Researchers have developed a statistical modelling tool to help astronomers determine the likelihood of life as we know it popping up on other planets.

What are the odds? After the discovery of the first exoplanet 25 years ago, and since then thousands more, the question has become a serious one.

One method to probe it is to examine the light scattered off a planet’s atmosphere in search of “biosignatures” – gases like oxygen, methane or ozone that could indicate the presence of living organisms, writesExternal link the Swiss Federal Institute of Technology EPFL.

And though it’s not the only indicator for guiding the search – other factors include the presence of water, or the distance from a star – the hunt for biosignatures is “probably going to become one of the most important” methods in the coming years, EPFL says.

Researchers the Lausanne-based universitiy, in collaboration with colleagues from the University of Rome, have thus tried to anticipate such efforts by developing a statistical model to analyse the results, it was announced this week.

“Intuitively it makes sense that if we find life on one other planet, there are probably many others in the galaxy with some type of living organism. But how many?” said one of the Rome-based researchers, professor of astronomy and astrophysics Amedeo Balbi.

“Our model turns that intuitive assumption into a statistical calculation and lets us determine exactly what the numbers mean in terms of quantity and frequency,” he said.

The model is built around various factors like the number of stars and rock-based planets in the galaxy and offers its calculation of probability according to how many biosignatures are found: one, several, or none at all.

The results are optimistic: if just one biosignature is found, it’s 95% probable that there are over 100,000 inhabited planets in our galaxy, the scientists estimate. And even if none at all are found, this still doesn’t rule out the possibility of life being found in the Milky Way.

The researchers hope the model will be useful when it comes to current projects that incorporate the search for biosignatures, including the recently launched Swiss CHEOPS satellite.