Scientists at The University of Washington have discovered that searching for Earth-like planets that contain methane and not oxygen is a much more productive way to find alien life on other planets. Methane isn’t the only gas that could be an alien-life indicator as carbon dioxide and a lack of carbon monoxide are also compelling signs, their research suggests.
“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,” says researcher Professor David Catling from the University of Washington.
As the Express reports, currently the search for alien life is centered around planets with high concentrations of oxygen in their atmospheres. This is because Earth-like organisms like plants produce oxygen, so planets with this gas would likely house organisms similar to those that can be found on our planet.
But the team at The University of Washington claims that approach is limiting. Oxygen development isn’t a simple, straightforward process, says study co-author Joshua Krissansen-Totton. So, there’s a possibility that alien life beyond earth may not be responsible for creating the atmospheric oxygen present on their planet. But methane is a bit different, the researchers say, and it gives us more clues.
While there are a variety of ways that methane can be produced on a planet, with asteroid collisions being just one example, it’s unlikely that there would be large amounts of methane on an Earth-like planet without the presence of living organisms. The conditions for life are even more favorable if you also find lots of carbon dioxide and no carbon monoxide. The lack of carbon monoxide means that the methane and carbon dioxide weren’t generated by volcanic eruptions since they produce carbon monoxide.
Furthermore, microbes consume carbon monoxide so large quantities of that gas would mean that there was no life around to eat it.
Astronomers from the University College London (UCL) and the University of New South Wales have devised a tool that can put this new “methane theory” to test. According to Gizmodo, the tool is called the transmission spectrum and it will be used to detect methane in the atmospheres of exoplanets.
While the technology has its limitations, the team says that they have already used to it to adjust some of the previous methane measurements they had collected from outer planetary atmospheres. One of these planets, HD 189733b, had over twenty times the methane than was originally estimated.