And of course bitcoin is perfectly feasible to be legal tender in the future, for everyone, mars colonies as well. It is nothing weird to plan any kind of future solutions (economic as well) long before the actual mission.
You are a funny one. I didnt mention any aliens in my post. I just relate bitcoin as a currency which is feasible when human colony is established outside our planet, earth. It may be far before that happens but remember that bitcoin will last 260 years from now then it could still survive and be used when space exploration is already a reality.