Shenzhou XV astronauts moved into the Tiangong space station on Nov 30 as they started their six-month stay. The station orbits Earth in about 90 minutes at an altitude of 400 kilometers. The temperature changes greatly, ranging from 150 ℃ when the station is exposed to the sun to -100 ℃ when over the night side of the planet.
On Earth, we have heating systems or air-conditioners at home to keep us warm. In Tiangong, what do they have? The answer lies in the designs of thermal (热量的) control system by the China Academy of Space Technology.
The fluid loop(流体回路),with liquid circulating（循环）through its pipes, is one of the technologies used.
"Just like the blood vessels (血管) in the human body, the loop pipes run all over the station modules (舱)," Huang Lei, one of the designers of the system, told Xinhua, "They maintain a temperature balance by removing heat from the parts that tend to overheat and adding heat to other components that tend to get cold," Huang added.
For the material outside, scientists have developed a silver-colored metallic-based coating to keep a balance between the deep freeze of space and the sun's heat. It is similar to coating the spaceship with "sunscreen".
The coating can not only absorb less solar energy but also block heat release from the inside. Being able to do this double-duty job, the coating keeps the environment inside between 18 and 26 ℃, allowing astronauts to stay comfortable in their orbiting home. It was first used on the Shenzhou XIII spaceship, which was launched on Oct 16, 2021.
Cargo（货物）spacecraft adopt another kind of design -multilayer insulation (多层隔热组件). For example, the Tianzhou 4's cargo cabin was given a gray-colored material to absorb more sunlight for human activities. Another part that was filled with equipment was painted with a white material to cool off.
