Oct 11, 2022 I Paul Seaburn

Don't Laugh! The Key to Finding Extraterrestrials May Be Laughing Gas

When you say the words “nitrous oxide” or “laughing gas,” there are people who will think of going to the dentist and being given a dose as an anesthetic. To others, it will remind them of a party (kids, don’t try this at home), a rocket propellant or a race car booster. There are very few people who hear the phrases and thing, “I’m not saying it’s a sign of aliens, but it’s a sign of aliens!”,  but if they do, they are probably researchers at the University of California, Riverside, Purdue University, American University, the Georgia Institute of Technology and the NASA Goddard Space Flight Center who participated in  a new study published in The Astrophysical Journal which determined that nitrous oxide is a "compelling exoplanet biosignature gas." In other words, if you want to find extraterrestrial intelligent life on planets outside of our solar system, look for signs of nitrous oxide. Shouldn’t they be listening for laughter too?

Who feelings liking laughing in the dentist's office?

“There’s been a lot of thought put into oxygen and methane as biosignatures. Fewer researchers have seriously considered nitrous oxide, but we think that may be a mistake.”

Eddie Schwieterman, an astrobiologist in the University of California, Riverside, Department of Earth and Planetary Sciences, explains in a UCR press release why he and colleagues from other universities and NASA came up with the idea to enhance the search for extraterrestrial intelligence (SETI) by add nitrous oxide to the list of biosignatures that are signs of life similar to that on Earth. That brings up an obvious question – if there is enough nitrous oxide in Earth’s atmosphere to make it a biosignature of our own planet, why aren’t we all (instead of just some strange individuals) laughing our heads off all of the time?

“There are multiple ways that living things can create nitrous oxide, or N2O. Microorganisms are constantly transforming other nitrogen compounds into N2O, a metabolic process that can yield useful cellular energy.”

Schwieterman at first avoids answering this question directly. Most nitrous oxide -- a colorless gas with a faint, sweet odor – is manufactured on an industrial scale by careful heating of ammonium nitrate to about 250 degrees C (482 degrees F) until it breaks down into nitrous oxide and water vapor. On a smaller scale, N2O can also be made by heating a mixture of sodium nitrate and ammonium sulfate. This is the familiar nitrous oxide and laughing gas used as an oxidizer in a rocket motors, as a fuel injection booster in race cars, as an aerosol spray propellant in whipped cream canisters and cooking sprays, and as an anesthetic and analgesic in dentistry and surgery. Because exposure to nitrous oxide causes short-term decreases in mental performance, audiovisual ability and manual dexterity, it is considered a significant occupational hazard for surgeons, dentists, nurses and others who come in close contact with it – something to keep in mind when considering its recreational use. Is Schwieterman’s study proposing that ETs are racing a lot of cars and getting enough dental work done to put so much nitrous oxide into their planet’s atmosphere that it would show up on our telescopes?

“Life generates nitrogen waste products that are converted by some microorganisms into nitrates. In a fish tank, these nitrates build up, which is why you have to change the water.”

OK, that makes more sense … not. Are ETs so enamored with the hobby of raising tropical fish that their tanks will expose them to discovery by other intelligent species?

“However, under the right conditions in the ocean, certain bacteria can convert those nitrates into N2O. The gas then leaks into the atmosphere.”

What are those “right” conditions for the natural creation of nitrous oxide? According to a 2010 report by the U.S. Environmental Protection Agency, about 29.5 million ton of nitrous oxide enters the atmosphere each year, with 64% coming from natural sources and the rest from human activity. Natural N2O is produced by microorganisms such as denitrifying bacteria and fungi in soils and oceans that turn nitrogen oxides back to nitrogen gas or nitrous oxide. Sources of atmospheric nitrous oxide emissions include fertilized agricultural soils, livestock manure, runoff of fertilizers, biomass burning, fossil fuel combustion, human sewage and thawing permafrost. These emissions can be difficult to measure because they vary over location and time. Nitrous oxide is a greenhouse gas, but its low concentration in the atmosphere is less than one third that of carbon dioxide, and also less than methane. The question once again arises in a different form – if nitrous oxide is not much of a biosignature for Earth, why do these scientists think it is a useful biosignature for the search for intelligent life on exoplanets?

“This conclusion doesn’t account for periods in Earth’s history where ocean conditions would have allowed for much greater biological release of N2O. Conditions in those periods might mirror where an exoplanet is today.”

According to Schwieterman, there was a time when humans would have had a difficult time not laughing – and eventually dying – because of the high concentration of nitrous oxide in the atmosphere. The study team thinks that there are exoplanets at that stage in their own developments that would carry the same biosignature of high concentrations of life in their oceans. Furthermore, K and M dwarf stars produce a light spectrum that is less effective at breaking down the nitrous oxide molecule than our own Sun is, so more N2O would survive and permeate their atmospheres. This combination could throw enough laughing gas into the exoplanetary atmosphere to potentially be detected by the James Webb Space Telescope. That telescope will soon be focused on the TRAPPIST-1 star system – a nearby red or M dwarf with rocky planets capable of having life-supporting atmospheres.

Will alien spaceships have nitrous boosters?

“We wanted to put this idea forward to show it’s not out of the question we’d find this biosignature gas, if we look for it,”  

The bad news is, SETI scientists are not yet looking for nitrous oxide in biosignature searches. Schwieterman and his research team hope their study will convince astrobiologists to consider adding it to their list of alternative biosignature gases to search for.

Will they? What kind of extraterrestrials could live and thrive in nitrous oxide atmospheres? Laughing dentists with fast cars and huge tropical fish tanks in their offices, of course!

Paul Seaburn

Paul Seaburn is the editor at Mysterious Universe and its most prolific writer. He’s written for TV shows such as "The Tonight Show", "Politically Incorrect" and an award-winning children’s program. He's been published in “The New York Times" and "Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. His “What in the World!” podcast is a fun look at the latest weird and paranormal news, strange sports stories and odd trivia. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn't always have to be serious.

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