Mantell UFO Incident - The Venus Explanation

The Venus Explanation

The Mantell Crash was quickly investigated by Project Sign, the Air Force's new research group which had been created to study UFO incidents. Though Project Sign's staff never came to a conclusion, other Air Force investigators ruled that Mantell had misidentified the planet Venus, and, wrongly believing that he could close in to get a better look, had passed out from the lack of oxygen at high altitude.

However, this conclusion was later changed, because although Venus was roughly in the same position as the UFO, astronomers working for Project Sign ruled that Venus would have been nearly invisible to observers at that time of day. The cause of Mantell's crash remains officially listed as undetermined by the Air Force.