Colonel Overmyer was the pilot for STS-5, the first fully operational flight of the Shuttle Transportation System, which launched from Kennedy Space Center, Florida, on November 11, 1982. He was accompanied by spacecraft commander, Vance D. Brand, and two mission specialists, Dr. Joseph P. Allen and Dr. William B. Lenoir. STS-5, the first mission with a four-man crew, clearly demonstrated the Space Shuttle as fully operational by the successful first deployment of two commercial communications satellites from the Orbiterís payload bay. The mission marked the first use of the Payload Assist Module (PAM-D), and its new ejection system. Numerous flight tests were performed throughout the mission to document Shuttle performance during launch, boost, orbit, atmospheric entry and landing phases. STS-5 was the last flight to carry the Development Flight Instrumentation (DFI) package to support flight testing. A Getaway Special, three Student Involvement Projects and medical experiments were included on the mission. The STS-5 crew successfully concluded the 5-day orbital flight of Columbia with the first entry and landing through a cloud deck to a hard-surface runway and demonstrated maximum braking. Mission duration was 122 hours before landing on a concrete runway at Edwards Air Force Base, California, on November 16, 1982.
Colonel Overmyer was the commander of STS 51-B, the Spacelab-3 (SL-3) mission. He commanded a crew of 4 astronauts and 2 payload specialists conducting a broad range of scientific experiments from space physics to the suitability of animal holding facilities. Mission 51-B was also the first Shuttle flight to launch a small payload from the -Getaway Special" canisters. Mission 51-B launched at 12:02 p.m. EDT on April 29, 1985 from Kennedy Space Center, Florida, and landed at Edwards Air Force Base, California, at 9:07 a.m. PDT on May 6, 1985. Mission 51-B completed 110 orbits of the earth at an altitude of 190 n.m.
Colonel Overmyer retired from NASA and the Marine Corps in May 1986.
Colonel Overmyer died on March 22, 1996, in the crash of a light aircraft he was testing.
Manned four crew. First mission to deploy commercial communications satellites (SBS 3, Anik C3). Payloads: : Satellite Business Systems (SBS)-C with Payload Assist ; (PAM)-D; Telesat-E (Canadian communications satellite) with PAM-D. Monodisperse Latex Reactor (MLR), Continuous Flow Electrophoresis System (CFES), three getaway specials (GAS), Student experiments, GLOW experiment, Vestibular experiment, Oxygen Interaction With Materials experiment.
Manned seven crew. Deployed Nusat; carried Spacelab 3. Payloads: Spacelab-3 experiments, habitable Spacelab and mission peculiar experiment support structure. The experiments represented a total of five different disciplines: materials processing in space, environmental observa-tions, life science, astrophysics, and technology experiments. Two getaway specials (GAS). The flight crew was split into gold and silver shifts working 12-hour days during the flight.