According to the China Manned Space Engineering Office, at 5:34 am on July 15, 2025, the Tianzhou-9 cargo spacecraft boarded the Long March 7 Y10 carrier rocket and was launched from the Wenchang Space Launch Site in China. At 8:52 am, it successfully docked with the aft port of the Tianhe core module of the space station. Tianzhou-9 is the fourth cargo spacecraft produced in the application and development stage of the space station, responsible for transporting materials for the crew of Shenzhou 20 and Shenzhou 21. After the rendezvous and docking are completed, the Tianzhou-9 spacecraft will enter the composite flight phase, and the crew of Shenzhou-20 astronauts will also enter the spacecraft to carry out related work such as cargo transfer as planned. Which space express delivery services are receiving attention? What are the technological highlights behind the rendezvous and docking? What are the future exploration directions for 'space couriers'? Experts from China Aerospace Science and Technology Corporation, China Astronaut Research and Training Center and Space Application Engineering and Technology Center of the Chinese Academy of Sciences answered these social concerns one by one. First question: Which space express delivery services are receiving attention? In this mission, the Tianzhou-9 spacecraft was loaded with astronaut in orbit consumables, propellants, application testing devices, and other materials. The weight of the materials is about 6.5 tons, setting a new record for the loading weight of materials on the space station application and development engineering cargo spacecraft. Among these materials, two new sets of extravehicular spacesuits have attracted considerable attention. According to experts from the China Astronaut Research and Training Center, after evaluation and calculation, the in orbit lifespan of the new extravehicular service will be increased from the previous "3 years and 15 times" to "4 years and 20 times". At the same time, the variety of space food transported this time is more diverse, with nearly 30 new dishes of space food added, bringing the total number of space food to more than 190, which can extend the flight recipe cycle from 7 days to 10 days. This mission also transported crew equipment such as a new in orbit core muscle exercise device, as well as materials in the field of aerospace medical experiments for astronauts. The materials for this space application system mainly include experimental payloads, experimental units, experimental samples related to scientific experiments, as well as key spare parts, application consumables, etc., with a total weight of 776.5 kilograms. According to experts from the Space Application Engineering and Technology Center of the Chinese Academy of Sciences, these materials involve 23 scientific experiments in the fields of space life science and biotechnology, space material science, microgravity fluid physics and combustion science. Question 2: What are the technological highlights behind the rendezvous and docking? The Tianzhou-9 spacecraft successfully completed its fully autonomous rendezvous and docking with the Chinese space station. This is the third 3-hour rendezvous and docking mission implemented by China after the Tianzhou-7 and Tianzhou-8 spacecraft, achieving the normalization of this mode after upgrading to the standard rendezvous and docking mode for cargo spacecraft. The entire rendezvous and docking process is controlled by the GNC (Guidance Navigation and Control) system developed by the Fifth Academy of China Aerospace Science and Technology Corporation. In terms of rendezvous and docking, China has successively verified and implemented the 2-day plan, 6.5-hour plan, 2-hour plan, and 3-hour plan in orbit. The 3-hour rendezvous and docking mode adopted by Tianzhou-9 spacecraft is the routine operation mode for Tianzhou-9 series missions in the following period. This mode is superior to the 6.5 hour mode in terms of time, and compared to the 2-hour mode, its related system requirements are more relaxed. The 3-hour mode not only reduces the requirements for rocket orbit conditions, measurement and control accuracy, sensor and navigation accuracy, guidance and control accuracy, but also enhances mission reliability. During the 3-hour rendezvous and docking, Tianzhou-9 is facing two new situations: one is to implement rendezvous and docking at a new orbital altitude; The second is the first rendezvous and docking under specific solar altitude conditions. In response to the risks and challenges brought by the new working conditions, the development team conducted extensive data analysis and simulation verification to ensure the stable operation of various systems of the spacecraft, fully verifying the high reliability of the 3-hour rendezvous and docking mode under complex working conditions. Question 3: What are the future exploration directions for "space couriers"? The Tianzhou cargo spacecraft, also known as the "space courier", is one of the currently operating cargo spacecraft with the largest cargo transportation capacity and the most comprehensive in orbit support capability internationally. Its main tasks are to transport cargo and replenish propellants for the space station, support attitude and orbit control of the space station, conduct space science experiments, and bring space station waste back to the atmosphere for burning. In addition to transporting supplies, the Tianzhou-9 spacecraft also carries two experimental payloads and will continue to conduct new space technology in orbit experiments to improve the overall efficiency of the mission. In this mission, the development team ensured that the Tianzhou-9 spacecraft had completed all development work before the launch of Tianzhou-8 spacecraft by planning the batch production process reasonably, and entered the standby state of the entire ship, with the first 3-month emergency launch capability. When the Tianzhou-9 spacecraft was launched, subsequent Tianzhou-9 spacecraft also had mission backup capabilities, further improving the safety and security of space station operations. In addition to the Tianzhou cargo spacecraft, there are currently two options available: the Qingzhou cargo spacecraft and the Haolong cargo space shuttle, which are about to enter the actual flight verification stage. With more forces joining the "space courier" team, the transportation system of space station cargo in China will be further enriched, transportation will be more flexible, and costs will be greatly reduced. (New Society)