Where does the oxygen that astronauts breathe come from and where does the carbon dioxide go?

There are three sources of oxygen that astronauts breathe:

1. Astronauts carrying pure oxygen cylinders will carry some oxygen cylinders before flying into space. Oxygen cylinders are filled with pure oxygen, which can ensure that astronauts have sufficient oxygen supply when they are in space. Therefore, astronauts don't have to worry about lack of oxygen when they are in space. After all, oxygen is the basic condition for astronauts to live in space.

Second, the method of electrolyzing water can produce oxygen and hydrogen by electrolyzing water. Oxygen can be used for astronauts to breathe, and hydrogen can also be used as fuel. Therefore, this method is also a main way for astronauts to provide oxygen in space, but the electrolytic reaction definitely needs the space station to provide energy, and the oxygen produced is limited. The efficiency of electrolysis of aquatic oxygen is not particularly high, and it will also cause energy consumption when producing oxygen.

Third, the solid oxygen generator In fact, this device uses chemical reactions to generate oxygen, rather than directly carrying oxygen. When the alkali metal in the device comes into contact with water, it will produce oxygen, and the biggest advantage of this device is that the carbon dioxide released by astronauts can be absorbed during the reaction. Therefore, using this reaction to produce oxygen is also a way to supply oxygen in space.

Because when the second method is adopted, if the space station can't provide energy and the solar cell fails, the process of electrolyzing water can't be completed, so the solid-state enterprise generator has become the main method of oxygen production. Astronauts will definitely not use only one method to make oxygen in space, and there must be alternatives to avoid accidents.

Carbon dioxide released by astronauts in space will also be absorbed through chemical reactions. Generally, substances such as potassium hydroxide or lithium hydroxide are used for peroxide reaction to absorb carbon dioxide, thus reducing the concentration of carbon dioxide in the space capsule.