Tianzhou

China’s automated cargo resupply vehicle, derived from the Tiangong 1 space laboratory. Capable of in-orbit cargo resupply and refuelling of propellants.

Type: Automated cargo spacecraft. Programme: Project 921-II, Project 921-III. Agency: CMSA. Primary contractor: CAST. Status: Development. First launch: exp. 2017. Launch vehicle: CZ-7. Launch complex: Wenchang-LC201. Orbit: 300—400 km LEO, 42.5º inclination. Mass (gross): ∼13,000 kg. Payload mass: 6,000 kg. Length: 10.6 m. Diameter: 3.35 m. Propellants: N2O4/MMH.

Programme

Just like the space stations built by Russia and the United States, China’s future space station will also require constant supply of consumable materials including food, water, and propellants from Earth. To support this role, the Chinese space industry developed a cargo resupply ship named Tianzhou (“Sky Vessel”), based on the design of the Tiangong 1 space laboratory module.

The cargo resupply spacecraft programme was initiated in late 2010, and China Academy of Space Technology (CAST) was awarded the development contract in January 2011. By August 2014, the cargo spacecraft design had been finalised and the spacecraft was officially named. The first full-size prototype of the Tianzhou spacecraft was completed in April 2015. Production of the Tianzhou 1 vehicle began in April 2016 and the spacecraft was completed in January this year.

Spacecraft Design

The Tianzhou cargo spacecraft was derived from the Tiangong space laboratory module, almost identical in appearance and size. The spacecraft consists of two cylinder-shaped sections: a habitable Cargo Compartment and an inhabitable Service Compartment that houses propulsion, power, life support, and communications systems. A pair of solar wings each with 4 solar panels are attached to the Service Compartment. The spacecraft is 10.6 m in length and 3.35 m in diameter, and weighs nearly 13 tonnes (12.91 tonnes for the Tianzhou 1 mission) when fully loaded—the heaviest spacecraft China has ever launched. It is capable of carrying 6.5 tonnes of cargo, including 2 tonnes of liquid propellants.

The front Cargo Compartment is surrounded by heat pipes designed to conduct heat from internal systems to an external radiator. Equipment and supplies are packed in bags and strapped to wall-mounted racks and shelfs inside the compartment, with a small corridor in the middle to allow movement of the crew from the receiving space station. Future Tianzhou vehicles will also include both partially pressurized and non-pressurized variants to meet different mission requirements.
- For the Tianzhou 1 mission, the spacecraft carried over 100 bags of equipment and supplies, including 90 man-days worth of supplies, an EVA space suit, a soft water tank and a rigid water tank, a pair of oxygen canisters, and a pair of nitrogen canisters. The spacecraft also carried about 2,000 kg of liquid propellants (both fuel and oxidiser), which will be used to demonstrate the in-orbit refuelling procedure. In addition, the spacecraft also carried 13 experiment packages. A scientific experiment CubeSat named Silu 1-01 was mounted on external pylon of the spacecraft and will be released during the mission.
- The module is connected to the Tiangong 2 space laboratory module via an androgynous docking mechanism developed by Shanghai Academy of Spaceflight Technology (SAST). Tianzhou 1 is said to feature an improved second-generation docking system, which is capable of the faster 6-hour docking procedure and transferring liquid propellants through 4 refuelling nozzles on the docking port. Rendezvous and docking aids will likely consist of radio beacons, transponders, communication antenna, UHF radar, laser rangefinder, and electro-optical tracking system.
Behind the experiment compartment is a 1.1 m-long transition section, tapered from 3.35 m diameter of the experiment compartment to the 2.25 m diameter of the aft service compartment. The section houses the nitrogen and oxygen tanks used for environmental control.
The aft Service Compartment is about 3.3 m in length and 2.5 m in diameter, and has been derived from the Shenzhou service module. The Tianzhou cargo spacecraft features an improved 2^nd-generation 490-N dual-chamber high-expansion-ration main engine, as well as 25-N, 120-N and 150-N control thrusters for pitch/yaw and roll control. Two four-panel solar wings, with a total span of about 23 m, deploy from the sides of the Service Compartment. These can be rotated to obtain maximum solar insolation regardless of spacecraft attitude.

Tianzhou features a number of new technologies that have been put in use for the first time. It is the first Chinese spacecraft to have been developed completely using digital 3D simulation throughout design, manufacturing and testing; the spacecraft is equipped with an improved dual narrow/wide-band data communication terminal, which provides extra redundancy in tracking and communications via the Tianlian tracking and data relay satellites; It is also equipped with an improved Control Moment Gyroscope (CMG) platform for better navigation and orbit insertion accuracy.

Associated Topics

CZ-7 — Medium-lift member of China’s next generation launch vehicles that have been developed based on several common rocket engines using environmentally friendly kerosene and cryogenic propellants. First flying in June 2016, the basic variant CZ-7 will be launched to loft the Tianzhou cargo resupply vehicle to orbit. Future variants of the CZ-7 may replace existing Chang Zheng orbital launchers for satellite launch missions. A man-rated variant may also be developed as the launcher for the next-generation multipurpose crew vehicle.

Mission History

Date           Mission         Type               Launch Site     Launch Vehicle
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2017-04-20     Tianzhou 1      Refuelling demo    Wenchang        CZ-7 (Y2)