We are already losing the technology and knowledge necessary for manned extra-terrestrial travel – critically that required to land people, we owe it to future generations to retain it.  If we compare the dual experience of Columbus and the Chinese Treasure Fleet of the fifteenth century, the Chinese decided not to pursue exploration and the technology of how to build and sail ships was lost until they were themselves colonized by sea-faring nations. Columbus’ voyages, by contrast were followed up with further expeditions, leading to the largest expansion in the history of humanity.  The technology required to land human beings on the surface of another planetary body is comparable.  All of those involved in the original moon landing are now elderly it seems sensible to deploy that expertise before it is lost. Recorded knowledge is all well and good but experience is also valuable.  Equally, one of the biggest justifications for NASA’s relatively modest budget – roughly nine billion dollars at the moment – is the trickledown technology from its innovations. Developing technology for survival in hostile alien environments may have applications on Earth such as inhabiting Antarctica or using resources vastly more efficiently