Bitcoin In Space
Bitcoin and space. When both are decentralized, they are natural allies.

What I think is that if the Internet could be made to work in space, so can Bitcoin and thatwould be essential for people wanting to make transactions from millions of miles away from the earth.
Business people are already exploring ways to make money out of the innovations made towards space colonization since it is a subject matter of great interest. Of course, safety comes first, but if people see that space travel is safe (or at least no more dangerous than air travel), there will be demand.

We already know that internet works in space, since the astronauts tend to use twitter from the International Space station.  There is no reason for bitcoin not to work in space. In fact, it would work much better than any other currency that we are familiar with today.

Once space travel and colonization are well underway, a currency will be among the first things to think about. You'll want to buy things, pay for favours, etc... I can imagine in the far away future some space stops where you'll be able to buy snacks and souvenirs, just like you can do that at a rest stop while travelling somewhere on our planet earth.

Bitcoin would make more sense because it is a digital currency and can by used anywhere.
I wouldn't exclude that other forms of currency will pop up in the future though. Anything new-ish gets competition eventually, so for the space travellers, it would be important to establish a solid base of bitcoin in order to leave the competition behind.

The trick would probably be to get the space explorers interested in bitcoin so that it becomes a common thing among space travellers right away.

Part of succeeding is trying really hard.

Cryptocurrencies would probably have to be improved to account for the speed of light and the fact that colonies probably won't want to throw a lot of resources at maintaining a cryptocurrency network at first. But there's no reason to assume that digital currencies like Bitcoin won't be ready for use throughout the solar system when space colonies are ready to use them.