As we get closer to life on Mars, we have to start thinking about what its economy would look like and how that might affect the rest of us here on Earth. There are plenty of creatives who have already been doing lots of brainstorming about this. Science fiction writer Kim Stanley Robinson is one. Marketplace Tech host Molly Wood talked with him about what colonizing the red planet might look like and how — or even if — that would be profitable. An edited transcript of their conversation follows.