The TKS spacecraft (Russian: Транспортный корабль снабжения, Transportnyi Korabl’ Snabzheniia, lit. Transport Supply Spacecraft; GRAU index 11F72) was a Soviet spacecraft system developed in the late 1960s to deliver crew, cargo, and fuel to the military Almaz space stations. It consisted of two linked but independently operable parts: the VA spacecraft, a compact capsule for crew launch and re-entry, and the Functional Cargo Block (FGB), which provided cargo space, docking hardware, and the main orbital maneuvering engines. When the VA returned to earth, the FGB could be left behind at the station.

Although designed for both crewed and uncrewed flights, the TKS was never used operationally. Only four test missions were launched, three of which docked with civilian Salyut stations. The spacecraft’s lasting contribution was its FGB design, which became the basis for station modules used on Mir and the International Space Station.

The TKS was designed under Vladimir Chelomey (VA capsule) and V. N. Bugayskiy (FGB block) as a crewed alternative to the Soyuz spacecraft for servicing Almaz stations, launched on the Proton rocket. Development began in 1965, but by the time the first TKS flew in 1977 the Almaz programme was already winding down.

Four test flights of the VA capsule were conducted without the FGB to validate the design, each launching two capsules stacked together. On one flight the launch vehicle exploded, destroying the lower capsule, while the upper capsule successfully used its launch escape system. Four flights of the complete TKS (VA with FGB) were also launched: one as a systems test, and three that docked with Salyut stations to deliver cargo.

The FGB could also be launched independently as an autonomous uncrewed cargo module, a role that led to its adaptation as the basis for later space station modules. The VA was likewise considered for the "Almaz APOS" concept, in which a crew would have launched docked to an Almaz core inside a VA capsule.

The VA was a compact reentry capsule derived from Chelomei's earlier LK-1 circumlunar spacecraft and LK-700 lunar lander capsule designs. It resembled the Apollo Command Module but was about 30% smaller. The pressurized capsule carried its own life-support system, reaction control thrusters, deorbit engine, parachutes, and soft-landing rockets. It could operate autonomously for up to 31 hours and typically reentered within two orbits. In addition to a three-person crew, the VA could return up to 50 kilograms (110 lb) of cargo, mainly KSI film-return capsules. Unusually, its docking hatch was located on the aft side, requiring crews to enter and exit through an opening in the heat shield. Although extensively flight-tested, no VA ever carried a crew.

The FGB provided cargo space, docking hardware, and the main orbital maneuvering engines. Crews accessed it through a short tunnel from the VA. At its aft end was a pilot station with controls and windows for manual docking with an Almaz station. Planned operational TKS flights would also have delivered KSI film-return capsules, stowed near the docking port and transferred to the VA spacecraft for return to Earth.

Four flights with eight VA spacecraft without an FGB module were conducted to speed up the development of the TKS spacecraft: