Geoscientist Dirk Schulze-Makuch, co-author with William Bains of The Cosmic Zoo (2017) and a number of other books on planetary habitability, thinks science needs standardized scales for assessing claims about extraterrestrial life.
There are lots of claims: life on Mars detected by the Viking landers (1976), fossil life in a Mars-origin meteorite (1996), phosphine on Venus (2020) … all have some evidence in their favor. But scientists need a way to express degrees of certainty. Recently, NASA has proposed the Confidence of Life Detection Scale (CoLD), featuring seven benchmarks.
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