China is gearing up for its next big leap in space exploration: the construction of its modular crewed space station, the Tiangong.
Starting in 2021, the construction of the Tiangong orbital space station is expected to be complete in 2022 after eleven missions, including three launches of different modules, four launches of cargo vehicles and four crewed launches.
This step comes after a phased approach to human spaceflight development, beginning with the uncrewed test flights of a crewed space vehicle (Shenzhou-1 to Shenzhou-4). This was followed by the launch of a crewed mission (Shenzhou-5 with one taikonaut), the launch of a space crew (Shenzhou-6 with two taikonauts and Shenzhou-7 with three taikonauts), and the execution of an extravehicular activity (Shenzhou-7).
China also achieved the launch of a Salyut-1 type space module (Tiangong-1 and Tiangong-2), the development of rendezvous and docking (Shenzhou-8), space module occupation and long duration flight (Shenzhou-9 and Shenzhou-10), and the launch of a cargo freighter (Tianzhou-1) for the regular resupply of orbital stations.
In just a few years, and following a properly phased program, China moved from short term crewed space flight to the construction of a modular space station that will allow six-month stays in Earth orbit, thus reaching a similar capability to the International Space Station program, which includes major contributions from the United States, Russia, Japan, Europe, Canada, and others, but not China.
The Tiangong Space Station
The Tiangong space station will be a Mir-type orbital laboratory, composed of a central module to which other modules will be added gradually.
The station will initially consist of the Tianhe-1 module (central module), the scientific modules Wentian and Mengtian, and the Xuntian.
The Tianhe-1 (Harmony of the Heavens) module will be put into orbit by the Long March-5B (Y2) rocket launched from the Wenchang Space Launch Center. With a mass of about 20,000 kilograms, the module will be placed in an orbit with an average altitude of 393 kilometer with an orbital inclination of 42 degrees, and will serve as the core of the Tiangong space station.
Tianhe-1 is divided into two large cylindrical sections, the largest with a diameter of 4.2 meters and the other section with 3.5 meters. Its total length is 16.6 meters, having a habitable volume of about 50 cubic meters. The Tiangong’s core module is also composed of a resource section and a cylindrical section with a diameter of 2.8 meters with five docking ports that will allow the joining of new experimental modules.
The core can accommodate three crew members and has a lifespan of 15 years with orbital maintenance. Tianhe-1 is equipped with life support systems for its crew.
The Wentian and Mengtian modules will be scientific modules with a mass of about 20,000 kg, 14.4 meters length and a diameter of 4.2 meters. The pressurized modules are developed based on experience from the Tiangong-2 orbital module and will be used to carry out experiments in the areas of life sciences, biotechnology, physics, materials sciences, microgravity, etc.
In addition to the experiments located in the pressurized interior, both modules will be able to host external experiments exposed to the space environment and fixed to the respective fuselages. The modules will be docked to the Tianhe-1 module’s axial section and later transferred to a side port using a remote manipulation system, operated either from inside the space station or remotely from the control center.
The combined living area of the three initial modules will increase to 110 cubic meters.
The Wentian module will be equipped with additional control systems that can be used in case of any arising problem with Tianhe-1. Mengtian has similar functions to Wentian, but is equipped with a special hatch to allow the entry and exit of cargo and instruments either with the help of the crew or independently using the remote manipulation system.
In total there will be sixteen experiment racks between the core module, the two experimental modules, and an external experiment platform. The experimental racks will be about 1.8 meters high, 1 meter wide and 0.9 meters deep, massing less than 500 kilograms.
Another experimental module, the Xuntian, will be a space telescope with a mirror two meters in diameter. The module will not be attached to the Tiangong complex, but rather orbit close to the station. The Xuntian may be attached to the station for repair operations. It will be used for study the mechanism of the accelerated expansion of the universe, dark energy and dark matter, and the origin and evolution of the universe.
The space station will be regularly resupplied with Tianzhou cargo vehicles, the first of which was launched in April 2017 for the Tiangong-2 space station.
Schedule
The launch of Tianhe-1 is expected to take place in April 2021. Its launcher arrived at Wenchang on February 21 and launch preparations began soon after.
Following the launch of the Tianhe-1 module, China will launch the Tianzhou-2 cargo vehicle that will be put into orbit by the Long March-7 (Y3) rocket from the Wenchang Space Launch Center’s LC201 Launch Complex. Tianzhou-2, which is also due to be launched in April, will dock with Tianhe-1 autonomously.
After an initial period of orbital commissioning, all will be ready for the launch of Tiangong’s first crew.
On the second week of February, the two launchers for the crewed missions were said to be ready for launch at the Jiuquan Satellite Launch Center. Everything going according to plan, Shenzhou-12 will be launched by the Long March-2F/G (Y12) rocket from Jiuquan’s LC43/91 Launch Complex for a multi-month orbital mission aboard the new space station. The launch of Shenzhou-12 is scheduled for June and is expected to carry three crew members who will remain in orbit for several months.
Both the Tianzhou-3 cargo vehicle and the Shenzhou-13 crewed space capsule are expected to be launched in 2021. The Tianzhou-3 cargo vehicle will be launched by the Long March-7 (Y4) launcher from Wenchang in August, and the Shenzhou-13 crewed mission is due to be launched in September or October by the Long March-2F/G (Y13) rocket from Jiuquan.
At this stage, it is not certain whether the Shenzhou-13 crew will replace the Shenzhou-12 crew still in orbit or whether if this crew it will return to Earth before the arrival of Shanzhou-13.
The Wentian module will be the first of the two scientific modules to be placed in orbit in 2022, followed by the Mengtian module. Both will be launched from Wenchang by Long March-5B rockets.
The Crews
At this point, it is not easy to define how the crews of the next Chinese space missions will be composed. However, it is possible to define a general group composed of four crews for flights that will take place in 2021 and 2022.
The group consists of Nie Haisheng (who participated in the Shenzhou-6 and Shenzhou-10 missions), Deng Qingming, Liu Boming (Shenzhou-7), Liu Wang (Shenzhou-9), Zhang Xiaoguang (Shenzhou-10), Chen Dong (Shenzhou-11), Liu Yang (Shenzhou-9), Wang Yaping (Shenzhou-10), Ye Guangfu, Zhang Lu, Tang Hongbo and Cai Xuzhe.
Some of the older taikonauts will already be out of flight rotation, but in reserve are still Jing Haipeng (who participated in the Shenzhou-7, Shenzhou-9 and Shenzhou-11 missions), Fei Junlong (Shenzhou-6) and Zhai Zhigang (Shenzhou-7).
For a long time now, it has been rumored that one of the two female taikonauts (Liu Wang or Wang Yaping) would be the commander of one of the missions to the Tiangong space station. In the last weeks, several photos have surfaced of Wang Yaping in training. Also, an article from Xinhua mentioned Wang Yaping in connection to EVA training. So, it is very possible that she will be on one of the first two missions to Tiangong, and probably will have the commanders seat on one of those missions.
Shenzhou-12 mission will last for 90 days, and during their stay in orbit, the crew will carry out various extra-vehicular activities for the installation of a robotic arm and other equipment, preparing the station for new modules.
Deng Qingming was a back-up crew member for three missions, and will possibly be part of one of the two missions to be launched in 2021.
The composition Chen Dong, Wang Yaping and Ye Guangfu, was reported to be the crew of Shenzhou-12, having circulated a photograph (provided by Tony Quine) showing Wang Yaping ingressing on Shenzhou-12 during a training session.
If the Shenzhou-12 mission lasts for about 90 days, this will allow Shenzhou-13 to start its mission in September or October, having a longer stay in orbit of around 180 days and “delivering” Tiangong to the Shenzhou-14 crew, to be launched in March 2022, and thus watching the arrival of the new modules.
First Experiments on Tiangong
Within the scope of space cooperation between China and several nations, nine experiments were selected to be carried out on board the Tiangong space station. The process of selection of the experiments was organized with the United Nations Office for Outer Space Affairs (UNOOSA).
These experiences cover the areas of astronomy, microgravity fluid physics and combustion, Earth sciences, space technology, and space life sciences and technology.
The experiments from the field of astronomy will study gamma-ray bursts (Switzerland, Poland, Germany and China) and will make spectroscopic investigation of nebular gas (India and Russia). The microgravity fluid physics and combustion experiments will study the behavior of partial miscible fluids in microgravity (India and Belgium), will use a high performance Micro 2-Phase cooling system for space applications (Italy and Kenia), and will study the flame instabilities affected by vortices and acoustic waves (China and Japan).
Coming from Mexico, the experiment on Earth sciences is going to use a mid-infrared platform for Earth observations, and the experiment on space technology (Saudi Arabia) is going to study the development of multi-junctions GaAs solar cells for space applications.
The space life sciences and technology experiments are going to study tumors in space (Norway, France, Netherlands and Belgium) and the effect of microgravity on the growth and biofilm production of disease-causing bacteria (Peru and Spain).
(Lead render via Mack Crawford for NSF/L2)