Hopes of finding evidence of life on far off alien worlds by studying their atmospheric chemistry have been dashed by a new study that concludes it's almost impossible. The research, reported in the Proceedings of the National Academy of Sciences, found atmospheric spectral readings from distant exo-planets will never be good enough to be useful in the search for life. The findings support an underlying view among astronomers that it was always going to be difficult to take the spectrum of an Earth like exoplanet, according to the study's lead author Dr Hanno Rein of the University of Toronto.
"I was a bit pessimistic when I calculated these numbers for the first time, they were not what I was expecting," says Rein. "We're not going to get any useful spectra at all."
Astronomers determine the chemical composition of a gas, by looking for specific signatures in light from a star shining through the atmosphere of a planet passing in front of it.
The strongest indicators of life on another planet would be chemical signatures for molecules of methane and oxygen in that planet's atmosphere.
"We think these two molecules are likely to be produced by life on Earth and also on other planets," says Rein.
"There are few geological mechanisms which produce molecules of methane and oxygen in large quantities. To be really sure, we want both molecules together at the same time, then we can be more certain that there's life on that planet."