Aliens flew to earth on peace missions to prevent nuclear war between America and the Soviet Union at the start of the Cold War, according to a former Nasa astronaut. Dr Edgar Mitchell has made a series of increasingly bizarre claims about extra terrestrial life. His status as the sixth man to walk on the moon - during the Apollo 14 mission in 1971 - gives his claims a ready audience. Now he says military top brass saw UFOs visiting Earth during weapons tests in the 1940s at American missile bases and the famous White Sands Proving Ground, in the New Mexico desert, where the world's first nuclear bomb was detonated in 1945. "White Sands was a testing ground for atomic weapons - and that's what the extra-terrestrials were interested in ... they wanted to know about our military capabilities," [Mitchell said]. "My own experience talking to people has made it clear the ETs had been attempting to keep us from going to war and help create peace on Earth." He claims other officers manning missile silos or Pacific bases back up his claims with stories of alien spacecraft shooting down test rockets mid-flight.