I am Just wondering do you ever think in the far future we could use btc to send money b/w different planet like from Earth to Mars is that even possible
Like With all that the time delay & no Global Government / system in space then how could that even work?
Would we need the separate blocKchain for each of the planet?
I know it's the hypothetical right now but curious what people think
I do not think so.
There is a large time delay from Mars to Earth.
That time delay may make mining on Mars impossible.
Maybe we could do the moon.
Give me a minute to show the time issue.
At op I think you are making a case for a POS coin.
https://www.space.com/24701-how-long-does-it-take-to-get-to-mars.html
3 to 22 minutes earth to mars.
That delay makes mining btc on earth and mars not practical
The delay from the moon to earth is around 3 seconds round trip so you could likely mine on the moon and earth.
So a real case need for POS coins does exist once space travel becomes common.
So Eth may be okay in hundred years or so. ALONG WITH Solana.
For now BTC seems okay.
Please realize just how centralized BTC becomes if we have a dozen planets with all mining on Earth and the Moon.
Just attack the earth and BTC grinds to a halt.
SO LETS GIVE THE OP cred for finally finding a reason. For POS coins. 
At op I gave you some merits for the topic.