Roswell alien. Computer illustration of an alien next to an Area 51 sign. This alien is based on stories of those allegedly captured by the US government near Roswell in 1947. In July 1947 something crashed near Roswell, new Mexico, with witnesses citing unusual metal pieces, scattered over a large area and a shallow trench several hundred feet long. The United States military reported that it was debris from an experimental high-altitude surveillance balloon, but many UFO proponents maintain that it was an alien craft and that its occupants were captured. Its body was thought to have been taken to a top-secret military facility at Area 51.