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.
#SpaceChina The Long March-7 Y7 carrier rocket, carrying the Tianzhou-6 cargo spacecraft, blasted off from the Wenchang Spacecraft Launch Site in China's southern island province of Hainan at 21:22 BJT on Wednesday. pic.twitter.com/VRk2NWt1Mi
— CGTN (@CGTNOfficial) May 10, 2023
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.
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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
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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.
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