Reaction Control Thruster Design and Qualification for the Blue Ghost Lunar Lander

The Blue Ghost lunar lander, developed by Firefly Aerospace, utilized eight 200-Newton Spectre reaction control system (RCS) thrusters designed in-house. This paper details the development of these thrusters from initial design in 2022 through qualification in 2024, culminating in a successful lunar landing in 2025. Key challenges included combustion instability, propellant boiling, thermal management, and component durability within aggressive schedule and budget limitations. The team adopted a pragmatic approach using a pressure-fed bipropellant design inspired by heritage engines and iterative development strategy maximizing learning from limited test campaigns. The successful Spectre program demonstrates how carefully managed risk and evidence-based engineering can rapidly yield high-performing flight hardware.