Humankind may be rapidly approaching the commercial exploitation and perhaps colonisation of the moon and Mars. Does history give us confidence that it will be peaceful and constructive, instead of a further reason for conflict, trouble and wars? Given the precedents – humanity’s ‘common inheritance’ of such places as the Antarctic and the world’s oceans – we must ask: how well have we succeeded in avoiding international competition and conflicts? How well do international agreements work? The philosopher and Principal of Northeastern University, London, asks what should be done to avoid competition in space becoming conflict on Earth?