Abstract
How may nations protect their interests in space if its fragility makes military operations there self-defeating? This essay claims nations are in Prisoners Dilemmas on the matter, and applies David Gauthier’s theories about how it is rational to behave morally—cooperatively—in such dilemmas. Currently space-faring nations should i) enter into co-operative space sharing arrangements with other rational nations, ii) exclude—militarily, but with only terrestrial force—nations irrational or existentially opposed to other nations being in space, and iii) incentivize all nations into co-operation by redistributing some space-generated wealth to nations that might otherwise ruin space. Further, since all nations are rationally incentivized to ever greater dependence on space, and since each, by threatening space, can hold hostage its benefits to all, each can demand resolution of terrestrial discontents with other nations. So each has a rational interest in treating others morally both in space and on terrestrial issues.