Astrobiologists Make List of Biosignature Gases to Aid Search for Alien Life

"Thousands of exoplanets are known to orbit nearby stars. Plans for the next generation of space-based and ground-based telescopes are fueling the anticipation that a precious few habitable planets can be identified in the coming decade," the authors wrote in their paper, published in Astrobiology . "Even more highly anticipated is the chance to find signs of life on these habitable planets by way of biosignature gases."

"This work reminds me of Darwin's voyage aboard The Beagle, exploring the vast diversity of life by sailing around the world," said Dr. Nancy Kiang, Senior Editor of the journal Astrobiology and a scientist at NASA's Goddard Institute for Space Studies. "In the search for life beyond our planet, we are currently at a similarly exciting, early but rapidly evolving stage of exploration as the discovery of exoplanets accelerates. Instead of netting strange creatures from the bottom of the sea, the authors here have searched and found thousands of curious, potentially biogenic gas molecules. These will inspire a new body of research into identifying also larger molecules, investigating their origin and fate here, and their potential expression on exoplanets as signs of life."

As of now, it would take a prohibitive amount of time to reach potentially habitable exoplanets to physically search for extraterrestrials. So in the search for alien life, the detection of biosignatures is of the utmost importance, and now, a group of astrobiologists has composed a list of possible gases that could be emitted by recognizable life forms to guide astronomers searching for signs of life outside our solar system.Whenever astronomers start looking in earnest for biosignature gases surrounding exoplanets, they will need to know which gases to search for. While a few biosignature gases are present in our atmosphere, theoretically, alien life could produce entirely different gases through their own biological processes. As a result of this, and for the sake of comprehensiveness, the researchers, led by MIT's Sara Yeager, have proposed that all molecules that are stable in the presence of water and volatile at STP (standard temperature and pressure) could be considered potential biosignature gases.The team made an exhaustive list of all known molecules (up to six non-hydrogen atoms), and came up with approximately 14,000 molecules. According to the researchers, this list can be used both in the search for biosignature gases in exoplanet atmospheres, but also to study the nature of life itself. By composing this list of gases that could be produced by any hypothetical life form, scientists may be able to gauge patterns that shed light on the "limits of terrestrial biochemistry."