For 60 years, Americans have pushed steadily into the suburbs, transforming the landscape and (until recently) leaving cities behind. But today the pendulum is swinging back toward urban living, and there are many reasons to believe this swing will continue. As it does, many low-density suburbs and McMansion subdivisions, including some that are lovely and affluent today, may become what inner cities became in the 1960s and ’70s—slums characterized by poverty, crime, and decay … As conventional suburban lifestyles fall out of fashion and walkable urban alternatives proliferate, what will happen to obsolete large-lot houses?

Ceres’s prime location as well as its gravitational benefits could (like Earth’s moon) help jump start our solar economy, if not give it a second wind. But how would an active mining industry aid a future Martian colony? After all, if Mars has very little to offer our species financially, why even bother colonizing it?