I'm quite not sure I understand the point here. Sure, by putting the hardware in outer space you make it harder to access, and if you boost it away from the sol

I'm quite not sure I understand the point here. Sure, by putting the hardware in outer space you make it harder to access, and if you boost it away from the solar system you can guarantee it would be cost prohibitive to catch up to it - but the physical security of monetary systems is rarely the problem. The main problem that any currency faces is why should anyone place any trust in it? Why does it provide a reliable record of wealth transfer? If it's a probe that Elon Musk has sent off, then you're asking me to trust Elon and his company. Will the hardware function correctly? Will the software? Is it free of accidental exploits or deliberate back doors? How much wealth am I prepared to wager on this? For all Bitcoin's flaws, it does have a robust trust infrastructure. You trust the processing-majority of miners, who have only become the majority because they have made a significant investment in the fidelity of the system. Their wealth (at least in theory) is tied to upholding an honest transaction record. Would Elon or SpaceX lose money if it turned out their interplanetary server was defective? Sure, but they'd only lose the cost of producing the probe and boosting it into space. If it costs $10 billion to do so, and Elon makes $11 billion from it before a flaw is discovered, then from a financial standpoint it's a still a success. Ideally a currency should be backed by a number of independent actors, whose stake scales with the currency's value.