“When I have money, I will build two spaceships! One is launched, the other is waiting for orders in place”

Five years later, the Long March II F carrier rocket, known as the “shen arrow”, once again carried the Shenzhou spacecraft from the 921 tower of the Jiuquan Satellite Launch Center. Low-Earth orbit once again welcomed visitors from China. Image source: Xinhua News Agency As the third mission of the space station construction phase, and also the first manned mission of this phase, Shenzhou 12’s every move is naturally very eye-catching. Compared with the predecessors of Shenzhou 9th, 10th and 11th, what are the highlights of this mission? The author is not talented, and I will sort it out from the perspective of a fan. First verification of the manned state Fast and autonomous rendezvous and docking You may still have the impression that whether it was the docking of Shenzhou 8, 9 and 10 with Tiangong 1, or the docking of Shenzhou 11 with Tiangong 2, the time interval from launch into orbit to handover and docking was one and a half days. To two days. In such a long period of time, astronauts can only move in the small (total volume of 10 cubic meters) spacecraft return module and orbital module, and the comfort is obviously not very good. Everyone can think about it in another way. Would you like to sit for a day and a half in a seat smaller than an economy class seat on an airplane? In order to solve this problem, this flight will verify the rapid rendezvous and docking in the manned state for the first time. The time from launch to rendezvous and docking has been drastically reduced from one and a half days to 6.5 hours . In other words, when the rocket is launched at more than nine o’clock in the morning, the first three astronauts can enter the core module of Tianhe at six o’clock in the afternoon, which greatly improves the comfort of the astronauts on the spacecraft. Shenzhou 12 rendezvous and docking process with core cabin丨CCTV News In order to achieve the goal of rapid rendezvous and docking, the flight control accuracy of the space station and the spacecraft needs to be greatly improved (the orbit of the space station also needs to be adjusted). Although the difficulty of control has been greatly increased, the astronauts should be confident in their hearts. The Tianzhou-2 cargo spacecraft launched on May 29 this year successfully implemented the rapid rendezvous and docking technology for the first time. As for this Shenzhou 12 mission, it is the first time that this new technology has been practiced in a truly manned state. In addition, since the previously launched Tianzhou-2 spacecraft has already occupied the backward docking interface of the Tianhe core module (Tianzhou is responsible for maintaining the orbital height of the space station, so the preset docking position is backwards), this time Shenzhou 12 The spacecraft was docked at the forward docking port of the Tianhe core module after completing a space somersault. This is also the first time that China Aerospace has achieved a three-cabin/ship combined flight . Although the “space somersault” sounds very thrilling, the relevant procedures have actually been verified close to actual combat conditions in the Tianzhou-1/Tiangong-2 missions four years ago. This is also another example of the “small steps and fast running” tactics in my country’s aerospace field. Figure丨Our space To put it aside, the technology of rapid rendezvous and docking has been the secret book of Russia and the United States, the two time-honored manned spaceflight names. In recent years, only the Russian Soyuz spacecraft has practiced this operation. This time China successfully realized the rapid manned rendezvous and docking, It also marks that China’s manned space system’s round-trip transportation level is no less than that of today’s International Space Station. . Dongfeng Landing Field was opened for the first time Another highlight of this mission that deserves special attention is that The Dongfeng Landing Field will be used for the first time when the flight crew returns . The Dongfeng Landing Site is located near the Jiuquan Satellite Launch Center, also known as the Dongfeng Base. The surrounding landforms are dominated by Gobi deserts and deserts, and there are also a small part of mountainous hills. The terrain is flatter than the Siziwangqi landing site. . In fact, since the Shenzhou-1 spacecraft, the Dongfeng Landing Field has been on standby as a backup landing field. However, as each flight mission went smoothly, the Dongfeng Landing Field had never been put into operation until 2016. In other words, 13 spacecraft, including the return capsule of the Shenzhou 1-11 spacecraft and two Chang’e project returners, all landed at the Siziwangqi landing site in Inner Mongolia. A new generation of manned spacecraft lands at Dongfeng Landing Site in May 2020丨Chinanews.com Because the new generation of manned spacecraft has a higher level of flat terrain, the main landing site of the new generation of manned spacecraft was selected at the Dongfeng landing site. The 2016 new manned spacecraft scaled return cabin and the 2020 landing of the new manned spacecraft test ship return cabin are the only two records of the Dongfeng landing site that have been put into actual use. However, because they are not manned missions, many personnel and equipment related to astronaut support have not been fully tested. The use of the Dongfeng Landing Field as the main landing field this time is believed to have the significance of actual combat training. After this mission, the dual landing sites of Dongfeng and Siziwangqi will be hot backup at the same time, which may become the norm. With two landing sites, the astronauts’ emergency return capabilities will be better guaranteed. In addition, since the Shenzhou 11 spacecraft deviated from the theoretical landing point by tens of kilometers when it returned, the return control system of the Shenzhou 12 spacecraft has also undergone some improvements compared with the previous Shenzhou spacecraft. Since then, the Shenzhou spacecraft has the ability to return to Earth from any orbital altitude between 330 kilometers and 420 kilometers. With the blessing of these new technologies, it can be expected that this mission may also achieve excellent results of the Chang’e-5 umbrella with an accuracy of 100 meters. Comprehensive emergency rescue capabilities Starting from Shenzhou 12, China’s manned spaceflight missions will begin normal operations. As the flight time in orbit increases (3-6 months per mission), the probability of unexpected situations requiring emergency evacuation will also increase. In order to ensure the safety of astronauts under all circumstances, Starting from Shenzhou 12, the emergency rescue capabilities of manned missions have also been fully upgraded . In addition to the opening of the Dongfeng landing site mentioned above, this mission also deliberately prepared an emergency rescue ship-Shenzhou 13. Unlike the past, during this mission, Shenzhou 12 and 13 spacecraft entered the launch site for testing at the same time. Simultaneously with the launch of Shenzhou 12, Shenzhou 13 and its mount Long March 2 F rocket have also been basically debugged, with an emergency launch capability of 8.5 days. In other words, if during the three-month flight, Shenzhou XII is hit by space debris and cannot guarantee the safe return of the astronauts, Shenzhou XIII will be able to take off in less than 10 days. The space station docked and picked up our flight crew from Tiangong. Of course, the probability of this happening is very small, but such a great effort to deal with such a small probability event is enough to reflect the fine tradition of “serious, thoughtful, reliable, reliable, and foolproof” of our astronauts from the side. After the start of the Shenzhou 12 mission, the construction of the Chinese space station will enter the hottest stage. The highlights during this period will naturally emerge in endlessly! Stay tuned for follow-up news reports! Let us wish the Shenzhou 12 mission and the construction of the Tiangong space station all the best! Produced by: Popular Science China Production: Tan Pu Producer: Computer Network Information Center, Chinese Academy of Sciences (The pictures with the source indicated in this article have been authorized)