Oxygen is the key to exploring alien life based on the earth? No, methane is the "must"

A person can go without food and water for a day, but if you don’t inhale for a minute, you may not be able to persevere. Our body has human fat that can store kinetic energy, and there is water in body cells that can be used.

In the earth's atmosphere on the earth, oxygen accounts for about 21%, and it is indispensable for everyone to absorb this oxygen according to inhalation. Without oxygen, basically all life on earth will die.

Therefore, whether it is looking for a second home for human beings or exoplanets with the potential to create life, everyone will focus on whether there is oxygen on such stars.

But here's the conundrum: Earth didn't start out with so much oxygen. In fact, biologists' research shows that the Earth's atmosphere has experienced a very long period of oxygen deficiency before there is sufficient oxygen for the survival of small animals that must breathe oxygen. This period is likely to be as long as a billion years. . Until the occurrence of anaerobic fermentation organisms such as cyanobacteria, a lot of oxygen was produced, which changed the natural environment on earth.

Therefore, some biologists have been thinking: If a planet we observe is similar to the Earth with only cyanobacteria, does it need to be discarded because there is no oxygen in its air? If so, then you may have missed many stars that are likely to have created anaerobic fermentation organisms!

So, do you also have other index values ​​to detect the probability of biological existence?

Methane

Nicholas Wogan from the Department of Earth and Space Sciences at the University of Washington and Nicholas Wogan from the Virtual Planet Laboratory recently published their new research in the Journal of Planetary Science, and they stress that many species of methane appear to be more abundant than oxygen. It may be a harbinger of the imprint of life, and everyone will be able to tell whether life has been created on a planet based on methane in the future.

They think that if a lot of methane occurs on a terrestrial planet, then it is likely to come from two sources, one is the life on the planet's surface, and the other is volcanic eruptions. Therefore, if we can understand non-biological elements such as volcanoes, it means that this planet is likely to have created life.

So, at such a long distance, how do you determine the source of methane?

Volcano Vs Creature

They designed a physical model to simulate how much methane and carbon dioxide would be released into the air by volcanic eruptions on terrestrial planets. Among them, they designed a total of two natural environments:

Pure deep-sea planets: all volcanoes are deep-sea volcanoes;

Earth-like planets: There are not only deep seas but also land, and both types of volcanoes have eruptions.

Based on simulations of the two conditions, they found that the proportion of methane and carbon dioxide caused by volcanoes on any planet is completely different from that of biological existence. This means that it is feasible to remove the elements of the volcano based on the proportion of the two gases.

The reason for this, they stress, depends on the lava being able to lock in large amounts of hydrogen. Because the solubility of water (H2O) in lava is relatively high, it will cause a large amount of hydrogen to remain in the lava, reducing the proportion of methane. It is worth mentioning that methane is released more easily only when the magma temperature is relatively low, and the general magma temperature is too high.

Especially in the case of the earth, the amount of methane caused by volcanic eruptions is basically negligible, which gives us more reason to believe that if the amount of methane is too large, it is more likely to come from biological biochemical reaction.

And, even if these are almost zero chance of happening, under the very unique standard, it is only by volcanoes that generate a lot of methane, and everyone has a way to prove that this methane does not come from living things.

The archaeological materials at this stage have confirmed that the earth also experienced the whole process of very frequent and intense volcanic eruptions in the early stage of production. During that period, the amount of lava on the earth was likely to be 25 times that of today, and it did cause a lot of methane. However, scientific researchers also noticed that in the whole process, there is also a kind of gas that will cause a lot, that is carbon dioxide.

For exoplanets, the situation is likely to be the same. Therefore, if we detect a lot of methane in the air of a rocky exoplanet, then it is likely to already have life on the subject. If we can still observe its proportion of carbon dioxide, it will be possible to remove the elements of the volcanic eruption, and its probability of creating life will be even higher.

In addition, we can further strengthen the data signal of life based on carbon monoxide. If the carbon monoxide content of the exoplanet's air is sufficiently low, it may be possible to enhance the existence of life, because life is more likely to consume this carbon monoxide. Oxidizing volcanic gases are more likely to increase the composition of carbon monoxide, so the composition of carbon monoxide is sufficiently low, which means that this methane is more likely not to come from volcanoes.

more powerful glasses

Well, if methane can indeed help you find life outside the universe, then the following problem is: how do you find methane on exoplanets hundreds or even hundreds of billions of light-years away? In addition, how should we integrate the natural environment of the planet to infer the source of this methane?

Sharpening knives does not cut wood by mistake, and workers want to do good things. To detect this kind of secret, you need a very powerful observation machine, such as the LeBron James Webb Space Telescope (JWST) that NASA will send off in 2020.

The LeBron James Webb Space Telescope is a new generation of space telescopes that are more excellent than the Hubble Space Telescope, with strong observation capabilities. The size of the Hubble telescope is only 2.4 meters, while the size of the JWST will be able to reach 6.5 meters. It can not only see farther, but also see in detail. It can observe many information contents beyond the reach of Hubble, so it is hoped by experts.

Before the JWST is sent, experts must think ahead about how it will be used to ensure that it can operate more efficiently after takeoff. And scientific research like that is to give scientific research orientation for the future JWST, to help experts to better use this powerful machine and equipment.

The scientific research staff also emphasized at the end of the graduation thesis that the results of this scientific research all come from the understanding of the earth's resources. On thousands of exoplanets, perhaps the gas circulation system or reaction is not the same as on Earth, so we still need a lot of scientific research. However, whether the results of this scientific research are appropriate or not, this is the only way for everyone to use intelligent technology. In any case, with the gradual advancement of relevant scientific research, we may be getting closer and closer to life outside the universe.