China News Service, Hainan Wenchang, January 18th, Title: Space "express delivery" changes to "fast transportation" Tianzhou-7 spacecraft unlocks new rendezvous and docking mode

　　Author Ma Shuaisha Chen Changqing

　　On January 18, the Tianzhou-7 cargo spacecraft successfully docked at the rear docking port of the Chinese Space Station, getting a good start for China's 2024 rendezvous and docking mission.

The 3-hour rendezvous and docking plan adopted this time is a new rendezvous and docking mode verified by China in orbit.

Compared with the conventional 6.5-hour rendezvous and docking, this plan further compresses the docking time and upgrades space "express delivery" to "express transportation".

　Fast and reliable: expected to become a new basic mode for rendezvous and docking

　　Judging from the length of rendezvous and docking, so far, China has verified and implemented 2-day, 6.5-hour, 2-hour and 3-hour rendezvous and docking plans in orbit, which are all pragmatically chosen optimal solutions at different stages of technological development.

　　Specifically, although the two-day rendezvous and docking plan is slow and difficult to respond to emergencies or meet some shorter mission requirements, it is suitable to adopt a more cautious plan in the initial stage.

Although the 2-hour rendezvous and docking scheme is currently the fastest rendezvous and docking mode, this scheme has higher requirements for various guarantee conditions. In comparison, the 6.5-hour rendezvous and docking scheme is more reliable.

　　With the maturity of technology and accumulation of experience, the Tianzhou-7 cargo spacecraft has unlocked the 3-hour rendezvous and docking mode, which is the optimal solution to explore for the next stage of rendezvous and docking missions. It has both the "fast" 2-hour solution and the 6.5-hour solution. "reliability" and other advantages.

Subsequently, after evaluation by the expert team, this model is expected to replace the 6.5-hour plan and become the new basic rendezvous and docking model.

　How does "express delivery" change to "express delivery"?

　　From a practical engineering perspective, the three-hour rendezvous and docking mode has its own special significance.

Compared with the 6.5-hour plan, the 3-hour rendezvous and docking plan has a shorter flight time, which can reduce the flight pressure of astronauts, reduce the need for battery fuel, etc., and improve the overall mission's ability to respond to failures.

Compared with the 2-hour plan, this mode has a slightly longer flight time and a slower pace, which can reduce the pressure on the ground flight control team.

　　Compared with the conventional 6.5-hour plan, how can the 3-hour rendezvous and docking mode reduce time?

As the technology matures, technicians can adjust the relative positions of the spacecraft and the space station in a shorter time.

By adjusting the flight trajectory of the spacecraft, technicians shortened the long-distance guidance section between the Tianzhou cargo spacecraft and the space station by one circle, and the duration was correspondingly reduced by 1.5 hours. In addition, in the short-distance guidance section, the short-distance flight process was compressed to reduce " Stop and go", the duration was shortened by about 2 hours.

　　The Tianzhou-7 cargo spacecraft successfully completed a three-hour rendezvous and docking on-orbit verification mission, further proving the high stability and reliability of the spacecraft's guidance, navigation and control system. It also improved the cargo spacecraft's autonomous rendezvous and docking capabilities and enriched the current rendezvous and docking model. Promote the development of China's space rendezvous and docking technology.

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