When we catch up with the robot, it is poking along in a herky-jerky and rather flummoxed fashion through the Atacama Desert, which covers much of far northern Chile. The Atacama is reputedly the driest place on Earth, with rainfall measured in millimeters per decade. It is a rough place for man or robot, a tawny maze of high plateaus and shaley foothills under constant sun and an enormous cobalt-blue sky.

When H.G. Wells sent the hero of The Time Machine into what Wells called "futurity," it was on a grim 30-million-year round-trip to pretty much the end of Earth time, when the last, poorest excuses for life were flopping around like squid under a darkening sun. Wells wasn't the first writer to imagine time travel, but he advanced the idea that a machine, rather than an angel or a bonk on the head, could accomplish it, and he pushed his machine to the limit.