Sniff Test

NASA Is Hunting Alien Civilizations by Looking for Their Pollution

NASA is actively searching exoplanets for signs of "industrialized civilization."
NASA scientists say they can hunt for alien civilizations by looking for industrial pollutants like nitrogen dioxide in exoplanets' atmospheres.
Image: NASA/Jay Freidlander

Garbage Day

A team of NASA scientists is taking a clever approach to hunting for alien life: scanning exoplanets for signs of air pollution.

Just as pollutants like nitrogen dioxide and greenhouse gases in Earth’s atmosphere are an indication of human activity below, a team of NASA researchers are now looking for pollutants on other, potentially-habitable exoplanets as a new alien technosignature, meaning a sign of an advanced extraterrestrial civilization. Their study, posted online and accepted for publication in The Astrophysical Journal, is the first to add nitrogen dioxide as a potential technosignature — giving scientists a new tool in the search for life.

Sniff Test

The idea of sniffing out aliens based on their pollution isn’t a new one. But adding nitrogen dioxide, a byproduct of burning fossil fuels in power plants or vehicle engines, helps broaden the search.

“Therefore, observing [nitrogen dioxide] on a habitable planet could potentially indicate the presence of an industrialized civilization,” lead study author Ravi Kopparapu, a researcher at NASA’s Goddard Space Flight Center, said in a press release.

Natural Gas

The problem is that many worlds might have naturally-occurring nitrogen dioxide in their atmospheres, especially since it can be given off by volcanic activity. So part of the new study was finding a way to model the amount of nitrogen dioxide there should be on a given exoplanet.

“If we observe more [nitrogen dioxide] than our models suggest is plausible from non-industrial sources,” study coauthor and Goddard researcher Giada Arney said in the release, “then the rest of the [nitrogen dioxide] might be attributed to industrial activity.”

READ MORE: NASA Study: To Find an Extraterrestrial Civilization, Pollution Could Be the Solution [NASA]

More on technosignatures: NASA Funds Harvard Hunt for Alien “Technological Civilizations”

Dan Robitzki is a senior reporter for Futurism, where he likes to cover AI, tech ethics, and medicine. He spends his extra time fencing and streaming games from Los Angeles, California.