GNMT v5.2 — Griffiths Nuclear‑Powered, Microwave–Thermal Propulsion Architecture

GNMT v5.2 “Heritage‑Derived, Experimentally Testable, Fundable Architecture” Is a 1–3 MWe nuclear‑electric propulsion architecture derived directly from NASA’s Prometheus/JIMO program (2003–2005), which invested $400M into fast‑spectrum reactor development, Brayton power conversion, and megawatt‑class thermal rejection. GNMT extends this validated foundation using modular reactor assembly, microwave volumetric plasma heating, and a rotating electromagnetic nozzle (REMN) to achieve 25–40 km/s exhaust velocity using fully conservative physics. The architecture enables fast outer‑system logistics, including 15–20 month Pluto round‑trip missions, supported by a complete worked example with traceable mass budgets, thrust calculations, and Δv analysis. GNMT incorporates realistic radiator mass fractions (25–40%), explicit nozzle efficiency (η_noz = 0.65–0.85), and uncertainty bounds (±10–15%) based on launch geometry, REMN performance variance, and propellant margins. The system includes a staged validation roadmap: REMN physics → GNMT system integration → DIGSP autonomy. DIGSP provides power governance, thermal management, RF control, and fault detection, with forward‑looking capabilities for multi‑system integration and autonomous deep‑space operations. This Zenodo release includes a 2‑page executive summary and an 80‑page technical document with mathematical derivations, mission analyses, cost estimates, and over 40 peer‑reviewed references. GNMT v5.2 represents a credible, heritage‑anchored pathway to megawatt‑class nuclear‑electric propulsion for rapid exploration of the outer solar system.