We’ve come a long way from mere snatches of (maybe) information to the need for standards in evaluating the expected incoming mass:
The main problem is that evidence that might suggest life could easily be a non-biological process:
Consider Jupiter’s moon Europa. A large asteroid impact could have volatilized ice on the surface, creating a water vapor atmosphere. Radiation from Jupiter could then have split the water molecules into oxygen and hydrogen, leaving the lighter hydrogen to escape to space and the heavier oxygen to be left behind. Just as with Europa, the discovery of oxygen in an exoplanet’s atmosphere, exciting at first, could turn out to have a purely physical explanation.
Finding large amounts of big organic molecules like chlorophyll in an alien atmosphere would be more exciting, since they are not known to form under abiotic conditions. By itself, however, that wouldn’t likely be proof enough. There would always be the nagging suspicion that some unknown non-biological chemistry is responsible.Dirk Schulze-Makuch, “Alien life: What would constitute “smoking gun” evidence?” at Big Think (March 29, 2022)
But, with so many new exoplanets coming into the view of the powerful new telescopes, a scale for assessing claims is an alternative to endless inconclusive buzz. NASA, for one, is on board with that:
The scale contains seven levels, reflective of the winding, complicated staircase of steps that would lead to scientists declaring they’ve found life beyond Earth. As an analogy [to the Confidence of Life Detection scale], Green and colleagues point to the Technology Readiness Level scale, a system used inside NASA to rate how ready a spacecraft or technology is to fly. Along this spectrum, cutting-edge technologies such as the Mars helicopter Ingenuity begin as ideas and develop into rigorously tested components of history-making space missions.
The authors hope that in the future, scientists will note in published studies how their new astrobiology results fit into such a scale. Journalists could also refer to this kind of framework to set expectations for the public in stories about new scientific results, so that small steps don’t appear to be giant leaps.Elizabeth Landau, “Are We Alone in the Universe? NASA Calls for New Framework” at NASA Astrobiology (October 27, 2021)
James Green, NASA’s chief scientist spearheaded the scale.News, “NASA develops a scale for assessing the chances of ET life” at Mind Matters News (April 2, 2022)
Takehome: The idea is to give media some idea of the level of confidence in what the apparent signal might be telling us — biological activity or just chemistry?
You may also wish to read:
The Drake equation at 60 years: The second most famous equation After e = mc2. New technology is improving our ability to search the skies for signs of possible extraterrestrial civilizations. Whatever the fate of current ET detection projects, a design filter of the sort proposed beats squabbling about the probability without collecting any data.
Astrophysicist: Stop looking for extraterrestrial civilizations. And accept that ‘Oumuamua was a natural object, though a very mysterious one. Paul Sutter is not saying that ET isn’t out there but that evidence of biosignatures (life) is more useful than technosignatures (intelligent life).