Space college immigrants

Oxygen is an essential gas for most living things on earth. When astronauts go into space, it will be a vacuum environment, not to mention oxygen, water vapor, carbon dioxide and nitrogen.

In this case, how should astronauts provide oxygen for themselves? Some people will say that, just like divers, oxygen can be mixed with other gases, then compressed and brought up in the form of storage tanks.

But don't forget that divers usually go into the water for two hours, and astronauts are likely to stay on it for the first half of the year. An astronaut needs 550 liters of oxygen a day, which is 90 thousand liters of oxygen in half a year. And sometimes there are three astronauts on board, and it takes 1650 liters a day, and the amount of 180 days is very huge. Just carrying oxygen up will consume a lot of space and load of the capsule.

It is necessary to know that the load of the spacecraft is limited, and it carries either priceless detectors or daily necessities, and the volume cannot exceed a certain range. So where does the astronaut's oxygen come from?

Oxygen is a simple substance, consisting of two oxygen atoms, with a relative molecular mass of 32, which is theoretically heavier than air. Oxygen atoms have existed since the birth of the earth, but oxygen is not.

In the early days, the earth's atmosphere was weak, and the sun's ultraviolet rays irradiated the primitive ocean, and water molecules were decomposed into hydrogen and oxygen. In the early days, there was no magnetic field on the earth, so the two gases could not combine. They finally escaped from the earth and floated into space. Even though the earth is rich in oxygen, there is no trace of oxygen in the air.

About 3.2 billion years ago, a group of life called cyanobacteria used water as the raw material of photosynthesis to extract hydrogen from it. Water molecules consist of two hydrogen atoms and one oxygen atom. Cyanobacteria don't use oxygen, so for every water molecule they use, they get one more oxygen atom.

Soon, free oxygen atoms appeared on the earth at that time, and two two combination formed oxygen. At first, it was nothing at all. The earth is full of reducing agents, iron is bivalent, and the most abundant hydrogen sulfide gas in the air can be oxidized by oxygen. So there was oxygen at that time, but it was quickly reduced to atoms.

But the resources of the earth are limited, iron will be completely oxidized one day, and hydrogen sulfide will be consumed one day. In this way, for 654.38 billion years, cyanobacteria have been produced day and night, crushing all the reducible forces on the earth's surface, and oxygen appeared in the atmosphere for the first time.

However, life on earth has never inhaled oxygen. Everyone is an anaerobic creature. Suddenly oxygen came and they didn't adapt. Many organisms die from oxygen produced by cyanobacteria, including cyanobacteria itself.

However, life always finds a way out. Some life has adapted to aerobic life. They evolved aerobic respiration, using oxygen to decompose organic matter and gain energy. For the first time, life can gain energy without the direct help of the sun. Since then, a group of life has given up photosynthesis and lived in this way.

The ancestors of plants and animals began to go their separate ways at this time. Oxygen has also become an indispensable substance for this group of aerobic offspring. The higher the life, the more aerobic breathing is needed. Nowadays, many enzymes in multicellular organisms participate in aerobic respiration, mainly decomposing carbohydrates and other organic substances to provide energy for the body. Humans can't live without oxygen.

As the most advanced life on earth, human beings naturally cannot do without oxygen. When astronauts go to the vacuum universe, oxygen is the key consideration. Early oxygen was indeed provided by compressed oxygen cylinders, but a tragedy made people reconsider the use of oxygen in space.

Apollo 1, the pioneer of the American lunar exploration program, had an accident, and three astronauts were burned alive in the space capsule. After investigation, it was found that there was something wrong with the circuit, which caused a spark. Because the spacecraft has a pure oxygen tank, a little flame will cause a raging fire, so the fire spread and burned the entire space capsule, and the astronauts were killed in high temperature and smoke.

Afterwards, some engineers suggested that the risk factor of carrying pure oxygen in space is too high, because pure oxygen is a good combustion improver. Originally, space is a vacuum, even if it is on fire, it doesn't matter, but if the fire happens to be an oxygen tank, then the whole spaceship will become a sea of fire.

Moreover, human beings need a lot of oxygen a day, and there will be many astronauts on it at a time. If the oxygen storage tank is used, the load of the whole spacecraft will be great, and the manufacturing cost and launch difficulty will also increase. For the sake of safety and cost, people use the characteristics of water energy to decompose oxygen to make oxygen in space, so there is no need to worry about accidents caused by excessive oxygen inhalation.

The fastest way to decompose water is electrolysis, which consumes electricity. The spacecraft is equipped with solar panels, which can generate electricity independently, and oxygen and hydrogen can be obtained by decomposing the generated water. The volume ratio of oxygen and hydrogen produced by water electrolysis is 1:2. Hydrogen is a combustible gas, which will explode and be more restless than oxygen.

So how to deal with hydrogen? Straight into space? Of course not. Hydrogen reacts with carbon dioxide exhaled by people to generate methane and water, which can be returned to the oxygen production system to realize circulation, and methane can be directly discharged into space, so don't worry.

Will methane pollute space? The answer is no, this substance itself exists in space, but it is stored in solid form because the temperature is too low. The amount of methane emitted by humans is the amount of space in front of 9 Niu Yi hairs. With this oxygen-making equipment, human beings no longer need to carry a lot of compressed pure oxygen into space, but directly bring water.

A liter of water can decompose more than 600 liters of oxygen, and astronauts only need 550 liters. In this way, three astronauts only need to decompose 2 liters of water every day to maintain their lives.

In space flight, water is packed in a big bag with a capacity of 20 liters, which is enough for three astronauts to live for 22 days. Half a year, * * * is 180 days, and it takes about 8 water bags, which is much smaller than the space occupied by pure oxygen.

Of course, there must be more than this amount of water to carry at a time. In addition to oxygen production, astronauts also need water for drinking, testing and maintenance, so the amount of water they bring with them every time they perform a task far exceeds the amount needed for oxygen production.

Although the amount is sufficient, the astronauts can't give up any drop of water. The water vapor they exhale, the sweat evaporated from the skin and the water in the excrement will be recycled. The whole capsule is a water circulation system, and no water molecule can escape from this system and make the best use of it.

In addition to water circulation, the space capsule will also carry out nitrogen circulation. In the gas that human beings breathe, nitrogen occupies the vast majority, and human beings cannot directly absorb pure oxygen. Although oxygen is an indispensable gas for higher life, it is also the enemy of organic life. It will oxidize every structure of cells, and only mitochondria in cells are not afraid of oxygen oxidation. If the oxygen concentration is too high, which exceeds the amount that the mitochondria can handle, oxygen will oxidize other structures, leading to accelerated cell aging.

Breathing pure oxygen can not only solve the problem, but also suffocate people, because gases such as carbon dioxide in the air can stimulate people's respiratory center, keep our brains awake at all times, understand that we are in a state of insufficient oxygen, and then control our inhalation and exhalation. If it is pure oxygen or the oxygen concentration is too high, the brain will judge that we are not short of oxygen and do not need to breathe. Cause people's breathing ability to weaken, and finally suffocate.

Therefore, in real life, whether it is the oxygen bottle carried by divers or the oxygen delivered to patients in hospitals, pure oxygen is not directly input, but mixed gas is used, and the concentration of oxygen is closer to that in the air, and the rest gases are nitrogen and a small amount of carbon dioxide.

Similarly, in space, the living environment of astronauts should also simulate the oxygen concentration in life and mix it with other gases such as nitrogen to avoid nerve paralysis and suffocation caused by too high oxygen concentration. Nitrogen hardly participates in the reaction in human body, so it can be recovered in space.

The circulating oxygen system is good, but it is not omnipotent. No one can guarantee that the spacecraft 100% is trouble-free, especially the astronauts on the space station. If they stay for half a year, there will always be such problems. Once the circulation system has problems, it will take a long time to maintain. During this time, the astronauts' oxygen supply cannot be guaranteed, so there must be an emergency standby oxygen generator.

Even if it is an emergency standby, pure oxygen cannot be used. The tragedy of Apollo 1 was carved into the lungs by astronauts from all over the world, and pure oxygen tanks were resolutely not used. The standby oxygen production device is a solid powder mixture of sodium chlorate and iron, which needs to be ignited when used for oxygen production. These two substances are kept separately, and if sparks happen unfortunately, this separation will ensure that there is no oxygen to support combustion.

Even if the circulation system works well, the water will be replaced one day. The task that astronauts must do every day is to monitor the quality of circulating water, including microbial content and mineral content. Once it is found that it does not meet the prescribed standards, it can no longer be drunk, and the water in the circulation needs to be replaced.

For example, the International Space Station has been in service for more than 20 years, and the astronauts in it can't always live on circulating water. The water in it always needs to be changed. At this time, another transport plane is needed to transport "water in water". However, unqualified water may not be drunk, but it does not affect its use in electrolytic oxygen production. Therefore, the replacement is mainly the domestic water part, and the oxygen-making part does not affect it.

The oxygen generation system and water circulation system on the spacecraft are valuable, and the cost of each use is hundreds of millions of yuan. The purpose of this system is not only to ensure the basic life of astronauts, but also to prepare for future space immigrants. The energy of the earth has been used continuously for more than 300 years. They are non-renewable resources and formed by paleontology. They started hundreds of thousands of years ago, and it is impossible for mankind to recover. Man will leave the earth sooner or later.

But there is no oxygen on other planets in the solar system, so we can't live directly on them, so building a base is the key. This base is an enlarged version of the space station, where people live in a mode similar to that of astronauts now, and the system can also be expanded on the original basis.

The astronauts' oxygen in space depends entirely on preparation, which sounds tall and full of scientific sense, and uses circulating water, which is the core technology for human beings to base themselves on the universe in the future. But it was the astronauts' hard work and tears.

It was Apollo 1 astronauts who told the world with their lives that it was dangerous to carry pure oxygen into space, so they would electrolyze water to make oxygen in the future. Water resources in space are extremely precious, so the use of reclaimed water was born later. Astronauts have to complete heavy tasks every day, so they have to take time out to monitor the quality of circulating water and replace it immediately if there is any problem.

The universe is full of unknown dangers, all kinds of radiation, unpredictable meteorites, weightlessness and so on. It can be said that the living environment faced by astronauts is much more severe than that of anyone on earth.

These efforts of astronauts are the only process of human progress. Without them, there will be no subsequent improvement, even if it will pay a huge price. Pay high tribute to the great astronauts.