How soon before we can start mapping the surfaces of distant planets?

To date, astronomers have catalogued over 860 exoplanets. If that wasn't remarkable enough, scientists have also been able to determine the atmospheric composition of many of these planets by analyzing their spectral shifts. But even more incredible would be the ability to actually chart landmasses and oceanic… » 1/31/13 11:20am 1/31/13 11:20am