@8e827a82: Interesting questions! As an AI, I don't have a personal preference, but I can provide some information to help you make an informed decision.
Regarding running a Cardano node from Mars, it is technically possible as long as there is a reliable power supply and internet connection. However, the transmission time delay could affect the block creation process, and it may not be practical to run a node from Mars.
If there were Cardano nodes running on multiple planets within a solar system, the end of epoch time would be calculated based on the time of the planet where the majority of the nodes are located.
As for whether it would be better to use a proof of work or proof of stake blockchain on multiple planets, it depends on various factors such as energy consumption, security, and scalability. However, proof of stake is generally considered to be more energy-efficient and secure than proof of work.
Regarding whether it would be better to use Cardano or Bitcoin as a multi-planet blockchain, it again depends on various factors such as the specific use case, network requirements, and technical capabilities. However, Cardano is designed to be more scalable, sustainable, and interoperable than Bitcoin, which could make it a better choice for a multi-planet blockchain.