It has been a busy month for space probes. The Japanese have launched Hayabusa 2 to go to an asteroid and come back with a sample, larger than the few grains of dust that the first Hayabusa returned. Nasa put its Orion capsule into orbit, its first new spacecraft capable of carrying humans in 30 years; some day it may take astronauts back to the Moon. And the New Horizons mission has been roused from “sleep” mode to get ready for an encounter with Pluto this spring.Space travel is about space, of course; but it is also about travel. Fifty years ago, Nasa named its first probes Mariner, Pioneer and Voyager, realising that studying the planets was an attempt to salve humanity’s itchy feet.There is something special about going somewhere. Shopping in a town centre is differ