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The space shuttle Columbia flared and broke up in the skies over Texas on Saturday, February 1,2003, killing the seven astronauts on board in what NASA and President Bush called a tragedy for the entire nation. NASA launched an investigation into the disaster and began searching for the astronauts' remains. It said that although there had been some data failures it was too early to nail down a precise cause. The break-up, 16 minutes before the shuttle was due to land at Kennedy Space Center in Florida, spread possibly toxic debris(有毒的残骸) over a wide swath of Texas and neighboring states.
