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…