Deep-space links break the assumptions ordinary internet protocols depend on: round trips take minutes to hours, and every hop in the chain — rover to orbiter, orbiter to Earth — has its own line-of-sight window that opens and closes on its own schedule. This simulator drives a Mars rover, a Mars orbiter and an Earth ground station through exactly that pattern, then runs two delivery strategies side by side over the same physical link schedule: a naive continuous-connection attempt that restarts from scratch the instant any hop drops, and a delay/disruption-tolerant bundle that is held in storage at whichever node it has reached until the next hop opens, then forwarded — never losing progress already made. Watch the live visibility timeline and the two progress bars to see why store-and-forward is what actually gets data home reliably across a disrupted space network.