How do you search for extraterrestrial life?

Extraterrestrial life

“Are we alone in the universe? Is there life outside the Earth?” These two issues are the big questions scientists are trying to unravel.

extraterrestrial life

It is those doubts that bring emotion to conversations, even among people who do not engage in science. And everyone has their own theory.

However, in order to answer these questions it is essential to seek extraterrestrial life. We already know that in the solar system it is difficult to find life.

Although it is not yet to be ruled out because perhaps on Mars, Io or Europe microorganisms can be found beneath its surface.

But then how are we looking for life outside the Earth to answer these great unknowns?

So far there are two ways: detect new exoplanets and radio waves. But a new technique could be used to search for life: artificial satellites. How does each of these techniques work? In other words, today we will analyze how extraterrestrial life is sought.


With the launch of TESS last week there has been a lot of talk about the search for exoplanets, i.e. planets similar to Earth, but outside the solar system. And what do they have to do with the search for extraterrestrial life?

We know that life already exists on Earth, so it is best to look for planets similar to it on which scientists hope to find life.

In the next decade several telescopes will be launched, such as the James Webb instrument or the Extremely Large Telescope (ELT) to try to detect what scientists call biomarkers: “If we find ozone, carbon dioxide, methane…

They are gases that are associated with biological processes,” Héctor Socas-Navarro, a researcher at the Instituto de Astrofísica de Canarias (IAC), explains to Hipertextual.

These large telescopes could find life in the next “ten or twenty years,” says Socas. “Although to go to that planet would be difficult because it could be 50 light years,” says the researcher.

Perhaps for the human being, knowing that they are there is enough, or perhaps the next big step would be to find a way to get there. Especially if the life out there is not intelligent, which would be most likely in the case of finding biological clues.

Radio waves and satellites

It is very difficult to find intelligent life, but if there is, it can be determined thanks to technomarkers, that is, thanks to technology such as radio waves or artificial satellites that orbit around a planet, as happens on Earth itself.

Researchers don’t rule out intelligent life, that’s why they look for radio signals: “In our day to day we are sending radio signals all the time, these are scattered around the universe, although they are like a light, the further away you go, the less sharp it is,” explains Socas-Navarro.

That’s why it’s harder to find life with radio waves. Although, if you know where to look, it might be easier because you can focus the listeners on a particular place. While we find that region, we have to develop other theories.

In the 1960s, one of Dyson’s spheres was raised, which pointed out that if there was intelligent life outside the Earth, we could find out by looking for a mega-structure around the stars that captures the energy from it and then uses it for them.

Since nuclear fusion is the most profitable energy, they are unlikely to make mega-structures around their star,” explains researcher Socas-Navarro.

The proposal of this IAC researcher is another: look at the Clarke belt, named after science fiction writer Arthur C. Clarke, pioneer in the concept of the geostationary orbit. But what is Clarke’s belt and why can it be a sign that there is intelligent life?

The Clarke belt is everything that is placed in the geostationary orbit, that is, where we have communication satellites, for example.

In this area “nothing can happen by chance”, explains Socas, hence the importance of this proposal. In his study he calculates that if intelligent extraterrestrials had a population of objects above 0.01%, we might be able to detect them with the probes we already have looking for planets, such as the recently launched TESS satellite.

But they could also detect us: “In the last 20 years, the satellites we have placed in geostationary orbit have grown exponentially, so by 2200 it is likely that, if we continue at this rate, we can also be detected,” illustrates the researcher.

That is why a new debate has been opened: should we allow ourselves to be found or, on the contrary, is it better for us to seek without being detected?

Although the debate is open, the truth is that the Voyager 2 probe already betrays us and carries recordings and data on human beings.

Asked about this, Socas points out that these satellites “drift” and that the probability that some extraterrestrial civilization will find them “is zero”.

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