Motivations for space exploration

Possibly the greatest barrier to progress in space exploration is the lack of compelling motivations to justify the necessary investments. Spaceflight, a concept that gained currency in the middle of the twentieth century, may not be well adapted to the twenty-first century without significant modification. This article assesses the traditional motivations for space exploration, documented in a Harvard study carried out over two decades ago, in the light of subsequent developments. It then reports on a recent NASA study of justifications for a renewed Moon program, and concludes with the conjecture that the very meaning of human travel in space needs to be redefined.