Solar Thermal Propulsion System for Lunar CubeSat Launch:A Lean Architecture Using Inflatable Concentrators and In-Situ Resource Utilization

This research presents a solar thermal propulsion system for launching 50 kg operational satellites to 100 km lunar orbit, achieving a 97% mass reduction compared to orbital tether architectures. The system deploys 2.5 tonnes of infrastructure comprising 50 inflatable parabolic reflectors (10 m diameter) that concentrate 1,361 W/m² lunar solar flux to generate 4.5 MW thermal power at a tungsten-rhenium heat exchanger operating at 2,200 K. The architecture produces 2,000 N continuous thrust, accelerating a 500 kg vehicle at 4 g—compatible with standard CubeSat components without high-g hardening. Specific impulse ranges from 190 seconds using lunar water-derived steam to 450 seconds with liquid hydrogen. A 50-meter electromagnetic launch rail provides initial vectoring, with burnout at 1.68 km/s achieving lunar orbital velocity after 4 minutes of powered flight. The system is designed for phased in-situ resource utilization, transitioning from imported propellant to hydrogen electrolyzed from confirmed Shackleton Crater water ice deposits. Unlike electromagnetic mass drivers requiring 400+ g acceleration or rotovator tethers demanding 85 tonnes of orbital infrastructure, this solar thermal approach leverages abundant lunar solar energy while preserving payload survivability for operational spacecraft missions including lunar relay networks and surface mapping constellations.