Bridging the Basilisk Astrodynamics Framework with ROS 2 for Modular Spacecraft Simulation and Hardware Integration

Integrating high-fidelity spacecraft simulators with modular robotics frameworks remains a challenge for autonomy development. This paper presents a lightweight, open-source communication bridge between the Basilisk astrodynamics simulator and the Robot Operating System 2 (ROS 2), enabling real-time, bidirectional data exchange for spacecraft control. The bridge requires no changes to Basilisk's core and integrates seamlessly with ROS 2 nodes. We demonstrate its use in a leader-follower formation flying scenario using nonlinear model predictive control, deployed identically in both simulation and on the ATMOS planar microgravity testbed. This setup supports rapid development, hardware-in-the-loop testing, and seamless transition from simulation to hardware. The bridge offers a flexible and scalable platform for modular spacecraft autonomy and reproducible research workflows.