Why do astronauts need spacesuits?

Astronauts flying in space and in the earth's atmosphere are completely different flight environments. Space belongs to a vacuum environment. In order to protect the life and working ability of astronauts, people must wear spacesuits specially designed for them. Space suit is actually an astronaut's personal airtight equipment. Wearing a spacesuit can not only prevent the harm of various environmental factors in space, such as low pressure or vacuum, hypoxia or hypoxia, high and low temperature, solar radiation, meteoroids and so on. Moreover, in the space and vacuum environment, the oxygen contained in the blood in the body can also be turned into gas, thus expanding in volume. If you don't wear a spacesuit, you will be life-threatening because of the disparity in air pressure between inside and outside. The spacesuit worn by astronauts is a kind of multifunctional clothing gradually developed on the basis of the pilot's closed suit (also called full pressure suit).

Astronauts not only have to move inside the cabin, but also outside the cabin, so the current spacesuits are all liquid-cooled structures. The spacesuit developed after 1970s still has quite good activity performance under high pressure, and astronauts can enter space directly from the cockpit without oxygen inhalation and exhaust.