Will humans ever inhabit Mars?
By 2050, humans should be fairly well established on Mars, but it will take centuries to fully terraform the surface. I would envision automated spacecraft redirecting icy comets to Mars to build up the water supply and provide organics to aid in the terraforming. Harvesting comets will also provide the rocket fuel we need to spread out into the solar system. By harvesting comets and near earth asteroids, maybe we can prevent one of these from slamming into the Earth again and causing mass extinction.
