On November 12, the Long March 7 (hereinafter referred to as the Long March 7) remote six carrier rocket, which was developed by the First Institute of China Aerospace Science and Technology Corporation, successfully put the Tianzhou 5 cargo spaceship into the scheduled orbit. On June 25, 2016, the first flight of China's new generation of medium launch vehicles was a complete success, marking the successful start of the mission of China's manned space engineering space laboratory. Over the past few years, the long seven rockets of the "five send off" have become a well deserved "freight train" in China's manned space program. From the optimization of the launch site process to the high-density launch, and then to the realization of the two-hour fast rendezvous and docking of Tianzhou spacecraft, through the continuous optimization and adjustment of the development team, the Long Seven Rocket has refreshed the "delivery" speed again and again, and the "freight train" has been upgraded to the "freight high-speed railway". "It is not only necessary to throw in, but also a beautiful hollow ball." Before the launch of this mission, Zhang Borong, the chief ballistic designer of the Long Seventh Rocket, was asked whether the rocket could be accurately put into orbit and help the Tianzhou-5 cargo spaceship to achieve a two-hour fast rendezvous and docking. His answer was confident: "If it was during the launch of the Long Seventh Remote One carrier rocket, I would not say so, but now I can tell you for sure, yes!" The high-accuracy orbit entry of the Changqi rocket is the basis for the rapid rendezvous and docking of the Tianzhou cargo spaceship and the space station assembly. In the construction phase of the space station, 11 launch missions are linked, and rendezvous and docking missions have high requirements on the accuracy of rocket launching into orbit. For the Changqi rocket, after the cargo spaceship is sent to the predetermined orbit, the period of one circle around the earth is about 5400 seconds, and the deviation of the accuracy of the Changqi rocket into orbit cannot exceed 4 seconds, which is the highest requirement for the accuracy of the launch vehicle in service in China. For this reason, the Chang 7 rocket adopts the design method of high-precision laser gyro and fiber optic gyro inertial measurement unit. During the flight, the control system can quickly plan the best flight path for the rocket; "Iterative guidance technology" can also help the rocket predict the deviation in advance, correct it in real time, and ensure the accuracy of orbit entry. After the successful launch of the Long Seven Remote Five carrier rocket, the development team received the technical requirements to perform the 2-hour fast rendezvous and docking mission. For this task, Zhang Borong described: "Before we had to shoot accurately into the basket, now we have to shoot not only into the basket, but also a beautiful hollow ball." After nearly three months of data analysis and deviation correction, the development team finally improved the comprehensive performance of the rocket systems again, and completed the task with excellent performance. "From quality to process, we should keep improving." In the early morning of May 10 this year, the Long Seven Remote Five carrier rocket was launched from the Wenchang launch site in Hainan, marking the beginning of China's space station construction. The mission impressed the members of the launch test team. "It used to be 12 hours before the launch, but my post had to work continuously for 13 and a half hours. High load continuous work is a big test for everyone's physical fitness." Chen Shan, the chief designer of the rocket gas supply system, said that thanks to the optimization of the launch site process, his on duty time was shortened by four hours. The reduction of working hours has made everyone relaxed. Also in that mission, the rocket development team carried out 17 projects including pre launch process optimization and reliability improvement