More than eight hours and 45,000 miles into their mission, the time had come for the men to slip out of their bulky space suits. They had been wearing them since long before launch in order to breathe pure oxygen. Doing so helped to purge nitrogen from their bodies, and that had been critical during launch. As expected, the cabin’s internal air pressure dropped rapidly as the spacecraft ascended. If the crew had not purged the nitrogen from their systems, the sudden drop in pressure could have caused the nitrogen to form bubbles in their tissues that could press on nerves, lungs, spine, even
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