Abstract

With increasing activity in the cislunar region, ensuring safe navigation has become a critical issue. This study proposes a tracking approach using visible and thermal infrared sensors to monitor and track non-cooperative objects. Thermal infrared sensing is utilized to improve observation opportunities under highly variable illumination conditions. To evaluate sensor performance, proxy satellites equipped with both sensors were placed in ten different cislunar orbits, observing targets across ten different orbits (100 cases total). Results showed that a 1 m aperture infrared sensor achieved a 99.1% observation rate from the proxy satellites. Subsequently, simulations were conducted with only three observer satellites in cislunar space using the same combined visible–infrared system. Tracking was primarily performed with infrared sensors based on extended Kalman filter estimates. To suppress error growth, a virtual window was defined on the infrared sensor image, and when the target exceeded this window, visible sensors were used for triangulation to update the propagated orbit estimate. The proposed method achieved continuous tracking over all time steps for targets in L2 North Halo 1 (without maneuver), L4 Axial (with/without maneuver), and L5 Axial (with/without maneuver), while target loss occurred on Distance Retrograde Orbit (DRO) 1, L2 South Halo, and L2 North Halo 2 due to rapid velocity changes near the Moon. While these results proved effective for cislunar orbits farther from the Moon, they highlight the need for improved estimation methods to account for highspeed, maneuverable objects near the Moon.

Date

2026

Authors

Shinsuke Takahashi, David Barnhart