From Scientific American:
According to Jon Morse, former head of NASA’s astrophysics program and current CEO of a research organization called the BoldlyGo Institute, ongoing technological progress makes this plan viable. “There’s a lot more capability out there for lower cost than there was 10 years ago, whether in spacecraft performance or in the availability of launch vehicles for access to space,” Morse says. BoldlyGo has partnered with another organization, Mission Centaur, to lead Project Blue.
Additionally, the thousands of worlds discovered by NASA’s planet-hunting Kepler mission strongly suggest that “there should be as many small planets like the Earth as there are stars,” Morse explains, meaning that to see one astronomers should not need to build a gargantuan telescope that could peer clear across the galaxy.
There’s just one catch. Project Blue’s proposed telescope would have a light-gathering mirror just half a meter wide—so small that it could only look for Earth-like planets around two stars: the Sun-like Alpha Centauri A and Alpha Centauri B, which along with the red dwarf Proxima Centauri form the nearest star system to our own at just over four light-years away. Proxima Centauri made headlines earlier this year when astronomers discovered a planet with a mass similar to Earth’s in a not-too-hot, not-too-cold “habitable zone.” Alas, this newfound world orbits so close to its small, dim star that it will be very difficult to image with a space telescope. No one yet knows whether any planets orbit Alpha Centauri A or B, but because both stars are so much larger and brighter than Proxima, their habitable zones are much further out, allowing any as-yet-undiscovered worlds to be more easily seen.
“Looking around the very nearest Sun-like stars is the next logical step in the search for another Earth,” says Supriya Chakrabarti, an astronomer …