Why "for life"? Even if a permanent base is established, what would stop people from traveling there to work for a year or so and then returning home? I know

Why "for life"? Even if a permanent base is established, what would stop people from traveling there to work for a year or so and then returning home? I know health concerns related to radiation and gravity may impose some constraints, but would a round-trip journey be out of the question? Musk's explicit goal is to make and use fully-reusable rockets, so obviously he intends them to travel both directions. If you're talking about an eventual permanent colony, it will definitely need some brave souls willing to make a one-way trip -- but so have many colonies in Earth history. And the colonists needn't be as cut off as you say if they could have visitors from Earth coming and going regularly. The round-trip radio delay between Mars and Earth is anywhere from 7 minutes to 45 minutes (I think your "ping time" was off by an order of magnitute or two), which is far shorter than the delay for, say, European colonists in 18th-century America or Africa to write to their friends back home. By the time we are thinking about raising children on another planet, we might even be able to build them an indoor swimming pool. :)