Laurenne Tynski, Department of National Defence Canada; Ivan Savytskyy, Department of National Defence Canada; Kian Fitzgerald, Department of National Defence Canada; Richard Trembinski, Department of National Defence Canada; Stefan Thorsteinson, Defence Research and Development Canada
https://doi.org/10.64861/RDYP2156
Keywords: Space Domain Awareness, Space-Based Optical, Leakproof Search Operations, Bullseye Search
Abstract:
Space assets are subject to a complex and evolving environment commonly understood as congested, contested, and competitive. The space domain has seen exponential growth in the Resident Space Object (RSO) population over the last few decades, and active payloads are vulnerable to numerous threats. In particular, the influx of unpredictable maneuvering activity warrants greater and timelier positional certainty of RSOs to maintain custody and security of the space domain.
In a period of abundant RSOs and increasingly non-routine maneuvering activity, search operations are employed to detect RSOs of an unknown position and contribute to the continuous tracking, monitoring, cataloguing, and assessment of space domain activities. A search pattern is advantageous in detecting an RSO of positional uncertainty by observing an area of the celestial sphere greater than the sensor Field of View (FOV). However, implementing a search pattern does not guarantee that an RSO in the searched area will be detected during the operation. RSOs may travel at an angular rate or trajectory that does not synchronize with the search pattern, or the sensor specification and operational capabilities may be insufficient, resulting in dwell gaps. Kinematic certainty of detection requires a leakproof solution, i.e., a 100% detection rate. At AMOS in 2022, Mulligan and Stephens proposed “Bullseye: a leakproof search strategy for space domain awareness”, which demonstrated a theoretically leakproof search pattern under certain constraints. The bullseye search consists of concentric rings of discrete dwells that overlap to generate a leakproof search area. Leakproof search operations employing such a search pattern can provide critical data to support the effort in gaining or regaining custody of RSOs of high positional uncertainty and unknown trajectory.
In this work, search trials employing both a bullseye and in-track search pattern were conducted using the Canadian Near-Earth Orbit Surveillance Satellite (NEOSSat), a Defence Research and Development Canada (DRDC) optical payload microsatellite in Low Earth Orbit (LEO). The search trials evaluated the efficacy and efficiency of a Narrow Field of View (NFOV) Space-Based Optical (SBO) sensor in performing a conclusive search operation, given NEOSSat’s constraints. The trial results suggest that the operational advantages specific to a NFOV SBO sensor can be attained while gaining the capability to provide conclusive data on Wide Area Search and Clearance (WASC) tasks. The search pattern algorithms were adapted to form a sequence of boresight pointing vectors integrated into NEOSSat’s tasking format to detect 1) an RSO crossing the search area in geostationary orbit using a bullseye search and 2) an RSO launched into geostationary transfer orbit using an in-track search. The trials replicate both the clearing of an area around a high-value asset to detect interlopers and the search of an RSO that maneuvered. The bullseye pattern was performed both in Star-Stare Mode (SSM), with a high field clearance rate but reduced sensitivity, and in Track Rate Mode (TRM), with a slower cadence for attitude control constraints, but maximal sensitivity. Since the sensitivity of TRM was favourable for detection, this configuration was leveraged for most scenarios. However, the low cadence of TRM constrained the solution to a single bullseye ring per RSO access. The increased cadence of SSM allowed for single orbit multi-ring bullseye searches and attempted leakproof in-track searches. NEOSSat was successfully configured within its attitude determination and control system limitations to demonstrate the effectiveness of conducting WASC operations with a NFOV SBO sensor, and for the bullseye scenario, a leakproof operation. This operation centred on a fictitious two-line element set offset from Anik G1 to simulate a maneuver within the leakproof search area.
This paper presents the bullseye and in-track search experiments conducted on the SBO sensor. Four test scenarios are discussed alongside the implementation methodology and optimal cadence characterization of the platform. NEOSSat’s limitations in conducting a leakproof search are analyzed given the platform’s slewing constraints, and a space-based advantage is characterized to evaluate the improvement to Space Domain Awareness (SDA) that can be realized with space-based search operations. The observations and the lessons learned from applying both search patterns on NEOSSat are discussed as well as their applicability to future space-based SDA missions.
Date of Conference: September 15-18, 2026
Track: Space-Based Assets