First Spacewalk (March 18, 1965)
Alexei Leonov was the first person to perform a spacewalk. The Soviet Union cosmonaut was outside for about 20 minutes and then encountered a problem getting back into the hatch because his suit had expanded. Leonov bled out some of his air to return. "It was the alpha and the omega: the first, and very nearly Leonov's last, spacewalk," said Nicholas de Monchaux, an associate design professor at the University of California, Berkeley who wrote a book called Spacesuit: Fashioning Apollo.