The asteroid rush sending 21st-century prospectors into space

A race is on to mine billions of dollars in resources from the solar system’s asteroids, fuelling our future among the starsIn an industrial park in San Jose, California, Grant Bonin is holding what looks like the end of a metal water bottle. It is the casing, he jokes, of his company’s “flying steam kettle”: a propulsion system for small spacecraft that uses super-hot water vapour, heated to 1,000C (1,832F), to produce thrust. The company has sold about 40 to date. &ldqu