If there’s one thing we humans are good at, it’s pollution. Whether it be plastic, nuclear waste, nitrogen oxide, or even light and noise, we’re really good at producing it. According to research out of NASA’s Goddard Space Flight Center, pollution could tip us off to alien civilizations.
NO2 as a technosignature for civilization
We, earthlings, emit a lot of nitrogen dioxide through driving our cars, planes, and burning coal in power plants. This, according to new research, could be a technosignature that tips us off to advanced life on other planets.
According to the research, the NO2 from a civilization on a planet the size of Earth could be detected from about 30 light-years away. For comparison, they say, the closest star to us is about 4 light-years away in the Alpha Centauri system.
By observing visible wavelengths, we could find just a planet by using a very large telescope. Plus, about 400 hours of observation. Which is a lot of observing, but not unheard of. The Hubble Space Telescope took that amount of time for the Deep Field observations.
The study also found that cooler stars will produce even stronger NO2 signals. This is because these types of stars, K and M-type, produce less ultraviolet light which breaks up NO2. The plus side is that there have been much more of these types of stars found.
Now all of this seems like a great idea. But there is a catch. Natural processes like volcanos and clouds also create nitrogen dioxide. That would mean that a NO2 observation could just be a natural occurrence. But with that being the case, new computer models could separate natural NO2 from alien made NO2.
There are other ways to find alien civilizations. Aerosols in the atmosphere is one. But aerosols may not be present in an alien civilization. But NO2, if aliens haven’t figured out clean energy, could be the sign we are looking for.
Alien pollution could be what finally proves advanced life outside our own.