Photo credit: www.nasa.gov
The Historic STS-51C: A Pioneering Space Shuttle Mission
On January 24, 1985, the space shuttle Discovery launched from NASA’s Kennedy Space Center (KSC) in Florida, marking the onset of STS-51C—the first shuttle mission specifically dedicated to the Department of Defense (DOD). Due to the classified nature of the flight, many operational details remain undisclosed. The crew included Commander Thomas “T.K.” Mattingly, Pilot Loren Shriver, Mission Specialists Ellison Onizuka and James Buchli, and Payload Specialist Gary Payton. Together, they successfully deployed a secret satellite utilizing an Inertial Upper Stage (IUS) to achieve its designated geostationary orbit. The three-day mission culminated with a smooth landing back at KSC.
The origins of STS-51C date back to October 1982 when NASA appointed Mattingly, Shriver, Onizuka, and Buchli as part of the STS-10 crew for a prior DOD mission aboard the Challenger, initially planned for September 1983. Gary Payton joined later as a payload specialist, supported by his backup, Keith Wright. However, challenges arose following the failure of the IUS during STS-6 in April 1983, leading to delays as engineers worked to rectify the issue. By September 1983, NASA remapped the crew and payload to STS-41F, originally intended for a July 1984 launch, which was subsequently modified to STS-41E. Due to ongoing IUS complications, the mission was further postponed, resulting in its rebranding as STS-51C, with a launch date pushed to December 1984 aboard Challenger.
STS-51C was a notable milestone for Mattingly, who had joined NASA’s astronaut group in 1966. Despite being set to fly on Apollo 13, he was replaced at the last moment due to illness. He subsequently flew on Apollo 16 and STS-4. For Shriver, Onizuka, and Buchli—who were selected in the 1978 astronaut class—this mission marked their inaugural journeys into space. Payton made his debut in manned spaceflight with STS-51C, having been chosen alongside Wright as part of the U.S. Air Force’s pioneering class of Manned Spaceflight Engineers.
In November 1984, NASA announced a shift of STS-51C’s launch from December 1984 to January 1985 and transferred the mission from Challenger to Discovery. Inspections after Challenger’s STS-41G mission indicated significant degradation in the thermal protection tiles, necessitating the replacement of around 4,000 tiles. This crucial repair work prevented a December launch. Conversely, preflight tests on Discovery verified that its bonding materials were intact.
Discovery was transported from the Vehicle Assembly Building to Launch Pad 39A on January 5, 1985, where engineers conducted the Terminal Countdown Demonstration Test. This test concluded with the crew’s participation in a countdown simulation on January 6-7. As the planned launch approached, NASA decided to postpone the launch briefly due to unexpectedly cold weather conditions, raising concerns about ice formation on the External Tank (ET). The DOD mandated that the launch time remain undisclosed until a mere nine minutes before liftoff, ensuring that most countdown activities remained obscured from public view.
When STS-51C finally launched at 2:50 p.m. EST on January 24, it represented the fifteenth shuttle flight. Discovery quickly ascended to orbit, achieving this status shortly after an impressive eight and a half minutes. Due to DOD stipulations, public coverage of the mission ceased soon after liftoff. Although NASA could not disclose specific orbital parameters, industry analysts inferred that Discovery initially entered into an elliptical orbit before transitioning into a circular one, leading to the deployment of the payload on the seventh orbit. To this day, neither the DOD nor NASA has released visual documentation of this crucial deployment.
Only 16 hours prior to the landing, NASA announced the touchdown time for STS-51C. Mattingly and Shriver successfully brought Discovery to land at KSC on January 27, concluding a mission that lasted three days, one hour, and thirty-three minutes—the briefest shuttle operation until that point beyond the initial test flights. During the mission, the astronauts orbited Earth 49 times. After a brief onboard stay, they exited Discovery and boarded the Astrovan, embarking on their return to crew quarters. Notably, NASA did not hold a public post-mission press conference, and the U.S. Air Force only confirmed the successful deployment of the IUS from the shuttle.
Postscript
In the aftermath of STS-51C, thorough inspections of the Solid Rocket Boosters (SRBs) were conducted. Engineers uncovered substantial erosion of critical O-ring seals initially designed to prevent the escape of hot gases from the field joints of the SRBs. This level of erosion was unprecedented within the shuttle program’s context. The cold weather during launch—characterized by temperatures in the teens and twenties, with O-rings registering only 60 degrees at launch—contributed to the seals’ increased brittleness and erosion susceptibility. These findings foreshadowed the catastrophe of Challenger’s STS-51L incident the following year, which was linked to O-ring failure under similar cold conditions. The Rogers Commission subsequently highlighted that the tragedy stemmed from a failure to adequately address the risks associated with O-ring erosion—a problem that had been previously noted during earlier flights.
Source
www.nasa.gov