Astrobiologists at MIT have proposed a new direction for the search for extraterrestrial life. Instead of looking for life similar to Earth, the researchers suggest looking for literally all chemically possible biomarkers, which are gases.
Projects like SETI are looking for civilizations that have mastered the technology and emit any radio signals into space. However, scientists would be interested in finding any form of life, even not so technically advanced - the main thing is that it be extraterrestrial. Therefore, many astrobiologists are looking for certain markers in the atmospheres of alien planets, signs of the presence of elements and their combinations, which could hardly have formed there without the participation of biological life.
For example, a planet whose atmosphere is rich in oxygen, or contains a large amount of methane, immediately deserves close attention of scientists. However, astrobiologists in Massachusetts believe that our search network should be significantly expanded.
They propose not to be limited to oxygen and methane, but to look for any volatile gases that can accumulate in the atmosphere due to the vital activity of organisms. To slightly limit the number of candidates, scientists selected six elements of the periodic table: carbon, nitrogen, oxygen, phosphorus, sulfur, and hydrogen (Carbon, Nitrogen, Oxygen, Phosphorus, Sulfur, Hydrogen = CNOPSH), and compiled a list of all isomers formed by these compounds (isomers are molecules that are identical in atomic composition and molecular weight, but differ in the structure or arrangement of atoms in space and, as a result, in properties).
Naturally, this approach raises other problems. First, scientists were able to observe the first exoplanet directly relatively recently, in 2004 - therefore, the search for gases from this list in the atmospheres of other planets is still a difficult task. Second, such a network of thousands of possible gases may be too wide, and random planets may appear in the search results.
Of course, until we have found a single planet from another life-supporting system, we have no idea how much life on other planets might differ from ours, and what omens might actually signal the existence of life on a planet. But, at least, it is better to expand the search area and pick up extra planets than to skip the necessary one, focusing on too narrow a group of parameters.