In-Situ Manufacturable Solid Fuels for Hybrid Rockets Using Lunar Resources

The advancement of sustained lunar and Martian exploration requires propulsion systems that minimize reliance on Earth-based resupply. In-situ resource utilization (ISRU) offers a pathway to develop energetic fuels from materials readily available on extraterrestrial surfaces. This work investigates solid fuel formulations composed entirely of ISRU-accessible elements, focusing on a sodium silicon-based binder with aluminum metal additives, which can be sourced via electrolysis of aluminum oxide found abundantly in the lunar regolith. The goal is to develop a solid fuel capable of achieving lunar escape velocity when used in a hybrid rocket configuration. A series of ground tests were conducted using a small-scale slab burner in a hybrid rocket test stand. Fuel samples were cast into rectangular grains and ignited using an H2 torch. Chamber pressure and temperature were recorded to calculate performance metrics, including specific impulse (Isp), characteristic velocity (C*), and combustion efficiency (η). The resulting data was used to assess whether the tested formulations can support a propulsion system capable of lunar ascent. This includes estimating the chamber pressures, oxidizer-to-fuel ratios, and burn durations required to reach escape velocity, guided by prior lunar mission propulsion. By experimentally validating ISRU-compatible fuels under hybrid rocket conditions, this work supports the development of self-sustaining propulsion systems for future planetary missions and lays the groundwork for fully off-Earth manufacturing of rocket-grade solid fuels.