NASA Determines Cause of Cracks

NASA said Tuesday that it had figured out what caused the cracking in the fuel tank of the space shuttle Discovery, which has been grounded repeatedly because of technical problems. John Shannon, the shuttle program manager, said Tuesday that inferior material and assembly problems were to blame for the trouble, which included cracks in five aluminum alloy struts in the center of the tank. Those have been patched, NASA said, and technicians will reinforce the dozens of remaining struts as a precaution. More

(Source: New York Times - Jan 13)