Transcription: The first shuttle voyage was an opportunity to test orbiter systems under actual space conditions. One such test was the payload bay door latch experiment. Empty except for data collection instruments, the payload bay was open two hours after liftoff and closed four hours before reentry. The test proved to NASA engineers that the bay doors would function properly in space. It also allowed instruments in the open bay to measure how well orbiter thermal loads were handled by onboard heat rejection systems.
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