Artist representation of Tianzhou vessel (Credits: CNSA)

Tianzhou-6: how to shorten a space station and make it into a transport vehicle

On May 10, 2023, a Long March-7 lifted the Tianzhou-6 vessel into orbit from the Wenchang Space Center, carriyng fuel and supplies to the Tiangong space station

On May 10, 2023, a Long March-7 launcher lifted the Tianzhou-6 unmanned transport vessel into orbit from the Wenchang Space Center. The launch, which took place at 15:30 CEST (13:30 UTC), carried fuel and supplies to the Tiangong space station. Tianzhou-6 will take the place of its sister ship Tianzhou-5, in the aft hatch of the Tianhe module.

The noble art of recycling

We are well aware that the Soviet Union, first, and then Russia, have always virtuously reused its projects, sometimes allocating them to other uses. The Chinese space program, which owes much of its development to the long and fruitful collaboration with its northern neighbors, has treasured this concept by obtaining from its first space station, the Tiangong-1, a versatile, roomy, and reliable vehicle: the Celestial Ship: Tianzhou.

Unlike Tiangong-1, Tianzhou is equipped with solar panels composed of three segments per side (compared to Tiangong’s four). The cargo compartment, which in some versions can also be pressurized, follows the volume of the space station from which it derives: 15 m3 of volume for a total length of 5 meters. The service module, 3.3 meters long, is equipped with four motors for a thrust of 490 N each.

Unlike Tiangong-1, it has larger tanks to allow the cargo ship to refuel the space station, similar to its Russian counterpart Progress.

The Tianzhou vessel (Credits: China Daily)
The Tianzhou vessel. Credits: China Daily


Progress Vs Tianzhou

If Shenzhou, visibly derives from Soyuz, it cannot be said that Tianzhou derives from Progress. Instead, if we speak of Russian influence, it is comparable to an early Saljut or, better still, to its military version Almaz.

Progress maintains the structure with three distinct modules: the bow one, vaguely spherical, is pressurized while the central one contains the fuel tanks for refueling.
The carrying capacity of the Russian cargo ship is 2,230 kg.

Tianzhou has taken the cargo concept to the extreme by increasing the volume cubage of the single payload module, up to 6,500 kg.
In both automated vehicles, the docking system has fuel lines for refueling the space station.

The Tianzhou freighter already has five missions under its belt, the first of which, was launched in 2017 toward the old Tiangong-2 space station

Progress (left) and Tianzhou cargo vessels (Credits: Roscosmos and CNSA)
Progress (left) and Tianzhou cargo vessels. Credits: Roscosmos and CNSA


For a bigger vehicle, a more powerful launcher

Remaining on the subject of differences between the two automated spacecraft, if on the Russian side, it was preferred, in order not to have to modify the production processes of the Soyuz 2.1 launcher, to keep the configuration of the Soyuz as such even in its cargo version, its counterpart more generously sized, requires a different type of launcher from the Long March 3B used for the Shenzhou: The Long March 7.

It is a medium-heavy, two-stage carrier with four lateral boosters, fully disposable, with a launch capacity of 13,500 kg in LEO. Powered by LOX-RP1 liquid fuel, it is, in terms of power, a cross between the Soyuz 2.1 and the Proton. It has eleven missions to its credit with ten successes.

Long March-7 Launcher on Wengchang Launchpad (Credits: CNSA)
Long March-7 Launcher on Wengchang Launchpad. Credits: CNSA


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Roberto Paradiso

Roberto Paradiso

Banker with a passion for cosmonautics, he tells in his blog, "Le storie di Kosmonautika" and in the book "Noi abbiamo usato le matite!" the history and stories of the Soviet and Russian space program and the people who made it.

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