Laughing gas on exoplanets could reveal signs of life: University of California experts

Experts from the University of California, Riverside, believe that scientists looking for biosignatures to confirm life on exoplanet are leaving a crucial element out– nitrous oxide (N2O)– also called the laughing gas. 

Typically, scientists look for gases such as oxygen and methane in the atmospheres of exoplanets as biosignatures as these are found in abundance on Earth. However, the UC Riverside researchers say that leaving laughing gas out of this list could be a mistake.

“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 UCR’s Department of Earth and Planetary Sciences, said in a statement. 

Why laughing gas has emerged as a potential candidate

During their study, Schwieterman and his team found that there are multiple ways living things can produce nitrous oxide which makes them a potential candidate for finding alien life. The experts arrived at this conclusion by determining how much nitrous oxide living things on a planet similar to Earth could possibly produce.

They also made models simulating a planet around different kinds of stars to determine amounts of N2O that could be detected by an observatory like the James Webb Space Telescope.

(An illustration of exoplanets; Image: NASA)

“In a star system like TRAPPIST-1, the nearest and best system to observe the atmospheres of rocky planets, you could potentially detect nitrous oxide at levels comparable to CO2 or methane,” Schwieterman said. In the study published in the Astrophysical Journal, the researchers noted that microorganisms can produce laughing gas in multiple ways, one of which is transforming nitrogen compounds into N2O, a metabolic process that can yield useful cellular energy.

According to the experts, certain bacteria, under the right conditions in the ocean, can convert nitrates into N2O and then release the gas into the atmosphere. They, however, mentioned that the detection of nitrous oxide in an atmosphere would not certainly mean the presence of life forms as the gas can also be created by lightning. But the nitrogen dioxide created alongside the laughing gas would give astronomers a chance to investigate if the gas was created due to weather or geological processes. They also underscored that since the element in conversation is scarce on Earth, it would be extremely to detect on other worlds.