Stellerian builds onboard autonomy for space missions, enabling satellites to detect, identify, track, and navigate relative to other objects without ground intervention. Our flagship product is a compact vision and compute module plus a flight software stack that delivers real time object tracking, relative pose estimation, and closed loop rendezvous and proximity operations. ACECam fuses neural networks with deterministic vision, navigation filters, and guidance and control to generate robust state estimates from star trackers and optical cameras, even for uncooperative targets. We provide mission ready software licenses, hardware integration kits, and simulation and synthetic data pipelines that accelerate model training, verification, and operator confidence. The same autonomy layer supports satellite servicing, inspection, collision avoidance, and proliferated space domain awareness across LEO, GEO, and cislunar environments.