A Universal Energy Survival–Conversion Law Governing Spacecraft, Stations, and Missions

Classical energy efficiency metrics systematically overestimate real-world system performance because they implicitly treat energy conversion as a single-stage process and neglect irreversible thermodynamic degradation. Across biological systems, terrestrial energy technologies, communication networks, and space systems, observed operational outputs fall far below laboratory or nameplate efficiencies. This discrepancy is especially pronounced in spacecraft and satellites, where fixed power budgets, radiative-only heat rejection, and strict thermal envelopes expose fundamental thermodynamic constraints. This paper introduces a Unified Energy Survival–Conversion Law that reformulates useful energy and information production as a survival-limited, multi-stage process governed by irreversible thermodynamics and reaction–transport constraints. An energy survival factor (Ψ) is defined to quantify the persistence of absorbed energy against transport losses and irreversible entropy generation. Coupled with an internal conversion competency term derived from the Life-CAES reaction–transport framework, the resulting law E_"useful" =E_"in" ⋅Ψ⋅C_"int" provides a universal upper bound on useful output. Validation using independently reported data shows strong agreement with observed limits in photosynthetic ecosystems (≈1–3%), photovoltaic systems (≈15–20%), data centers (heat-dominated regimes), mobile communication networks (throughput saturation), and spacecraft subsystems (duty-cycle-limited operation). The framework explains why increasing power supply alone frequently yields diminishing or negative returns in space missions and establishes energy survival—rather than efficiency or power availability—as the governing constraint on sustainable mission performance.