As part of the Gemini 4 mission, on June 3, 1965, Air Force Maj. Edward H. White II spent 20 minutes outside of the space vehicle in the first U.S. extravehicular activity during orbital flight. He was attached to Gemini 4 by a 25-foot (8 m) tether and was wearing a 31 -pound (14 kg) space suit designed specifically for this mission. White moved about by firing a twin-barreled gas gun.