The hunt for technological optical signatures of extraterrestrial civilizations has finally gone mainstream. For practically six decades, a small, however, a gung-ho group of scientists have been looking for radio and optical signals from space aliens. Now, the Seek for Extraterrestrial Intelligence (SETI) has been adopted by a more mainstream group of researcher’s eager to search for optical techno signatures of otherworldly civilizations.
On the recent AbSciCon 2019 conference on astrobiology in Bellevue, Wash., the topic was very well represented in a series of oral presentations.
Instead of merely in search of signs that a planet might have microbial life, why not additionally look for signs that an extrasolar planet’s atmosphere has been artificially modified by some anthropogenic activity? That’s, such as harnessing the power, industrial exercise, and even nuclear fallout which may provide a tell-tale sign of a past or present civilization.
In his AbSciCon presentation abstract, Adam Frank, a University of Rochester astrophysicist and author of “Light of the Stars: Alien Worlds and the Fate of the Earth,” divides terrestrial planetary atmospheres into five classes. These classes start with no atmosphere on up through Class 4 and Class 5 atmospheres which have thick biospheres where life changes how the “planetary systems” (atmosphere, hydrosphere (oceans, rivers), cryosphere (ice, glaciers), geosphere (surface rocks) function, he advised me. Then finally, he says, a Class 5 planetary atmosphere is one in which a technological civilization has adapted itself to work with the biosphere to create a sustainable whole.