#A group of scientists is carefully examining cave paintings made by humans in the Paleolithic Age. In the mural, an ‘unknown being’ who looks like a human but is very tall is pointing to the sky with his finger. The fingertips are studded with dots that look like an arrangement of stars or planets. Paintings like this can be found not only in one site, but all over the world.
After some time, the scientists who excavated the ruins form a space expedition together with researchers from different fields. He went on a field investigation to find a planetary system similar to the arrangement of the heavenly bodies engraved on the cave paintings. After reaching the target planet, the expedition team enters the habitation of extraterrestrial life on this planet. Then, after checking the gas composition using the sensor, he immediately removes the spacesuit helmet. They breathe the fresh oxygen that exists on exoplanets to fill their heart.
A 2012 film directed by Ridley Scott. begins with the imagination that extraterrestrial life with a higher civilization has created humans by simulating their own bodies, and that humans go looking for them. The oxygen inhaled by the members of the expedition is strong evidence that it is habitable space.
In fact, there is a strong perception in the scientific community that an exoplanet with oxygen is likely to be the ‘Home of Life’. Because the Earth is the best example. The James Webb Space Telescope, the most powerful space telescope ever launched last year, was also designed to check the presence of oxygen molecules in the e-planets’ atmosphere.
However, a different view has recently emerged in the scientific community. It is said that we shouldn’t fuss about discovering oxygen on an alien planet or drinking kimchi soup first. This means that oxygen can be produced without living things such as plants. There is an opinion that it will be difficult to move forward with the search for life on exoplanets if only the presence of oxygen is in question.
‘Polpol’ oxygen from volcanic activity
Recently, researchers at the University of Gothenburg, Sweden, published the results of a study in the latest issue of ‘Science Advance’ which found a way to produce oxygen even if there was no life on extraterrestrials.
The researchers discovered that the source of oxygen is sulfur dioxide that comes out of the surface during volcanic eruptions. Volcanic activity is a common phenomenon not only on Earth but also on different planets.
The researchers found that X-rays or gamma rays emitted by the star change the properties of sulfur dioxide molecules in the atmosphere due to volcanic activity. These rays shake the oxygen atoms in the sulfur dioxide. When this happens, the sulfur disappears, leaving only oxygen. As a result, oxygen dissolves in the atmosphere even when there are no plants. In 2015, Japanese researchers also discovered that oxygen is produced when titanium dioxide, a type of pigment, interacts with water.
Oxygen in the Earth’s atmosphere did not form this way. Oxygen surged in the Earth’s atmosphere around 2.4 billion years ago, and the first contributor was ‘cyanobacteria’. Cyanobacteria are microorganisms that live in water with a size of several nanometers (nanometer, 1 nm is one billionth of a meter). The most important feature is photosynthesis. Photosynthesis produces oxygen. Thanks to cyanobacteria, the proportion of oxygen in the atmosphere rose to 10% 600 million years ago. After that, the plants took over the baton, and the earth became a planet of oxygen. Currently, the percentage of oxygen in the Earth’s atmosphere is 21%. However, the researchers’ diagnosis is that there is no law that says that the fact that the Earth made oxygen in this way does not necessarily mean that other planets do the same.
Find another ‘gas of life’
Oxygen induced volcanic activity can also be seen not far away. Io is a moon of Jupiter, a planet in the solar system. Io has a radius of 1820 km and is about the same size as the moon (1730 km).
However, Io has a very different characteristic to the moon. Volcanic activity is so active that there are more than 400 active volcanoes. This is caused by the gravitational pull of Jupiter and its moons squeezing Io, causing the earth to tremble. During this process, sulfur dioxide is continuously emitted from the surface of Io.
Some oxygen is found in Io’s atmosphere. Naturally, there are no photosynthetic organisms on Io. As the sulfur dioxide decomposes, a small amount of oxygen is released into the atmosphere, according to the researchers. This means that oxygen can appear even in environments hostile to life.
Summarizing the research team’s analysis, it is possible to misunderstand a volcano-filled exoplanet as a land of life if you rely only on the presence or absence of oxygen. In the future, efforts by the scientific community to find other gases that harbor signs of life other than oxygen are expected to accelerate.
