Discovery in orbit; in-flight photography of the Department of Defense support mission is limited.
NamesSpace Transportation System-15
Mission typeSIGINT satellite deployment
U.S. Department of Defense
COSPAR ID1985-010A Edit this at Wikidata
SATCAT no.15496
Mission duration3 days, 1 hour, 33 minutes, 23 seconds (achieved)
Distance travelled2,010,000 km (1,250,000 mi)
Orbits completed49
Spacecraft properties
SpacecraftSpace Shuttle Discovery
Launch mass113,802 kg (250,890 lb)
Landing mass(Classified)
Payload mass(Classified)
Crew size5
Start of mission
Launch dateJanuary 24, 1985, 19:50:00 UTC
RocketSpace Shuttle Discovery
Launch siteKennedy Space Center, LC-39A
ContractorRockwell International
End of mission
Landing dateJanuary 27, 1985, 21:23:23 UTC
Landing siteKennedy Space Center,
SLF Runway 15
Orbital parameters
Reference systemGeocentric orbit[1]
RegimeLow Earth orbit
Perigee altitude332 km (206 mi)
Apogee altitude341 km (212 mi)
Period91.30 minutes

STS-51-C mission patch

Back row: Gary E. Payton, James F. Buchli, Ellison S. Onizuka
Front row: Loren J. Shriver, Thomas K. Mattingly II
← STS-51-A (14)
STS-51-D (16) →

STS-51-C (formerly STS-10) 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, 1985. 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.


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

Launch of STS-51-C as seen from an IMAX camera attached to the Fixed Service Structure

STS-51-C launched from Kennedy Space Center (KSC) on January 24, 1985, at 19:50:00 UTC, and was the first of nine shuttle missions in 1985. 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's length of three days was shorter than the week or longer of most civilian shuttle flights. It was the first dedicated to the U.S. Department of Defense (DoD),[3] 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 U.S. Air Force only stated that the shuttle successfully launched its payload with an Inertial Upper Stage (IUS) on the mission's seventh orbit. It is believed that the payload was a Magnum SIGINT satellite into geosynchronous orbit.[4] 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".[5] Payton was a USAF Manned Spaceflight Engineer (MSE); the USAF declined a NASA offer to fly another MSE on the mission.[6]

Also, according to Aviation Week, the shuttle initially entered a 204 × 519 km (127 × 322 mi) orbit, at an inclination of 28.45° 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 km (322 mi).

The mission lasted 3 days, 1 hour, 33 minutes, and 23 seconds. Discovery touched down on SLF Runway 15 at KSC on January 27, 1985, at 21:23:23 UTC. IMAX footage of the STS-51-C launch was used in the 1985 movie The Dream is Alive.

Mission insignia

The crew insignia for STS Flight 51-C includes the names of its five crewmembers. The STS 51-C mission marked the third trip of the Space Shuttle Discovery into space, which is referenced by the three colored trailing strips behind the orbiter in the United States red, white and blue. It was the first Space Shuttle mission totally dedicated to the U.S. Department of Defense, hence the DoD central eagle on the mission patch. The five stars on the upper part of the golden band of the DoD insignia represent the five astronauts. As this mission was classified, the patch includes no further detail as to the mission's payload or nature. For similar reasons, the name of the used orbiter was omitted from the patch.

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 Space Shuttle 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.[7]

This information is 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 12 °C (54 °F).[7]

See also


  1. ^ "SATCAT". Jonathan's Space Report. Retrieved March 24, 2014.
  2. ^ "STS-51C". Spacefacts. Retrieved February 26, 2014.
  3. ^ Blakeslee, Sandra "Astronauts return from secret" (sic) The New York Times, October 8, 1985
  4. ^ Vick, Charles (June 27–28, 2007). "MAGNUM-ORION NRO/CIA/NSA, SIGINT spacecraft". Global Security. Retrieved January 17, 2021.
  5. ^ Cassutt, Michael (August 2009). "Secret Space Shuttles". Air & Space magazine. Retrieved April 18, 2015.
  6. ^ Cassutt, Michael The Manned Space Flight Engineer Programme Archived December 30, 2008, at the Wayback Machine" Spaceflight January 1989
  7. ^ a b Rogers Commission Report (1986). "Report of the Presidential Commission on the Space Shuttle Challenger Accident, Volume 1, Chapter 6". NASA. Public Domain This article incorporates text from this source, which is in the public domain.