Soviet cosmonaut Aleksei Leonov leaves his spacecraft the Voskhod 2 for twelve minutes. At the end of that time Leonov’s spacesuit had inflated in the vacuum of space to the point where he could not re-enter Voskhod’s airlock. He opened a valve to allow some of the suit’s pressure to bleed off, was barely able to get back inside the capsule, and in so doing became the first person to complete a spacewalk.