What makes oxygen so life-friendly

Looking for a planet: People want to go into space

We have not yet found extraterrestrial life. But what about a life-friendly planet for humans?

Astronomers around the world are looking for an Earth 2.0 - a planet that people can relocate to. The search is difficult because a planet has to meet a number of criteria. But even if we find this planet, building a station would involve considerable risks.

What does a habitat need?

A life-friendly planet - what does it need? First of all, the planet has to be warm enough that liquid water can also be found on the surface. To do this, it must orbit a star close enough, as is the case with the earth and the sun. In addition, the atmosphere on the planet must be able to support life, i.e. not be toxic.

Planets that are warm enough are in the so-called “habitable zone” (see graphic above). You are at the correct distance from a star so that it is neither too cold nor too warm. The basics for life as we know it are: "You need oxygen, water in liquid form and the influence of energy from a central star," says Theresa Lüftinger from the University of Vienna. "These are the basic requirements."

The blue planet

In addition to the three “basic elements” oxygen, water and energy, the earth has another bonus that is believed to have made life possible: plate tectonics.

According to Lüftinger, it is assumed that the mobility of the plates made it possible for CO2 to penetrate the earth even in the early phase of the earth's development, which meant that the quality of the atmosphere was good enough to make life possible.

Venus, for example, has no plate tectonics, which is probably why the atmosphere there is toxic to life as we know it.

Mars is too small

Another candidate for a life-friendly planet would have been Mars. With him, water was found below the surface. “With Mars, one thinks that some time ago there might have been an atmosphere that could have been very friendly to life, at least for certain microorganisms,” says Lüftinger.

But Mars is too small to maintain a magnetic field that protects it from solar winds and radiation. “The lack of a magnetic field meant that the atmosphere was destroyed by the solar wind,” says Lüftinger. "If there was life there, it couldn't survive."

The Trappist system

There are also candidates for possible future habitats outside of our solar system. The comparatively very small red dwarf Trappist-1a, a so-called M-dwarf in the Trappist planetary system, is orbited by several earth-like planets. Four of the seven planets are in the habitable zone, and some of them are likely to have water.

The problem with the Trappist planet is that, due to the low mass of their central star, they orbit very close to it. "In the case of a sun-like star, the habitable zone is always in a similar area in the course of development," says Lüftinger. "With the M-dwarfs, the region changes, that is, the habitable zone moves." This constant change could have negative effects on the atmosphere of the planets.

Life on the moon?

However, we may not even have to move out of our immediate neighborhood to find another life-friendly planet. The moon has not seen people since the 1970s, but that may change in the future. With its underground water resources and the relative proximity to the earth (and thus to the sun) it has no bad chances of becoming a hostel for a new space station.

Into space for the sake of the environment?

For many, climate change and the scarce resources on earth are a reason to look for an “Earth 2.0”. But that would not solve our problems here. Building a habitat on the moon or another celestial body would cost us so many resources that it would not help the earth.

"Mars and the moon will not be able to accommodate so many people that that would be a relief for the earth," said Lüftinger. “Instead, from my point of view, it is essential that we change our lifestyle. If we don't do that, we'll have big problems. "

This article belongs to the series:

How and where climate change is already being felt

The effects of global warming are diverse, long-term and difficult to stop. What are we doing about it?

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