Space Shuttle Atlantis returns to Earth from a classified four-day mission to deploy a payload for the Department of Defense, and on only the second flight since the Challenger disaster, most of Atlantis’ crew are surprised to return to Earth at all. During the mission, they note that Atlantis is missing numerous heat shield tiles along the vehicle’s right side and its wing – a post-landing damage survey counts over 700 missing tiles, making Atlantis the most-damaged orbiter to return safely from space. The damage had been pointed out to ground controllers by the crew, but when NASA asks permission from the Defense Department to allow the crew to send a live TV signal to Earth so engineers can survey the damage in orbit, that permission is refused. A slow-scan encrypted video system is used instead, and its low resolution doesn’t reveal the extent of the damage. The damage is believed to have been caused by insulation vibrating loose from the solid rocket booster and the external fuel tank and striking the shuttle during launch, an almost identical cause of damage that proves catastrophic to another shuttle 15 years later.