Darren Thornton, Air Force Institute of Technology; Bryan Little, Air Force Institute of Technology; Bryan Steward, Air Force Institute of Technology, Resonant Sciences; Richard Cobb, Air Force Institute of Technology
Keywords: Cislunar SDA, SSA, optical sensors, multifunction systems
Abstract:
Given the recent increased international interest in exploiting cislunar space and lunar resources, the need for cislunar space domain awareness (SDA) has never been greater. This research considers whether adding upward-pointing optical sensors to an all-GEO/HEO missile warning constellation could provide adequate cislunar SDA. This papers scope is limited only to the target detection component of SDA; we consider the performance of optical sensors tracking a hypothetical satellite at the apoapsis of a near-rectilinear halo orbit (NRHO) in a 9:2 resonance with the lunar synodic period (where the satellites apolune radius is approximately 71,000 km). Targets are modeled in multiple variations of this orbit, and a baseline probability of detection for each target is determined. Simulations are created within Systems Tool Kit (STK), and sensor parameters, satellite size and reflectance, and lunar/solar exclusion angles are all taken into account.
This research shows that by enlarging sensor integration times or stacking sequential frames, these GEO/HEO optical sensors can with very high probability detect otherwise dim targets while minimizing the number of false alarms. This research highlights the importance of considering system jitter (especially relative to the detectors instantaneous field of view) and strategically choosing optimal integration times or number of stacked frames, given the targets expected relative motion. In the present research, the impact of 0, 1, and 5 arcseconds of jitter is demonstrated, finding a significant (but not insurmountable) impact on detection probabilities from jitter as large as 5 arcsec. Additionally, the viability of using short-integration, multi-frame stacking as an alternative to longer integration times is demonstrated, and initial results suggest that a minimum of 20 frames with 1 second integration time each are needed to achieve desired detection probabilities with sufficiently low false alarm rates. Subsequent research will provide recommendations on specific jitter and integration times/number of stacked frames to maximize probability of target detections while minimizing false alarms.
Date of Conference: September 14-17, 2021
Track: Cislunar SSA