SIMPLE SCIENCE (via Glenn Dryfoos):

Decoding Columbia: A detective story: In an inquest fraught with questions of guilt and shame, scientists unravel the mystery of a shuttle's demise. (Robert Lee Hotz, December 21, 2003, LA Times)

James Hallock discovered just how little it takes to bring down a space shuttle.

He did it by playing with pencils.

As a member of the Columbia Accident Investigation Board, the pear-shaped, bewhiskered expert on flight safety had a New Englander's flinty skepticism and a physicist's distaste for untested accident theories.

On this day, Hallock, 62, scowled at specifications for the reinforced carbon panels that shielded the leading edge of Columbia's wings from the heat of reentry.

If one of the $800,000 panels had cracked, it might have been the flaw that on Feb. 1 caused the $1.8-billion spacecraft and its crew of seven astronauts to plummet in a shower of molten debris across six states.

Hallock brooded over a simple question: What would it take to break one?

Engineers gave him the original 25-year-old NASA specifications, which said the panels must withstand an impact equal to the kinetic energy of 0.006 foot-pounds.

What did that mean? Hallock twiddled a yellow No. 2 pencil between his fingers. How far, for instance, would he have to drop the pencil to generate that kind of impact?

In the mailroom at the board's makeshift headquarters in Shirlington, Va., he found a box of pencils and a postal scale.

He weighed the pencils, then calculated the mass of the average pencil. With that number, he worked out how much punch each pencil would pack.

"The answer," he would say later, "is that a No. 2 pencil dropped from about 6 inches equals the kinetic energy number they had."

The panels, in actual manufacture, were much stronger. But that remarkably low standard, Hallock believed, was a tangible measure of how confident NASA engineers were that nothing would hit the leading edge of the wing.

"The number didn't matter to them," Hallock said, "because they assumed nothing would ever hit the shuttle."

Eeerily reminiscent of the famous incident when Richard Feynman demonstrated the effect of cold on the O-rings in Challenger:

After one too many tutorials in doctoral-level dissembling from Lawrence B. Mulloy, then head of NASA's solid-fuel booster rocket project at the Marshall Space Flight Center in Huntsville, Ala., Feynman famously clamped a piece of O-ring material and dipped it into a glass of ice water. There was, as national television audiences saw repeatedly, no resilience. Talk about smoking guns.

"I believe that has some significance for our problem," Feynman observed dryly.

Posted by Orrin Judd at January 28, 2004 10:27 PM