The presence of oxygen in the atmosphere is not always reliable. It's methane that can send a stronger signal,
The atmosphere of modern Earth contains about 21%oxygen, and most of it comes from organisms in the oceans of the planet. But there is a catch: once cyanobacteria on ancient Earth began to produce oxygen as a byproduct of photosynthesis, it still took a very long time before the atmosphere became saturated with oxygen. Perhaps a billion years.
Rocky exoplanets have manyoxygen scavengers, and biologically produced gas will not be free in the atmosphere until these scavengers become saturated. This can take millions of years. And researchers can simply miss an exoplanet with life if they focus on the presence of oxygen.
Planetary scientists decided to focus onsearching for other signatures in planetary atmospheres. For example, on methane (CH₄). In a new paper, researchers examined methane's ability to signal biological activity. Scientists say the methane in the planet's atmosphere is unlikely to come from volcanoes and is most likely of biological origin. Publishes resultsThe Planetary Science Journal.
Of course, detect potential biosignatures,such as methane, in the atmospheres of distant exoplanets is not easy. But as soon as something like methane is found, even more hard work lies ahead. Its presence must be examined in the context of the planet itself. Now scientists are trying to come up with a way to detect biosignatures using a telescope.
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