In the late fifteenth century, early transoceanic navigators, such as Vasco da Gama and Christopher Columbus for the first time lost sight of land for a long period. They then had to make their way through a no man’s land or rather through a no man’s sea. Possibly, they had to overcome greater navigational and psychological barriers than our first present day space travellers. who could always see the globe from where they started their mission and maintained constant contact with their base. To avoid getting lost, there was only one thing our early explorers could do: keep track of their own position relative to their point of departure.