A surprising twist has emerged in the study of astrobiology: Researchers recently suggested a new way of looking for alien life based on the idea that while the type of biosignatures is important, their organization is what really matters.
While compounds such as amino acids and fatty acids are often associated with life, they can also be produced by abiotic chemical reactions, making it difficult to confirm the presence of life on other planets.
“Our approach could help make the search for life more efficient. If the molecular assembly shows no life-like organization, this could make it a lower priority target,” said Fabian Kleiner of the University of California, Riverside. space.com.
Researchers have discovered a new way to distinguish between sources: organic amino acids are more diverse and more evenly distributed than nonbiological varieties, while organic fatty acids are less diverse and less evenly distributed.
However, this method requires an extensive “inventory” of molecules to be effective. As a result, it cannot yet be applied to distant exoplanets such as K2-18b, where we currently only detect single molecules such as dimethyl sulfide (DMS).
“We focused on amino acids and fatty acids because they are central molecular classes to life as we know it and because appropriate datasets exist,” Klein said.
A major advantage of this technique is that these organizational patterns persist even when biological samples degrade – a fact proven by fossilized dinosaur eggs, which still retain their characteristic molecular distribution.
Researchers caution that this is not a surefire way to detect life. First of all, they have only shown that it works with amino acids and fatty acids. “In principle, similar organizational trends may exist for other molecular classes, but this still needs to be tested,” Kleiner said.
“For a single molecule like DMS, the situation is different,” Kleiner said. “For K2-18b, DMS alone will not be sufficient for our analysis – we will need a comprehensive list of relevant molecules.”
Because the patterns survive degradation, this technique is highly promising for searching for ancient life on Mars or investigating eruption sites on Jupiter’s moon, Europa.
This technique is most effective in our Solar System, where we have access to more complex datasets and physical samples.
An important breakthrough is that molecular organizational patterns remain intact even in highly degraded or ancient samples, such as fossilized dinosaur eggs. This robustness makes the method an important tool for searching for signs of life on Mars billions of years ago, despite the planet’s current harsh conditions.
Although this technology cannot 100% confirm alien life, it serves as a refined guide to help scientists identify the most promising locations for further study.
One of the instruments aboard Clipper, the Surface Dust Analyser, will be able to measure the abundance ratio of organic molecules in ice particles ejected from Europa, Kleiner said. “If families of organic molecules are detected, our diversity-based approach will help explain whether these molecules appear more consistent with inorganic chemistry or biological organization.”
