One of the most significant activities conducted in space takes place when human beings depart their spacecraft and travel about and perform work in a spacesuit. Extravehicular activities (EVA) require some of the most complex technical skills, sophisticated technologies, and human capabilities of all missions undertaken in space. The first of these EVAs took place on 18 March 1965 during the Soviet Union's Voskhod 2 orbital mission when cosmonaut Alexei Leonov first departed the spacecraft in Earth orbit to test the concept. In June of 1965, during the flight of Gemini 4, Edward White II, performed the first EVA by an American. Since that time hundreds of hours have been amassed by humans conducting EVAs in both Earth orbit and on the lunar surface.
These total EVAs have not only accomplished significant work in space, work impossible through any other means, but also yielded enormous knowledge, skills, and experience among the astronaut and cosmonaut corps about how to perform meaningful work beyond the confines of Earth's atmosphere. The two volumes of Walking to Olympus: An EVA Chronology, are a comprehensive chronicle of all of the EVAs conducted since the dawn of the space age to 2011.