Abstract

A fundamental challenge in space-based optical surveillance constellation design is the quantitative evaluation of coverage capability across the entire low-Earth-orbit (LEO) space. A phase-volume coverage model in the 4D (a,i,Ω,u) phase-space is proposed, and the multi-coverage ratio Rmulti, mean covering satellite count N¯sat, and Observation Geometry Quality Index (OGQI) are introduced to overcome the limitations of single-metric coverage evaluation. A theoretical motivation for the relationship between OGQI components and orbit determination error covariance is provided via Fisher information matrix theory. Spherical-shell 3D spatial and phase-space 4D orbital frameworks are compared: the two frameworks are shown to be mathematically non-equivalent, and phase-space evaluation provides orbit-type-based diagnostic capability unavailable in spatial methods. Within the Walker-Delta framework with Sun-synchronous dawn–dusk orbits, camera pointing and constellation configuration are systematically optimized, yielding a preferred altitude of 1700 km and a P=6-plane layout with coverage saturation at T≥18. Validation against the Space-Track TLE catalog (22,471 LEO objects) yields 95.49% coverage and 83.47% multi-coverage within a 1-h window. The phase-volume framework unifies coverage evaluation and constellation design in a common orbital element space, enabling systematic space-based optical surveillance constellation design.

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