A new breakthrough in how to recognise alien biology at work could greatly increase the chances of finding life on other planets, it was today claimed.
US scientists said they were searching for signs of planets with atmospheres rich in methane and carbon dioxide and lacking in carbon monoxide.
Researcher Professor David Catling, from the University of Washington, said: "Our study shows that this combination would be a compelling sign of life.
"What's exciting is that our suggestion is doable, and may lead to the historic discovery of an extraterrestrial biosphere in the not-too-distant future."
Writing in the journal Science Advances, the team pointed out that it was very hard to make much oxygen without Earth-like alien life.
Searching for atmospheric oxygen was therefore a sensible strategy - but one that was limited.
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