AUTONOMOUS ON-BOARD COLLISION RISK ASSESSMENT AND AVOIDANCE FOR SMALL SATELLITE PLATFORMS

Space traffic management functions have traditionally been performed on ground with significant operator involvement. However, the rapid growth in active spacecraft in Low Earth Orbit (LEO) and the increasing number of conjunction events are driving the need for higher levels of automation and, in some cases, onboard autonomy. ESA’s annual Space Environment reports highlight a continuous rise in collision avoidance events and emphasize the importance of improved traffic coordination to mitigate risks from both active spacecraft and non-maneuverable debris. OB-ASTRA (On-Board Autonomous Space Traffic Risk Avoidance) is an onboard collision avoidance system designed to address the constraints of small satellites in terms of size, mass, power, computation, and interfaces. The system performs onboard conjunction detection, collision risk assessment, maneuver coordination and execution by leveraging commonly hosted sensors such as GNSS receivers and star-tracker-class optical sensors. This approach avoids the need for dedicated collision-avoidance sensors while enabling autonomous navigation services and targeted optical observations of conjunction objects. The subsystem adopts a modular hardware architecture compatible with the CubeSat standard within a compact payload-class unit, approximately 2U. To support cooperative space traffic management scenarios, OB-ASTRA also incorporates an interface towards the existing infrastructure and a lowpower LoRa-based intersatellite link enabling OB-ASTRA devices to directly exchange compact ephemeris and maneuver coordination information.