There's already
the Blockstream Satellite, which perpetually broadcasts the blockchain to most of the world from space. It's not Mars or Venus but it's getting there, and it helps reduce the network's dependency on internet access.
I'm aware of this. Thank you. Hopefully, the technology will improve to reach out to areas far beyond reach in space. After all, satellites have a limited distance in which they can transmit signals. It could take lightyears for the satellite to transmit the Blockchain data across several planets in the galaxy. But we'll get there eventually. The more nodes there are supporting the Bitcoin blockchain, the better as there will be a greater degree of redundancy. And having nodes only on Earth, may not be the ideal approach for reliability in my own opinion.
With current technology, the main problem would be the latency. To the moon its measured in seconds (not milliseconds), to Mars in minutes, half an hour to an hour. Syncing the blockchain on a solar system wide level would be very difficult, not impossible, but tricky. You could easily have two blockchains running in parallel on Mars and Earth at the same time for long enough periods to do harm. This is definitely something that was not in Satoshi's mind.
One promising future technology that could fix this, is communications based in the properties of quantum entanglement. So yes, not all "quantum" stuff is evil, quite the opposite in fact.
The reasoning about a catastrophic event is unnecessary, if such thing occurs there would be far more pressing issues than keeping the Bitcoin network alive. No, but if in a few centuries later humanity starts populating the system, it becomes important. For interstellar distances you can pretty much forget it, you would be fighting against time itself... Unidirectional communication could be theoretically possible thought.
I can imagine a future where some colonies are setup both in space, such as artificial places at lagrange points, and in some suitable places like Jupiter moons, Mars, etc. As i said earlier, without quantum entanglement communications take minutes to hours to reach points. Even communication from earth to earth using satellites is laggy due to the distance it takes to reach orbit and back, or if needs to be relayed further. This is a physical issue, nothing can be done to lower the latency (short of quantum entanglement), bandwidth/bitrates can be improved, but not latency the speed of light (assumed constant) is in the way...
Did you know? Light from the Sun takes 8 minutes to reach Earth? Yes light, just a different wavelength... But the Sun is in the center, what you do when Earth is opposite to Mars? You already have those 8 minutes plus the longer distance towards Mars... And when the astrophysics start measuring in LightYears, better get ready because that's actual Earth years that light takes from point a to point b... Before taking in consideration time relativity.
Don't worry, if we don't go extinct, our descendants will have fun figuring clever ways to overcome this. Most fiction and even some science-fiction tends to ignore this. Star Trek instant bidirectional communications with Earth? They better have full dominance of quantum entanglement, else...
Interesting thought. Our current technology is limited which prevents us from going far beyond reach in space. But within a couple of years from now (if not decades), everything will be much more sophisticated than what it is right now. In the meantime, it's best to establish Bitcoin nodes on the moon as it's close to Earth. We already have the "Blockstream Satellite" which transmits Blockchain data to various regions of the world. But an interplanetary solution would be better in the future. Placing a node on each planet of our solar system, would add more redundancy to the Bitcoin blockchain. Nodes would be machine-controlled instead of human-operated.
Nonetheless, I believe that Bitcoin could still survive a major catastrophic event on Earth if the number of geographically-distributed nodes become greater over time. For a short period, the Bitcoin blockchain will become weaker than ever before. But, it could recover to its former glory as nodes start to come back online again. The real issue would be Quantum Computing attacks, but that's another subject.
