STS-51-C (formerly STS-10) was the 15th flight of

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

Space Shuttle program The Space Shuttle program was the fourth human spaceflight program carried out by the U.S. National Aeronautics and Space Administration (NASA), which accomplished routine transportation for Earth-to-orbit crew and cargo from 1981 to 2011. I ...

, and the third flight of Space Shuttle ''Discovery''. It launched on January 24, 1985, and made the fourth shuttle landing at

Kennedy Space Center The John F. Kennedy Space Center (KSC, originally known as the NASA Launch Operations Center), located on Merritt Island, Florida, is one of the National Aeronautics and Space Administration's (NASA) ten field centers. Since December 196 ...

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and ...

, on January 27, 1985. STS-51-C was the first shuttle mission to deploy a dedicated

United States Department of Defense The United States Department of Defense (DoD, USDOD or DOD) is an executive branch department of the federal government charged with coordinating and supervising all agencies and functions of the government directly related to national sec ...

(DoD) payload, and consequently many mission details remain classified.

Crew

Backup crew

Crew seating arrangements

Mission summary

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''

thermal protection tiles The Space Shuttle thermal protection system (TPS) is the barrier that protected the Space Shuttle Orbiter during the searing heat of atmospheric reentry. A secondary goal was to protect from the heat and cold of space while in orbit. Materia ...

. STS-51-C marked the 100th

human spaceflight Human spaceflight (also referred to as manned spaceflight or crewed spaceflight) is spaceflight with a crew or passengers aboard a spacecraft, often with the spacecraft being operated directly by the onboard human crew. Spacecraft can also be ...

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),Blakeslee, Sandra
Astronauts return from secret
(sic) ''The New York Times'', October 8, 1985 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 The Inertial Upper Stage (IUS), originally designated the Interim Upper Stage, was a two-stage, solid-fueled space launch system developed by Boeing for the United States Air Force beginning in 1976 for raising payloads from low Earth orbit to ...

(IUS) on the mission's seventh orbit. It is believed that the payload was a Magnum

SIGINT Signals intelligence (SIGINT) is intelligence-gathering by interception of '' signals'', whether communications between people (communications intelligence—abbreviated to COMINT) or from electronic signals not directly used in communication ...

satellite into

geosynchronous orbit A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbita ...

. 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". Payton was a USAF Manned Spaceflight Engineer (MSE); the USAF declined a NASA offer to fly another MSE on the mission.Cassutt, Michae
The Manned Space Flight Engineer Programme
" ''Spaceflight'' January 1989 Also, according to ''Aviation Week'', the shuttle initially entered a orbit, at an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Ea ...

of 28.45° to the

equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can also ...

. 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 . 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 The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...

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 STS-51-L was the 25th mission of the NASA Space Shuttle program and the final flight of Space Shuttle ''Challenger''. Planned as the first Teacher in Space Project flight in addition to observing Halley's Comet for six days and performing a ...

mission including

Ellison Onizuka was an American astronaut, engineer, and USAF test pilot from Kealakekua, Hawaii, who successfully flew into space with the Space Shuttle ''Discovery'' on STS-51-C. He died in the destruction of the Space Shuttle ''Challenger'', on which he ...

, a crew member on both flights. As part of the investigation into the disaster, it was reported to the

Rogers Commission The Rogers Commission Report was written by a Presidential Commission charged with investigating the Space Shuttle ''Challenger'' disaster during its 10th mission, STS-51-L. The report, released and submitted to President Ronald Reagan on Jun ...

that during the launch of STS-51-C, the worst

Space Shuttle Solid Rocket Booster The Space Shuttle Solid Rocket Booster (SRB) was the first solid-propellant rocket to be used for primary propulsion on a vehicle used for human spaceflight. A pair of these provided 85% of the Space Shuttle's thrust at liftoff and for the first ...

(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 chamber A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process. Intern ...

s 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. 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 .

References

External links

NASA mission summary
{{Orbital launches in 1985 Space Shuttle missions 1985 in spaceflight Spacecraft launched in 1985 1985 in the United States Spacecraft which reentered in 1985 Department of Defense Space Shuttle missions Ken Mattingly