Later this century giant robotic fabricators may assemble vast lightweight structures in space (gossamer-thin radio reflectors or solar energy collectors , for instance) — using raw materials mined from the Moon or asteroids. Robotic and AI advances are eroding the practical case for human spaceflight. Nonetheless, I hope people will follow the robots, though it will be as risk-seeking adventurers rather than for practical goals. The most promising developments are spearheaded by private companies. Elon Musk’s Space X, has launched unmanned payloads and docked with the Space Station — and has successfully recovered and reuseed the launch-rocket’s first stage — presaging real cost-saving. He hopes soon to offer orbital flights to paying customers. Wealthy adventurers are already signing up for a week-long trip round the far side of the Moon — voyaging further from Earth than anyone has been before I’m told they’ve sold a ticket for the second flight but not for the first flight. We should surely acclaim these private enterprise efforts in space — they can tolerate higher risks than a western government could impose on publicly-funded civilian astronauts, and thereby cut costs compared to NASA or ESA. But they should be promoted as adventures or extreme sports -- the phrase ‘space tourism’ should be avoided. It lulls people into unrealistic confidence. By 2100 courageous pioneers in the mould of (say) Felix Baumgartner, who broke the sound barrier in free fall from a high-altitude balloon -- may have established ‘bases’ independent from the Earth — on Mars, or maybe on asteroids. Musk himself (aged 45) says he wants to die on Mars — but not on impact. But don’t ever expect mass emigration from Earth. Nowhere in our Solar system offers an environment even as clement as the Antarctic or the top of Everest. It’s a dangerous delusion to think that space offers an escape from Earth's problems. There’s no ‘Planet B’. Indeed, space is an inherently hostile environment