Scientists Propose a New Test for Detecting Alien Life Unlike Anything on Earth

Scientists at the University of Glasgow propose a new test for detecting alien life, different from Earth-based methods. The approach focuses on the difficulty of creating a molecule, using mass spectrometry and machine learning to estimate "molecular assembly" (MA), a concept from Assembly Theory. The study suggests that highly complex molecules may indicate a consistent chemical process, making MA an "agnostic" biosignature. The researchers trained an XGBoost model on standardized mass spectra to estimate MA directly from single-stage spectra, improving accuracy by threefold compared to a baseline model.

The study found that the model underestimated molecules with especially high MA values, which could be preferable for life-detection systems. The method is not yet ready for use in planetary missions due to instrument settings affecting performance. In simulated experiments, changing impact energies could nearly double prediction error, and some comparisons increased it by more than 2.3 times. The researchers describe the study as a proof of concept, emphasizing the need for standardized databases, instrument calibration, and chromatographic separation to isolate molecules before analysis. Future versions could combine mass spectrometry with other techniques like nuclear magnetic resonance or infrared spectroscopy.

The proposed method could help identify complex molecules without knowing what they are, which is especially useful on worlds like Mars or Europa where spacecraft may encounter unfamiliar compounds. The study suggests that particularly complex artificial molecules might serve as "molecular technosignatures," but currently, the approach remains limited by instrument constraints and the need for further development. The study appears in the Proceedings of the National Academy of Sciences, and the researcher, Tim McMillan, is a retired law enforcement executive and investigative reporter.

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