It stands at Pluto's north pole - a mesmerising icehenge. Slabs of ice frozen harder than stone, towering two hundred feet above the crater-pocked surface. The central slab bears an inscription in Sanskrit.
A message from an alien race? Or the mark of a human-powered voyage that might have passed this way? There were vague rumours of such a ship, forgotten decades ago. But could the crew have survived? Did the ship exist at all?