Tiangong-3

Tiangong-3 (Chinese: 天宫三号; pinyin: Tiāngōng sānhào; literally: "Heavenly Palace 3") will be a Chinese space station module, part of the Tiangong space station program. The China National Space Agency was originally expected to launch Tiangong-3 around 2015, following the launch of the Tiangong-2 laboratory module originally planned for 2013.^[1] As of September 2014, it is expected to launch in 2022.^[2] Tiangong-3's design will form the basis of Chinese large modular space station, which is expected to launch in the 2020s.^[3]

Development

In 2008, the China Manned Space Engineering Office published a brief description of Tiangong-2 and Tiangong-3, indicating that several manned spaceships would be launched in the late 2010s to dock with Tiangong-3.^[4] The first Tiangong module, Tiangong-1, was launched in September 2011, and docked with the unmanned Shenzhou 8 spacecraft in November 2011, marking China's first orbital docking.^[5]

Specifications

Tiangong-3's 22-metric-ton core module will be around 18.1 metres (59 ft) long and will have a maximum diameter of 4.2 metres (14 ft).^[3] It is expected to provide:

• Unaided 40-day habitability for three astronauts.^[1]
• Testing for regenerative life-support technology, and verification of methods of orbital replenishment of propellant and air.^[1]
• A multi-docking berthing mechanism,^[3] allowing up to four spacecraft to dock with it simultaneously.

Structure and assembly

Tiangong-3 is a 'third generation' or modular space station project. Other examples of modular station projects include the Soviet/Russian Mir, the International Space Station (ISS) and the planned Russian OPSEK.^[6] The 'monolithic' first-generation space stations, such as the Soviet Salyut 1, Salyut 3, Salyut 4 and Salyut 5 and NASA's Skylab stations, were not designed for resupply, possessing only one docking port. Second-generation station projects, such as Soviet Salyut 6, Salyut 7 and Tiangong-2, feature a second docking port, allowing for resupply and multiple crewed missions.^[7][8] Modular stations allow new modules to be added or removed from the existing structure over time, saving considerable costs and allowing greater flexibility.

Additional modules will dock to the axial port of Tiangong-3's core module. Using a mechanical arm, similar in function to the Lyappa arm on the Mir space station, modules will then be moved to the radial ports of the docking node.

Future modular space station

Project 921-2 Phase 3 Space Station

A diagram of the completed orbital station, shown with a Shenzhou manned spacecraft and a Tiangong-1-derived cargo vessel docked.
Station statistics
Crew	2-3
Launch	~2020–2022
Mass	82,000 kilograms (181,000 lb)
Length	~20 meters (66 ft)
Diameter	~4.2 meters (14 ft)

Tiangong-3's design will form the basis of a larger, multi-module space station, which China plans to launch in the 2020–2022 timeframe.^[3] When complete, the station will have a total mass of approximately 60,000 kilograms (130,000 lb), and will support three astronauts for long-term habitation.^[1] The space station will have a design lifetime of up to ten years, and its components and service craft will be largely based on previous Tiangong modules. Its primary components will include:^[1]

• A Core Cabin Module (CCM) – based on the Tiangong-3 design and analogous to the Russian Mir Core Module, the 18.1-meter (59 ft) CCM will have a maximum diameter of 4.2 meters (14 ft) and a launch weight of up to 22 tonnes (49,000 lb). It will be launched first, to serve as a docking hub for future modules and resupply spacecraft.^[9]
• Two Laboratory Cabin Modules (LCM-1 and LCM-2) – based on Tiangong-2, the two laboratory modules will each be 14.4 meters (47 ft) long, with the same maximum diameter and launch weight as the core module.^[9] They will be used to perform scientific research in microgravity.
• A robotic resupply craft – based on the original Tiangong-1 module, the automated cargo spacecraft will have a diameter of 3.35 meters (11.0 ft) and a launch weight of around 13 tonnes (29,000 lb). It will be used to transport supplies and lab facilities to the space station.^[9][10]
• A manned Shenzhou spacecraft will be used to transport crewmembers to and from the space station.

In 2011, Wang Wenbao, the director of the China Manned Space Engineering Office, asked the public to submit suggestions for names and symbols to adorn the space station and its cargo ship. He stated that "the crewed space program should have a more vivid symbol and that the future space station should carry a resounding and encouraging name", insisting that "the public should be involved in the names and symbols as this major project will enhance national prestige, and strengthen the national sense of cohesion and pride".^[9]

See also

• Chinese Lunar Exploration Program
• Chinese space program
• International Space Station

References