Tiangong space station


The Tiangong space station is a permanently crewed space station constructed by China and operated by China Manned Space Agency. Tiangong is a modular design, with modules docked together while in low Earth orbit, between above the surface. It is China's first long-term space station, part of the Tiangong program and the core of the "Third Step" of the China Manned Space Program; it has a pressurised volume of, slightly over one third the size of the International Space Station. The space station aims to provide opportunities for space-based experiments and a platform for building capacity for scientific and technological innovation.
The construction of the station is based on the experience gained from its precursors, Tiangong-1 and Tiangong-2. The first module, the Tianhe core module, was launched on 29 April 2021. This was followed by multiple crewed and uncrewed missions and the addition of two laboratory modules. The first, Wentian, launched on 24 July 2022; the second, Mengtian, launched on 31 October 2022.

Nomenclature

Early names used in the Chinese space program were largely drawn from the revolutionary history of the People's Republic of China. In recent decades, these have been replaced by names with mythological or religious connotations. Examples include the Shenzhou crewed spacecraft, the Shenlong spaceplane, the Shenguang high-power laser, and the Shenwei supercomputer.
These mythological names continue in the Chinese Lunar Exploration Program, whose probes are named Chang'e after the Moon goddess. The name Tiangong was similarly reported to evoke cultural and romantic imagery, with the launch of Tiangong-1 inspiring public expressions such as love poetry, and media comparing the docking of spacecraft to the reunion of the cowherd and the weaver girl from folklore.
In 2011, Wang Wenbao, director of the China Manned Space Agency, stated that the agency sought names that would "carry a resounding and encouraging" message and reflect public participation in the program.
On 31 October 2013, CMSA announced standardized names for space station elements:
  • Tiangong would refer to both the precursor space labs—Tiangong-1 and Tiangong-2 —and the modular space station.
  • Tianzhou for the cargo spacecraft
  • Tianhe for the core module of the modular space station, launched on 29 April 2021.
  • Wentian for the first laboratory module of the modular space station, launched on 24 July 2022.
  • Mengtian for the second laboratory module of the modular space station, launched on 31 October 2022.
  • Xuntian for the co-orbiting space telescope module, scheduled for launch in 2026.

    Purpose and mission

According to CMSA, which operates the space station, the purpose and mission of Tiangong is to develop and gain experience in spacecraft rendezvous technology, permanent human operations in orbit, long-term autonomous spaceflight of the space station, regenerative life support technology and autonomous cargo and fuel supply technology. It will also serve the platform for the next-generation orbit transportation vehicles, scientific and practical applications at large-scale in orbit, and technology for future deep space exploration.
CMSA also encourages commercial activities led by the private sector and hopes their involvement could bring cost-effective aerospace innovations. Space tourism aboard the station is also being considered.

Scientific research

The space station will have 23 experimental racks in an enclosed, pressurised environment. There will also be platforms for exposed experiments; 22 and 30 on the Wentian and Mengtian laboratory modules, respectively. Over 1,000 experiments are tentatively approved by CMSA, and scheduled to be conducted on the space station.
Agriculture in microgravity was explored with cultivation of rice and Arabidopsis thaliana as sustainable food sources for long-term spaceflight.
The programmed experiment equipment racks for the three modules as of June 2016 were:
  • Space life sciences and biotechnology
  • * Ecology Science Experiment Rack
  • * Biotechnology Experiment Rack
  • * Science Glove-box and Refrigerator Rack
  • Microgravity fluid physics and combustion
  • * Fluids Physics Experiment Rack
  • * Two-phase System Experiment Rack
  • * Combustion Experiment Rack
  • Material science in space
  • * Material Furnace Experiment Rack
  • * Container-less Material Experiment Rack
  • Fundamental Physics in Microgravity
  • * Cold Atom Experiment Rack
  • * High-precision Time-Frequency Rack
  • Multipurpose Facilities
  • * High Micro-gravity Level Rack
  • * Varying-Gravity Experiment Rack
  • * Modularized Experiment Rack

    Education and cultural outreach

The space station features space lectures and popular science experiments to educate, motivate and inspire the younger Chinese generation and world audience in science and technology. Each lecture is concluded with a question-and-answer session with school children's questions from classrooms across China. The first and second Tiangong space lesson was conducted in December 2021 and March 2022, as a part of the Shenzhou 13 mission. This tradition continued with the Shenzhou 14.
The CSSARC is the Amateur Radio payload for the Chinese Space Station, proposed by the Chinese Radio Amateurs Club, Aerospace System Engineering Research Institute of Shanghai and Harbin Institute of Technology. The payload will provide resources for radio amateurs worldwide to contact onboard astronauts or communicate with each other, aim to inspire students to take interests and careers in science, technology, engineering, and math, and encourage more people to get interested in amateur radio.
The first phase of the payload is capable of providing the following functions utilising the VHF/UHF amateur radio band:

Structure

Tiangong is a third-generation modular space station. First-generation stations, such as the early Salyut and Almaz stations and Skylab, were single-module outposts that were not designed for resupply. Second-generation stations, including Salyut 6 and 7 and Tiangong 1 and 2, incorporated docking ports that enabled mid-mission resupply. Third-generation stations, such as Mir and the International Space Station, are modular complexes assembled in orbit from multiple components launched separately. Modular design can improve reliability, reduce costs, shorten development cycles, and support more diverse mission requirements.
Below is a diagram of major station components.
Key to box background colors:
  • Pressurised component, accessible by the crew without using spacesuits
  • Docking/berthing port, pressurized when a visiting spacecraft is present
  • Airlock, to move people or material between pressurized and unpressurized environment
  • Unpressurised component

Modules

Tiangong was completed in a three-module configuration in 2022. China has proposed several expansion concepts. Initial proposals called for enlarging the station to six modules by duplicating the original trio, but by 2023 this evolved into a plan to add a fourth module with six docking ports to accommodate future growth. In October 2023, China announced a revised roadmap to expand Tiangong to six modules beginning in 2027.
The Tianhe core module provides life support and living quarters for three crew members and houses the station’s guidance, navigation, and orientation control systems. It also contains the main power, propulsion, and environmental control systems. Tianhe is divided into three sections: living quarters, a service module, and a docking hub. The living area includes a kitchen, toilet, fire suppression equipment, atmospheric control systems, computers, scientific apparatus, and communications equipment for contact with ground control in Beijing. Tianhe also carries the Chinarm, a larger manipulator arm used for EVA support and as a backup for module relocation. A full-scale mockup of Tianhe was displayed at the China International Aviation & Aerospace Exhibition in Zhuhai in 2018. CMSA videos have shown that two core modules have been constructed.
The first of the two Laboratory Cabin Modules, Wentian, provides additional avionics, propulsion, and life-support capacity as backups to Tianhe. It includes three short-term crew quarters for use during handovers and features a dedicated airlock for extravehicular activities, replacing the temporary use of Tianhe’s docking hub, which was not purpose-built for that function. Wentian carries internal experiment racks and 22 external experiment adapters. It was launched and docked with Tianhe on 24 July 2022 and moved to its permanent starboard position on 30 September.
The second LCM, Mengtian, provides expanded in-orbit experiment capability with 13 internal experiment racks and 37 external experiment adapters. It also features a dedicated cargo airlock designed specifically for transferring scientific payloads between the station interior and exterior. Mengtian was launched and docked with Tianhe on 31 October 2022 and moved to its permanent port-side position on 3 November.
Together, the two LCMs support microgravity and freefall research that cannot be conducted on Earth for extended periods. Experiments can also be mounted externally for exposure to the space environment, including cosmic radiation, vacuum, and the solar wind. Wentian focuses primarily on life sciences, while Mengtian is oriented toward microgravity research.
Both LCMs are equipped with rendezvous hardware for automated docking to the forward port of Tianhe. After docking and inspections, the indexing robotic arms mounted on Wentian and Mengtian—similar in function to the Lyappa arm used on Mir—were used to relocate Wentian to the starboard port and Mengtian to the port-side port. The Chinarm on Tianhe can also serve as a backup for module relocation.