Space Shuttle Atlantis (Designated OV-104) as it was the fourth shuttle to become operational with it's first flight being STS-51-J on October 3rd 1985. This orbiter was a major workhorse for NASA having the second highest number of missions, only beaten by Discovery. Atlantis is symbolic as it was the orbiter used on STS-135, the final shuttle flight thus it was the last orbiter ever in space. As such it is now on display at the Kennedy Space Center Vistor Complex, tilted at 43.21 degrees to symbolize the countdown prior to launch of all vehicles.
Durning STS-27, a classified Department of Defense mission Atlantis lost part of her heat shielding on liftoff. Due to the encryption required for any transmissions durning the flight the engineers at mission control thought the damage to be only shadows and the low quality of the images. Upon returning to Earth however it was seen that Atlantis's right wing was exposed due to over 700 damaged heat protective tiles, leading the aluminum frame to melt and twist when exposed to re-entry forces. Fortunetly the vehicle did not suffer catostrophic damage and was landed safely with all crew unharmed.