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Experts cautioned that NASA should not rely excessively on untested computer models to decide whether the new shuttle modification is secure enough to face any heat shield failures during its re-entry into the earth's atmosphere, said an interim report issued by the Return to Flight Task Group of NASA. The task group had made the statement after examining the new fuel tank that NASA has designed for the shuttle. The new fuel tank was designed after the Columbia space shuttle disaster in Texas that took lives of seven astronauts. The Columbia space shuttle was burnt during its re-entry into the earth's atmosphere. Investigations had revealed that few heat-resisting tiles had been scraped off from the shuttle's wing due to a falling piece of 1.67-pound foam from the fuel tank. The panel, headed by the former astronauts Thomas P. Stafford and Richard O. Covey, said that while models were useful, NASA should guard against using them to make assumptions about equipment changes and flight performance that are not backed up by actual testing and hard data. Based on computer modeling, NASA redesigned the external tank so that no piece of foam larger than 0.3 ounces will break off during launch, far smaller than the 1.67-pound chunk that punched a hole in the heat shielding protecting the space shuttle Columbia's left wing, causing it burn up on reentry in February 2003. NASA is unable to test the effects of such a small foam "bullet," but slightly larger pieces - 0.7 ounces - have caused potentially catastrophic damage in tests of the "reinforced carbon-carbon" shielding on the leading edge of the shuttle's wings. "NASA has yet to demonstrate the rigor of the models necessary to certify the space shuttle TPS (therma protection system) including the ET (external tank)," the report said, without specifically mentioning the tests. "Without validation of models, they should not be used for certification or risk assessment." The fuel tank, made by the Lockheed Martin Corporation, will be mated with Discovery shuttle to be launched somewhere in May or June. Related Links SpaceDaily Search SpaceDaily Subscribe To SpaceDaily Express 
NASA Asks Lehigh Students To Analyze Debris From Failed Columbia Shuttle
Bethlehem PA (SPX) Jan 31, 2005Every year, seniors in Lehigh University's Failure Analysis course peer through microscopes to learn the variety of ways in which different materials deform and crack. They apply their new skills to specimens from machines, factories and buildings that have been damaged in real-life situations. |
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