If people take permanent residence on another planet like mars, information will take way too long to go back and forth in-between both planets for them to be able to use Bitcoin as well. Do you think there will be a different Bitcoin for every planet? Each planet will need its own local miners and nodes to validate tx's I think
Discussion
There are several solutions to the interplanetary block propagation problem.
One is a Bitcoin clone with a 10 hour block time. This is enough time to propagate blocked throughout most of the solar system.
Another is a soft fork to increase the block time of the terrestrial chain. This could be phased in over time, like the halving. Perhaps doubling the block time with some regular cadence.