Core Points - The Shenzhou 21 manned spacecraft achieved a significant milestone by completing a 3.5-hour rendezvous and docking with the Tianhe core module of the Chinese space station, marking a breakthrough in China's autonomous rapid rendezvous technology [1][2] - This achievement reflects a major evolution in China's docking technology, transitioning from the initial 44-hour docking with Tiangong-1 to a standard of 6.5 hours, and now to the current 3.5 hours [1][2] Summary by Sections Technological Advancements - The reduction in docking time was achieved by decreasing the number of orbits from 3 to 2 during the remote guidance phase and shortening the initial distance in the close-range guidance phase [2] - The GNC (Guidance, Navigation, and Control) system plays a crucial role in managing the entire docking process, from launch to docking and return, by processing vast amounts of data for precise decision-making [3] Energy Management - The rapid docking mode presents new challenges for the spacecraft's power distribution system, requiring quick maneuvers and adjustments that demand reliable energy supply [3] - Upgrades to the power distribution system allow the solar panels to quickly orient towards the sun, ensuring stable energy conditions and enhancing mission reliability [4] Mission Flexibility - The new docking mode eliminates previous constraints on launch windows related to solar panel angles, significantly improving mission planning flexibility and overall reliability [4]