Despite the recent NASA announcement, which kind of fizzled. From ScienceDaily:
Researchers led by space physicist Chuanfei Dong of the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL) and Princeton University have recently raised doubts about water on — and thus potential habitability of — frequently cited exoplanets that orbit red dwarfs, the most common stars in the Milky Way.
In two papers in The Astrophysical Journal Letters, the scientists develop models showing that the stellar wind — the constant outpouring of charged particles that sweep out into space — could severely deplete the atmosphere of such planets over hundreds of millions of years, rendering them unable to host surface-based life as we know it.
“Traditional definition and climate models of the habitable zone consider only the surface temperature,” Dong said. “But the stellar wind can significantly contribute to the long-term erosion and atmospheric loss of many exoplanets, so the climate models tell only part of the story.”
…
Scientists spot potentially habitable worlds with regularity. Recently, a newly discovered Earth-sized planet orbiting Ross 128, a red dwarf star that is smaller and cooler than the sun located some 11 light years from Earth, was cited as a water candidate. Scientists noted that the star appears to be quiescent and well-behaved, not throwing off flares and eruptions that could undo conditions favorable to life.Paper. (paywall) – Chuanfei Dong, Manasvi Lingam, Yingjuan Ma, and Ofer Cohen. Is Proxima Centauri b Habitable? A Study of Atmospheric Loss. Astrophysical Journal Letters, 2017 DOI: 10.3847/2041-8213/aa6438 More.
What would be the psychological impact, at this point, of drawing the conclusion that even if there are habitable planets out there, they are so few and far that it would not be feasible to look for them?
See also: Pretty discouraging news from exoplanet research: We’re not sure what to look for
Researchers: Water flow on Mars turns out to be sand and dust Mars is so close to Earth that it benefits from some features that enable life on Earth. Dashed hopes for Mars probably reduce the chances for similar exoplanets in galactic habitable zones.
Rob Sheldon: NASA’s big announcement about exoplanets “underwhelming.” A inside-Mercury-orbiting rock that is over 800 degrees hot? And the Google AI angle was just an algorithm that learned to do pattern recognition on Kepler-data? This isn’t exactly new, just cheaper than the previous alternative. I’m underwhelmed. So many other things NASA could talk about in a press release, and this is the best they can offer?
and
How do we grapple with the idea that ET might not be out there?