In the course of his 172 patrol flights, Pirx had run the gamut of psychic responses, having been subject to attacks of drowsiness, crotchetiness, even fits of feebleminded eccentricity… and once was on the verge of committing some far-from-harmless prank. Lately he had begun concocting plots to various stories, a hangover from his student days, some of which turned out to be so intricate in construction as to defy finding a resolution before the end of the flight. But did it help to relieve the boredom? Not a bit.

As he ventured into the labyrinth of lonely contemplation, Pirx realized he would never solve the mystery of his two missing comrades, not when the most high-powered experts at the Base had been beating their brains out, for months on end, without cracking it. No, he was better off with his piggy game, a no less idle but certainly more harmless pastime—if only he could get it to work! But the engines were quiet, nor was there any reason to fire them up, what with the ship now cruising along the segment of a protracted ellipsis, one of whose foci was the Sun. No, the piggies would have to wait for sunnier days.

Okay, so what could have happened to Thomas and Wilmer?

An ordinary layman would have presumed a collision with something—with a meteor, for example, with a cloud of cosmic dust, a comet’s tail, or the wreckage of some old rocket ship. But the chances of such a collision’s occurring were about as remote as finding a mammoth diamond in the middle of a busy street; statistics showed, in fact, that the odds in favor of finding the diamond were much greater.