During the indexing period, the Wentian Experimental Cabin first completes the relevant status settings, and then separates from the Tianhe core Cabin. Then, the indexing is completed by a plane indexing method and re-connects with the lateral port of the node cabin.

◎ Guo Rui Shi Jixin Shangshuai Science and Technology Daily reporter Fu Yifei

Beijing time on September 30, 2022, after about 1 hour of heaven and earth coordination, the Wentian Experimental Cabin completed the transfer. During the indexing period, the Wentian Experimental Cabin first completed the relevant status settings, and then separated from the Tianhe core Cabin. Then the indexing method was completed by plane indexing, and then connected with the lateral port of the node cabin again.

This is the first time in my country that the indexing mechanism is used to carry out large-scale cabin indexing operations in orbit. After the transfer of the Wentian experimental cabin was completed, the space station assembly changed from the two-cabin "one" configuration to the two-cabin "L" configuration. Subsequently, the space station assembly will fly in orbit in a "L" configuration, and wait for the launch, rendezvous and docking of Mengtian Experimental Cabin, and will also be transposed to form the space station's three-cabin "T" configuration assembly.

Use a shoulder pole to lift two elephants

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Space station cabin section index technology is one of the key technologies that must be broken through in the construction of China space station . The seemingly simple movement of is actually a "combination punch" that combines difficult movements such as forward evacuation, cabin section indexing, and lateral docking. During the indexing of the cabin section of

, the experimental cabin of more than 100 kilograms is driven by an indexing mechanism of more than 20 tons for large-scale transfer. Just like carrying two elephants with a shoulder pole, it is the state with the most fragile dynamic characteristics, and slight vibrations at both ends may have serious consequences. To ensure structural safety, the combined attitude active control must be temporarily turned off to allow the space station to complete the cabin transition in a free floating state.

But it is not easy to let a behemoth like a space station assembly with dozens of tons in a passive and stable state in space. To this end, the developers of the Fifth Academy of China Aerospace Science and Technology Corporation opened up their brainstorms and conducted multiple rounds of brainstorms: "Learn from the principle of pendulum to stand up the combination?" "Then let the combination turn around and turn backwards." "Let the combination stabilize the earth axis with gravity and stabilize the yaw axis like a pendulum, and rely on the two large solar wings of the Wentian Experimental Cabin to stabilize the yaw axis like a badminton, thus forming a three-axis passive and stable flight state..." As the thoughts were storming, the passive and stable indexing plan gradually became clear.

Multiple test verification preparation for the "big test"

In the space station construction task, the cabin section transfer action can be called a "big test". In order to hand over a perfect transcript, the development team conducted multiple simulations and carried out a large number of experimental verification work.

This index is carried out using a plane indexing method. In this way, the development team can use a floating platform on the ground to conduct a large number of indexing tests to fully verify the indexing path.

space station always adopts the "three-cabin flight" model, and the "electrical space station" on the ground conducted full-process simulation tests for this task; the "digital space station" in the "cloud" uses a multi-disciplinary simulation model to carry out multi-disciplinary joint simulations such as attitude prediction, relay measurement and control link occlusion and energy balance during the transposition process driven by flight programs. These technical means fully verify the implementability of the indexing implementation plan and the matching degree of multiple majors such as attitude, energy, measurement, control and communication during the indexing process.

On January 6, 2022, the space station robotic arm indexing cargo spacecraft test was a complete success. This is the first time that my country has used a space station robotic arm to operate a large in-orbit aircraft for indexing tests, and it is also an official rehearsal before the transfer of the Wentian Experimental Cabin. This indexing test completed a series of predetermined actions such as robotic arm capture Tianzhou-2 , docking mechanism separation, Tianzhou-2 indexing, and two cabins docking again, laying a solid foundation for the successful implementation of the Wentian experimental cabin indexing task.

Image source: China Manned Space Flight

1 months later welcoming Mengtian Experimental Cabin

During this transfer mission, the various subsystems of the space station cooperated vigorously and collaboratively to ensure it.

Deputy chief designer of the space station Wentian Experimental Cabin of the Fifth Hospital Space Station Luo Chao said that during the task, the space station robotic arm subsystem always serves as a backup means for the indexing mechanism to ensure the platform security; the GNC subsystem is always precisely controlled to ensure that the combination enters the stop-control state with the highest stability; the measurement and control and communication subsystems build a smooth communication link between the world, transmit high-definition images, making the entire indexing process 100% controlled; the CNC subsystem plays the role of a "intelligent brain" and deals with a series of complex instructions, and zero errors throughout the process...

With the efficient cooperation of each subsystem, the task was successfully completed in just about an hour.

According to the plan, the space station L configuration combination will continue to fly for about 1 month. The Mengtian Experimental Cabin will be welcomed in the future to form a T configuration, and the Chinese space station will be fully built by then.

Editor: Wang Yu

Review: Zhu Li