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).

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.

There are only five spaceflights of the Soyuz 7K-TM spacecraft, mostly in support for the joint US-Soviet Apollo–Soyuz mission.