The U.S. space agency says bits of insulating foam less than half an ounce can damage the space shuttle's skin, the New York Times said Thursday.
The National Aeronautics and Space Administration has spent $50 million testing what size foam fragments, which typically dislodge on takeoff from the spacecraft's external fuel tanks, can be deflected safely by the shuttle skin.
Two years ago a 1.67-pound foam fragment hit one of Columbia's wings, creating a hole through which super-heated gases entered, destroying the wing and then causing the shuttle to break apart.
NASA's tests showed a piece of insulating foam just 2.3-hundredths of a pound, or 37-hundredths of an ounce, falling off the top of the external tank and striking the leading edge of a wing could cause enough damage to bring down a shuttle.
The agency expects to continue testing smaller and smaller bits of foam to see exactly where the shuttle skin's limits are.
