What is the knowledge of the universe?

The space environment is very different from the earth environment. There is no air, no gravity and dangerous space radiation. The universe outside the earth's atmosphere, the whole space outside the atmosphere. Physicists divide the atmosphere into five layers: troposphere, stratosphere, mesosphere, thermosphere and outer atmosphere. Space refers to the space outside the earth's atmosphere, which is divided into troposphere (sea level to 9 kilometers), stratosphere (9-45 kilometers), mesosphere (45-80 kilometers), thermosphere (80-400 kilometers) and outer atmosphere (more than 400 kilometers). About 3/4 of the atmosphere above the earth is in the troposphere, and 97% is below the stratosphere. The outer edge of the stratosphere is the highest limit for an aircraft to fly with air support.

The space station, also known as "space station", "orbital station" or "space station", is a manned spacecraft for many astronauts to cruise, work and live for a long time. During the operation of the space station, the replacement of astronauts and the supplement of materials and equipment can be transported by manned spacecraft or space shuttle, and materials and equipment can also be transported by unmanned spacecraft.