At 6:33 on June 4, 2023, the Reentry capsule of Shenzhou 15 manned spacecraft landed successfully at Dongfeng landing site, and astronauts Fei Junlong, Deng Qingming and Zhang Lu returned home safely.
As the deputy commander in chief of the China Manned Space Program, CETC has conscientiously completed the search and rescue mission of the Shenzhou 15 manned spacecraft, deployed a dense and safe measurement and control communication network, built a three-dimensional search and rescue guidance network with short, medium and long distance matching and air sea coordination, created a shining "bright eye" for the return of the spacecraft, and successfully completed the return search and rescue mission.
Return Journey "Eternal Online"
From the Reentry capsule to the re-entry orbit at variable speed, to the Service module separating from the Reentry capsule, from the Reentry capsule to the atmosphere, to the safe landing... Shenzhou 15 returns from the orbit of the space station about 400 kilometers from the ground, each step requires the relay traction of the TT&C communication system to complete telemetry and external measurement to receive and send commands, observe and analyze the position, speed and flight attitude of the Reentry capsule.
At the main landing site, CETC sets up portable stations, airborne stations, vehicle mounted stations, fixed stations and other station type and multi model satellite communication systems, weaves a dense and safe measurement and control communication network, which, like "Stethoscope", "remote control" and "mobile phones", measures the flight trajectory in real time, monitors the power supply, temperature, pressure and other parameters of the Reentry capsule and various physiological parameters of the astronauts, transmits commands sent from the ground in real time, commands the Reentry capsule to change its orbit and adjust its attitude, Real time transmission of voice and image data enables real-time communication between the ground and astronauts.
In the newly built and upgraded system, high-power amplifiers and high-speed modems have been developed, greatly improving satellite communication transmission capacity and increasing transmission capacity by 5-10 times. The Ka band satellite terminal equipment developed will transmit real-time high-definition images and multi-channel voice of the landing site back to the mission command hall via satellite at the first time, ensuring the uninterrupted transmission of audio information between Dongfeng landing site, Jiuquan Satellite Launch Center and Beijing Command and Control Center.
Breaking through the "black barrier" and stabilizing tracking
With the "End of Mountain and Sea Tracking" dispatching password sounded, it means that the Reentry capsule of Shenzhou 15 successfully passed through the "Communications blackout" and the most dangerous moment on the way back.
"When the spacecraft is in the black barrier area, all communications will be interrupted, and the ground commanders cannot command and contact them. At this time, the continuous and stable tracking of the ground measurement radar is particularly important. It can monitor the altitude, speed, attitude, etc. of the spacecraft in real time, so as to ensure the safety of the spacecraft and astronauts." CETC technical experts said that in the field of measurement and control, the continuous and stable tracking of the "Communications blackout" has also been a major problem.
Since the Shenzhou 15 Reentry capsule entered the atmosphere, the measuring radar developed by the group is like a "bright eye", which is responsible for the first point interception in the re-entry area, continuous tracking in the Communications blackout and other tasks, and accurately "sees" the flight path of the spacecraft in space.
In order to achieve higher accuracy and reliability in measurement, China Electronics Technology has upgraded and renovated multiple measurement radars at measurement and control stations such as Jiuquan, Weinan, and Taiyuan, enabling them to have precise coordinate measurement and fine imaging processing capabilities. They have innovatively adopted target detection and tracking technologies such as intelligent sheath discrimination and complex waveform design to break through the "black barrier" and provide radio wave protection for astronauts returning home