Recently, the Shenzhou 13 manned spacecraft was successfully launched and completed radial rendezvous and docking with the Tianhe core module of the Chinese space station. Three Chinese astronauts Zhai Zhigang, Wang Yaping and ye Guangfu entered the core module and started a six-month space life. The Chinese space station has welcomed the second batch of visitors from "Hometown", opening the era of long-term residence. In the twinkling of an eye, the Shenzhou 13 mission has been going on for more than ten days. Throughout China, the "capture" of the space station in the night sky has become a new fashion for many astronomy lovers. In space, Chinese astronauts will also carry out extravehicular activities, space science experiments and technology experiments during their stay. Radial rendezvous and docking jump "space waltz" The rendezvous and docking between Shenzhou 13 and Tianhe core module is the first radial rendezvous and docking implemented by Chinese manned spacecraft in space, that is, rendezvous and docking with the space station through the interface below Tianhe core module. Why radial rendezvous and docking? Sun Jun, chief mission engineer of the space station of the Beijing space flight control center, said that when the astronauts rotate in the later stage, two spacecraft will dock with the space station at the same time, and radial rendezvous and docking can improve the channels and means of entering the space station. Previously, Tianzhou II, Shenzhou XII and Tianzhou III spacecraft were docked forward or backward. During docking, the core module and the spacecraft are "connected into a line". After docking, Shenzhou 13 is vertical to the core module. At present, the Chinese space station has realized the operation of four aircraft combinations, including the core module, two cargo spacecraft and one manned spacecraft. According to experts, the engine, control system and sensor of Shenzhou spacecraft are specially designed for all-round docking with the space station. Only Shenzhou spacecraft can conduct radial rendezvous and docking with the space station. Although the radial docking direction has only changed by 90 degrees, the difficulty of "space waltz" is not small. During forward and backward rendezvous and docking, the spacecraft has a 200m holding point. Even if the engine does not work, the spacecraft can maintain a stable attitude and orbit for a long time. However, there is no stable midway docking point for radial rendezvous, which requires continuous control of spacecraft attitude and orbit, resulting in large propellant consumption and difficult fault handling. In the process of radial rendezvous, the spacecraft needs to make a wide range of attitude maneuvers from horizontal flight to vertical flight. This puts forward higher requirements for the sensor of the spacecraft. Like the "eyes" of a spacecraft, the sensor must have high ability to identify targets and not be disturbed by complex illumination changes. The whole process of radial rendezvous and docking of Shenzhou 13 was completed by the spacecraft intelligently and independently under the command of the guidance, navigation and control (GNC) system. According to experts, in the future manned rendezvous and docking mission of the space station, radial rendezvous and forward rendezvous will be used alternately. The successful implementation of the first radial rendezvous and docking is inseparable from several years of technical research and ground experiments by the Shenzhou spacecraft development team of the Fifth Academy of China Aerospace Science and Technology Corporation. In order to adapt to different configurations of the space station assembly and different docking states of visiting spacecraft, the development team designed new rendezvous paths and fly around modes, and added various functions of fly around, rapid rendezvous and docking and radial rendezvous and docking. More than a month ago, the Shenzhou 12 and space station assembly completed flying around and radial rendezvous tests, which laid a technical foundation for the Shenzhou 13 mission. Robot task upgrade "space class" continues to open In the Shenzhou 12 mission, the "all-round" core module manipulator has become the focus of attention from all walks of life. Through two extravehicular activities, Shenzhou 12 mission first tested the ability of astronauts and mechanical arms to work together and the reliability and safety of supporting equipment related to extravehicular activities. In the Shenzhou 13 mission, the manipulator is still one of the "protagonists" of the mission. Lin Xiqiang, spokesman for China's manned space engineering and deputy director of China's manned space engineering office, said that the main purposes of Shenzhou 13's mission include carrying out key technology tests for the assembly and construction of the space station, such as manipulator assisted cabin transposition and manual remote operation; Carry out 2-3 outbound activities, install double arm combined adapters and suspension devices of large and small manipulators, and prepare for the subsequent construction tasks of the space station. Zhou Jianping, chief designer of China's manned space engineering, said that the tasks undertaken by the manipulator will be more complex in the future. For example, after the space station is built, if the solar panels of the core module need to be put away, it needs the cooperation of astronauts and mechanical arms. Shenzhou 13 is the longest manned flight in China so far. It will assess and verify the long-term on orbit dwell capability of the space station mission astronauts for the first time. Lin Xiqiang said that the six-month stay in orbit is the normalized stay cycle of astronauts and crew during the operation of the space station. To this end, the Shenzhou 13 mission will further verify the health, life and work support technology of astronauts staying in orbit for six months. Lin Xiqiang said that the Shenzhou 13 mission will conduct a comprehensive assessment of the health status of astronauts every month according to the physical and mental characteristics of different periods and individuals. According to the evaluation results, timely adjust the astronauts' weightlessness protection exercise program, astronauts' nutritional catering program and psychological support activities. At the same time, for female astronauts to participate in flight missions, focus on targeted design from the aspects of life security and health security, so as to ensure long-term flight, healthy life and efficient work of female astronauts. Carrying out scientific experiments in space is also one of the main missions of the space station. The Shenzhou 13 mission will carry out scientific and technological experiments and applications in the fields of aerospace medicine and microgravity physics. It can be predicted that in the next work, China space station is expected to obtain a large number of scientific research data from different fields and produce high-level scientific achievements. In the Shenzhou 10 mission in 2013. Astronaut Wang Yaping once conducted a new "space teaching", 60 million primary and secondary school students in the country took classes on the ground, and the "space class" received a warm response. Following Shenzhou 13 into the space station, Wang Yaping will continue to start classes. Lin Xiqiang said that as a national space laboratory, the space station contains unique and extremely rich popular science education resources. The Chinese space station is not only a research platform for global scientists to carry out space science, space technology and space applications, but also a practical platform to encourage young people to love aerospace, participate in exploration and pursue science. To this end, the mission has planned more forms of popular science education activities. The third module assembly of the space station will be completed by the end of next year Shenzhou 13 mission is the sixth mission in the key technology verification stage of the space station, and it is also the "closing battle" of this stage. Subsequently, China's manned space project will be fully transferred to the construction stage of the space station. Lin Xiqiang introduced that during the construction phase of the space station, a total of six missions were planned to be implemented - first, the Tianzhou 4 cargo spacecraft was launched to transport supplies and prepare for the subsequent Shenzhou 14 manned mission; During the stay in orbit, the Shenzhou 14 crew will successively launch the sky asking experimental module and the dreamtime experimental module to dock with the sky and core module for segment transposition. By the end of 2022, China will complete the construction of the three module assembly of the space station, and then implement the cargo supply of Tianzhou 5 and the manned flight of Shenzhou 15. The Shenzhou 15 crew will carry out on orbit rotation with the Shenzhou 14 crew. After a comprehensive assessment of the status of the space station, it will be transferred to the application and development stage of the space station. Subsequently, China will also choose an opportunity to launch the sky survey space telescope, share orbit with the space station, fly independently for a long time, carry out sky survey observation, and stop at the space station for short-term replenishment, maintenance and upgrading. Zhou Jianping introduced that the resolution of the Sky Survey Telescope is equivalent to that of the Hubble telescope, but the field angle of view of the Sky Survey Telescope is more than 300 times larger than that of the Hubble telescope, which is of great interest to many international scientists. "We have been promoting this work. We will open up scientific facilities and welcome more scientists to cooperate." Lin Xiqiang said that China welcomes astronauts from other countries to enter the Chinese space station and carry out international cooperation. It is believed that after the construction of the Chinese space station is completed and enters the stage of operation and application development, you will see astronauts from other countries participate in the flight mission of the Chinese space station. Lin Xiqiang said that the completion of the Chinese space station will provide a better platform for broader international cooperation, including joint astronaut flights. At present, many countries and regions have expressed their willingness in this regard. Sino foreign cooperation in astronaut selection and training has been carried out. For example, Chinese astronauts went to Russia to participate in training. For another example, ye Guangfu, an astronaut of Shenzhou 13, participated in the cave experiment organized by ESA in 2016, and European astronauts also participated in the maritime life-saving training organized by China in 2017. (reporter Liu Yi) (outlook new era)