Merkur Transport Supply Spacecraft [TKS] 11F72

The TKS spacecraft (Russian: Transportnyi Korabl’ Snabzheniia, Transport Supply Spacecraft, GRAU index 11F72) was a Soviet spacecraft conceived in the late 1960s for resupply flights to the military Almaz space station. "Transport Supply Ship" (TKS) was developed by OKB-52 (now KB "Salyut" of the State Space Research and Production Center (Khrunichev State Research and Production Center) under the leadership of Vladimir Chelomey for the delivery of crew and cargo to the Orbital manned space station (OPS) for military purposes "Almaz".

There were projects of wingless reusable descent vehicles with small aerodynamic quality, used in the composition of disposable space ships and orbital stations. The greatest success in the creation of such devices OKB-52 Chelomey. After the closure of the LKS theme, OKB-52 examined a three-seat returnable vehicle (VA) in a reusable version for use in the transport supply ship (TKS) 11F72 and military orbital station "Almaz" (11F71). VA had a starting mass of 7,3 tons. length of 10.3 m. and diameter of 2.79 m. The mass of the device in orbit is more than 4.8 tons. when descending from orbit - about 3.8 tons. Inhabited volume of VA is 3.5 cubic meters. The maximum weight of the returnable useful cargo at the start of the TCS with the crew up to 50 kg. without a crew -500kg. Time autonomous flight VA in the orbit -3 hours. The maximum time of the crew's stay in the IA is 31 hours.

The device was equipped with an inseparable frontal heat shield. First flight was held on December 15, 1976. under the name "Kosmos-881" second - March 30, 1978. under with the designation "Kosmos-997". VA Chelomey became the world's first reusable space apparatus. However, the Almaz program was closed, leaving a vast reserve, which is still used today in the manufacture of modules of the Russian segment of the ISS.

The spacecraft was designed for both piloted 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.

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

1. the VA spacecraft (known in the West as the Merkur spacecraft), which would have housed the cosmonauts during launch and reentry of an TKS spacecraft, while traveling to and from an Almaz space station.
2. 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 unmanned cargo module without an 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 a FGB. As of August 2009, Excalibur Almaz planned to use the VA capsule as low-cost cargo return vehicles.

The descent device, among other things, was reusable. After landing, the heat protection on the capsule was restored. Thus, the VU could be used up to 10 times. A distinctive feature of the returned TKS was a transitional hatch in the FGB, located at the bottom of the capsule. When landing - this is the most heat-stressed place of the ship and this arrangement of the hatch has caused a lot of controversy. There was a danger of burning the hatch and killing the astronauts. However, all subsequent tests showed the reliability of the design.

The TSS launches (with the FGB) began in 1977, with a total of 4 launches.

1. July 17, 1977 - "Cosmos-929". First start of TCS. As ballast cargo was used. The ship carried out several maneuvers in orbit. On August 17, VA separated and landed. The FGB was in orbit until February 3, 1978 and carried out several independent maneuvers. The movements of the ship were closely followed by the Americans, and thought that the Russians were experiencing some kind of interorbital tug.
2. April 25, 1981 - "Cosmos-1267". The ship was in an autonomous flight until June 19, after which it was docked to the station "Salyut-6". VA separated from the ship a month earlier - on May 24. A full-fledged docking of the station and the station was not, since the docking nodes were different. The joint flight lasted until July 29, 1982. During this time, TCS corrected the OPS orbit several times. After that, the TSS, together with the Salyut, were removed from orbit.
3. March 3, 1983 - "Cosmos-1443". The ship was successfully and fully docked to the Salyut-7 station, thanks to a new spacer for docking units. The joint flight lasted until August 14, 1983. After that, VA returned to the Earth with the results of experiments, and the FGB worked in orbit for another 26 days.
4. September 27, 1985 - "Cosmos-1686" . Was docked to the OPS Salyut-7. The ship several times raised the station's orbit. In the IA, the "Pion-K" complex was installed to monitor the objects of a potential enemy. The ship descended into orbits on February 7, 1991.

In 1982, the state commission decided to abandon the use of TCS as a manned spacecraft. And this despite the fact that a lot of cosmonauts were prepared for flights. The fourth TCS was already preparing for the manned flight. Urgently, it was converted into an automatic (modification of TCS-M). And after that, the rest of the plans for the release of TCS were suspended. The main reason for abandoning the ship is the toxic fuel of the Proton rocket and the TSS itself. However, there is an opinion that they abandoned the ship for domestic political reasons.

The already manufactured FGB were used as the basis for several spacecraft. The FGB was used in the construction of the Kvant module of the Mir station, and the SKIF-DM (Polyus) apparatus launched by the Energia missile. The module "Dawn" of the International Space Station was also made on the basis of the FGB, and its stand-in module "Science" (FGB-2) has yet to be launched. The returned device was less fortunate - it never found its use. Based on the VA, it was proposed to make rescue ships for the American station Freedom, and then the ISS. But the idea did not develop. From the Russian side there was no money, and the Americans did not want to sponsor other people's developments. In 1993, two VAs were sold at auction and ended up in the American Museum.

In 2005, the Khrunichev Center participated in the Roskosmos competition for a manned spacecraft of a new generation with a project based on the VA TKS. But the competition won RSC Energia with the ship, which now is called the Federation. The launch of the PTC from the Khrunichev Center was proposed at the Angara carrier rocket.

TKS is a ship with a complex history. It was created as an alternative to the "Union" and surpassed them in many ways. The carrier for it was the Proton rocket - the most powerful workhorse of domestic cosmonautics, not counting the superheavy H-1 and Energia. But after several starts, the project was completely closed. Subsequently, TKS received a second birth, serving as the basis for the modules of Mir orbital stations and the ISS.