In 1974, Skylab 4 astronauts returned after 84 days in orbit; flipped circuit breakers cut pitch-and-yaw control before Carr used backup mode for reentry

Skylab 4 launched from Kennedy Space Center on November 16, 1973, with Commander Gerald P. Carr, Pilot William R. Pogue and Science Pilot Edward G. Gibson as its crew. According to the NASA mission summary, all three crew members had gone into space for the first time ever and their scheduled duration in space on Skylab was to be for 59 days, which could be extended on a weekly basis for up to 84 days.

The mission ran a record-setting 84 days

They actually utilized the entire extension provided. NASA's fiftieth-anniversary retrospective notes that the 84 days that the crew spent in orbit made their stay in space the longest ever until four years after that date. While in orbit, the crew conducted biomedical investigations concerning the effects of long-term space flights, conducted Earth observations using the Earth Resources Experiment Package and solar observations with instruments mounted on the Apollo Telescope Mount. The mission overview also notes that due to more exercise and proper nutrition in orbit, the crew came back in better physical shape compared to the previous two shorter Skylab crews.


Before undocking, the crew fired the spacecraft's thrusters to boost Skylab into a higher orbit

With their mission drawing to an end, Carr, Pogue and Gibson packed their equipment and left the station via the Apollo spacecraft in order. Before leaving on February 8, 1974, Carr and company boosted Skylab to a higher orbit by firing the Reaction Control System thrusters of the Service Module. This was done in order to prolong the life of the unmanned space station.

Carr found neither the pitch nor the yaw controllers responding before re-entry

After separation of the Command Module from the Service Module, Carr had to use the Command Module's own Reaction Control System to realign the spacecraft with its heat shield facing ahead, the proper orientation for re-entry. According to that account, when he attempted to do so, 'nothing happened.' This is corroborated by a separate account, published in the book 'The Human Touch: The History of the Skylab Program.' According to that version, both the pitch and the yaw controls failed in response to Carr's actions.

Flipped circuit breakers had cut power to the thrusters

The cause turned out to be human error rather than equipment failure. Both accounts agree that the crew had inadvertently activated the wrong set of circuit breakers, which had the effect of cutting power to the thrusters controlling the capsule's pitch and yaw. The same official history notes that Carr was, in his own telling, only momentarily puzzled by the malfunction before identifying what had happened.

The solution given by Carr was immediate and simple. Carr switched the control of the spacecraft's orientation to the backup mode, which enabled him to orient the spacecraft in such a way that its heat shield faced forward again, thus continuing the descent procedure without problems. From that time on, everything went according to plan: two drogue parachutes were released at an altitude of 24,000 feet, followed by three main parachutes at 10,000 feet.

The command module splashed down 176 miles from San Diego on February 8, 1974

Skylab 4 landed in the Pacific Ocean at 10:17 a.m. CST on February 8, 1974, in a location approximately 176 miles off the coast of San Diego; the recovery ship USS New Orleans, positioned in the designated area several days early to guard against any contingencies, retrieved Carr, Pogue and Gibson approximately an hour after the splashdown. With this mission, the operational part of Skylab came to an end. Shortly after their return to Earth, the three astronauts returned to Johnson Space Center for debriefings, participated in a television press conference on February 22, during which they aired some film footage of their stay at the station, and received the Distinguished Service Medal from President Richard Nixon at a ceremony held in March.