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Sacramento - Apr 21, 2003 In response to Gutierrez' complaint that NASA's own post-Challenger documents call for the probability of safe return to be 99.99%, NASA Administrator Sean O'Keefe responded by calling that guideline a "grandiose requirement" which was in reality hopelessly impractical. The Panel was not amused. Gutierrez suggested that O'Keefe was "kicking the can down the road" by ignoring the problem until the development of the OSP, and this is "not acceptable". And the Panel, in its most recent official report, demanded that NASA cease dodging the issue and either devise a crew escape system or officially and publicly state why it believes that such a system is unworkable or unacceptable. But O'Keefe may well be right; such a system may be totally unworkable without destroying the Shuttle's ability to carry the Space Station's remaining modules up to it. The Shuttle has also survived 111 out of 112 reentry attempts -- again impressive, until you consider that all other reentry vehicles, designed as capsules, have carried out thousands of reentries over the decades (including dummy warheads on ballistic missile tests) with virtually no burn-ups. Capsules are self-stabilizing during a reentry. But a winged vehicle is self-unstabilizing as since it must reenter belly-first to spread out the temperature of frictional heating over as wide a part of its surface as possible, and engage throughout its reentry in extremely complex and lightning-fast readjustments of its control surface to keep from tumbling disastrously. Fall off that tightrope -- as Columbia did -- and the result is disaster, no matter what kind of heat-resistant tiles you have. And any attempt to design a crew capsule to survive such a reentry accident would be much more difficult even than designing a cabin launch escape system. It would have to survive the wholesale breakup of the rest of the vehicle around it without any serious damage to its heat shield -- vastly further increasing its weight, should such a system be possible at all. In short, the Shuttle, as a manned vehicle, remains a flying deathtrap, and very likely there is no workable way to change that fact. If it continues to fly for more than a few more years, then the odds of losing a third Shuttle and crew are, as Gutierrez said, very high.
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Beyond Columbia
Sacramento - Apr 21, 2003
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