🚀 Interplanetary Blockchain: Can We Synchronize a Chain with 7-Hour Latency Between Nodes?

Imagine a future where every planet in the solar system is colonized.
How would we handle money when the delay between two nodes can reach 7 hours one-way (Earth ↔ Pluto)?

🔹 Proposed model: a two-tier monetary system

Local planetary currencies (e.g., MarsCoin, TitanToken)
➤ Fast, independent transactions
➤ Classic consensus, planet-level only

Global interplanetary currency (e.g., SolarLedger)
➤ Block time ~21h to respect light-speed constraints
➤ Used for rare but critical cross-planet trades

💡 Based on the Nyquist theorem, with a 7h one-way signal delay, the network needs at least 14h, ideally 21h per block, to reliably propagate state changes and maintain consensus.

🔐 To avoid double spending, interplanetary transactions would:

Be "reserved" on the local chain
Then validated globally once propagated across the SolarLedger

🧠 A hybrid architecture that combines:

Speed and usability locally
Global consistency and physics-respectful consensus
And a new approach to time and trust in distributed systems

➡️ How would you build monetary systems in a space economy?
➡️ What kind of consensus algorithm could handle this kind of delay?