A surprising twist has emerged in the study of astrobiology: Researchers recently proposed a new way to search for extraterrestrial life, based on the idea that while the type of biosignature is crucial, their organization really matters.
Although 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 a molecular assembly does not show lifelike organization, it could become a lower priority target,” Fabian Klenner of the University of California, Riverside, told IPS. Space.com.
Researchers have discovered a new way to distinguish between sources: organic amino acids are more diverse and more evenly distributed than abiotic varieties, while organic fatty acids are less diverse and less evenly distributed.
However, this method requires a broad ‘inventory’ of molecules to be effective. Consequently, 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 these are central molecular classes for life as we know it and because suitable data sets exist,” says Clenne.
A major advantage of this technique is that these organizational patterns persist even as biological samples deteriorate – a fact proven by fossilized dinosaur eggs, which still retained their distinct molecular distributions.
This is not a foolproof method for detecting life, the researchers warn. 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 remains to be tested,” says Klenner.
“For a single molecule like DMS, the situation is different,” says Klenner. “For K2-18b, DMS alone would not be enough for our analysis – we would need a broader inventory of related molecules.”
Because the patterns survive degradation, the technique holds great promise for searching for ancient life on Mars or for exploring eruptive sites on Jupiter’s moon, Europa.
The technique is most effective within our solar system, where we have access to more complex data sets and physical samples.
A major breakthrough is that molecular organizational patterns remain intact even in highly degraded or ancient samples, such as fossilized dinosaur eggs. This persistence makes the method an essential tool in the search for signs of life on Mars from billions of years ago, despite the planet’s current harsh conditions.
While the technique cannot provide 100% confirmation of extraterrestrial life, it serves as an advanced guide to help scientists identify the most promising locations for further research.
One of the instruments aboard Clipper, the Surface Dust Analyzer, will be able to measure the abundance ratios of organic molecules in ice grains emitted from Europa,” Klenner said. “If families of organic molecules are detected, our diversity-based approach will help interpret whether these molecules appear more consistent with abiotic chemistry or biological organization.”
