WIRED: But now the fields are coming back together a little bit?

Tarter: Historically we've been looking for signals in the electromagnetic spectrum. That's what SETI has done. More recently, considering the new ground-based telescopes that we're building and the new space-based telescopes that we're building, we begin to think, “How can we use those to find something that only a technology could do?”

Signals is still a good idea, but there may be many other things that, with these new observational characteristics, we can find. And so the astrobiology community was sort of schizophrenic for a while, and it was OK to look for microbes through kind of the beginning of complex life. But they said, “Nah, SETI, that's not part of astrobiology.” But we've just now seen a revisit of that, as the astronomers prepare for the next decadal review where we all sit down and prioritize what we want to do for the next decade. And a National Academy of Sciences committee looked at an astrobiology strategy, and they are far more willing to level playing the field, to accept the idea that both technosignatures and biosignatures belong under a large umbrella of astrobiology observations.

WIRED: What are your favorite examples of possible alien technology that is potentially detectable by our instruments?

Tarter: There is this fabulous star system or planetary system called Trappist-1. Seven planets orbiting a tiny dwarf star. They're very closely packed; all of their orbits would fit inside the orbit of Mercury if they were in our solar system. And three of them are perhaps at the right distance from their star so that if they had an atmosphere they could have liquid water. All right so now take those seven planets at different distances from their star. And say when we get an opportunity to actually explore them we find out they're all the same. They aren't different temperatures. They actually all look identical. Well that's not likely, given nature, but if some technological civilization arose on one of them and decided they wanted more real estate they might in fact transform all the other planets in their system to be the same.

WIRED: Maggie, tell us about the telescope you're working on and what that can detect.

Turnbull: Right now my biggest project my biggest and most overwhelming project is with the WFIRST telescope. (As we get closer to launch it will get a more fun name than that.) But it means the Wide Field Infrared Space Telescope; most of the observatory is designed for deep sky work and looking at dark energy and dark matter. Two of the sexiest topics in astrophysics … but the first sexiest topic in astrophysics is definitely exoplanets and life. So, as a technology demonstration, we're including the first ever space-born camera to directly take pictures of the nearest planetary systems. That’s never been done before.

What we're going to do is start with a few of the planetary systems that we know for sure exist. We've detected them through the gravitational pull that those planets have on their star. We've never seen them directly, but we know for sure they're there.

WIRED: What will you look for?

Turnbull: Water in the atmosphere has very very strong absorption feature. Plants have a very distinct signature because they're very dark. We think of them as being green because they reflect a little bit of green light. But for the most part, they are very dark because they're absorbing all of that light and using it as the energy source to build their bodies. Then they get really reflective in the infrared and there's a lot of theories as to why this might be. Maybe it's a cooling mechanism—whatever the point is, it's really visible. The vegetation is very visible and it's been a signal being broadcast in reflected sunlight to the universe for the last billion years. So that's something that we could potentially see for an Earth-like planet.