A NASA poster shows a fanciful future view of a spaceport on Trappist-1e, one of seven planets in the tightly packed system. Several of the planets may reside in the habitable zone, the distance from the star (known as Trappist-1) where temperatures are just right for liquid water to exist on the surface. And all of the planets are much closer to Trappist-1 than Mercury is to the Sun. [NASA]