Step Outside

摘要

From the beginning, nasa knew astronauts would have to leave their spacecraft. They'd have to fix things outside, transfer between orbiting vehicles in an emergency, and-most ambitious of all-walk on the moon.rnAll the techniques of extravehicular activity (EVA) had to be invented and perfected beforehand-how to "ingress" and "egress" through hatches, then airlocks; how to pre-breathe oxygen to avoid the bends (which also afflicts divers); how to anchor yourself in weightlessness; and how to maintain a comfortable temperature in your spacesuit.