Laughing gas, according to researchers at the University of California, Riverside, is missing from the standard list of compounds.
Biosignatures, as we know them, are chemical components in a planet’s atmosphere that may be indicative of life, and they typically include gases that are prevalent in our planet atmosphere.
“Oxygen and methane have received considerable consideration as biosignatures. Fewer researchers have carefully explored nitrous oxide, but we believe that is a mistake,” said Eddie Schwieterman, an astrobiologist in UCR’s Department of Earth and Planetary Sciences, in a release.
The study that identified the maximum amount of nitrous oxide that living creatures on a planet like Earth could possible create was led by Schwieterman. The amount of N2O that could be detected by an observatory like the James Webb Space Telescope was then computed using models that represented the planet’s orbit around various kinds of stars.
You might be able to find nitrous oxide at levels comparable to CO2 or methane in a star system like TRAPPIST-1, which is the nearest and best system to monitor the atmospheres of rocky planets, according to Schwieterman.
Nitrous oxide, or N2O, is a gas that is produced by a number of different processes in living things. Other nitrogen molecules are continuously transformed by microbes into N2O via a metabolic process that might generate useful cellular energy.
“Nitrogen waste products produced by life are transformed into nitrates by some microbes. These nitrates accumulate in fish tanks, which is why you need to replace the water, according to Schwieterman.
But under the correct circumstances in the ocean, certain bacteria can turn those nitrates into N2O, according to Schwieterman. Following that, the gas leaks into the atmosphere.
It is difficult to detect elsewhere
N2O can be present in the atmosphere without being a sign of life. This was considered when modelling Schwieterman’s group. For instance, a little amount of nitrous oxide may be produced by lightning. However, nitrogen dioxide is a byproduct of lightning, which suggests to astrobiologists that the gas was created by non-living meteorological or geological processes.
Many people who have considered N2O as a potential biosignature gas come to the conclusion that it would be impossible to detect at such a distance. Schwieterman claims that the current levels of N2O in the Earth’s atmosphere are what led to this conclusion. Some believe that because there isn’t much of it on this planet, which is packed with life, it would likewise be challenging to find elsewhere.
“This conclusion does not account for periods in Earth’s history when ocean conditions would have allowed for a much larger biological release of N2O. The conditions in those time periods could reflect where an exoplanet is today,” Schwieterman said.
Schwieterman claims that the light spectrum emitted by ordinary stars like the K & M dwarfs is less effective than the sun at dissolving the N2O molecule. If these two effects combine, the estimated concentration of this biosignature gas on a populated world could increase significantly.
The results were published in The Astrophysical Journal on October 4.