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On June 4th, the return capsule of the Shenzhou-15 manned spacecraft successfully landed at the Dongfeng landing site. Astronauts Fei Junlong, Deng Qingming, and Zhang Lu all safely and smoothly exited the spacecraft, and the Shenzhou-15 manned flight mission was a complete success.
What innovative technologies are there to safeguard the return journey of Shenzhou 15 in this mission?
On June 4th, the return capsule of the Shenzhou-15 manned spacecraft successfully landed at the Dongfeng landing site. Photo by Xinhua News Agency reporter Lian Zhen
"Heaven and Earth" to ensure high-precision return of spacecraft
For the Shenzhou series spacecraft, the return and re-entry GNC technology is directly related to the life safety of astronauts. Taking the success of this return mission as a symbol, China has comprehensively upgraded its GNC system, which features autonomous rapid rendezvous and docking, autonomous adaptive prediction, and re-entry guidance, since the Shenzhou-12 manned spacecraft.
China's spacecraft return and re-entry GNC technology has gone through two generations. The first generation is known as the "standard ballistic adaptive guidance method", while the Shenzhou-12 to Shenzhou-15 manned spacecraft used the "adaptive predictive guidance method", which is the second generation of return and re-entry technology. In addition, the application of China's "Starlight Satellite Constellation Strapdown Inertial Navigation" technology enables the entire return process of the Shenzhou-15 manned spacecraft to achieve high-precision autonomous navigation.
"The worst return accuracy after adopting the second-generation return technology is better than the best of the first generation!" said Hu Jun, Deputy Chief Designer of Manned Spacecraft Systems at the Fifth Academy of Aerospace Science and Technology Group. If the first generation technology is adopted, manual intervention from the ground is required when there are large-scale changes in orbital conditions; If second-generation technology is adopted, the GNC system can autonomously adapt and achieve a series of "stronger" and "better".
In addition, at the main landing site, China Electronics Technology Corporation (CETC) has deployed portable stations, airborne stations, vehicle mounted stations, fixed stations, and other types of satellite communication systems, weaving a dense and safe measurement and control communication network. Like stethoscopes, remote controls, and mobile phones, it measures the flight trajectory in real time, monitors parameters such as power supply, temperature, and air pressure of the return capsule, as well as physiological parameters of astronauts. It also transmits commands issued by the ground in real time, instructs the return capsule to change orbit and adjust attitude, and transmits voice and image data in real time, allowing the ground to communicate with astronauts in real time.
On June 4th, the return capsule of the Shenzhou-15 manned spacecraft successfully landed at the Dongfeng landing site. Photo by Xinhua News Agency reporter Lian Zhen
"Super Umbrella" Protects the Spaceship's Safe Landing
As the return capsule of the Shenzhou-15 manned spacecraft was about to land, a large red and white umbrella bloomed as promised, guarding the capsule as it slowly drifted down and landed steadily. This oversized parachute is the "parachute of life" for astronauts, developed by the 508 Institute of the Fifth Academy of Aerospace Science and Technology Group. The umbrella covers an area of 1200 square meters and can cover approximately three standard basketball courts if spread on the ground.
The main parachute of the 1200 square meter Shenzhou spacecraft, as the largest spacecraft parachute in China, consists of over 7000 components. The stitching of the entire umbrella is 10 kilometers long, and it takes more than ten processing personnel to work closely together for 3 to 4 months to complete. There are over 30 processing steps for the main parachute alone.
At the parachute development center of 508 Institute of Aerospace Science and Technology Group, workers hold calipers and carefully measure the size of each piece of cloth and the spacing between each pin. Each large parachute is composed of 1920 wedge-shaped small cloth pieces. Due to the high precision requirements of manned spaceflight, it cannot be processed on a large mechanical cutting machine like other parachutes, and can only be manually cut layer by layer.
From the successful launch and return of Shenzhou-1 in 1999, to the completion of China's first manned flight of Shenzhou-5 in 2003, and now the glorious return of Shenzhou-15, the parachute has not only bloomed 15 times for the Shenzhou series spacecraft, but also achieved continuous innovation and optimization. In the spacecraft missions from Shenzhou 12 to Shenzhou 15, the development of the recovery and landing subsystem batch products involved a total of 12 technical status changes in 5 categories.
On June 4th, the return capsule of the Shenzhou-15 manned spacecraft successfully landed at the Dongfeng landing site. Photo by Xinhua News Agency reporter Ren Junchuan
Multiple technologies support ground search and rescue
After the return capsule of the Shenzhou-15 manned spacecraft successfully returned to Earth's home, how to quickly find the return capsule and astronauts became the most important concern for ground search and rescue personnel.
The return module antenna network developed by the Xi'an Branch of the Fifth Academy of Aerospace Science and Technology Group is selected to connect the antenna facing above the ground through a switch after the spacecraft lands, ensuring that ground search and rescue personnel can find the return module through the antenna network.
The antenna network is responsible for establishing independent channels for communication signals, measurement and control signals, positioning signals, and search and rescue signals, ensuring their stable and smooth transmission, and building important channels and bridges for the return capsule of the Shenzhou spacecraft and ground signal transmission, effectively ensuring the safe and smooth "return home" of the spacecraft and astronauts.
China Electronics Technology Corporation (CETC) has developed the BeiDou situation system for search and recovery missions, aiming to address the challenges of a wide range of areas and difficult rescue operations. The system has been continuously iterated and upgraded, utilizing the positioning and short message functions of the BeiDou navigation system to build a command center, forward command, and search platform integrated command system.
The system can locate helicopters, vehicles and other search and rescue carriers in real time through the BeiDou Navigation Satellite, and use the short message function to send the location information to the command center in real time. Command type terminals, like "smart brains," are deployed in the command center and can receive and display real-time location information transmitted by onboard and vehicular terminals, enabling on-site command personnel to control the position and movement of search and rescue carriers in real time, and timely command search and rescue forces to move towards the landing point of the return capsule.
