The farthest apart Mars and the Earth can be is about 400 million km. It means, a signal from Mars needs ~23 minutes to reach the Earth. There are also days when the Earth is unreachable (because the Sun is in between).
Say, we established a colony on Mars. There is a full Bitcoin node and maybe a small miner too. I'm one of the colonists. I want to send 1 BTC to the Earth. Will it work?