“DON’T be excited,” says Sara Seager. She is speaking about putative signs of life from observations of the atmospheres of different worlds, and her phrases are a sobering counterbalance to hyperbolic headlines.
Of course, a real sighting of the signature of life past Earth would be something however humdrum. On the opposite, it could be momentous. Given that we have investigated only a tiny fraction of the numerous billions of planets assumed to exist in our personal galaxy, it could indicate that life is considerable within the universe.
That explains the regular drumbeat of tales about molecular “biosignatures” spotted on different worlds, thanks primarily to the James Webb Space Telescope (JWST). Last September alone, it detected carbon dioxide on Jupiter’s icy moon Europa that seems to come back from its doubtlessly life-friendly hid ocean and, presumably, dimethyl sulphide on exoplanet K2-18b, a chemical produced on Earth solely by residing issues. “Tantalising sign of possible life on faraway world,” was the BBC’s take.
But Seager, an astrobiologist on the Massachusetts Institute of Technology, urges warning for good motive: on the subject of proof for extraterrestrial life, the distant detection of molecules tends to be inconclusive. Even if the detection proves dependable – and that’s usually an enormous if – there might nicely be a believable non-biological rationalization for a chemical’s presence.
To make sense of such findings, then, and to calibrate our pleasure concerning the probabilities they herald aliens, it pays to familiarize yourself with the guarantees and pitfalls of the biosignatures we seek for. Can they ever present definitive proof of life?
When astrobiologists speak about searching for atmospheric biosignatures,…