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

NASA The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States ...

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. Its ...

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

Shuttle Landing Facility The Shuttle Landing Facility (SLF), also known as Launch and Landing Facility (LLF) , is an airport located on Merritt Island, Florida, Merritt Island in Brevard County, Florida, Brevard County, Florida, United States. It is a part of the Kennedy ...

at the

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 NASA, National Aeronautics and Space Administration's (NASA) ten NASA facilities#List of field c ...

Florida Florida ( ; ) is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. It borders the Gulf of Mexico to the west, Alabama to the northwest, Georgia (U.S. state), Georgia to the north, the Atlantic ...

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

United States Department of Defense The United States Department of Defense (DoD, USDOD, or DOD) is an United States federal executive departments, executive department of the federal government of the United States, U.S. federal government charged with coordinating and superv ...

(DoD), and consequently many details remain classified. NASA reported that a satellite ( USA-8) was deployed during the mission using an

Inertial Upper Stage The Inertial Upper Stage (IUS), originally designated the Interim Upper Stage, was a Multistage rocket, two-stage, Solid-propellant rocket, solid-fueled space launch system developed by Boeing for the United States Air Force beginning in 1976 for ...

booster was deployed and met mission objectives. At just over three days, the mission was shorter in duration than most civilian missions and was the shortest of ''Discovery''s career.

Crew

Backup crew

Crew seat assignments

Mission summary

STS-51-C launched from Kennedy Space Center (KSC) on January 24, 1985, at 19:50:00

UTC Coordinated Universal Time (UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communica ...

, 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 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 The United States Department of Defense (DoD, USDOD, or DOD) is an executive department of the U.S. federal government charged with coordinating and supervising the six U.S. armed services: the Army, Navy, Marines, Air Force, Space Force, t ...

(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

U.S. Air Force The United States Air Force (USAF) is the air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its origins to 1 ...

only stated that the shuttle successfully launched its payload with an

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

SIGINT Signals intelligence (SIGINT) is the act and field of intelligence-gathering by interception of ''signals'', whether communications between people (communications intelligence—abbreviated to COMINT) or from electronic signals not directly u ...

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 orbital ...

. Other DoD flights STS-33 and

STS-38 STS-38 was a Space Shuttle mission by NASA using the Space Shuttle ''Atlantis''. It was the 37th shuttle mission and carried a classified payload for the U.S. Department of Defense (DoD). It was the seventh flight for ''Atlantis'' and the seve ...

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. 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 Eart ...

of 28.45° to the

equator The equator is the circle of latitude that divides Earth into the Northern Hemisphere, Northern and Southern Hemisphere, Southern Hemispheres of Earth, hemispheres. It is an imaginary line located at 0 degrees latitude, about in circumferen ...

. It then executed three

Orbital Maneuvering System In spaceflight, an orbital maneuver (otherwise known as a burn) is the use of propulsion systems to change the orbit of a spacecraft. For spacecraft far from Earth, an orbital maneuver is called a ''deep-space maneuver (DSM)''. When a spacec ...

(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 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 disastrous 25th mission of NASA's Space Shuttle program and the final flight of Space Shuttle ''Challenger''. It was planned as the first Teacher in Space Project flight in addition to observing Halley's Comet for six day ...

mission including

Ellison Onizuka was an American astronaut, engineer, and U.S. Air Force flight test engineer 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 ''Cha ...

, 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 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 them 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-ring An O-ring, also known as a packing or a toric joint, is a mechanical gasket in the shape of a torus; it is a loop of elastomer with a round cross section (geometry), cross-section, designed to be seated in a groove and compressed during assembl ...

s were not sufficiently sealing the hot gases inside the

combustion chamber A combustion chamber is part of an internal combustion engine in which the air–fuel ratio, fuel/air mix is burned. For steam engines, the term has also been used for an extension of the Firebox (steam engine), firebox which is used to allow a mo ...

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 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 .

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