As we continue to search the universe for signs of intelligent life, perhaps we might attain success quicker if we searched for unintelligent life – the kind that’s slowly killing itself off by polluting its atmosphere – you know, like us.
That’s sort of the idea behind new research at the Harvard-Smithsonian Center for Astrophysics (CfA). Harvard student Henry Lin authors a report in the current edition of The Astrophysical Journal on how we might go about looking for extraterrestrial polluters. The CfA researchers think the James Webb Space Telescope (JWST), the Hubble successor scheduled for launch in 2018, will be able to identify two kinds of chlorofluorocarbons (CFCs). To be spotted, the levels of CFCs would have to be at least 10 times those currently eating their way through the ozone on Earth. Co-author Avi Loeb puts it this way:
People often refer to ETs as 'little green men,' but the ETs detectable by this method should not be labeled 'green' since they are environmentally unfriendly.
Unfortunately, the JWST will only be able to find alien pollution on exoplanets orbiting a white dwarf which would no longer be emitting energy to interfere with the observance of the exoplanet’s atmosphere. The ability to analyze planets orbiting active stars like the Sun will have to be built into JWST 2.0.
Searching for CFCs could bring the good news of the existence of other life forms. It could also bring the bad news of an alien civilization that destroyed itself and their planet has nothing left but the smoke. Here’s how Loeb describes it:
In that case, we could speculate that the aliens wised up and cleaned up their act. Or in a darker scenario, it would serve as a warning sign of the dangers of not being good stewards of our own planet.
On the other hand, it could speed up our own planet being discovered by more intelligent life forms that may want to use us as a bad example for their kids.