STS-51-J

STS-51-J

DSCS-III satellites in Atlantis' payload bay
Names	Space Transportation System-21
Mission type	Satellite deployment
Operator	NASA / U.S. DoD
COSPAR ID	1985-092A
SATCAT no.	16115
Mission duration	4 days, 1 hour, 44 minutes and 38 seconds
Distance travelled	2,707,948 km (1,682,641 mi)
Orbits completed	64
Spacecraft properties
Spacecraft	Space Shuttle Atlantis
Launch mass	N/A
Landing mass	86,400 kg (190,500 lb)
Payload mass	19,968 kg (44,022 lb)
Crew
Crew size	5
Members	Karol J. Bobko Ronald J. Grabe David C. Hilmers Robert L. Stewart William A. Pailes
Start of mission
Launch date	October 3, 1985, 15:15:30 (October 3, 1985, 15:15:30) UTC (11:15:30 pm EDT)
Launch site	Kennedy, LC-39A
Contractor	Rockwell International
End of mission
Landing date	October 7, 1985, 17:00:08 UTC (October 7, 1985, 17:00:08 UTC) UTC (10:00:08 am PDT)
Landing site	Edwards, Runway 23
Orbital parameters
Reference system	Geocentric orbit
Regime	Low Earth orbit
Perigee altitude	475 km (295 mi)
Apogee altitude	484 km (301 mi)
Inclination	28.50°
Period	94.20 minutes
STS-51-J mission patch From left: Stewart, Hilmers, Bobko, Pailes and Grabe Space Shuttle program ← STS-51-I (20) STS-61-A (22) →

STS-51-J was NASA's 21st Space Shuttle mission and the maiden flight of Space Shuttle Atlantis. It launched from Kennedy Space Center, Florida, on October 3, 1985, carrying a payload for the U.S. Department of Defense (DoD), and landed at Edwards Air Force Base, California, on October 7, 1985.

Seat[1]	Launch	Landing	Seats 1–4 are on the flight deck. Seats 5–7 are on the mid-deck.
1	Bobko
2	Grabe
3	Hilmers
4	Stewart
5	Pailes
6	Unused
7	Unused

All five astronauts on the secret mission were active-duty military officers.^[2] Before William A. Pailes was assigned to the STS-51-J flight, Mike Mullane was rumored to have been assigned as mission specialist 3 on his second trip to space.

STS-51-J launched on October 3, 1985, at 15:15:30 UTC (11:15:30 a.m. 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 United States Department of Defense payload,^[2] 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 geostationary orbits by an Inertial Upper Stage (IUS). 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.^[3]

The mission was deemed successful. After a flight lasting 4 days, 1 hour, 44 minutes and 38 seconds, Atlantis landed on Runway 23 at Edwards Air Force Base at 17:00:08 UTC (13:00:08 EDT) on October 7, 1985. During STS-51-J, mission commander 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 orbiters.

The 51-J mission insignia, designed by Atlantis's first crew, pays tribute to the Statue of Liberty and the ideas it symbolizes, but also as not to emphasize the "classified" nature of the mission like the first one did. The historical gateway figure bears additional significance for astronauts Karol J. Bobko, mission commander; and Ronald J. Grabe, pilot, both New York City natives.

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  Atlantis lifting off the pad.

• List of human spaceflights
• List of Space Shuttle missions

• NASA mission summary