NASA Marks 40th Anniversary of First Defense Shuttle Mission

NewsNASA Marks 40th Anniversary of First Defense Shuttle Mission

The Secretive Space Mission: A Closer Look at STS-51C

On January 24, 1985, the space shuttle Discovery launched from NASA’s Kennedy Space Center in Florida, embarking on a mission known as STS-51C. This mission was particularly notable as it was the first space shuttle flight dedicated entirely to the United States Department of Defense (DOD), which meant that many details of the mission were classified and kept from public knowledge. The crew of Discovery included Commander Thomas "T.K." Mattingly, Pilot Loren Shriver, Mission Specialists Ellison Onizuka and James Buchli, and Payload Specialist Gary Payton. During this mission, they deployed a classified satellite that utilized an Inertial Upper Stage (IUS) to achieve its geostationary orbit. The mission lasted three days and concluded successfully with a landing back at the Kennedy Space Center. However, a post-flight inspection revealed significant erosion of the O-ring seals in the Solid Rocket Boosters (SRBs), attributed to unusually cold weather conditions during the launch.

The Journey to STS-51C

The journey to this historic mission began in October 1982 when NASA assigned astronauts Mattingly, Shriver, Onizuka, and Buchli as the crew for a dedicated DOD flight initially scheduled aboard the space shuttle Challenger. This mission, originally designated as STS-10, was planned for September 1983. In the summer of 1983, Gary Payton joined the crew as a payload specialist, with Keith Wright as his backup. However, the mission faced delays due to the failure of the IUS on the STS-6 mission in April 1983. This issue needed to be resolved before the STS-10 mission could proceed.

NASA re-scheduled the mission several times, remanifesting the crew and payload to STS-41F with a tentative launch in July 1984, and later changing it to STS-41E by November 1983. Additional setbacks in addressing the IUS problems led to further delays, and by June 1984, the mission was redesignated as STS-51C and slated for a December 1984 launch aboard Challenger.

The Crew and Their Experience

STS-51C marked the third spaceflight for Commander Thomas Mattingly, who was selected as part of NASA’s fifth group of astronauts in 1966. Mattingly had a notable career, having been part of the prime crew for the Apollo 13 mission before being replaced due to exposure to German measles. He later flew on Apollo 16 and STS-4. For Shriver, Onizuka, and Buchli, all selected as astronauts in the class of 1978, STS-51C was their inaugural journey into space. Meanwhile, Payton and Wright were selected by the U.S. Air Force in August 1979 as part of its first class of Manned Spaceflight Engineers, with STS-51C being Payton’s first and only space mission.

Last-Minute Changes and Preparations

In November 1984, NASA made a key decision to delay the STS-51C mission from December 1984 to January 1985 and to switch orbiters from Challenger to Discovery. This decision came after post-flight inspections of Challenger following its STS-41G mission revealed degradation in the bonding materials that held the thermal protection system tiles in place. This required the replacement of approximately 4,000 tiles, making a December launch unfeasible. In contrast, tests conducted on Discovery before its November STS-51A mission showed that its bonding materials were in good condition.

Discovery was rolled out from the Vehicle Assembly Building at Kennedy Space Center on January 5, 1985, where it was mated with its External Tank (ET) and SRBs before being moved to Launch Pad 39A. Engineers conducted the Terminal Countdown Demonstration Test, a dress rehearsal for the actual countdown, on January 6-7, with the crew participating in the final hours as they would on launch day. The astronauts returned to Kennedy Space Center on January 20 to prepare for the anticipated launch on January 23. However, due to concerns about sub-freezing temperatures potentially causing ice to form on the ET and damaging the vehicle during ascent, NASA managers decided to postpone the launch by one day.

The Launch and Classified Mission

The launch of Discovery on its third mission, STS-51C, took place at 2:50 p.m. Eastern Standard Time on January 24, 1985, marking the 15th space shuttle flight. Within eight and a half minutes, Discovery and its five-man crew were in orbit. At the request of the DOD, public coverage of the mission was halted after this point. While NASA could not disclose the spacecraft’s orbital parameters, industry publications deduced that Discovery initially entered an elliptical orbit, which was circularized over subsequent revolutions. During the seventh orbit, Onizuka deployed the IUS and payload combination. Both NASA and the DOD have withheld imagery of the deployment and the payload bay, releasing only a limited number of in-cabin and Earth observation photographs.

To maintain the mission’s confidentiality, NASA was only permitted to announce the touchdown time 16 hours before the event. On January 27, Commander Mattingly and Pilot Shriver successfully landed Discovery at Kennedy Space Center’s Shuttle Landing Facility after a flight that lasted three days, one hour, and 33 minutes. This mission was the shortest space shuttle flight aside from the first two orbital test flights. During the mission, the astronauts orbited Earth 49 times. About an hour after landing, the crew exited Discovery and returned to crew quarters. Neither NASA management nor the astronauts held a post-mission press conference. The U.S. Air Force only announced that the "IUS aboard STS-51C was deployed from the shuttle Discovery and successfully met its mission objectives." Later that day, ground crews transported Discovery to the Orbiter Processing Facility to begin preparations for its next mission, STS-51D, scheduled for March.

Post-Mission Reflections and Lessons Learned

After each shuttle mission, engineers conducted thorough inspections of the SRBs before approving them for reuse. Following STS-51C, inspections of the critical O-ring seals, which prevented hot gases from escaping the SRB field joints, revealed significant erosion and "blow-by" between the primary and secondary O-rings. Both the left and right SRBs exhibited this erosion, which was the most severe seen in the program at that time. The O-rings were exposed to colder weather than any previous shuttle mission, with temperatures dropping into the teens and twenties overnight. Even at launch, the O-rings only reached 60 degrees Fahrenheit. Engineers believed these cold temperatures made the O-rings brittle and more susceptible to erosion.

One year later, a similar scenario unfolded when the space shuttle Challenger launched after a night of cold temperatures, with O-rings at 57 degrees Fahrenheit at launch. The Rogers Commission report later attributed the STS-51L accident to the failure of O-rings, which allowed super-hot gases to escape from the SRB and impact the hydrogen tank in the ET, resulting in an explosion that destroyed the orbiter and claimed the lives of seven astronauts. The commission also criticized NASA’s safety culture for not adequately addressing the issue of O-ring erosion, a problem first observed on STS-2 and to varying degrees on several subsequent missions.

The story of STS-51C serves as a reminder of the challenges and complexities involved in space exploration, particularly when national security interests are intertwined. It highlights the need for continuous vigilance in safety protocols and the importance of learning from past experiences to prevent future tragedies. This mission, though shrouded in secrecy, played a significant role in the ongoing evolution of NASA’s shuttle program and its approach to balancing security with safety and transparency.

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Neil S
Neil S
Neil is a highly qualified Technical Writer with an M.Sc(IT) degree and an impressive range of IT and Support certifications including MCSE, CCNA, ACA(Adobe Certified Associates), and PG Dip (IT). With over 10 years of hands-on experience as an IT support engineer across Windows, Mac, iOS, and Linux Server platforms, Neil possesses the expertise to create comprehensive and user-friendly documentation that simplifies complex technical concepts for a wide audience.
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