Speaker
Description
The growing number of active satellites and resident space objects is pushing the limits of ground-based collision avoidance workflows. Latency in decision loops, scalability limitations, and coordination overhead in dense orbital environments are increasingly incompatible with the responsiveness that effective collision risk management demands. Achieving zero debris ambitions at scale requires not only robust mitigation at end-of-life, but also active, responsive, and autonomous collision avoidance throughout a spacecraft's operational lifetime.
OB-ASTRA (On-Board Autonomous Space Traffic Risk Avoidance) is an autonomous onboard collision avoidance system developed under the ESA ARTES 4.0 Advanced Technology Programme by a consortium led by Nautilus – Navigation in Space Srl, together with the University of Bologna, SpaceDyS, and INAF. The system relocates conjunction detection, collision probability estimation, maneuver planning, and inter-spacecraft coordination directly onboard the spacecraft, reducing reliance on ground infrastructure while remaining interoperable with existing Space Situational Awareness (SSA) services through a ground companion application and CDM ingestion capability. As a result, OB-ASTRA enables the hosting spacecraft to autonomously mitigate the risk of collisions, contributing to the long term preservation of the orbital environment.
OB-ASTRA is implemented as a compact, standalone subsystem and leverages sensors already standard on most spacecraft platforms: a GNSS receiver for precise onboard orbit determination and a star tracker for attitude knowledge and optical tracking of secondary objects. This design philosophy minimises integration burden across a wide range of platform classes and avoids additional sensor mass while enhancing navigation fidelity. An onboard ephemeris catalogue enables autonomous conjunction screening independent of ground contact, and a low power LoRa-based Inter-Satellite Link (ISL) supports cooperative ephemeris and intent exchange between equipped spacecraft.
A central feature of OB-ASTRA's operational concept is its progressive, late-commitment risk refinement strategy. As the time of closest approach nears, state uncertainty is reduced through updated onboard orbit determination of the hosting spacecraft and, where possible, ephemeris updates on the secondary object, either via optical tracking for uncooperative targets or ISL data exchange for cooperative ones. This just-in-time approach minimizes unnecessary maneuvers and associated propellant expenditure, directly supporting mission lifetime and sustainable operations.
The Concept of Operations is organized around two decision deadlines: a first checkpoint for maneuver drafting and coordination initiation, and a second for final commitment. Established traffic coordination rules and inter-spacecraft intent sharing are applied during this window, promoting predictable and transparent collision avoidance behavior consistent with emerging space traffic management frameworks.
OB-ASTRA has currently entered Critical Design Review (CDR) and is progressing toward engineering model manufacturing and integration, followed by a test campaign in Q3 2026, with TRL 5 validation targeted by year end. The validation will be conducted using a high-fidelity sensors-in-the-loop testbed, in which representative conjunction scenarios are reproduced by stimulating the GNSS receiver, ISL transceiver, and star tracker through dedicated signal and optical scene emulators.
These activities are expected to demonstrate how scalable onboard autonomy can strengthen collision risk management in increasingly congested orbital environments.