We can't sustain a space industry with chemical rockets. We need a clean source of high-yield energy and fast space propulsion. Until we have these, everything else is a waste of time and money. It's too early in our history to be pursuing manned space exploration. Scrap the mission to Mars, the shuttles, the International Space Station, the zero-G ant farms and spend the money on technological advancement.
Given the resolution of todays computer graphics and the fact most of the world doesn't believe we even went to the moon: what would be the point of going to Mars? No-one will believe it.
Our oil-based civilisation is already in decline. Our planet is overpopulated. One third of the world is starving and most of the rest live in poverty. The environment is collapsing, the greenhouse effect is kicking in. Entire ecosystems are becoming extinct. These are all serious issues that should be resolved before we step foot off this planet again.