The 1975 Apollo–Soyuz Test Project version of the Soyuz spacecraft (Soyuz 7K-TM) served as a technological bridge to the third generation Soyuz-T (T - транспортный, Transportnyi meaning transport) spacecraft (1976–1986).

Soyuz 7K-TM

Soyuz 19, a Soyuz 7K-TM spacecraft, during the Apollo–Soyuz Test Project (ASTP).
Manufacturer	OKB-1
Country of origin	Soviet Union
Operator	Soviet space program
Applications	Crewed spacecraft
Specifications
Dimensions	Height 7.48 m (24.5 ft) Diameter 2.72 m (8 ft 11 in) Volume 9 m3 (320 cu ft)
Regime	Low Earth
Production
Status	Retired
Launched	5
Retired	5
Maiden launch	Kosmos 638 3 April 1974
Last launch	Soyuz 22 15 September 1976
Last retirement	Soyuz 22 23 September 1976
Related spacecraft
Derived from	Soyuz 7K-T
Derivatives	Soyuz 7K-S Soyuz 7K-ST

The Soyuz ASTP spacecraft was designed for use during the Apollo Soyuz Test Project as Soyuz 19. It featured design changes to increase compatibility with the American craft. The Soyuz ASTP featured new solar panels for increased mission length, an APAS-75 docking mechanism instead of the standard male mechanism, and modifications to the environmental control system to lower the cabin pressure to 0.68 atmospheres (69 kPa) prior to docking with Apollo. The ASTP Soyuz backup craft flew as the Soyuz 22 mission, replacing the docking port with a camera.