During the Apollo program, NASA had to decide if its spacecraft cabin hatches should open inward or outward. A door that opened outward would be easier for the crew to operate and could be rigged with explosive bolts that could blow the hatch off in an emergency, so that was the initial choice. But after the ocean splashdown of NASA’s second human spaceflight, Mercury-Redstone 4, the hatch unexpectedly opened, and astronaut Gus Grissom had to get out as seawater started flooding in.
