If we Detect This gas on Other Planets, it’s a Good Sign There’s Life There

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Here is an idea that likely never crossed the mind of most space enthusiasts – a gas emitted from broccoli (and other plants) is one of the most indicative signs of the existence of life on a planet. At least according to a new study from researchers at the University of California Riverside.

That gas, methyl bromide, has long been associated with life on Earth. It occurs naturally from the process of plants defending themselves. Methylation, as the defense process is known, allows plants to expel foreign contaminants, such as bromide, by attaching a series of carbon and hydrogen atoms to it, thereby gasifying it and allowing it to escape into the air.

Methyl bromide, in particular, is interesting from an astrobiological perspective. It was used as a pesticide until the early 2000s and has several important advantages over other potential biosignatures if it shows up in an exoplanet’s atmosphere.

First, it has a relatively short lifespan in a planet’s atmosphere. This is particularly important for exoplanet searches, as it means whatever process produces the gas is most likely still active. Its presence isn’t simply a result of a geological event that happened eons ago.

A second advantage is one that all astrobiologists love to see – there are very few non-biological processes that produce the gas, and even those processes aren’t typically natural. Despite now being considered a hazardous chemical, methyl bromide was produced in large quantities for use as a pesticide before being regulated due to its deleterious health effects.

A third advantage is the spectroscopic wavelength it shares with a “cousin” gas that is also a biosignature – methyl chloride, which also results from the methylation process. Their combined signature would make them much easier to detect from far away, and both are indicative of the existence of a biological process, though being able to distinguish between methyl chloride and methyl bromide, as methyl chloride has already been seen around some stars, which was likely caused by an inorganic process.

Read more: https://www.universetoday.com/158102/if ... ife-there/