Senior GNC Engineer

Vast is seeking a Senior GNC Engineer to own guidance, navigation, and control for a new constellation-ready spacecraft bus — a product line designed to scale to hundreds of spacecraft per year.

The satellite bus uses a CMG-based attitude control system — four Vast Mini CMGs in a pyramid configuration. ADCS performance is a defining capability of the bus — it's what enables high-power payloads that demand precise pointing and rapid slew. You'll own the GNC algorithms, simulation environment, sensor suite definition, and pointing performance for the satellite.

This is end-to-end ADCS ownership: from architecture trades and algorithm development through 6DOF simulation, hardware-in-the-loop testing, and on-orbit commissioning. You'll engage directly with payload customers on pointing and stability requirements, and you'll define the CMG and sensor performance specs that drive hardware development and procurement across the program.

This will be a full-time, exempt position located in our Long Beach location.

Responsibilities:

• Define the ADCS architecture — CMG pyramid configuration, sensor suite selection, pointing modes (nadir+yaw steer, LVLH fixed, 3-axis sun tracking)
• Develop GNC algorithms — attitude determination, CMG steering law (including singularity avoidance), momentum management, desaturation strategy
• Own the pointing budget — pointing accuracy, stability, jitter, and smear allocation across the sensor and actuator chain
• Define the simulation strategy — determine how the spacecraft design, simulation, and digital twin tool and Vast’s flight-validated 6DOF physics sim (GTsim) work together, what fidelity is needed for upfront system design vs flight readiness
• Build and validate the 6DOF simulation environment
• Define CMG performance requirements — momentum capacity, gimbal rate, gimbal limits, pyramid angle — feeding the electronics lead for box design
• Define sensor performance requirements — star tracker, IMU, sun sensor, magnetometer, GNSS receiver accuracy and noise specs (feeding the procurement lead for vendor selection)
• Support CMG Rev 1 bring-up with closed-loop testing
• Define and commission the HITL (hardware-in-the-loop) lab — flight processor, spoofed I/O, real-time simulation
• Magnetic field modeling for torque rod sizing
• Run Monte Carlo analysis campaigns to demonstrate pointing performance and flight readiness
• Assess flexible body dynamics — structural mode coupling with large solar arrays and cantilevered payloads, define appendage first-mode frequency requirements for structures
• Engage directly with payload customers on pointing and stability requirements — assess feasibility on the bus, define GNC data interfaces, and negotiate what we can support
• Ensure controllability during electric propulsion maneuvers — coordinate with the EP team on thrust vector, disturbance torques, and momentum impact
• Build a GNC team as the program scales — define roles and hire as complexity demands
• Support on-orbit commissioning planning for ADCS

Minimum Qualifications:

• Bachelor's degree in Aerospace Engineering, Mechanical Engineering, Physics, Mathematics, or a related technical discipline
• 6+ years of spacecraft GNC or ADCS development experience
• GNC algorithm development experience for spacecraft — attitude determination, control law design, actuator management
• Experience with reaction wheels or CMGs — actuator sizing, control allocation, momentum management
• Built and validated 6DOF spacecraft simulations
• Pointing budget development and allocation across sensor/actuator chains
• HITL test environment design and execution
• Comfortable working from architecture trades through flight software implementation
• Strong dynamics and controls fundamentals

Preferred Qualifications:

• Able to obtain a security clearance
• CMG experience — steering laws, singularity avoidance, pyramid configuration optimization
• Momentum management for LEO spacecraft (magnetic desaturation, gravity gradient)
• Star tracker and IMU selection / characterization experience
• Agile / small-sat GNC development — you've done this with a small team on a fast timeline
• GNC flight software implementation experience