This is the kind of scenario where I find a side-chain much more useful actually. Because even if they decide to use lightning for mars-to-mars transactions, nothing really guarantees that a LN peer is actually in Mars. It could be someone on Earth trying to convince a martian to open a payment channel to later try to cheat, taking advantage of the fact that the one on earth is closer to the center of hash.

A sidechain like Liquid would make more sense here. Assuming that all members of the federation are on martian soil, then you can build a lightning network on top of that sidechain and use that instead.

The monetary base doesn't need to be expanded.