STS-51-C

STS-51-C

Discovery launches on STS-51-C
Mission type	Satellite deployment
Operator	NASA
COSPAR ID	1985-010A
SATCAT №	15496
Mission duration	3 days, 1 hour, 33 minutes, 23 seconds
Distance travelled	2,010,000 kilometres (1,250,000 mi)
Orbits completed	49
Spacecraft properties
Spacecraft	Space Shuttle Discovery
Launch mass	113,802 kilograms (250,891 lb)
Crew
Crew size	5
Members	Thomas K. Mattingly II Loren J. Shriver Ellison S. Onizuka James F. Buchli Gary E. Payton
Start of mission
Launch date	January 24, 1985, 19:50:00 UTC
Launch site	Kennedy LC-39A
End of mission
Landing date	January 27, 1985, 21:23:23 UTC
Landing site	Kennedy SLF Runway 15
Orbital parameters
Reference system	Geocentric
Regime	Low Earth
Perigee	332 kilometres (206 mi)
Apogee	341 kilometres (212 mi)
Inclination	28.4 degrees
Period	91.3 minutes
Epoch	January 26, 1985[1]
Back row: L-R: Payton, Buchli, Onizuka Front row L-R: Shriver, Mattingly Space Shuttle program ← STS-51-A STS-51-D →

STS-51-C was the 15th flight of NASA's Space Shuttle program, and the third flight of Space Shuttle Discovery. It launched on January 24, 1985, and made the fourth shuttle landing at Kennedy Space Center, Florida, on January 27. STS-51-C was the first shuttle mission to deploy a dedicated United States Department of Defense (DoD) payload, and consequently many mission details remain classified.

Crew

Position	Astronaut
Commander	Thomas K. Mattingly II Third spaceflight
Pilot	Loren J. Shriver First spaceflight
Mission Specialist 1	Ellison S. Onizuka First spaceflight
Mission Specialist 2	James F. Buchli First spaceflight
Payload Specialist 1	Gary E. Payton, MSE First spaceflight

Backup crew

Position	Astronaut
Payload Specialist 1	Keith Wright, MSE First spaceflight

Crew seating arrangements

Seat[2]	Launch	Landing	Seats 1–4 are on the Flight Deck. Seats 5–7 are on the Middeck.
S1	Mattingly	Mattingly
S2	Shriver	Shriver
S3	Onizuka	Onizuka
S4	Buchli	Buchli
S5	Payton	Payton

Mission summary

STS-51-C launched from Kennedy Space Center (KSC) on January 24, 1985 at 14:50 EST, and was the first of nine shuttle missions that year. It was originally scheduled for January 23, 1985, but was delayed because of freezing weather. Challenger had been scheduled for this flight, but Discovery was substituted when problems were encountered with Challenger's thermal protection tiles. STS-51-C marked the 100th human spaceflight to achieve orbit.

The mission was the first shuttle flight dedicated to the Department of Defense (DoD), and most information about it remains classified. For the first time, NASA did not provide pre-launch commentary to the public until nine minutes before liftoff. The Air Force only stated that the shuttle successfully launched its payload with an Inertial Upper Stage on the mission's seventh orbit. It is believed that the payload was an Magnum/ORION ELINT satellite into geosynchronous orbit. Other DoD flights STS-33 and STS-38 could have carried similar payloads. Payton stated in 2009 that STS-51-C's payload is "still up there, and still operating."^[3]

Also according to Aviation Week, the shuttle initially entered a 204-kilometer (127 mi) x 519-kilometer (322 mi) orbit, at an inclination of 28.45 degrees to the equator. It then executed three Orbital Maneuvering System (OMS) burns, the last being executed on the fourth orbit. The first burn was conducted to circularize the shuttle's orbit at 519 kilometres (322 mi).

The mission lasted 3 days, 1 hour, and 33 minutes. Discovery touched down on Runway 15 at KSC on January 27, 1985, at 16:23 EST. IMAX footage of the STS-51-C launch was used in the 1985 movie The Dream is Alive.

Connection to the Challenger disaster

Almost exactly a year after STS-51-C, Space Shuttle Challenger was destroyed with all hands on board during the STS-51-L mission including Ellison Onizuka, a crew member on both flights. As part of the investigation into the disaster, it was reported to the Rogers Commission that during the launch of STS-51-C, the worst solid rocket booster (SRB) blow-by effects of any mission prior to STS-51-L occurred, indicating conclusively that the Viton O-rings were not sufficiently sealing the hot gases inside the combustion chambers of the SRBs while firing. After they were recovered post-flight, the O-rings in both the right and left SRBs showed some degree of charring, but analysis of the center field joint of the right SRB showed an unprecedented penetration of the primary O-ring and heavy charring on the secondary O-ring.^[4]

This information was significant to the established consensus that low air temperature was a major factor in Challenger's destruction because the temperature at STS-51-C's launch was also, up to its time, the coldest recorded during a shuttle launch, at only 53 °F (12 °C).^[4]

See also

• List of human spaceflights
• List of Space Shuttle missions

References

 This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration.

1. McDowell, Jonathan. "SATCAT". Jonathan's Space Pages. Retrieved March 24, 2014.
2. "STS-51C". Spacefacts. Retrieved February 26, 2014.
3. Cassutt, Michael (August 2009). "Secret Space Shuttles". Air & Space. Retrieved April 18, 2015.
4. Rogers Commission Report (1986). "Report of the Presidential Commission on the Space Shuttle Challenger Accident, Volume 1, Chapter 6".

External links

• NASA mission summary