S66-54934 (29 Oct. 1966) --- Astronaut Edwin E. Aldrin Jr., pilot for the Gemini-12 spaceflight, practices work tasks in preparation for his extravehicular activity (EVA) during the flight of Gemini-12. He works with a telescoping handrail he will use to move from the spacecraft to the Agena Target Docking Vehicle. The underwater environment closely simulates the zero-gravity condition found in space. Photo credit: NASA