Interplanetary failover is often drawn as a clean diagram. One node goes dark, another takes over, and the system continues with only modest disruption. That image is useful for slides and misleading for operators.
Real failover across Earth, Moon, and Mars is staged, negotiated, and partial. A continuity event usually begins with degraded confidence rather than total silence. Operators have to decide whether the disruption is transient, whether the canonical copy remains trusted, and whether local autonomy thresholds have been crossed.
Each location also fails differently. Earth-side nodes may lose political clarity before physical capacity. Lunar nodes may preserve custody better than throughput. Mars nodes may keep running while losing the social permission to represent the whole system. That means failover is not only about where compute survives. It is also about where authority survives.
The best way to understand interplanetary failover is as structured downgrade. The system sheds expectations, narrows scope, and preserves the most defensible functions first. Full continuity is a marketing phrase. Managed degradation is the real operating model.