SCI/TECH: NASA Identifies Foam Flaw That Killed Astronauts

www.reuters.com
A suitcase-sized chunk of foam from an area of the tank known as the left bipod, one of three areas where struts secure the orbiter to the fuel tank during liftoff, broke off 61 seconds into the flight on Jan. 16 of last year. It gouged a large hole in Columbia's left wing.

The damage went undetected during the shuttle's 16-day mission, but caused the nation's oldest spacecraft to break apart under the stress of re-entering the Earth's atmosphere on Feb. 1, killing the astronauts.

"We now believe, with the testing that we've done, that defects certainly played a major part in the loss. We are convinced of that," said Neil Otte, chief engineer for the external tanks project. He spoke at the Michoud Assembly Facility in New Orleans, where the half-million pieces of every shuttle fuel tank come together.

The fault apparently was not with the chemical makeup of the foam, which insulates the tanks and prevents ice from forming on the outside when 500,000 gallons of supercold liquid hydrogen and liquid oxygen are pumped aboard hours before liftoff.

Instead, Otte said NASA concluded after extensive testing that the process of applying some sections of foam by hand with spray guns was at fault.

Gaps, or voids, were often left, and tests done since the Columbia accident have shown liquid hydrogen could seep into those voids. After launch, the gas inside the voids starts to heat up and expand, causing large pieces of insulation to pop off.


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