The piece of foam that took the lives of seven astronauts, was found to be defective, the result of applying insulation to the shuttle's external
fuel tank, NASA said on Friday. This accident was left open, since none of the foam or the fuel tank could be recovered for study.
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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This happened on nearly 60% of all launches! The piece of foam the caused this weighed only 1.67 pounds (0.75 kg), but at the speed involved, it hit
the orbiter with enough force to shatter the reinforced carbon-carbon panels of the wing's leading edge.
NASA has made several changes to the foam-application process and still has alot of tests to certify the tanks for flight.
New regulation have said that pieces of foam weighing only half an ounce are allowed to pop of during the first 135 seconds of flight. Obviously ALOT
[edit on 8-13-2004 by Valhall]