The Search For Technosignatures
For those familiar with indie space game Stellaris, one of the key moments before encountering ancient intelligent life is finding traces of technology. While the game is a work of science fiction, the concept isn't outlandish to those behind the real life search for extraterrestrial life (SETI). According to astronomer Jason Wright, discovering traces of advanced technology, termed technosignatures, from alien civilizations is just as important as looking for biosignatures. He outlines his theory in new paper published online, and while he doesn't claim there's existing, direct evidence of aliens, he does wonder if we're just not looking hard enough – or for the right signs.
Contrary to what some have said, Wright's paper isn't saying that there's already evidence pointing to an alien civilization that existed in the solar system before us. Instead, he merely asked whether we've exhausted all possible angles in our search for extraterrestrials.
“There is zero evidence for any prior indigenous technological civilizations,” Wright told Gizmodo. “My paper asks, have we completely foreclosed the possibility, or is there a chance that there could be some evidence we overlooked? [And] if we have overlooked something and we find it in the future, what are the chances it could have come from a prior indigenous technological species versus an interstellar one?”
Currently, the hunt for aliens is focused on finding even the smallest signs of life, or mechanisms that could support life (most notably, the presence of water). These are all good, of course, but Wright suggests that we might also start looking for technosignatures from ancient alien civilizations.
"A ‘technosignature’ is evidence of technology," he said, which potential could have been left behind by some long-gone alien civilization. In his paper, he explained his point further: “We might conjecture that settlements or bases on [rocky moons or asteroids] would have been built beneath the surface for a variety of reasons, and so still be discoverable today."
What Are We Really Searching For?
The discovery of a new planet — or even better, a new system in some near or distant galaxy — is always good news for alien hunters. Most recently, the TRAPPIST system presented some possibilities — albeit ones quickly dashed by the intensity of solar flares its planets experience. Another possible candidate is a huge, Earth-like planet dubbed super-Earth LHS 1140b. Inside our own solar system, the planetary satellites of Jupiter and Saturn — particularly Europa and Enceladus — tickle the imagination because of the presence of water. And where there is water, the chance of life is higher.
However, despite the odds seemingly in our favor, we really haven't found any such example of alien life out there — yet. Fermi Paradox, yes? But, could it be that we've been looking at the wrong things? Or are we simply not looking hard enough?
Wright just wants us to explore all possible options: "While all geological records of prior indigenous [extraterrestrial] technological species might be long destroyed, if the species were spacefaring there may be technological artifacts to be found throughout the Solar system."