Why do it? It’s not for practicality. We didn’t go to the moon to spin off cooling suits and freeze-dried fruit. Any technological return is a bonus, not a reason. We go for the wonder and glory of it. Or, to put it less grandly, for its immense possibilities. We choose to do such things, said JFK, “not because they are easy, but because they are hard.” And when you do such magnificently hard things — send sailing a Ferdinand Magellan or a Neil Armstrong — you open new human possibility in ways utterly unpredictable.