What it was: A Soviet transport and resupply spacecraft for use with the Almaz space station.

Details: On February 7, 1991, Salyut 7 orbited the Earth for the final time, re-entering over southern Argentina and scattering its pieces over a wide area. Sixteen hours before this the Federation of American Scientists used Doppler radar to image it as it flew overhead, producing this remarkable picture. The murky image clearly showed the thing that made Salyut 7 most notable: on the top of the station proper was what was then known as Kosmos 1686. The Soviet station had been the first truly modular space station, and the Kosmos 1686 module had been docked to Salyut 7’s core module for more than five years. It was the harbinger of a new thing in orbit, space-based construction, that would be followed up in both Mir and the ISS. But as well as being the start of something it represented the end of one too: a crewed spacecraft that shares with the shuttle Buran the peculiar distinction of having flown, but never with anyone aboard.

The Kosmos label was used as a smoke screen for a variety of Soviet programs, and Kosmos 1686, along with numbers 929, 1267, and 1443 were used to hide perennial bridesmaid Vladimir Chelomei‘s answer to the Soyuz: the Transport Supply Spacecraft, or TKS, to use its Russian acronym (“Transportnyi Korabl’ Snabzheniia”).

The story of the TKS begins with the fallout of the battle between Chelomei’s OKB-52 and Sergei Korolev‘s OKB-1 over the Soviet Moon program in 1964-65. Korolev won the war but died before he could make his victory complete. Chelomei’s contribution was greatly reduced but still consisted of the rocket for the the circumlunar Zond mission, the capsule for which was to be based on OKB-1’s tech. Chelomei reloaded for space stations and took the capsule he was developing for the LK-1 (his alternative circumlunar craft) and the LK-700 into the new project. The station was soon dubbed Almaz, and the LK-derived TKS was worked up to serve as a crew and supply ferry, much as the Soyuz and Progress do for the ISS.

The first thing to note is that the TKS would run both missions simultaneously, as opposed to the aforementioned ISS ships, which do one or the other. Despite countless upgrades over the years the Soyuz spacecraft is still rather cramped and there’s only enough room for astronauts or supplies, not both. As a result the Russians have been trying to replace the Soyuz for almost as long as they’ve been flying it, which accounts for the Zarya, the Kliper, the Energia/Buran shuttle, and the one they’re working on now, Federation, just to name a non-exhaustive few. The TKS was bigger—a lot bigger—and was Chelomei’s flying rebuke to OKB-1’s compact ship.

The TKS consisted of two modules. The first was the orphaned VA crew capsule (Vozvraschaemyi Apparat, “Return Vehicle”), which was attached to the new FGB support module (Funktsionalno-Gruzovoy Blok, “Functional Cargo Block”) which also served as a crew habitation module.

The VA was made of two components itself (three, if one includes the abort tower that was jettisoned after launch). The main portion was a truncated-cone capsule with a habitable volume of 4.56 cubic meters and a base of 2.79 meters. While originally designed for one person to make a loop around the Moon, as a LEO craft it was to hold three. Many commentators have mentioned the similarity in appearance of the VA’s capsule and the Apollo capsule, but the TKS’ was considerably smaller than the one used by NASA, which came in at 6.17 cubic meters and 3.91 meters. Where the VA diverged from Apollo even more sharply was in its nose module, the NO (Nosovoj Otsek, “Nose Compartment”), which took some of the support functionality out of the FGB support module and perched it at the front of the craft. Most notably this included the de-orbiting engines, but the communications equipment and the parachutes were loaded in it as well. Altogether this part of the ship weighed 3800 kilograms and was 7.3 meters long.

The rather beaky-looking VA was attached at its base to the FGB, which was a cylindrical module another 5.9 meters in length and 4.15 meters in diameter. While the VA was capable of being used as a complete craft it had endurance for only 31 hours and could carry only 50 kilograms of cargo. This was where the FGB picked up the slack. Sporting two solar panels with a span of 17 meters and a habitable volume of 41.08 cubic meters, it extended the TKS’ mission duration to a week, or 200 days if docked to an Almaz. Discounting the abort tower, together they made a 17,510 kilogram spacecraft which meant that it cleared the payload limit of a Proton-K (AKA the UR-500 designed by Chelomei’s bureau) by a couple of tonnes. With the joint capabilities of its modules, the TKS was specifically designed to be a “space truck”, ferrying passengers and cargo to a space station: the FGB’s maneuvering engines (which burned N2O4 and UDMH, like the Proton) would let it rendezvous with one in a higher orbit, and the docking adapter at its aft end would let it connect up. As the adapter took up the usual position of a rocket motor, the engines—four of them—were moved to the sides of the FGB, as were the engines’ fuel tanks.

The most revolutionary aspect of the TKS was what happened when it was time to go home. If so desired the entire TKS could disconnect and return its cosmonauts to Earth (in particular to a landing in the Kazakh SSR, softened by last-moment solid fuel rockets), with the FGB burning up. However, the other possibility was to use the VA’s autonomous capability to do the same while the FGB, which could be customized to one of many roles, stayed behind to be the latest module of the station.

What happened to make it fail: Chelomei’s efforts were an entirely parallel space program to the one being run by Glushko’s Energia, a military one comparable to the X-20/Manned Orbiting Laboratory on the American side. It ran into the same difficulty as the American one too: there turns out to not be a lot of military use for crewed spacecraft and stations. As Buran was also being built on the insistence of the Soviet military and it was tremendously expensive, the TKS and the Almaz stations were constantly in danger of being cut entirely or folded into the Buran/Mir ecosystem.

The TKS had a champion, Minister of Defense Andrei Grechko, who died in 1976. From then on Chelomei was unable to resist the pressure coming from Valentin Glushko and his champion Dmitri Ustinov, candidate member of the Politburo and then full member and Grechko’s successor as Minister following Grechko’s death.Ustinov is known to have had a personal grudge against Chelomei dating back to Chelomei’s temporary time in the sun under Nikita Khrushchev: he perceived Chelemei as an interloper from the Aviation Ministry whereas he represented the Artillery, under which ballistic missiles had been assigned for decades. Well before he reached the height of his power, in 1970, Ustinov as the Deputy Minister responsible for space travel had already ordered that Almaz be melded with the Salyut station project underway at TsKBEM (as NPO Energia was called at the time). From 1976 onwards he continued picking away at it, eventually leading to the TKS program being subsumed by Mir.

Before then, though, Chelomei’s bureau managed to get off six uncrewed flights and recoveries of the VA capsule beginning in 1976 and four uncrewed flights of an integrated TKS (VA with NO, and FGB) beginning in 1977. The spacecraft was tested and ready to go. But Ustinov had his way and there was never a full-up flight of a TKS with a crew aboard—three of the four TKS flights were in support of NPO Energia’s Salyut 6 and 7, while Kosmos 1686 in particular was modified so that it could not undock from Salyut-7, and its VA was gutted and filled with instruments. While two cosmonauts used the final TKS for some experiments during the Soyuz T-15 mission in 1986 it was merely a part of the space station at the time.

What was necessary for it to succeed: A lot of the projects we’ve discussed on False Steps are well down at the far end of the plausibility spectrum; “on paper only” is one of the most commonly used meta-tags around here. TKS is the antithesis of that. It was done, had been flown remotely, and needed only a final push to turn it into an operational system. As a result there’s several possible ways one can imagine that gets flying cosmonauts.

When OKB-1 was shaken up and Vasily Mishin relieved of his leadership, have Chelomei be the new leader instead of Glushko. This is not very likely because of Ustinov, but is the most direct route.

Have Marshal Grechko live and stay on as the Minister of Defense for a few years more than he did.

Have Minister Ustinov hold less of a grudge against Chelomei despite events in the Khrushchev era.

Have Energia/Buran be just slightly less of a money sink than it actually was.

Or give Energia some teething pains rather than two successful launches out of two tries, so that the Soviet leadership outside of Ustinov started looking more closely at the alternatives.

Any one of these would have been enough, and once flying it’s easy to see the TKS becoming the Soyuz replacement that Russia has been looking for since before the fall of the Berlin Wall.

As it was, the intriguing ability of the FGB to dual-purpose between being a spacecraft component or a space station component led to it alone becoming one of the cornerstones of space station construction from 1986 to the present day. No less than five of Mir‘s modules were based on the FGB, and on the ISS one current (Zarya) and one future (Nauka) module have the same base. The jerry-built Polyus payload for Energia’s first launch was also based on an FGB.

Sources

Khrushchev, Sergei N. Nikita Khrushchev and the Creation of a Superpower. Penn State University Press. University Park, PA, 2010.

Portree, David S.F. Mir Hardware Heritage. Houston, Texas. Johnson Space Center, 1995.

“The TKS ferry for the Almaz Space Station“, Sven Grahn.

“TKS“, Anatoly Zak.