Scientific American August 2003 [antikvár]

t SA Perspectives Houston, You Have a Problem In retrospect, the missteps that led to the loss ofthe space shuttle Columbia seem so obvious. In every one of the 113 shuttle flights since the program began in 1981, small pieces of insulation foam peeled off the vehicle's external tank during launch and dinged the or-biter. In at least eight flights, larger hunks of foam detached from the bipod ramps (the insulation covering the areas where struts attach the external tank to the orbiter). During the launch of the shuttle Atlantis last October, a foot-long chunk fell from a bipod ramp and hit one ofthe solid-fuel boosters. But in the Flight Readiness Review for the next shuttle mission, NASA managers concluded that the foam strikes did not pose a threat. Instead of thoroughly analyzing the problem, they put out a perfunctory rationale including statements such as "Ramp foam application involves craftsmanship" and "All ramp closeout work was performed by experienced practitioners." One minute and 21 seconds into Columbia's final launch on January 16, a briefcase-size piece of foam separated from the bipod area and slammed into the orbiter's left wing at more than 500 miles an hour. According to the Columbia Accident Investigation Board, which is due to release its report this summer, the impact most likely opened a breach in the wing's leading edge. On February 1, when the the shuttle reentered the atmosphere, superheated gases jetted through the hole like a blowtorch. Hindsight is 20/20, of course. How could anyone have known that a routine problem that had caused only nicks to the orbiter in 112 flights would do lethal COLUMBIA ASTRONAUTS Kalpana Chawla and Rick Husband shortly before the accident. damage in the 113th? But this wasn't the first time that NASA failed to recognize the dangers of a routine anomaly. In several shutrie flights during the mid-1980s, engineers had noticed an ominous sign—partial erosion of the O-rings in the solid-fuel boosters— but nobody heeded their warnings. After an 0-ring leak caused the explosion of Challenger in 1986, NASA revamped its procedure for launch decisions to involve more engineers and safety experts. Events during the Columbia flight, however, showed that the space agency still hadn't learned how to listen to the cautions of its own personnel. When NASA engineers asked the National Imagery and Mapping Agency to take satellite photographs of the shuttle to look for damage from the foam impact, their superiors overruled the request. To do justice to the seven astronauts killed in the Columbia accident, NASA must go far beyond technical fixes to the bipod area. Before the space shuttles are allowed to fly again, the agency must restructure its mission teams so that engineers and safety experts have sufficient resources to fully investigate flight anomalies and enough independent clout to challenge program administrators. In testimony before Congress in May, Harold W. Gehman, Jr., the retired admiral who heads the accident investigation board, observed that NASA engineers cannot persuade the agency to focus on a safety problem unless they have hard data to back up their concerns. Noted Gehman: "The people who would say, 'Wait a minute, this is not safe,' can't come argue their cases with 18 inches worth of documentation, because they aren't funded well enough." Given the inherent risks of spaceflight and the ungainly design of the shuttle, NASA may not be able to bar a third catastrophe (especially if it keeps the aging shuttles flying imtil 2015 or longer). But the agency can reduce the chances of another accident in space by improving its communications on the ground. THE EDITORS [email protected]