Shuttle Insulation Drew ’79 Warning

NASA officials were warned even before the first space shuttle launch more than two decades ago that foam insulation could peel off the external fuel tank and damage the orbiters’ protective tiles.

In a 1979 report that now seems prescient, two Texas A & M professors studied the potential impact of insulation hitting the tiles and concluded that the damage could impair the tiles’ “thermal performance.” The ceramic tiles protect the shuttles during reentry, when temperatures can reach 3,000 degrees and cause most metal structures to break apart.

An independent board investigating the Columbia disaster on Feb. 1 is focusing on, among other things, three pieces of foam, one weighing about 2.6 pounds, which apparently fell off a bipod strut on the external tank before striking the orbiter’s left wing during ascent.

Experts believe the resulting damage to the tiles may have caused the shuttle’s skin to be breached by superheated gases during reentry, leading Columbia to break apart.

The 96-page study, completed while the shuttle fleet was still in development, predicted that fragments of foam insulation weighing as much as 2.5 pounds could come loose from the bipod, which connects the shuttle to the external tank, and damage the tiles.

In addition to the 24-year-old report, revelations contained in several more recent internal studies suggest NASA officials have been shadowed by concerns with detaching foam insulation throughout the orbiter’s history.

But it appears that many of those concerns and studies largely were forgotten in an agency that has lost many veteran engineers, along with their institutional memory.

Moreover, aerospace experts say, the agency is notorious for commissioning studies whenever anyone raises a safety concern -- however arcane it may be -- and overloading managers with technical reports and studies. In 2001, amid several incidents of foam insulation damage, NASA completed a 56-page report detailing the photographic techniques used for assessing foam loss.

“It’s unbelievable how much they spend on studies,” said Howard McCurdy, a space policy analyst at American University. “Not only do they produce a large number of reports, but the reports can easily go unread. There is just so much information that people would say: ‘If you paid attention to every contractor study, you’d never launch.’ ”

NASA officials said Tuesday they were not even aware of the 1979 report and asked the Los Angeles Times for details. The Times had obtained a copy of the report, “Effects of Soft Foam Insulation Impact,” from NASA’s archives.

The authors of the report said in an interview this week that NASA appeared to have forgotten about the study. They also could not recall how the agency responded to the report at the time.

Under pressure during the 1990s to cut costs, NASA reduced its work force by nearly a third, from 25,000 to about 17,000. Many of those who left were veterans taking early retirement. The agency recently began adding staff amid concerns that the cuts went too deep.

“It’s been a long time,” said David J. Norton, who co-authored the report with James L. Rand while they were at Texas A & M. “There have been a lot of changes at NASA, so I’m not sure if anybody would have remembered.”

It’s not clear whether the assessments made in the 1979 study would be applicable today, because NASA switched to a new type of foam insulation for the tank in 1997.

The insulation protects the fuel tank from heating up during launch. The newer insulation, which was developed for environmental reasons, created more problems. A 2001 NASA report said the foam actually caused “greater damage” to the shuttles than in previous flights.

Also, the 1979 study was completed before the shuttle fleet became operational, and some improvements may have been made that could have changed the outcome of the tests.

Still, some experts said, the study is another example of how the space agency seems to be “reinventing the wheel.”

In 1999, after several incidents of foam insulation-related tile damage, NASA commissioned a research firm in San Antonio to conduct tests similar to the 1979 study.

The space agency so far has refused to publicly release results of those tests. But according to the firm’s annual report, researchers fired pieces of foam insulation at tiles using a small compressed-gas gun.

The Texas A & M team also used guns of varying bore sizes to fire foam insulation of different sizes and weights at the tiles.

A NASA spokesman said Tuesday that the agency plans to post the 1999 report on its Web site later this week, after a review by the agency’s legal department.

In the 1979 study, “We shot foam at various velocities and angles,” Norton said. “They caused cracking. In some cases, it was severe.”

Norton and Rand then measured the “failure threshold” for different types of debris and found that foam insulation, traveling at 740 feet per second, cracked the tile coating. NASA officials estimate the foam insulation that hit Columbia’s left wing was traveling about 750 feet per second.

“Even before the first launch, they were thinking about this and anticipating problems with the foam insulation,” said Paul Fischbeck, a Carnegie Mellon professor who in 1990 had warned NASA about debris problems. He said he was not aware of the 1979 report when he completed his study. “It’s unbelievable prognostication.”

The 1979 report, which is filled with photographs and diagrams of cracked tiles, was completed at the request of Maxime Faget, a legendary engineer who helped design the Gemini, Apollo and space shuttle vehicles, Norton said.

“Very early on, they began to worry about the foam insulation shedding from the external tank,” he said. “We turned in our results, had a few discussions about it with them and then we just moved on.”

Rand said they recommended that NASA continue the tile study and subject the cracked tiles to high heat to replicate the effects of plasma, the superheated gas that engulfs the shuttle during reentry. But neither Norton nor Rand could recall whether any such study was done.

“It occurred to me that there was no way the foam could penetrate [through the tiles] to the metal structure of the wings; but then again, I was concerned about what could happen if plasma was to seep through the cracks,” Rand said. “I don’t think we ever found out.”

It’s not clear whether the study would have helped NASA better assess the potential tile damage from the debris that hit Columbia during its Jan. 16 liftoff.

NASA officials discovered the incident while reviewing film of the launch the next day and asked Boeing Co., a prime NASA contractor, to assess the possibility of the damage.

In a series of reports over three days, Boeing engineers weighed the potential for falling foam insulation to damage the tiles and concluded that the Columbia would have a “safe return.” Both NASA and Boeing said they continue to stand by that assessment.

But Norton said he suspected as soon as he heard about the Columbia crash that damaged tiles could be the cause.

“I immediately thought this could very well be a tile problem,” said Norton, who is now the science director for a school district in suburban Houston.