Soviet cosmonaut Alexei Leonov and American astronaut Deke Slayton launched on the 15th of July 1975. The spacecraft docked successfully on the 17th of July 1975 after a brief orbital rendezvous period.
American astronauts Tom Stafford, Vance Brand, and Deke Slayton flew alongside Soviet cosmonauts Alexei Leonov and Valery Kubasov. Deke Slayton made his only space flight despite being grounded since 1959 due to an irregular heartbeat while Alexei Leonov was humanity's first spacewalker from March 1965.
Toxic monomethylhydrazine fumes entered the Apollo cabin via unignited reaction control system propellants venting into air intakes. High noise levels prevented Commander Vance Brand from hearing instructions regarding switch closures needed for drogue parachute deployment which allowed ingestion of hypergolic propellant gases through ventilation systems.
The ships remained connected for one day twenty-three hours seven minutes and three seconds total. After separation they maneuvered to create artificial solar eclipses enabling Soyuz instruments to photograph the solar corona before returning home independently.
Bill Creasy designed the Androgynous Peripheral Attach System adapter to allow either ship to dock with the other regardless of which was active or passive. This docking module became essential because surplus Apollo hardware lacked the standard APAS collar so the Saturn IB rocket carried this special module into orbit after launch.