TKS (spacecraft)

TKS spacecraft

Applications	Crewed spacecraft to supply the military Almaz space station
Specifications
Crew capacity	3
Volume	45.00 m3 (1,589 cu ft)
Regime	low Earth orbit
Design life	7 days
Dimensions
Length	13.2 m (43 ft)
Diameter	4.15 m (13.6 ft)
Maximum thrust	7,840 N (1,760 lbf)
Propellant	N2O4/UDMH
Configuration
Cutaway of TKS vehicle. Details are conjectural. The broad black line outlines the vehicle's pressurized compartments. A tunnel (stippled) connects the FGB and VA spacecraft

The TKS spacecraft (Russian: Транспортный корабль снабжения, Transportnyi Korabl’ Snabzheniia, Transport Supply Spacecraft,^[1] 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 and autonomous uncrewed cargo resupply flights, but was never used operationally in its intended role – only four test missions were flown (including three that docked to Salyut space stations) during the program. The Functional Cargo Block (FGB) of the TKS spacecraft later formed the basis of several space station modules, including the Zarya FGB module on the International Space Station.

The TKS spacecraft consisted of two spacecraft mated together, both of which could operate independently:

• The VA spacecraft (known mistakenly in the West as the Merkur spacecraft), which would have housed the cosmonauts during launch and reentry of a TKS spacecraft, while traveling to and from an Almaz space station.
• And the Functional Cargo Block (FGB) which, in order to resupply an Almaz space station, carried docking hardware, tanks, and a large pressurized cargo compartment. Furthermore, the FGB carried the on-orbit maneuvering engines for the TKS.

While the VA carried the reentry hardware, and only minimal life support and maneuvering systems, the FGB would have been used as the primary orbital maneuvering system and cargo storage for the TKS spacecraft.

The FGB could also be used alone as an uncrewed cargo module without a VA spacecraft, which enabled the FGB design to be re-purposed as FGB space station modules later on. The VA spacecraft, on the other hand, was also intended to be launched as "Almaz APOS", mated with an Almaz-OPS space station core as the primary orbital maneuvering system, instead of an FGB.

In the 2010s, Excalibur Almaz planned to use old VA capsules as low-cost cargo return vehicles.^[2] However, the company ultimately sold much of their equipment and announced that the remainder was to become an educational exhibit.^[3]