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NASA says we might find alien pollution before we find aliens

Published Feb 13th, 2021 10:33AM EST
alien pollution

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  • If intelligent alien civilizations exist in space, it’s possible that we may find signs of their existence before we find the aliens themselves.
  • A new study by NASA suggests that industrialized civilizations on distant worlds may be just as bad at managing their pollution as we are, and we may be able to spot their dirty atmospheres from afar.
  • If we can detect the presence of nitrogen oxide in a planet’s atmosphere, it may be a sign that they are burning fuels like oil or coal, just like we do. 

If there’s one thing humans are really good at, it’s messing up the planet. I mean, we’re the only species on the planet capable of ruining it on a large scale, and that’s exactly what we’re doing. Since we are the only “intelligent” life form that we know about, it makes sense that, if intelligent alien civilizations exist, they might be just as bad at managing their pollution as we are. NASA says that could end up being helpful if we ever want to find aliens.

In a new NASA study set to be published in the Astrophysical Journal, researchers explain that by hunting for planets with certain ingredients in their atmospheres, we may be able to filter for planets with a higher probability of hosting life akin to our own species. Put simply, if we can find a planet with a dirty atmosphere, something may be responsible for it being dirty, and that something could be aliens.

In the paper, the researchers focus on the idea that, since humans burn fossil fuels, and those fossil fuels fill the atmosphere with nitrogen dioxide gas, we should look for planets with a similar atmospheric makeup. NO2 can be generated by natural processes, but the burning of fuels is a major contributor to how much of it is floating high above our heads. Would aliens face the same problem? We can’t say for sure, but the scientists involved in the study say it’s worth considering.

“On Earth, most of the nitrogen dioxide is emitted from human activity — combustion processes such as vehicle emissions and fossil-fueled power plants,” NASA’s Ravi Kopparapu, lead author of the study, said in a statement. “In the lower atmosphere (about 10 to 15 kilometers or around 6.2 to 9.3 miles), NO2 from human activities dominate compared to non-human sources. Therefore, observing NO2 on a habitable planet could potentially indicate the presence of an industrialized civilization.”

When a planet passes in front of its star, from our perspective, the light that shines through the atmosphere can offer clues as to what gasses are present. We could use those signatures to hunt for planets with elevated levels of NO2 in their atmosphere, and in doing so we may find intelligent alien life.

Of course, this idea is based entirely on the possibility of another planet meeting a number of criteria that, as far as we know, don’t exist anywhere but Earth. The would-be alien world would need fuel that, when burned, produces NO2. It would also need an alien race advanced enough to have figured out how to burn that fuel and, perhaps most importantly, those aliens can’t be too advanced, or they probably would have figured out a way to clean up their atmosphere and stop burning the fuels that are polluting it.

It’s an interesting idea, but for the time being, we don’t’ have a way to communicate with worlds outside of our solar system, much less visit them, so even if we found a planet that screamed alien life, it would be a while before we could do anything about it.

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