As Chris Impey points out in Beyond: Our Future in Space, wanderlust can be considered as one of our most innate emotions. Since humans appeared on Earth, they never stopped exploring, and this is certainly what gave them the best opportunities to be creative and to invent new techniques and technologies. Those things made them the happiest. The history of humankind demonstrates it, but children's dreams and adventures offer the best of confirmations of the extent to which exploring makes us feel alive. But now that there is almost nothing left for us to discover on Earth, a crucial part of our psychological and physical needs finds itself increasingly hard to fulfill. Indeed, our planet's geographical conquest, which accelerated suddenly with the Age of Discovery in the fifteenth century after thousands of years of relatively slow motion, came to an end with the detailed satellite cartography of even the world's darkest nooks and crannies. Only a few regions remain unexplored or barely known: the Mariana Trench, the region of Sierra de Maigualida in Venezuela, the Antarctic, and several mountainous areas of Vietnam, Laos and Indonesia. There are no deserted islands left to visit, no ocean depths left to chart and no mysterious mountains left to climb. Earth has been laid bare and exposed, with each square meter now referenced on Google Earth. There are no more expeditions to explore new lands, so the world is now traveled only by tourists. Geographically, all is henceforth known, including our planet's historical physiognomy, right down to its earliest volcanoes and its first bacterial life forms.

Exploration has always implied a strong physical commitment, along with enormous risks. Throughout humanity's conquest of the world, many people died while trying to cross mountains, rivers, jungles, deserts and seas. But despite our apparent weaknesses (we’ve got no fur, no shell, no claws or venom), we are actually quite resistant and adaptable, at least enough for our intelligence to compensate for our physical deficiencies. Our bodies have been designed for walking long distances, running and even swimming. There are not many animals as polyvalent as us. So, in addition to frustrating our taste for adventure, the end of the terrestrial exploration era has had an unexpected and desolating consequence on our condition: the obsolescence of our bodies.