STS-51-D

STS-51-D
Name	STS-51-D
Operator	National Aeronautics and Space Administration
Spacecraft	Space Shuttle Challenger
Launch date	February 1985
Landing date	February 1985
Launch site	Kennedy Space Center

STS-51-D was the tenth mission of the Space Shuttle program flown by Space Shuttle Challenger in late February 1985. The flight carried a multinational crew and a mixed manifest of communications satellites, scientific payloads, and technology demonstrations, operating from Kennedy Space Center to landing at Edwards Air Force Base. The mission is notable for on-orbit deployment anomalies, a rare in-orbit crew intervention, and ensuing investigations by National Aeronautics and Space Administration panels and United States Congress oversight.

Mission overview

The mission lifted off during the Ronald Reagan presidency with objectives to deploy commercial communications satellites for Satellite Business Systems and Telesat, to operate the OAST experiments and the Getaway Special canisters, and to perform biomedical and materials science investigations associated with Marshall Space Flight Center and Johnson Space Center. It was part of the broader post-Space Transportation System manifest that included STS-51-B and preceded missions such as STS-61-A and STS-26. Flight control involved Mission Control in Houston, Texas and coordination with contractors including Rockwell International and Hughes Aircraft Company.

Crew

The six-person complement included veteran and first-time flyers drawn from United States Air Force, National Aeronautics and Space Administration corps, and international partners. The crew comprised a commander experienced in orbiter operations, a pilot with prior flight test background, and four mission specialists tasked with extravehicular operations, payload handling, and scientific monitoring for organizations like Ames Research Center and Goddard Space Flight Center. Crew training involved facilities at Johnson Space Center, flight simulators developed by Rockwell International, and payload integration at Kennedy Space Center's Vehicle Assembly Building.

Payload and experiments

Primary payloads included two commercial satellites: a SBS model supplied by Satellite Business Systems and a Telesat communications satellite, both intended for geostationary insertion using upper stages. Secondary payloads encompassed experiments from Get Away Special canisters sponsored by universities and companies, materials processing modules from Marshall Space Flight Center, biomedical studies coordinated by National Institute of Health collaborators, and technology demonstrators involving partners such as Hughes Aircraft Company and Goddard Space Flight Center. The mission also carried astronomy and atmospheric sensors affiliated with Ames Research Center and international payload contributions managed through European Space Agency contacts.

Flight timeline

After liftoff from Kennedy Space Center the orbiter achieved low Earth orbit and conducted separation burns for the attached upper stages, with deployment windows coordinated via Mission Control and range safety assets from Patrick Air Force Base. Planned satellite deployments were scheduled over successive orbits, interleaved with operation of the Getaway Special canisters and onboard experiments run in coordination with Johnson Space Center science teams. The mission profile included rendezvous readiness and contingency consumables margins calculated by flight dynamics teams at Johnson Space Center and Goddard Space Flight Center.

Anomalies and contingency operations

During deployment, one of the primary satellite missions failed to achieve commanded separation and telemetry, triggering onboard troubleshooting by the crew and uplinked commands from Mission Control. The crew executed contingency procedures, worked with engineers from Hughes Aircraft Company and Rockwell International to cycle deployment mechanisms, and prepared for a possible unplanned recontact operation. The situation required coordination with the Federal Communications Commission for frequency management and with United States Air Force tracking assets to assess orbital parameters. The anomaly prompted use of onboard tools and improvised solutions under guidance from specialists at Johnson Space Center and resulted in successful partial recovery actions while leaving some aspects unresolved until postflight review.

Mission aftermath and investigations

Following landing at Edwards Air Force Base, recovery teams from Kennedy Space Center and Dryden Flight Research Center supported postflight inspections. Investigations led by National Aeronautics and Space Administration engineering panels, with participation from contractors Rockwell International and Hughes Aircraft Company, analyzed telemetry, deployment hardware, and command sequences. Findings influenced revisions to satellite separation procedures, upper stage interface designs overseen by Marshall Space Flight Center, and updates to crew contingency training at Johnson Space Center. Congressional hearings by committees in the United States Congress and internal NASA programmatic reviews addressed operational risk, procurement practices, and contractor responsibilities, shaping follow-on policies for Space Shuttle program missions and commercial satellite deployments.

Category:Space Shuttle missions Category:1985 in spaceflight