How can astronauts ensure that there is enough oxygen to support life in space?

In order for astronauts to breathe fresh air in the sky, besides the oxygen we just talked about, it is also important to have carbon dioxide. Normal breathing on the ground doesn't care about carbon dioxide. Recently, the greenhouse effect has been mentioned more on environmental protection issues. In a closed space, the role of carbon dioxide is very obvious. In normal life, people constantly breathe oxygen and produce carbon dioxide. When the concentration of carbon dioxide reaches a certain level, it will affect people's life safety, so it is very important to remove the carbon dioxide exhaled by people. In order to remove moisture, we need to remove carbon dioxide now. There are also traces of harmful gases, mainly non-metallic materials, including the human body will release some very small amounts of toxic gases and harmful gases, which we must remove. For example, in a newly renovated house, the door is closed and you come in once every two days. Its smell is very strong and it keeps releasing these things, so we must get rid of it. An aircraft is equivalent to a closed room with astronauts inside. These harmful gases are constantly released, and our job is to remove them. Is to poison yourself with poison gas. It is mainly produced by nonmetallic substances, including urine and urine just mentioned, and some peculiar smells, which are also gases to be removed. The main problem is diffusion, because it is in a closed space, there is no way to open the window, and we can easily solve it on the ground. What other life support links are different from the ground? As for the oxygen used for astronauts, we are now using high-pressure compressed gas. This compressed gas, we must now have a pressure of several hundred kilograms. There is such a container, which contains several hundred kilograms of pressure gas. In this case, the security requirements are very high. As we all know, the gas tanks and oxygen cylinders used in our hospital are usually pressure vessels, and our pressure is many times higher than this pressure. Dozens of times the pressure is quite dangerous. If something goes wrong, it will explode, which is very dangerous for us. It is also very difficult for us to do these things well, which is different. We can also see that although it is two nouns and eight words, it covers some very important information and equipment related to the life of astronauts. These two words, we can also hear and understand in previous flight experiments, but in previous flights, a single flying body flew into space. The mission this time is "Ba Shen, Shenjiu, Shenshi ...", which is to dock with Tiangong-1. What are the new challenges in environmental control and life support compared with the previous tasks? For us, at present, the biggest challenge is time. Our previous spacecraft carried people from Shenzhou 5 to No.6 and No.7, and the longest flight time in orbit was five days. Judging from the current rendezvous and docking mission, Tiangong-1 will fly in orbit for two years, and the work requirements for two years are our biggest challenge. This poses a great challenge to the life and reliability of our products. We have to work in the sky for two years, especially some rotating parts. For example, if you drive a car for thousands of kilometers or months, you should maintain it. For us, there is no maintenance opportunity and we must do it at once. This is the biggest challenge. In addition, technically, there is still some assembly space. In the early days, the spacecraft had only one orbital module and one flight module. Since the rendezvous and docking mission, there has been a bigger hall here. We call it Tiangong-1 target aircraft, which is equivalent to its volume being much larger than the orbital module and the return module. Tiangong-1 target aircraft has a set of aviation life support system, and so does the spacecraft. For the rendezvous and docking mission, two aircrafts are required to complete flight support and life control in orbit. There is a problem here, that is, how to centrally control the assembly, how to use related resources, and how to control the flight mode of the assembly to the best, which we have never done before. The other is the problem of comprehensive purification just mentioned. Our flight time for microorganisms and trace harmful gases in the spacecraft is very short and not very prominent. For the two-year rendezvous and docking mission, trace harmful gases are very prominent, including microorganisms. This is the comprehensive purification we want to mention, including the carbon dioxide mentioned just now, including trace harmful gases, including microorganisms. This is the comprehensive purification problem that we should focus on in this task. There are some dust particles, and we also have a set of special equipment to remove them. We also have intermittent jobs. Shenzhou VIII was the first unmanned flight. Our Tiangong-1 has been launched for several months and has been in orbit for several months. "Shenzhou VIII" should catch up and dock. For aviation, it will change from unmanned flight of Shenzhou-8 to manned flight of Shenzhou-9, and then become unmanned flight. This intermittent flight mode used to be. In addition, for Tiangong-1, we have prepared some new technical verifications for the space station of the follow-up countries, which is an experimental platform to prepare for the follow-up tasks. It used to be a spaceship, but now there is Tiangong-1 here, which is actually equivalent to giving astronauts an extra life and work security system. But there are many such systems, which actually require a large system, and the overall arrangement and design are much more complicated. Including Tiangong-1, the return capsule and Shenzhou-9, there is a studio, a kitchen and a bedroom. When this system is big, the whole layout needs more overall design. What is the specific arrangement? From now on, before the spacecraft flies autonomously without docking, it relies on its own set of aviation life insurance to maintain the general environment, temperature, humidity, air and pressure, all of which rely on its own equipment. After docking, after the assembly is formed, the target aircraft, Tiangong-1, is taken as the main component, and the function is switched to Tiangong-1, which is the main component in aviation life support, but there is a section in the middle, that is, the flight orbital module is taken as * * *. Just now you mentioned that Tiangong-1 is used as a working cabin, a living cabin and a medical cabin, and the astronauts' main life and work are in Tiangong-1 target aircraft. However, the kitchen of life mentioned just now is actually in the orbital module of the spacecraft. We can make comprehensive use of resources and reduce the pressure on Tiangong-1 target aircraft to carry more materials and equipment. Are Tiangong-1, orbital module, return module and orbital module the smallest space? The return capsule is the smallest. There is almost no life support in the return capsule, so there is no need to do some life support work at this stage. Of course, the return capsule has its own life support system when it returns. It also has a complete system for astronauts to return to the ground.