Design and application prospect of China’s Tiangong Space Station

First, authors introduce the system scheme design of Tiangong space station. Overall, the Tiangong space station shows a T-shaped configuration, with the Tianhe core module in the middle and two experiment modules, namely Wentian and Mengtian, being assembled on the 2 sides respectively (Fig. 1). The Tianhe core module consists of 3 parts: a node cabin, a life control cabin, and a resource cabin. It has a total axial length of 16.6 m and a maximum diameter of 4.2 m, as shown in Fig. 2. The Wentian experiment module consists of 3 parts: a working cabin, an airlock cabin, and a resource cabin. It has an axial length of 17.9 m and a maximum diameter of 4.2 m, as shown in Fig. 3. In addition, a small robotic arm, an experimental platform, and a truss structure are arranged outside the module. The Mengtian experiment module consists of 4 parts: a working cabin, a cargo airlock cabin, a load cabin, and a resource cabin. It has an axial length of 17.9 m and a maximum diameter of 4.2 m, as shown in Fig. 4. Two deployable platforms for exposed payloads are installed outside the load cabin, unfolding in orbit after launch. Moreover, the Tiangong space station has 3 docking hatches: forward (mainly for docking with manned spaceship and the Xuntian space telescope), backward (mainly for docking with cargo spaceship), and radial ones (mainly for docking with manned spaceship). As for the system function design, the control and propulsion system includes control moment gyros, a reaction control system, a propellant refueling system, and the Hall electric propulsion system. The energy system is equipped with a large area of flexible solar arrays. The manned environment system possesses complete regenerative and nonregenerative life-support systems. The robotic arms are the large 7-degree-of-freedom robotic arm and the small 7-degree-of-freedom robotic arm, with rich sensors of visual measurement, joint torque, and end-effector force. The extravehicular activities are supported by both the node cabin of the Tianhe core module and the airlock cabin of the Wentian experiment module. The crew’s residence is provided with an activity space of no less than 110 m³.

Then, authors summarize technical characteristics of advanced nature. Generally, the technical characteristics of the Tiangong space station are mainly reflected in the 4 aspects. (1) The advanced design concept. China adopts a unified design framework and technical system for the Tiangong space station, under which the GNC, energy, information, thermal control, and manned environment systems of all the 3 modules will be interconnected to work together. And, the space station integrates intermodule resources efficiently, thus improving its overall capacity and system reliability. (2) The high proportion of new technology. Space robotic arms, physicochemically regenerative life support, and the large-area flexible solar arrays of this space station are all brand-new technologies applied in orbit for the first time in China with high application difficulty and development risk. Besides, the Tiangong space station embodies a high degree of intelligence from both equipment and system levels. (3) The excellent cost-effectiveness ratio. In line with China’s national conditions and practical needs in terms of building costs and application benefits, the Tiangong space station is designed to be moderate scale, relative to the ISS and Mir. Moreover, having more economical and reasonable construction and operation, it will be superior in some aspects, such as the power generation efficiency, application support capability, building ways, replenishment demand. (4) The safe and efficient residence. The Tiangong space station is designed in line with the human-oriented concept. The design not only ensures the safety and comfort of the crew in orbit but also focuses on supporting the effective exertion by the crew’s intelligence.

At last, authors propose the prospect for subsequent applications and development of Tiangong space station in five aspects. (1) In terms of scientific and technological experiments, various scientific and technological experiments will be conducted continuously by extravehicular and intravehicular experiment support facilities as shown in Fig. 16. The main research interests include space medicine, space life science and biotechnology, space astronomy and astrophysics, microgravity fluid physics and combustion science, space material science, basic microgravity physics, space geoscience and applications, space environment and physics, new space technology, space-based information technology, and space parts and components. (2) In terms of on-orbit services, the Tiangong space station can be used as an on-orbit service platform of a low-Earth orbit, providing on-orbit services of co-orbital motion (i.e., the Xuntian space telescope flying co-orbitally with the space station) and on-orbit facility construction services (such as large space antennas and telescopes). (3) In terms of technology upgrading, the software of the space station can be upgraded through uploading from the ground, thus continuously improving its technical level. Technical upgrades can be considered in the aspects of intelligence upgrade, life-support system, and robotic arm. (4) In terms of extended building, the future expansion of the Tiangong space station has been planned overall during the design. The expansion module will permanently berth at the forward berthing hatch of the Tianhe core module; a Tianzhou cargo spaceship will berth at the backward docking hatch of the Tianhe core module; and a Shenzhou manned spaceship will berth at the forward docking hatch of the expansion module, forming a 4-module assembly. After this, subsequent expansion modules can be further launched to form a 180-ton 6-module assembly. (5) In terms of international cooperation, the international cooperation of the Tiangong space station can be divided into 3 levels: (a) providing standardized and specialized resources for payloads, (b) playing a good role of a test platform for promoting and developing follow-up space technology, and (c) developing large-scale module-level cooperation to jointly expand the Tiangong space station.