For the first time, the fast return mode was adopted, faster and more comfortable - "God Thirteen" went home like this

Draft: Wang Zheping

On the morning of April 16, the Shenzhou 13 manned spacecraft return capsule successfully landed at the Dongfeng landing field, and the Shenzhou 13 astronauts Zhai Zhigang, Wang Yaping, and Ye Guangfu, who were called "feeling good" crews, ended their "space business trip" and returned to the earth after a six-month absence, bringing a successful end to the mainland's longest space manned flight so far.

The return of the Shenzhou 13 manned spacecraft for the first time adopts a fast return mode, enabling astronauts to return to the ground faster and more comfortably. To this end, scientific and technological personnel have made a careful design and guarantee.

The time required to return is reduced from 11 flight laps to 5

The Shenzhou XIII manned spacecraft is not only the spacecraft with the longest stay in orbit on the mainland at present, but also the spacecraft with the fastest return speed.

According to experts, the return technology of manned spacecraft is the key and necessary technology for the construction of the space station, which is related to the success or failure of the mission and the safety of astronauts' lives. The implementation of the rapid return is to further improve the efficiency of the return mission, shorten the implementation time of ground flight control, and improve the comfort of astronauts' return.

Compared with the Shenzhou XII manned spacecraft, the rapid return did not have much technical upgrade or change, and still adopted the intelligent adaptive prediction guidance method. However, the technicians of the Fifth Academy of China Aerospace Science and Technology Corporation have reduced the time required for return from the previous 11 flight circles to 5 flight circles by reasonably cutting and adjusting the mission events and compressing the operation time.

After the Shenzhou 13 spacecraft was evacuated from the space station, it first made five flights around the earth, each of which took about 1.5 hours. Previously, the Shenzhou XII manned spacecraft returned around the earth 18 times, which lasted more than a day.

The first rapid return puts higher demands on the search and rescue capabilities of the landing field. Dongfeng landing field is located in the east of Dongfeng Space City, located in the northwest inland Gobi depths, the area is vast, sparsely populated, is the spacecraft return search and rescue natural landing site. However, the search area of the landing site is tens of thousands of square kilometers, and there are a variety of terrains and landforms such as Gobi, desert, saline land, and water areas, which are difficult to search and span a wide range. To this end, the Shenzhou No. 13 search and rescue and recovery team put into the drill early, gathered the search and rescue air detachment, ground detachment, medical supervision and medical insurance and other forces, and added a number of new intelligent equipment in the search and rescue recovery air and ground detachments to ensure the high efficiency of search and rescue recovery.

Safe return to control 3 "degrees"

The return of the Shenzhou 13 manned spacecraft to the earth can be said to be a complex and thrilling process, and it must go through key links such as orbital return separation, pushback separation, re-entry into the atmosphere, crossing the black barrier area, opening the parachute, and landing the reverse thrust engine, and the return process must also undergo the test of the harsh space environment and orbital conditions. Through the control of 3 "degrees" by scientific and technological personnel, the Shenzhou 13 spacecraft finally landed steadily.

Speed control should be just right. The speed of the Shenzhou spacecraft in orbit is about 7.8 km / s, close to the first cosmic speed. At such a fast speed, to ensure the safety of astronauts, it is necessary to control the final landing speed after returning to Earth. In order to achieve this goal, the technical personnel of the Fifth Academy of China Aerospace Science and Technology Corporation carried out a large number of test verification and data interpretation in the development stage of the spacecraft to ensure that the speed of the spacecraft was gradually reduced during the landing process and to ensure the smooth re-entry of the spacecraft into the atmosphere. After that, after the return capsule enters the atmosphere, it relies on the resistance and lift generated by aerodynamics to slow down, open the parachute when moving near the ground, further reduce the speed, and open the landing reverse thrust engine at the bottom of the return capsule at the landing moment, thereby reducing the landing speed to a certain range.

The temperature control should be moderate. When the return capsule enters the atmosphere, it rubs violently with the air, and the local temperature on the surface of the capsule can reach thousands of degrees Celsius. In order to ensure that the temperature in the cabin is still comfortable, the main means of temperature control of the spacecraft is to rely on the heat-proof structure to protect the cabin. The researchers of the Fifth Academy of China Aerospace Science and Technology Group designed a heat-proof coating on the surface of the cabin, and a layer of ablative material was applied, and when the temperature reached a certain level, the ablation material sublimated and fell off, taking away a lot of heat, thereby reducing the temperature.

In addition, the accuracy of the return landing of the Shenzhou spacecraft is extremely high, and in order to make the return capsule land in the designated area, the accuracy of the landing site of the spacecraft must be controlled. Technicians from the Fifth Academy of China Aerospace Science and Technology Corporation (CSTC) controlled the speed, angle and direction of Shenzhou 13 during its flight to finally land at the intended location.

The "black barrier zone" is a heart-wrenching journey of the spacecraft's return capsule into the atmosphere. When the return capsule enters the atmosphere, it violently rubs against the surrounding air to form a high-temperature and high-pressure ionized gas layer, which is wrapped around the surface of the return capsule, isolating the communication between the return capsule and the ground measurement and control station, forming a communication black barrier area. Once there is a problem, it will deviate the return capsule from the scheduled landing area, delay the timely search and rescue of the return capsule, and in serious cases, endanger flight safety.

In order to solve the problem of tracking and measuring in the black barrier area, the scientific and technological personnel of the Second Academy of China Aerospace Science and Industry Group used the radar developed by themselves to track and measure from the time the Shenzhou 13 spacecraft entered the atmosphere.

The spacecraft withstood the stability test of 10 months and completed the mission well

The Shenzhou series of spacecraft is a life boat for astronauts to realize the round-trip between heaven and earth, and is developed by the Fifth Academy of China Aerospace Science and Technology Corporation. As the second manned spacecraft launched during the key technology verification stage of the Chinese space station and the Longest-stayed Shenzhou spacecraft, it has achieved several firsts in the Shenzhou XIII manned mission.

For example, because space station assemblies have different configurations, spacecraft that come to visit the space station will have different docking states when they dock. During the 6-month space residency, Shenzhou 13 verified the reliability of different rendezvous and docking states through radial rendezvous docking and separation with the space station, and the radial rendezvous and docking technology was verified for the first time.

In fact, the Shenzhou XIII manned spacecraft also completed the first emergency rescue launch standby mission. In order to cope with the failure of the spacecraft docked in orbit and cannot return, the space station mission phase for the first time established an emergency rescue mission mode, using the "rolling standby" strategy, that is, when the first manned spacecraft is launched, the latter manned spacecraft is on standby at the launch site, and the safety of astronauts in orbit is jointly ensured by the spacecraft docked in orbit and the launch site standby spacecraft. That is to say, when Shenzhou XII was launched, Shenzhou XIII was already on standby at the launch site, and from its launch to the present, it has actually been tested for 10 months of stability.

Source: People's Daily

Guangzhou Daily New Flower City Editor: Zhang Ying