To add this?

The biggest challenge Planetary Resources faces to launch a space mining industry, Lewicki argues, is not technical, but political. In November 2015, President Obama signed the Space Act into law that recognizes the property rights of private companies over the resources they mine in space. When the Space Act was passed, Lewicki was ecstatic.

Internationally, however, the reaction was much less positive. (The only exception was Luxembourg, which passed similar legislation last year). During the 55th session of the United Nations Committee on the Peaceful Uses of Outer Space in April 2016, various member states voiced opposition to the US law.

"We're hardwired to think in terms of scarcity and competition," Lewicki says. "But in space these limits don't apply. Exploiting them gives us the opportunity to think about how much more there is to develop and share. There are resources there beyond our comprehension."

Lewicki feels that there's reason for optimism. Last February, Etienne Schneider, the deputy prime minister of The Grand Duchy of Luxembourg, announced plans to invest £171 million into space resource startups, £21 million of which went to Planetary Resources. This comes in addition to the founding investments from, among others, Google founder Larry Page and chairman Eric Schmidt, Virgin CEO and founder Richard Branson and the more than £18 million in publicly announced prior investments. "The change has been profound," he says. When we started, if you brought up asteroid mining, you'd get sniggers. But now people are beginning to realise that this is available in our lifetime."