Energy Optimization in Nuclear Electric Propulsion: Solar-Nuclear Integration for Mars Missions

Castellano H.A.; Ramos M.; Villanueva D.M. · Proceedings of the International Astronautical Congress, IAC (2025) · DOI: 10.52202/083089-0042

Resumen

Optimizing energy consumption in long-duration space missions is key to sustainable exploration of the solar system. Nuclear Electric Propulsion (NEP) stands out for its high specific impulse (Isp), but its reliance on nuclear reactors poses challenges in sustainability and management of fissile resources. This study evaluates the feasibility of a hybrid solar-nuclear NEP system, combining solar energy and modular microreactors (MMR) to improve energy efficiency and reduce the demand for nuclear fuel. Performance comparisons are also made for architectures based on ion, Hall, and MPD thrusters, including an analysis of integration with NTP maneuvers for planetary operations. The numerical model employed estimates energy and mass balances, propellant consumption (Xe, H2), and approximate use of fissile material across a series of scenarios (solar/nuclear split and thruster technologies) using conservative values. The results show the impact of energy partitioning on initial mass in LEO, propellant requirements, and integrated energy, and allow discussion of trade-offs between mass, energy, and mission feasibility. The analysis indicates that, while chemical propulsion (CP) provides high thrust levels, its low Isp (∼ 4500 m/s) limits its efficiency in interplanetary missions. Nuclear Thermal Propulsion (NTP), with an Isp of ∼ 9000m/s, improves performance but requires large amounts of propellant. In contrast, NEP maximizes efficiency by reducing propellant mass, at the cost of sustained high energy demand, whereas Solar Electric Propulsion (SEP) is highly efficient within 1.5 AU, with a solar irradiance of ∼ 1367 W/m2 at 1 AU, but loses performance beyond Mars. The solar-nuclear integration allows a reduction in fissile material demand in the range of 35-65% compared to a strict NEP case, depending on the solar/nuclear split and thruster technology selected, providing competitive operational alternatives. Overall, this study maintains the methodological reference of a sustainable approach, in line with the vision of "Sustainable Space and Resilient Earth".

Instituciones: Universidad Nacional Mayor de San Marcos; Universidad Nacional de Ingeniería