caused the breach.”

The announcement renewed debate about the potential damage caused when a piece of foam insulation fell from an external tank during liftoff and struck the shuttle’s left side, possibly damaging some heat-resistant tiles.

Portions of the shuttle that encounter the highest temperatures are covered with 24,000 to 26,000 tiles that typically protect it against the heat. If a section of those tiles fails -- or if the plasma finds another way inside -- it would mark the beginning of a devastating chain reaction.

“In our study, one of the most likely scenarios is what happened here,” said Paul Fischbeck, one of the authors of the 1994 tile study. “Given that you have several pounds of foam hitting tiles that you can crumble in your hand, it is going to damage five or six or seven tiles. They have to do the study to determine the extent of that damage.”

Fischbeck’s study suggested that a large piece of foam debris would cause enough tile damage to lead to a burn-through of the aluminum skin, which would trigger a series of system failures and finally the loss of the orbiter.

The board’s statement came hours after NASA officials conceded that they failed to act on the suggestion of one of their own engineers that they use a sophisticated flight simulator to test the shuttle’s ability to fly if it had been severely damaged by the insulation. A NASA engineer in Virginia had suggested those tests two days before the Feb. 1 destruction of Columbia -- and called it a “no-brainer,” according to internal e-mails.

NASA sources also confirmed Thursday that a group of engineers gathered at the Kennedy Space Center in Florida on Jan. 24, halfway through Columbia’s mission, to discuss lingering concerns about the liftoff incident.

That meeting came a day after five engineers from the Boeing Co., a key NASA contractor, assured the space agency that even if the foam insulation had caused “significant” damage, the crew would have a “safe return.” NASA and Boeing have said they stand by that assessment, and NASA has said repeatedly that its engineers were unified in their belief that the falling foam insulation did not pose a threat.

Several of the engineers that day appear to have questioned that diagnosis, however. A NASA spokeswoman on Thursday characterized the discussion as “normal dissent.”

NASA’s preliminary analysis has also not ruled out the possibility that the problem originated within the shuttle, including a theory that one of Columbia’s six tires exploded and pierced the craft’s skin from the inside of the wheel well. On Thursday, a search-and-recovery team found one of the shuttle’s six tires, burned and badly damaged, near Hemphill, Texas.

NASA officials at mission control in Houston detected a series of temperature spikes and other failures about seven minutes before they lost communication with the shuttle. The spacecraft is equipped with 4,000 internal and external sensors, and the failures were clustered near its left wing, the same portion struck by the 20-inch-wide, 2.7-pound piece of foam insulation about 80 seconds after liftoff.

Temperatures in the left wheel well, the sensors indicated, had risen by about 30 degrees. NASA officials have said that those temperature spikes are not severe enough in and of themselves to have caused the shuttle’s demise.

But Paul Czysz, professor emeritus of aerospace and mechanical engineering at St. Louis University and a veteran NASA consultant, said they could be an indication that the plasma had penetrated the shuttle.

Plasma is encountered by every spaceship returning from space, and it appears to the naked eye as a colorful, jelly-like cloak that the shuttle seems to be shoveling through the atmosphere during reentry. In effect, that’s precisely what’s happening -- plasma is essentially air that can’t get out of the way fast enough, so it compresses and heats up so quickly that it becomes electrically charged.

What’s more, the shuttle had two pressurized helium tanks and an oxygen tank above the left wheel well, according to NASA schematic drawings. Two additional tanks containing explosive liquid hydrogen are a few feet forward of the wheel well, the blueprints indicate.

Czysz, like several other analysts reached Thursday, said the board’s announcement points to the insulation as the culprit. Czysz believes the insulation damaged either the leading edge of the wing, the landing gear door or the tubular support beams that hold the shuttle to its external fuel tanks.

Czysz said his calculations, conducted using NASA data he has obtained, show that the foam would have carried eight times more kinetic energy than a bullet fired from a high-powered rifle. The foam was traveling at almost 800 mph, he noted.

“It’s not trivial,” he said. “What if you had a 2 1/2-pound block coming at you at 800 mph? Would you duck?”

Internal documents revealed this week that a veteran engineer at NASA’s Langley Research Center in Hampton, Va., sent an e-mail two days before the accident warning that the shuttle could be in a “world of hurt” if it was sufficiently damaged by the foam insulation.

The engineer, Robert H. Daugherty, admittedly assuming the worst-case scenario, warned that the insulation could have penetrated the craft near its wheel well. That could cause a tire to explode once temperatures rose during reentry, he surmised. That, in turn, could cause “carnage in the wheel well.”

At the end of the e-mail, Daugherty suggested that NASA should use its most sophisticated simulator, based at the Ames Research Center in Mountain View, Calif., to conduct further tests on the potential damage caused by the liftoff incident. In particular, Daugherty wrote, the tests could help engineers understand whether the shuttle could still land if its tires had been damaged.

“Simulating this, because it is so ridiculously easy to do ... seems like a real no-brainer,” he wrote on Jan. 30, two days before Columbia broke apart.

The e-mail exchange did not reach senior NASA officials at Johnson Space Center in Houston until after the accident. NASA officials never requested those tests, said Mike Mewhinney, a spokesman at Ames.

The tests were not requested because senior officials were satisfied with the Boeing analysis concluding that the insulation incident posed no threat, said Catherine Watson, NASA spokeswoman at Johnson Space Center.

After the Boeing analysis, however, there appear to have been lingering fears about the liftoff incident.

NASA officials, for instance, made a second inquiry into the potential damage on Jan. 27, informally calling engineers at Langley for advice. Daugherty’s e-mail came in response to that inquiry.

The machine Daugherty recommended is NASA’s Vertical Motion Flight Simulation Laboratory. According to NASA documents and officials, the lab is cutting-edge and unique, largely because it offers the space agency the highest “fidelity” of any research tool. That means the machine reproduces flight patterns with a high degree of accuracy.

The simulator, because it is so sophisticated, could have helped engineers understand the spacecraft’s ability to fly under various scenarios posed by the foam insulation impact, analysts said Thursday.

Even if the tests had confirmed Daugherty’s fears, it remains unclear whether anything could have been done to save the crew. The shuttle was not equipped with an escape pod or a mechanism that would have allowed its crew to repair the craft’s protective tiles or shell.