CORTEX framework guides spacecraft docking with 8 mm error on hardware testbed

Aerospace engineers have developed and validated CORTEX (Convex Optimization for Rendezvous Trajectory EXecution), an autonomous guidance framework designed for close-range rendezvous with uncooperative spacecraft, according to a paper published in Acta Astronautica sciencedirect.comActa Astronauticasciencedirect.comOpen source ↗. The system calculates approach trajectories and tracks them under dynamic, actuation, and sensing uncertainties without requiring real-time commands from Earth.

Autonomous rendezvous capabilities are aimed at servicing inactive satellites and managing orbital debris, where communication delays prevent direct ground control. According to European Space Agency estimates cited by the authors, low Earth orbit contains roughly 19,440 satellites, of which 3,540 are non-functioning, along with more than 8,000 metric tons of orbital debris. CORTEX schedules rendezvous operations around illumination conditions, aiming to complete proximity operations during sunlight windows rather than in darkness.

Algorithmic Architecture and Trajectory Replanning

The framework combines a visual perception pipeline with convex-optimization-based trajectory planning and tracking. CORTEX continuously evaluates trajectory deviations against safety constraints. If thruster malfunctions or external perturbations push the spacecraft away from its nominal path, the system either replans a new approach trajectory or executes an abort maneuver, retreating into a passively safe holding orbit to protect the keep-out zone.

Numerical Simulations and Hardware Testing

The engineering team evaluated CORTEX through a two-tier validation program sciencedirect.comActa Astronauticasciencedirect.comOpen source ↗. First, a numerical Monte-Carlo campaign of 500 trials per error regime was executed on a Basilisk-based simulation platform incorporating orbital dynamics, perception, and attitude control. Under the highest simulated error conditions, the software achieved a terminal docking accuracy of 25.99 ± 21.00 mm in relative position and 0.371 ± 0.440 mm/s in relative velocity.

Physical validation followed with 18 nominal and off-nominal test runs on a planar air-bearing hardware testbed equipped with cold-gas thrusters and motion-capture feedback. During hardware stress testing involving artificial thruster shutdowns and manual perturbations, the spacecraft achieved terminal errors of 8.09 ± 5.29 mm in relative position and 2.23 ± 1.72 mm/s in relative velocity.