S66-31665 (3 May 1966) --- Astronaut Eugene A. Cernan, pilot of the Gemini-9 spaceflight, participates in extravehicular training under zero-gravity conditions aboard a KC-135 aircraft. Here, he is donning the Astronaut Maneuvering Unit (AMU) backpack after egressing a Gemini mock-up. The AMU backpack is mounted in the adapter equipment section of the mock-up. Cernan wears an extravehicular activity (EVA) life support system chest pack. Cernan will use the AMU during his scheduled EVA on the Gemini-9 mission. The KC-135 flew a parabolic curve to create the weightlessness condition for training purposes. Photo credit: NASA