We are seeking a Principal Spacecraft Guidance, Navigation & Control Engineer to serve as the technical authority for the GNC subsystem across multiple spacecraft programs, leading architecture, design, procurement, integration, and verification. Where You'll Make an Impact • Own the end-to-end GNC/ACS architecture from concept development through flight operations. • Own GNC subsystem level requirements. • Lead spacecraft attitude and control system design, including actuator sizing, sensor selection, control authority, and momentum management strategy. • Define and implement control laws for high-ΔV maneuvering, precision pointing, station-keeping, and proximity operations. • Architect state estimation frameworks (EKF/UKF, sensor fusion pipelines, covariance management) for robust on-orbit performance. • Develop and maintain high-fidelity 6DOF spacecraft simulation environments for analysis, trade studies, verification, and anomaly resolution. • Establish GNC verification and validation strategy across analysis, SIL/HIL, hardware integration, and flight test. • Support propulsion-coupled dynamics modeling, including thrust misalignment, slosh effects, and flexible-body considerations as needed. • Lead GNC participation in system-level reviews (MCR, SRR, PDR, CDR, TRR) and serve as the primary technical voice for the discipline. • Analyze flight telemetry and test data to assess performance, diagnose anomalies, and drive configuration or algorithm updates. • Define safe-mode, fault management, and degraded control strategies in partnership with FSW and systems engineering. • Mentor and manage GNC engineers, establishing best practices, code standards, simulation frameworks, and technical rigor across the team. • Support early-orbit operations and critical mission phases as required. What It Takes • B.S., M.S., or Ph.D. in Aerospace Engineering, Mechanical Engineering, Electrical Engineering, Robotics, or related field. • 15+ years of experience in spacecraft GNC/ACS development, including full lifecycle flight programs. • Demonstrated ownership of a spacecraft attitude and/or orbit control system through design, integration, and flight. • Deep expertise in rigid-body dynamics, orbital mechanics, estimation theory, and modern control methods. • Strong experience with thruster-based ACS architectures and propulsion-coupled control systems. • Proven ability to independently architect GNC systems and make system-level trade decisions. • Experience implementing flight algorithms in C++, Python, or MATLAB/Simulink, with awareness of real-time constraints. • Experience integrating GNC with flight software and avionics, including SIL/HIL validation. • Ability to analyze telemetry and diagnose complex on-orbit or integrated system anomalies. • Systems-level thinking across propulsion, avionics, software, and mission design. • Demonstrated technical leadership and mentorship experience. • Comfort operating in a fast-paced, hardware-integrated environment with evolving mission needs. Nice-to-Have Experience • Experience with high-ΔV vehicles, cislunar missions, GEO servicing, or RPO missions. • Experience designing control systems for agile or propulsive maneuvering spacecraft. • Background in autonomous maneuver planning or onboard decision-making systems. • Experience with flexible-body dynamics, propellant slosh modeling, or structural-control interaction. • Familiarity with MAX FSW and MAX GDS or other modern COTS flight software frameworks. • Experience with multi-agent relative navigation or machine learning for estimation, perception, or task planning. • Experience leading small technical teams in startup or NewSpace environments. • Prior support of on-orbit commissioning or anomaly resolution efforts. What You'll Get • Ownership - Build and validate the GNC capability that defines how our spacecraft maneuver, point, and operate autonomously. • Innovation - Shape next-generation GNC architectures, algorithms, and tools for high-agility missions. • Impact - Directly influence spacecraft controllability, autonomy, and mission success across cislunar and GEO operations. • Growth - Collaborate across avionics, FSW, systems, and mission ops, with opportunities to expand into dynamics modeling, autonomy, or flight operations. • Compensation - Competitive salary, equity, and comprehensive benefits including medical, dental, vision, generous leave, HSA, 401(k) matching, and equity participation. Location: Rockville, MD or Hawthorne, CA Base Salary: $175,000 - $225,000 The salary range for this role is determined based on a variety of factors including work experience, education, technical expertise, certifications, critical skills, and business considerations. Highly competitive equity grants are included in the majority of full-time offers and are considered part of Quantum Space's total compensation package. Apply now. Join us in building the next generation of spacecraft.