How do scientists search for aliens?

In our galaxy there are more than 24 extraterrestrial planets, potentially harboring life. That's not to mention the countless worlds that can reside in 100 billion other galaxies across the universe.

Looking for aliens like?

In terms of quantity, the opportunity for life to exist outside the Earth is promising, but the opportunity to find that life is less. Why is that? For one thing, we simply don't know what alien life looks like .

Life is beyond carbon dependence

All life forms on Earth rely on carbon , which means that the molecules that make up all known human beings contain carbon atoms linked to other atoms. Even so, life on Earth revolves around oxygen : plants absorb carbon dioxide (a carbon atom linked to two oxygen atoms) and emit oxygen - the human gas that breathes and needs for life.

However, alien life forms may depend entirely on something else , such as a simple organic methane compound, consisting of a carbon atom linked to four hydrogen atoms. Take Saturn's Titan moon as an example. Titan is rich in lakes containing liquid methane on the surface and has very low oxygen - a condition that makes it difficult for people to survive there. However, these lakes can tolerate methane-based life forms, much different from the life we ​​have on Earth.

The problem is, our life-tracking tools are currently only designed to test life like ours . Humans will probably never know whether life on Saturn or other life forms with chemical characteristics on other planets exists.

Christopher Adami, professor of microbiology and molecular genetics at the University of Michigan (USA) is studying to solve the challenge. In the 1990s, Mr. Adami helped develop a very complicated computer program called Avida. This program examines how digitized organisms - computer programs with the ability to copy and transform themselves without human intervention - evolve over time. Scientists use programs like this to better understand the characteristics that promote evolution according to Darwin's hypothesis. The process of artificial replication makes them a great replica of real life on Earth.

However, Mr. Adami had larger plans for Avida. This professor is looking for a trait that all life forms across the universe have - universal that surpasses those that make up them. If this universal trait exists and we know how to identify and test it, we can quickly identify life on other moons or planets, even if that life possesses properties. chemistry is completely different from life on Earth.

Mr. Adami believes he has come very close to finding the universal trait above. It is information stored inside each organism's genome. A good way to describe this information is to think of it as individual pieces, like bits - the unit used to measure the amount of information in a binary number system in a computer.

The main challenge

The key question is, how to distinguish between the information stored in the molecules of living things and how the information is stored in non-living things . According to Professor Adami, we can search for patterns.

Unlike living organisms, which always produce certain patterns when they replicate and reproduce themselves (like the way our DNA sequences repeat themselves), non-living things will show bits of information. Random news , never repeat at regular frequency. Therefore, the task here is to search for repeating strings. Unfortunately, this is easier said than done.

Professor Adami said, the best way to achieve the goal is to study the chemicals inside the soil of the moons or other planets in our solar system . Until now, no scientist or research organization has started to do so.

Although the discovery of extraterrestrial life within other worlds' lands may be far-fetched, scientists on Earth are aiming to hunt unseen forms of life before on their own. his planet. Their approach is one of the most promising experiments that can ultimately help us find extraterrestrial life.

In November 204, a team of experts from the American Genome Research Institute (JGI) proposed a fourth search for the world of life on Earth. There are currently only three known leaders of life, including bacteria, ancient bacteria and eukaryotes. Each world leader has a characteristic sequence in its RNA gene structure, which distinguishes them from the other two groups.

The JGI team suspects there is also a fourth world with a complete sequence of RNAs unlike anything ever seen before . To discover it, they wanted to look at the genes of cells in tiny life forms that existed more than 2.3 billion years ago, into a stage where the Earth's atmosphere has far less oxygen than nowadays. Such low-oxygen conditions may have prompted a genetically unique form of life, similar to life forms on other planets with little oxygen in the atmosphere, like Mars.