12 August 2015 - habitable zone 3

Here in the solar system, where our astrobiology targets are close enough to visit, we see ice moons like Europa and Enceladus as likely habitats because they have liquid water under the surface. Mars and Venus, our companions in the “habitable zone”, are written off as lost causes. “Habitable planet” doesn’t mean “a planet where life might arise,” it means “a planet where we might like to live.”