Detectability Range Modeling for CQD-CMOS SWIR Sensors in Satellite Proximity Operations

Abstract

A constrained-physics analysis is presented of optical detectability for small orbital debris using a colloidal quantum dot (CQD) SWIR CMOS sensor in low Earth orbit (LEO), motivated by proximity navigation applications where onboard awareness of untracked centimeter-scale debris is operationally critical. Signal and noise expressions are derived from first-principles radiometry using solar spectral irradiance, Lambertian reflection with empirically measured albedos from NASA ODPO and ESA BRDF datasets, phase-angle corrections, and SWIR-band optical throughput. Signal propagation is modeled through a small-aperture telescope and an ACUROS6-class CQD SWIR CMOS detector using datasheet-sourced quantum efficiency, read noise, and dark current. Two background regimes are evaluated: a conservative baseline with debris viewed against the bright Earth limb, and an optimistic upper bound with the line of sight directed off-limb into dark space. Under bright-limb baseline conditions with a 5 cm aperture, 10 ms per-frame exposures, and stacking of up to 50 frames (0.5 s total), detection of 1 cm low-albedo debris is limited to approximately 13 km slant range; 5 cm debris extends this to approximately 66 km and 10 cm debris to approximately 133 km. In dark-sky conditions, these ranges increase by a factor of approximately 2.5. Results are benchmarked against operational SSA systems including GEODSS, SBV, and SBSS. The analysis demonstrates that a compact CQD-CMOS SWIR payload can meaningfully contribute to onboard proximity debris awareness at short ranges, complementary to global cataloging systems.