Leah-Nani Alconcel, University of Birmingham; Gruffudd Jones, University of Birmingham; Morgan Coe, University of Birmingham; Marina Gashinova, University of Birmingham
https://doi.org/10.64861/FUIZ2817
Keywords: space assets, radar imagery, operational constraints, CoSDA, constellation dynamics
Abstract:
This paper discusses opportunities for conducting on-orbit Space Domain Awareness (SDA) cooperatively using a satellite constellation, with existing and planned commercial constellation deployments considered as examples. The work explores the feasibility of hosting compact sub-THz radar payloads [1, 2] on a proportion of the constellations’ constituent satellites. These payloads will perform co-operative monitoring of their local space domain using synchronously-acquired monostatic and bistatic inverse synthetic aperture radar (ISAR) imagery. The considered sub-THz frequency range allows for high-resolution, diverse-aspect radar imagery to be obtained [3]. This concept of co-operative space domain awareness (CoSDA) is accompanied by an analysis of rates of conjunctions suitable for imagery. The orbital densities of satellites in altitudes from 250 to 600 km (VLEO to LEO) at present, and in the near future, are considered. Populations in this orbital range are projected to 2035, based on available public information for current and planned constellations.
To demonstrate the value to SDA in VLEO and LEO of the proposed payload’s output, high-resolution ISAR image sequences of encountered satellites from diverse perspectives and illumination angles have been generated in the Graphical Electromagnetic ISAR Simulator for Sub-THz waves (GEIST), in monostatic and bistatic imaging configurations. Key satellite features are extracted from the imagery, including core subsystems and deployable structures. Frequent encounters between constituent satellites permit repeated observation of key features over the course of multiple orbits, which allows a life pattern of each observed satellite to be established. Changes in life patterns can subsequently be identified clearly. The most favourable conditions for image generation are determined by applying specific constraints on the bistatic imaging angles and payload subsystem power requirements to ensure sufficient signal-to-noise ratio (SNR) is achieved.
Other practical aspects of operational implementation of the hosted payload are investigated. The sub-THz ISAR sensing system will operate only briefly during an imaging encounter, which is typically of less than a minute’s duration. It will, however, produce a substantial volume of data during the encounter. As a hosted payload, its data provision and downlink will be secondary to the main payload(s). This work therefore considers the data volume, sensor tasking, and signal processing aspects of payload operation. These considerations are critical as high-resolution ISAR imagery produced from CoSDA observations should enable conditional monitoring, e.g. for identification and repair of damaged and worn satellite elements. To provide the most efficient benefit to constellation operators, it should be possible for sub-THz ISAR CoSDA data to be rapidly downlinked, assessed, and actioned.
Date of Conference: September 15-18, 2026
Track: Space-Based Assets