New Technique Can Spot Intelligent Alien Polluters On Other Planets

There may be a new method to search for advanced alien life. Scientists have found that they could potentially spot the fingerprints of certain pollutants under ideal conditions on other planets, which could be a new approach when it goes to the search for extraterrestrial intelligence (SETI).

"We consider industrial pollution as a sign of intelligent life, but perhaps civilizations more advanced than us, with their own SETI programs, will consider pollution as a sign of unintelligent life since it's not smart to contaminate your own air," said Henry Lin, one of the researchers, in a news release.

The scientists first found that they could potentially detect pollution through two kinds of chlorofluorocarbons (CFCs). These are ozone-destroying chemicals used in both solvents and aerosols. The scientists found that the James Webb Space Telescope (JWST) could tease out the signal of CFCs if atmospheric levels were 10 times those on Earth.

There is a catch, though. JWST can only detect pollutants on an Earth-like planet circling a white dwarf star, which is what remains after a star like our own sun dies. This would maximize the atmospheric signal and make JWST able to actually detect the pollution.

Yet a white dwarf may actually be a better place to look for life than previously thought. Recent observations have found planets in similar environments; planets could have survived the bloating of a dying star from its giant red phase, or could have formed from material shed during a star's death throes.

This method could also potentially detect the remnants of a civilization that annihilated itself. Some pollutants can last for tens of thousands of years in the atmosphere, which means that it's possible they could persist in alien atmospheres long after life has vanished.

The findings are published in The Astrophysical Journal.