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Tiangong

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Tiangong Credit: � Junior Miranda

Status: Operational 2011. First Launch: 2011-09-29. Last Launch: 2011-09-29. Number: 1 . Gross mass: 8,000 kg (17,600 lb). Height: 9.00 m (29.50 ft). Diameter: 3.50 m (11.40 ft). Span: 20.00 m (65.00 ft).

Tiangong is not a true space station but rather a man-tended facility. On-board experiments will be operated continuously, and about one Shenzhou flight per year will dock with the station to change out experiment payloads and results, and conduct repairs. The orbital module's habitable volume is quite small, 70% that of the American Manned Orbiting Laboratory of the 1960's and less than one tenth that of the Almaz and Salyut Russian stations of the 1970's.

A total of three Tianqongs are to be launched, in 2011, 2015, and 2020. Each will be visited by three Shenzhou spacecraft (the first two to Tiangong-1 unmanned). Crew dwell times will progressively increase from a week, to 20 days, to 40 days. The design will then be modified for use as an unmanned cargo carrier to the future multi-module Chinese space station (to be completed in 2020). In that role total mass will grow from 8.5 to 13 metric tons and require use of one of the new-generation launch vehicles currently being developed.

When used for Tianqong (without the need for the launch escape system for Shenzhou), the CZ-2F booster payload increases from 7.8 to 8.5 metric tons that defines the spacecraft's gross mass. Tiangong is encased in a large, orange-brown clamshell fairing until the booster is clear of the atmosphere.

Tianqong consists of three modules:

• The aft service module, providing electrical, environmental control, and propulsion services. This is a cylinder, about 2.5 m in diameter and 3.3 m long, probably a modification of the Shenzhou service module. Tiangong has a different propulsion scheme than Shenzhou, with two small high-expansion-ration main engines (versus four larger engines for Shenzhou). Four sets of two small aft-firing engines at the base provide vernier thrust for fine maneuvers (versus four sets of canted engines for pitch, yaw, and vernier maneuvers on Shenzhou). Pitch, and yaw control is via four sets of two small engines mounted around the external base of the module (as on Shenzhou). Location of roll control thrusters is unclear, but apparently in the pods for the other thrusters at the base.

  The unified propulsion system of the service module feeds both attitude control and main engines from four 230-litre-capacity propellant tanks loaded with up to 1,000 kg of N2O4/MMH propellants. The engines are pressure fed using six 20-litre titanium cold gas tanks pressurized to 23 Mpa. This gas is used to force propellant at 2 Mpa using diaphragms within the propellant tanks.

  Two four-panel solar wings, with a total span of about 23 m, deploy from the sides of the service module. These can be rotated to obtain maximum solar insolation regardless of spacecraft attitude. Each wing, about 3.1 m x 10 m, provides about double the electrical power of the Shenzhou system (total about 7 kW peak, 2.5 kW average). The back surface filled silicon solar cells of the arrays have an efficiency of 14.8% on Shenzhou. Sun sensors between the panels measure the sunlight incidence angle which allows the panels to be automatically commanded to an optimum angle. Silver-zinc batteries in the service module provide emergency power in case of failure of the solar arrays. The spacecraft's power bus operates at 28 V.

  The Tianqong service module lacks the flared base of Shenzhou, and is longer. The external radiator surface for the spacecraft's thermal regulation system has been moved from the service module to the orbital module. Within the service module were several ellipsoid-shaped compartments that house avionics and electrical system equipment.

• The transition section, 1.1 m long, flares outward from the 2.5 m diameter of the service module to the 3.35 m of the orbital module. This probably houses the nitrogen and oxygen gases for the environmental control system. These are stored in steel alloy spheres at a pressure of 21 Mpa. Possibly water tanks are also located here.
• The orbital module, 3.35 m in diameter and 5 m long provides the crew space in orbit. To reject the 2 kW of heat generated by Tiangong's crew and internal systems, a cooling system uses heat pipes to conduct heat from internal systems to an external radiator. This surrounds the aft 2.3 m of the orbital module, increasing the diameter here to nearly 3.5 m. It seems the interior of the module inside the radiator is packed with equipment and experiments, with perhaps a narrow space for crew access. A mockup seems to indicate that only the forward 2.5 m of the orbital module is free space for the crew, indicating a habitable volume for the entire module of only about 17 cubic meters.

  At its forward end the orbital module slopes to a 1.4-m-diameter APAS-type universal docking mechanism (as used for Apollo-Soyuz, Shuttle-Mir, and Shuttle-ISS). This indicates the possibility crew rescue from one Shenzhou to another in case a crew is stranded. Concepts of a Shenzhou-Tiangong docking shows homing radar towers on each spacecraft as used in the pre-1986 Soyuz 7K-T and Soyuz T. This would indicate that long-range rendezvous operations will be carried out by a radar-based system (based on published information or as part of the Soyuz data package delivered to China in the 1990's). Docking operations may use some kind of optical/laser ranging and alignment system. Various devices shown arranged around the docking mechanism are probably for this purpose.

Family: Chinese Manned Spacecraft, Logistics spacecraft. Country: China. Launch Vehicles: Chang Zheng 2F, Chang Zheng 2FT1. Launch Sites: Jiuquan, Jiuquan SLS. More at: 6982.

Photo Gallery

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Tiangong Tiangong space laboratory, image exhibited at UN exhibit, Vienna, 2011 Credit: � Mark Wade

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Tiangong Credit: � Junior Miranda

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Tiangong Credit: � Junior Miranda

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Tiangong Tiangong docking with Shenzhou, image exhibited at UN exhibit, Vienna, 2011 Credit: � Mark Wade

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Tiangong Credit: � Junior Miranda

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Tiangong Tiangong and Shenzhou drawing Credit: &169; Junior Miranda

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Tiangong Credit: � Junior Miranda

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Tiangong Credit: � Junior Miranda

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Tiangong Credit: � Junior Miranda

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Tiangong 1 Credit: Manufacturer Image

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• Tiangong 1 - . Mass: 8,500 kg (18,700 lb). Nation: China. Class: Manned. Type: Manned space station. Spacecraft Bus: Shenzhou. Spacecraft: Tiangong. USAF Sat Cat: 37820 . COSPAR: 2011-053A. Apogee: 339 km (210 mi). Perigee: 330 km (200 mi). Inclination: 42.8000 deg. Period: 91.20 min. First Chinese manned space laboratory. Placed initially into a 198 km x 332 km x 42.8 deg orbit. Maneuvered to a 336 km x 353 km operational orbit by 30 September in preparation for arrival of the Shenzhou 8 spacecraft that would dock with it..