Methylated vapors could be an unmistakable indicator of alien life

Seattle – Attention alien hunters: If you want to find life on distant planets, look for signs of toxic chemical cleanup.

Gases produced by organisms cleaning their environments could provide clear signs of life on planets orbiting other stars, researchers announced at the January 9 meeting of the American Astronomical Society. All we need to do is look for signs of alien life in these gases in the atmospheres of those exoplanets, in images from the James Webb Space Telescope or other observations that could soon come online.

Interstellar radio emission, the chemistry of a remote planet is one of several promising ways that researchers could detect extraterrestrial life. Life on Earth produces many chemicals that change the atmosphere: Plants disturb the environment, for example, many animals and plants emit methane. Life elsewhere in the galaxy could do the same, with a chemical signature humans could detect from afar.SN: 9/30/21).

But many of the gases of life are also dissolved in processes which have nothing to do with life at all. Their detection could lead to the false impression of a living planet in the distant solar system, when it is really barren of rock.

At least one class of compounds that some organisms use to defend themselves against toxic elements may, however, provide dubious signs of life.

Life-positive methylated compounds are called gases. Microbes, fungi, algae and plants are among the terrestrial organisms that create chemicals by attaching carbon and hydrogen atoms to toxic materials such as chlorine or bromine. Exhaling from it, he sweeps away the deadly elements.

The fact that animals almost always have a hand in making methylated spirits means the presence of compounds in planetary atmospheres is a strong sign of life of some kind, planetary astrobiologist Michaela Leung of the University of California, Riverside, said at the meeting. .

The same can be said about oxygen and methane. Oxygen can especially accumulate when a hot star heats the planet’s ocean. “You have a vaporous atmosphere, and [ultraviolet] radiation from the star splits the water” into its constituent parts, oxygen and hydrogen, Leung says. Hydrogen is light, it is only lost to space in small planets. “What you have left is all this pain,” which, he says, leads to “really the conviction that the oxygen signals in this process that no life is actually involved.”

Similarly, while living organisms produce abundant methane, inanimate geological phenomena such as volcanoes do.

At concentrations of methylated gases typical of Earth, these gases will be difficult to see in the atmospheres of distant planets, even with instruments as powerful as the Webb telescope.SN: 12/20/22). But Leung has reason to believe that there are planets where the gas is many thousands of times that of Earth.

“rich environment” [for releasing methylated gases] Here, he says, we see things like streams and wetlands on earth. A watery planet with many small continents and corresponding coastlines, for example, could be cleaned of toxic chemical organisms with methylated vapors.

One of the benefits of looking at composites as a sign of life is that it doesn’t require that we have anything like life on our planet. “Maybe it’s not DNA, maybe there’s some weird chemistry going on,” Leung says. But assuming that chlorine and bromine are likely to be toxic in general, the methylated gases offer what Leung calls an agnostic biosignature that can tell us something lives on the planet, even if it’s completely alien to us.

“The more signs of life we ​​know to look for, the better the chances of recognizing life when we encounter it,” says Vikki Prata, an astrobiologist at the University of Washington in Seattle, who was not involved in the study. “It also helps us understand what kind of telescopes to build, what to expect and what equipment is required. Michael’s work is really important for that reason.