“快递”已送达，“取件人”下月报到！
5月10日1时56分，长征七号运载火箭在中国文昌航天发射场点火起飞，随后成功把天舟四号货运飞船送入太空，中国空间站建造阶段大幕正式开启。
据中国载人航天工程办公室消息，天舟四号货运飞船入轨后顺利完成状态设置，于北京时间5月10日8时54分采用自主快速交会对接模式，成功对接空间站天和核心舱后向端口。
据介绍，天舟四号货运飞船装载了神舟十四号3名航天员6个月在轨驻留消耗品、推进剂、应用实（试）验装置和样品材料、备品备件及部分载荷等物资，交会对接完成后，将转入组合体飞行段。
China's Tianzhou-4 cargo spacecraft successfully docked with the nation's orbiting space station on Tuesday to deliver supplies to its space station, which is scheduled to be completed this year.
Carried by the Long March-7 Y5 rocket, the Tianzhou-4 blasted off from the Wenchang Spacecraft Launch Center on the southern island province of Hainan at 1:56 a.m. (Beijing Time), according to the China Manned Space Agency.
Like previous cargo flights, the Tianzhou-4 carries three categories of supplies, including six-month living supplies for astronauts, spare parts for space station maintenance, and space research equipment.
“快递小哥”升级了？
“天舟”系列货运飞船是专门用于为中国空间站在轨运行提供补给的飞行器。其中，天舟四号货运飞船为全密封货运飞船，是世界上现役货物运输能力最大、在轨支持能力最全面的货运飞船。它不仅承担着为神舟十四号乘组提供物资保障任务，还肩负着空间站在轨运营支持和空间科学实验的任务。
据悉，此次天舟四号采用了快速交会对接技术，仅用了6.5小时就与空间站组合体完成自主快速交会对接。
The Tianzhou-4 cargo craft is a fully sealed cargo craft with a total weight of 13.5 tonnes. It carries 6.9 tonnes of cargo, making it the world's most capable cargo craft in service, according to China Media Group.
Li Zhihui, deputy commander of the cargo spacecraft system of the No. 5 Research Institute under the China Aerospace Science and Technology Corporation has explained the process of the docking in a previous interview with China Media Group.
Li explained that after separating from the rocket, the cargo craft moves from the perigee orbit to that of the space station by means of long-range autonomous guidance and near-range autonomous control to achieve fast-docking.
"The long-range autonomous guidance is realized through an orbital change powered by jet engine, which takes Tianzhou cargo spacecraft from a 200-kilometer-high perigee orbit to a space station orbit at 393 kilometers. Then the cargo craft enters the phase of autonomous control, where it docks with the core module after passing through four anchoring points including 5 kilometers, 400 meters, 200 meters and 19 meters away from the space station. The whole process takes 6.5 hours," he said.
包裹里都装了啥？
据了解，天舟四号装载了航天员系统、空间站系统、空间应用领域、货运飞船系统共计200多件（套）货物，包括货包货物和直接安装货物以及补加推进剂等。这些物资都将为未来的航天员在轨驻留、空间站组装建造、开展材料科学、微重力、航天医学试验等空间应用领域提供物资保障。
为确保货物安全快递到“太空之家”，天舟四号具备承担空间站姿态轨道控制、并网供电以及空间站遥测、数据传输支持等能力，支持空间站运营及科学实验。
天舟四号货运飞船系统副总设计师徐小平透露，天舟四号将在陪伴神舟十四号飞行乘组度过空间站的时光后离轨。货运飞船在空间站多驻留一段时间，这样一来，放物品、废弃物的空间就比较大，从而增大航天员在舱内活动的有效空间，保持空间站的整洁。
Tianzhou-4 is 10.6 meters long and its width reaches 14.9 meters when solar panels are fully unfolded. It consists of two parts: propelling module with a diameter of 2.8 meters and cargo storage module with a diameter of 3.35 meters.
The spacecraft has over 200 packages in more than 40 cabinets for different units.
The craft has also brought seeds, including wheat, soybean and corn varieties, collected from universities for experiments in space.
According to Li, the research team made several adjustments on Tianzhou-4 to enable the astronauts to find the packages more easily, besides expanding storage by optimizing package designs. Xu Xiaoping, deputy chief designer of Tianzhou-4 cargo craft, said that the planning will be more precise in future missions as the consumption of the propellant in this mission is used just as planned. "We can bring more packages next time" without carrying extra fuel, Xu said.
Tianzhou-4 is expected to remain with the space station till the completion of Shenzhou-14 mission.
何时有人“签收”？
今年6月，神舟十四号载人飞船将发射，3名航天员将进入中国空间站组合体，并在轨驻留6个月。在今年年内，中国空间站也将完成在轨建造。
Five more space flight missions will be carried out this year to complete the in-orbit construction of China's space station.
The Shenzhou-14 spacecraft will take three astronauts to the space station in June, stationing them in the core module for six months. The Wentian lab module will dock with the Tianhe core module in July, and the Mengtian lab module will be docked with the core module in October to complete the in-orbit construction of a T-shaped space station.