Life on Venus? That outrageous-sounding possibility understandably made headlines a couple weeks ago. In part, the news grabbed people’s attention because Venus seems like such an unlikely place to find anything alive. The surface temperature there averages 460 degrees C, and the pressure at sea level is a crushing 93 times the atmospheric pressure on Earth–except, of course, there is no actual sea on Venus.
There was another startling aspect of the life-on-Venus story, however: the nature of the evidence itself. There are no rovers rolling across Venus. We do not have any samples of Venusian rocks to put under the microscope. We have no physical samples at all of the planet. The search for life was conducted from afar, entirely indirectly, using radio telescopes. Those provocative hints of life came in the form of an extremely slight radio shadow indicating the presence of a molecule known as phosphine, a phosphorus atom bonded to three hydrogen atoms.
It was an unexpected, confoundingly obscure signal. It was also a telling preview of things to come. As scientists expand the search for life across the solar system, and on planets around other stars, there will be more and more reports of possible life detections. As with phosphine on Venus, they will be indirect detections. They will be ambiguous. They will be debated.
And the signals of alien life will all, with near-certainty, take the form of a molecule.
Astrobiologists call it a “biosignature”: detectable evidence that life is present now, or that it was present in the past. In principle, a biosignature could come in the form of a flying saucer with aliens parading down a set of impeccible white stairs, or as a radio signal containing instructions on how to build an interstellar gateway. I can’t say that these things are impossible. Nobody can. But the overwhelming likelihood is that the first indications of alien life will take the form of molecules like phosphine—molecules that are commonly associated with biological processes, and that seem difficult to explain without them.
Jane Greaves, an astronomer at Cardiff University in Wales, and her colleagues used the James Clerk Maxwell Telescope in Hawaii and the ALMA radio observatory in Chile to scan for phosphine in Venus’s atmosphere. To their surprise and delight, the found the signal they were looking for.
Phosphine on Venus??
What is a biosignal. Challenge of identifying.
Biosignals on Mars? Dunno. Venus, Enceladus, Europa? Really dunno.
What about exoplanets? Could be life everywhere.
Will end up with a future full of odds-makers & no answers.
May have to settle for the statistics.
Life on Venus? How Rocket Lab, Breakthrough Initiatives & NASA Plan to Find Out
