Welcome home! What innovative technologies will help Shenzhou 15 return home?

On June 4, the return capsule of the Shenzhou XV manned spacecraft successfully landed at the Dongfeng landing site. Astronauts Fei Junlong, Deng Qingming and Zhang Lu all exited the capsule safely and smoothly. The Shenzhou XV manned flight mission was a complete success.

In this mission, what innovative technologies will escort Shenzhou 15's return journey?

On June 4, the return capsule of the Shenzhou 15 manned spacecraft successfully landed at the Dongfeng landing site. Photo by Xinhua News Agency reporter Lian Zhen

“In the sky and underground” ensures the high-precision return of the spacecraft

For the Shenzhou series of spacecraft, the return and reentry GNC technology is directly related to the life safety of astronauts. With the success of this return mission, my country's GNC system, which has been fully upgraded since the Shenzhou XII manned spacecraft and features autonomous rapid rendezvous and docking, and autonomous adaptive predictive reentry and return guidance, has completed a comprehensive upgrade.

my country's spacecraft return and reentry GNC technology has gone through two generations. The first generation is called "standard ballistic adaptive guidance method", while the Shenzhou XII to Shenzhou XV batch of manned spacecraft use "adaptive prediction guidance method", which is the second generation of return and reentry technology. In addition, the application of my country's "starlight-satellite constellation-strapdown inertial integrated navigation" technology enables the Shenzhou XV manned spacecraft to achieve high-precision autonomous navigation throughout the return process.

"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 the manned spacecraft system of the Fifth Academy of China Aerospace Science and Technology Corporation. If the first-generation technology is used, when there are large-scale changes in orbital conditions, manual intervention is required on the ground; if the second-generation technology is used, the GNC system can adapt autonomously and can achieve a series of "stronger" and "better" results.

In addition, at the main landing site, China Electronics Technology Group Corporation has deployed portable stations, airborne stations, vehicle-mounted stations, fixed stations and other types of stations and multi-model satellite communication systems to weave a dense and secure measurement and control communication network. Like a "stethoscope", "remote control" and "mobile phone", it measures the flight orbit in real time, monitors the power supply, temperature, air pressure and other parameters of the return capsule and the various physiological parameters of the astronauts, transmits commands issued by the ground in real time, commands the return capsule to change orbit and adjust its attitude, and transmits voice and image data in real time, allowing the ground to communicate with astronauts in real time.

On June 4, 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 Big Umbrella" protects the spacecraft to land safely

When the return capsule of the Shenzhou 15 manned spacecraft was about to fall to the ground, a large red and white parachute bloomed as promised, guarding the return capsule to slowly float down and land steadily. This extra-large parachute is the "life umbrella" of astronauts. It was developed by the 508th Institute of the Fifth Academy of China Aerospace Science and Technology Corporation. The canopy area is 1,200 square meters. If it is spread out on the ground, it can cover about three standard basketball courts.

The 1,200-square-meter main parachute of the Shenzhou spacecraft is the largest parachute in China and is made up of more than 7,000 parts. The entire parachute has a 10-kilometer-long seam, and it takes more than a dozen processing personnel to work closely together for 3 to 4 months to complete. There are more than 30 processing steps for the main parachute alone.

At the parachute research and development center of the 508th Institute of the Fifth Academy of China Aerospace Science and Technology Corporation, workers use calipers to carefully measure the size of each piece of cloth and the spacing of each stitch. Each large parachute is made up of 1,920 wedge-shaped small pieces of cloth. Because manned spaceflight requires high precision, it cannot be processed on a large mechanical cutting machine like other parachutes, and can only be cut manually, layer by layer.

From the successful launch and return of Shenzhou-1 in 1999, to the completion of my country's first manned flight of Shenzhou-5 in 2003, to the glorious return of Shenzhou-15 today, parachutes have not only been used 15 times for the Shenzhou series of spacecraft, but also achieved continuous innovation and optimization. In the missions of the Shenzhou-12 to Shenzhou-15 spacecraft, the development of the recovery and landing subsystem batch products involved 12 technical status changes in 5 categories.

On June 4, 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 help ground search and rescue

When the Shenzhou 15 manned spacecraft's return capsule successfully returned to home Earth, how to quickly find the return capsule and the astronauts became the top concern of ground search and rescue personnel.

The return capsule antenna network developed by the Xi'an Branch of the Fifth Academy of China Aerospace Science and Technology Corporation will 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 capsule 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, building an important channel and bridge for signal transmission between the Shenzhou spacecraft's return capsule and the ground, and effectively ensuring the spacecraft and astronauts' safe and smooth "return home."

In order to address the difficulties of the wide search and recovery mission area and the great difficulty of rescue, China Electronics Technology Group Corporation has developed the Beidou situational system for the recovery area and continuously upgraded it, using the Beidou navigation system's positioning and short message functions to build a three-in-one command system consisting of a command center, front command, and search platform.

The system can locate rescue vehicles such as helicopters and vehicles in real time through Beidou navigation satellites, and use the short message function to send the location information to the command center in real time. The command terminal is like a "smart brain" and is deployed in the command center. It can receive and display the location information sent back by the airborne and vehicle-mounted terminals in real time, so that the on-site commander can control the location and movement of the rescue vehicle in real time and command the rescue force to move to the landing point of the return capsule in a timely manner. (Reporters Song Chen and Wen Jinghua)