Aviv & Yonatan: Could GHOST work in the situation that transaction & block propagation across the whole network happens much slower than block generation? For instance, in inter-planetary distances? We'd expect blocks to be made on Mars every few seconds but each would not make it to Earth for a few minutes.
It would work, in the sense that the 50% attack remains hard to carry out, but the number of transactions per second would be really low. Too low to be of any use.
We're working on an extension that would fix that issue as well. It's a bit too early to tell if we'll be able to close all the holes. I haven't thought of it as a solution for an interplanetary currency though
DAGKnight
https://eprint.iacr.org/2022/1494.pdf