The new James Webb Space Telescope, which launches in October, “could feasibly detect ammonia around six gas dwarf planets after just a few orbits”:
Gas dwarf planets have the potential to foster life. But because none of these super-Earths or mini-Neptunes exist within our solar system, scientists struggle to determine whether their atmospheres contain ammonia and other potential signs of living things.American Physical Society, “Scientists may detect signs of extraterrestrial life in the next 5 to 10 years” at ScienceDaily
We shall see. It would be great to find them, but if we don’t, is that evidence too?
See also: SETI director warns: Those aliens could be malevolent. Harvard astronomer agrees: We’ve sent a lot of signals in recent years; they may have got them. But now what? Astronomer Avi Loeb has a low-risk practical idea: Look for alien debris on our still, lifeless, atmosphere-free Moon