interplanetary communication is bounded by the speed of light so that even if there are bitcoin full nodes on Mars, the latency will make them a fork of the earth net unless you are willing to accept a transaction rate of 1 per several minutes.
Maybe each planet will have its own main net and we need to figure out offline valua transaction between nets.
(4-24 minutes + block mining delay) * 2
It just occurred to me that lighting and ecash would work perfectly well despite the delay.
But I think there will be a long period where the majority of humans live in earth orbit. (More than the sum of those on earth and those outside of earth’s gravity well). There is just so much volume and sunlight power once you go 3d.
