On November 23rd, China successfully launched a satellite internet technology test satellite into orbit using the Long March-2D carrier rocket at the Xichang Satellite Launch Center, and the launch mission was a complete success. The rocket and upper stage launched this time were developed by the Eighth Academy of China Aerospace Science and Technology Group, and the satellites were developed by the Eighth Academy of China Aerospace Science and Technology Group and the Institute of Microsatellite Innovation of the Chinese Academy of Sciences. The Long March-2D carrier rocket carrying out this launch mission is a two-stage liquid carrier rocket at room temperature, with the ability to launch single and multiple satellites with different orbital requirements, corresponding to a solar synchronous orbit carrying capacity of 1.3 tons at 700 kilometers. Since 1992, the Long March 2D carrier rocket has been successfully launched 84 times. Tan Xuejun, the overall commander of the Long March 2D carrier rocket, introduced that the team has carried out design innovation work for customized products such as support modules, adapters, and connection separation devices, and continuously optimized the satellite configuration layout. In order to continuously improve the reliability and mission adaptability of rockets, as well as conduct research and improvement on rockets, the model team fully utilizes the characteristics of multiple launches and loading opportunities, and installs off-orbit systems, flight mechanics measurement systems, etc. The results are used to enhance technical capabilities and product reliability. This mission is the second mission of the upper stage of the Expedition 3 after a five-year hiatus, and it is also its first mission to be carried out at the Xichang Satellite Launch Center. The upper stage of Expedition 3 has autonomous orbital maneuverability, with a flight time of about 48 hours in orbit and multiple ignition maneuvers. It can autonomously plan the optimal flight path based on the orbital state when separated from the rocket, and execute multi satellite cross orbit deployment and constellation network repair deployment in medium and low orbits. At the same time, the upper stage of the Expedition 3 adopts a modular and standardized design, which can adapt to the use of multiple launch vehicles, and can improve China's ability in quickly and flexibly entering space, space transfer, and space utilization. In order to further improve the carrying capacity of the carrier system, the upper stage of the Expedition 3 and the Long March 2D carrier rockets in this mission adopted a joint flight state for the first time, similar to the third stage of the third stage rocket. Unlike the first flight where the Long March 2D carrier rocket sent the combination of the upper stage and satellite of the Expedition 3 into a circular orbit at an altitude of 200 kilometers, the separation point of this stage rocket was a sub orbit, and it was "relayed" by the upper stage three seconds after separation, By first igniting into orbit and then igniting again to reach the predetermined orbit, when the satellite is successfully delivered to its destination, the upper level will actively control and derail through two rounds of ignition. Faced with significant changes in technological status and long product storage times, the model team has carried out more than 10 reliability improvement projects, represented by single machine upgrades of control systems. Multiple rounds of electrical performance testing have been carried out, and the test data has been compared and trend analyzed to ensure stable product performance. Under the premise of ensuring test coverage, the testing process has been continuously optimized, and the launch site process has been shortened from 43 days to 29 days. (Lai Xin She)