The TKS spacecraft (, , Transport Supply Spacecraft, GRAU index 11F72) was a Soviet spacecraft conceived in the late 1960s for resupply flights to the military Almaz space station. The spacecraft was designed for both crewed or autonomous uncrewed cargo resupply flights, but was never used operationally in its intended role – only four test missions were flown to Salyut space stations during the program. However the Functional Cargo Block (FGB) of the TKS spacecraft would later form the basis of several space station modules, including the Zarya FGB module on the International Space Station.