"I just have to say pretty bluntly here: we've been there before." So said President Obama in 2010 as he ruled out a return to the moon. But there are signs on the NASA grapevine and from the world of commercial space flight that humans are once more headed that way.

A NASA crewed mission to lunar orbit could focus on exploring the moon's dark side and testing technologies to speed up exploration of Mars and other planets. Unfettered by the demands of state funding, a private mission may attempt something even more novel.

Since Obama's speech, there have been hints that NASA might be changing its tune. Rumour has it that the agency plans to build a hovering moon base about 60,000 kilometres above the moon's far side at a Lagrange point, where the pull of Earth's gravity cancels out the moon's. From this point – called L2 – astronauts would steer rovers round the surface in close to real time, much cheaper than actually landing on the moon.

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