According to internal NASA reports filed by Payload Specialist crew member Story Musgrave, the UFO was "disc-shaped" and much larger than the space shuttle itself. The UFO was seen at a height of 190 nautical miles and Musgrave said that "it appeared to [have] come from nowhere". Below is a still image of the UFO from a video recording made by NASA.
The UFO "seemed to be intelligently controlled, changed its flight vector and -- most unnerving of all -- seemed to track the Columbia and her crew through space". The encounter convinced Musgrave that extra-terrestrials do exist.