The high technology behind the Mengtian experimental cabin

  On October 31, 2022, the Mengtian Experimental Module, the third module of the China Space Station, was launched by the Long March 5B carrier rocket at the Wenchang Space Launch Site, and successfully entered the scheduled orbit, and the launch mission was a complete success. On November 1, the Mengtian experimental module was successfully docked with the Tianhe core module. Subsequently, through the horizontal transfer of the Mengtian experimental module, the three modules will form a balanced and symmetrical “T” configuration. The three modules of the Chinese space station Witness the historic “fit” moment together. The Mengtian Experimental Module is the last of the three modules of the Chinese space station. It is 17.88 meters long, with a maximum diameter of 4.2 meters and a weight of about 23 tons. What are the similarities and differences in the division of labor and positioning between it and Tianhe Core Module and Wentian Experimental Module? What is unique about Mengtian Experimental Cabin? What are the high-tech behind it?
The cabin with the highest load capacity

  The division of labor and positioning of the Mengtian experimental cabin is different from that of the Tianhe core cabin and Wentian experimental cabin. It has similarities with the latter two in terms of configuration, but also has its own characteristics.
  Mengtian Experimental Module is positioned as the place where astronauts work, so there is no regenerative life support system, sleeping area, and sanitation area similar to Tianhe Core Module and Wentian Experimental Module, but the three cabins are equipped with training equipment for astronauts. . The Mengtian experimental cabin is equipped with resistance exercise equipment, similar to the rowing machine in the gym.
  Judging from the overall configuration, the “belly” of the Mengtian experimental cabin is more round. It consists of four cabin sections and adopts a unique “matryoshka” design. The working cabin is at the front end and is connected to the core cabin through a docking mechanism. It is mainly used for astronauts to work and exercise in the cabin, and the scientific experiment cabinet in the cabin is also installed here. The load compartment and the cargo airlock compartment are connected to the working compartment in the form of “double compartment nesting”. That is to say, inside the load compartment, there is a cargo airlock hidden, which is a special passage for cargo out of the cabin. The front end is the resource cabin, which is also the place where the sun orientation device and the flexible solar wing are installed.

  As a “studio”, the Mengtian experimental cabin is the section with the strongest load-supporting capacity among the three cabins. It is equipped with 13 standard load cabinets, mainly for microgravity scientific research, and can support fluid physics, material science, and ultra-cold atoms. Cutting-edge experimental projects such as physics can be called Tiangong’s “Dream Factory”. At the same time, in order to maximize the ability to support extravehicular experiments, Mengtian experimental cabin is equipped with 37 load installation stations, which can provide mechanical, electrical, and information capability support for various scientific experimental loads to ensure that they are safe in the space environment. Conduct various experiments. In particular, there are two exposed load test platforms that can be deployed in orbit on the load compartment, which further enhances the load support capability of the space station.
Contains the most complex experimental cabinet on the space station

  The Mengtian experimental cabin is equipped with 8 scientific experimental cabinets in 7 aspects, including ultra-cold atomic physics experimental cabinets and high-precision time-frequency experimental cabinets in the field of space science research and application. Among them, the high-precision time-frequency experimental cabinet is the most complicated experimental cabinet in the space station. The high-precision time-frequency experimental system will be built into the world’s most precise space-time-frequency system operating in orbit through the combination of atomic clocks with different characteristics in the cabin. The system is mainly composed of the ground test evaluation and experimental verification system and the space load part. Among them, the space load part mainly includes 11 subsystems such as the active hydrogen atomic clock. The active hydrogen atomic clock is the core load of the high-precision time-frequency experimental system, which provides the basic time-frequency signal for the space time-frequency system, and lays a solid foundation for the application of the miniaturized active hydrogen atomic clock on the satellite platform.
The space station’s “international cargo port”

  If the airlock of the Wentian experimental module is compared to an “international airport”, then the cargo airlock of the Mengtian experimental module is the “international cargo port” of the space station. In the past, carrying out scientific experiments outside the cabin required astronauts to go out of the cabin to carry out installation operations, but this method would be limited by the number of astronauts out of the cabin, the number of loads, and the volume. The unique function of automatic load entry and exit in the Mengtian experimental module will further improve the ability and efficiency of the space station to conduct extravehicular load experiments. The Mengtian experimental cabin is equipped with a load transfer mechanism, which can stably perform the task of sending cargo from the cabin to the outside of the cabin, or transporting the cargo outside the cabin to the cabin.
  At the same time, in order to meet the requirements for the entry and exit of larger-sized and heavier cargo in the future, a unique square hatch with a width of up to 1.2 meters is also installed on the cargo airlock of the Mengtian Experimental Cabin. The hatch adopts a fully automatic arc-shaped sliding design, which can provide a wide corridor for cargo to enter and exit the cabin. It is also a key device for isolating the space environment inside and outside the cabin. It is the first square automatic hatch on my country’s space station.
Support the release of microsatellites in orbit

  The Mengtian experimental module is specially equipped with an in-orbit release mechanism for micro-aircraft, which can meet the in-orbit release requirements of 100-kilogram-level micro-aircraft or cubesats of multiple specifications, and solve the problem of low-cost entry of micro-satellites and cubesats into space. Astronauts only need to fill the cubesat or microsatellite into the “belly” of the release mechanism in the cabin, and the release mechanism can take the load transfer mechanism to transport the small satellite to the outside of the cabin. After leaving the cabin, the mechanical arm grabs the release mechanism and moves to the designated release direction. The release mechanism will eject the small satellite like a slingshot, realizing the “satellite release” in orbit.
Double “wing” drive realizes worry-free power consumption

  With the development of more scientific experiment missions, the demand for power supply of space station loads has also doubled. Therefore, the Mengtian experimental cabin and the Wentian experimental cabin have the same configuration and power, and also have a “giant wing” with a length of 27 meters on one side and a expandable area of ​​​​nearly 138 square meters – a flexible solar wing.
  After the basic configuration of my country’s space station is assembled, the two experimental cabins equipped with four sets of solar wings will create the most powerful energy source for my country’s space station, allowing the space station to generate nearly 1,000 kilowatt-hours of electricity per day, which is equivalent to nearly half a year for an ordinary family. Power consumption, truly realize “no worry about power consumption”.
  It is worth noting that, as a brand-new solar cell wing, the system composition, deployment principle, and technical difficulties of flexible solar wings are quite different from traditional rigid and semi-rigid solar wings. Traditional rigid and semi-rigid solar wings are deployed once, while the flexible solar wing of my country’s space station is the first in the world to “secondary deployment” technology, which is to ensure the absolute safety of the key movement of rendezvous and docking.
  Take the solar wing of the Mengtian experimental cabin as an example. During the rendezvous and docking process, if the solar wing is fully deployed, it is like two hands holding a huge sail. Even a small shake will lead to a serious decline in the control accuracy of the speed, relative position and flight attitude of the experimental cabin, and the difficulty of control will increase exponentially. To this end, the design team of the Eighth Academy of China Aerospace Science and Technology Corporation broke through the key technology of “secondary deployment”. During the independent flight stage after the launch of the Mengtian experimental module, the flexible solar wing first unfolded part of the solar panels to meet the energy requirements of the experimental module and reduce the energy consumption of the experimental module. The difficulty of flight control is to complete the rendezvous and docking; after the docking is completed, it will be launched in an all-round way to establish a complete energy system.