Bolt Catcher May Be Too Prone To Fail

You already know about the problem with insulation foam breaking away from the external fuel tank on launching space shuttles. Now, a new problem has surfaced - one that, if it failed, could cause another shuttle disaster.

So says the Columbia Accident Investigation Board (CAIB). Failure of the bolt catcher had "the potential to be catastrophic in the future," said Air Force Major General John Barry, a member of the CAIB.

Even now, engineers and scientists at the Marshall Space Flight Center are working to resolve the problems with the bolt catcher.

Both of the solid rocket boosters that help propel the shuttle into orbit are attached by four of the 80-pound bolts. Each bolt is covered by an aluminum housing at the point where it attaches to the shuttle's external fuel tank. When an explosive charge disengages the bolt from the external fuel tank, the aluminum housing - the bolt catcher - captures and holds the resulting fragments.

The problem is that the bolt catcher may not be strong enough to capture or hold the bolt fragments without giving way, meaning dangerous debris could shower down on the external tank as well as the shuttle itself.

Lab Test Failures - Real World Concerns

No bolt catcher has ever failed on any shuttle mission. But, in stress tests conducted a couple of weeks ago, stress testing showed the weld at the bottom of the aluminum housing was prone to crack under stress. "They saw that the weld was typically where it failed first," said Marshall spokeswoman June Malone. "There was not enough of a safety margin."

A worst-case scenario would mean that both the bolt catcher and a 40-pound bolt fragment could impact the external tank or the shuttle itself, causing major - if not catastrophic - damage.

Could Columbia Have Suffered Bolt Catcher Damage?

Why is all this pertinent to STS-107? The bolt catchers aboard STS-107 were brand new - from a new manufacturer. They had not been stress-tested. Maj. Gen. Barry told reporters Friday that investigators found radar evidence of something trailing Columbia just after the SRB's separated during launch on Jan. 16. It shouldn't have been there, according to NASA officials. Analysis of the imagry indicates it could have been a .6 meter long bolt fragment that wasn't snagged by the bolt catcher. There's no indication that the trailing radar image had anything to do with the Feb. 1. disintegration of Columbia and the deaths of all seven astronauts aboard.

"If (the bolt catcher) comes loose - with or without that half of the bolt in it - it still can cause some serious risk to the orbiter," Barry said. "So this is a possible return-to-flight issue. We need to close this out, and we need to make sure that we understand it, if not for STS-107 [Columbia's last flight], then certainly for the future," said Maj. Gen. Barry.

FMI: www.caib.gov