||This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. (May 2008)|
Liftoff of the first flight of Atlantis and the STS 51-J mission.
|Mission type||Military satellite deployment|
|Mission duration||4 days, 1 hour, 44 minutes, 38 seconds|
|Distance travelled||2,707,948 kilometres (1,682,641 mi)|
|Spacecraft||Space Shuttle Atlantis|
|Landing mass||86,400 kilograms (190,400 lb)|
|Payload mass||19,968 kilograms (44,020 lb)|
|Start of mission|
|Launch date||3 October 1985, 15:15:30UTC|
|Launch site||Kennedy LC-39A|
|End of mission|
|Landing date||7 October 1985, 17:00:08UTC|
|Perigee||475 kilometres (295 mi)|
|Apogee||484 kilometres (301 mi)|
L-R: Stewart, Hilmers, Bobko, Pailes, Grabe
STS-51-J was the 21st NASA Space Shuttle mission and the first flight of Space Shuttle Atlantis. It launched from Kennedy Space Center, Florida, on 3 October 1985, carrying a payload for the U.S. Department of Defense, and landed at Edwards Air Force Base, California, on 7 October.
|Commander||Karol J. Bobko
Third and last spaceflight
|Pilot||Ronald J. Grabe
|Mission Specialist 1||David C. Hilmers
|Mission Specialist 2||Robert L. Stewart
Second and last spaceflight
|Manned Spaceflight Engineer||William A. Pailes, MSE
Backup crew 
|Manned Spaceflight Engineer||Michael Booen, MSE|
Mission summary 
STS-51-J launched on 3 October 1985, at 11:15 EDT, from launch pad 39A at the Kennedy Space Center. The launch was delayed by 22 minutes and 30 seconds due to a problem with a main engine liquid hydrogen prevalve close remote power controller; the controller was showing a faulty "on" indication.
The mission was the second shuttle flight totally dedicated to deploying a Department of Defense payload, after STS-51-C. Its cargo was classified, but it was reported that two (USA-11 and USA-12) DSCS-III (Defense Satellite Communications System) satellites were launched into stationary orbits by an Inertial Upper Stage. The DSCS satellites used X-band frequencies (8/7 GHz). Each DSCS-III satellite had a design life of ten years, although several of the DSCS satellites have far exceeded their design life expectancy.
The mission was deemed successful. After a flight lasting 4 days, 1 hour and 45 minutes, Atlantis landed on Runway 23 at Edwards Air Force Base at 13:00 EDT on 7 October 1985. During STS-51-J, mission commander Karol Bobko became the first astronaut to fly on three different shuttle orbiters, and the only astronaut to fly on the maiden voyages of two different shuttles.
See also 
- Day, Dwayne (2010). "A lighter shade of black: the (non) mystery of STS-51J". The Space Review. Retrieved 4 January 2010.