Anthony Zara, Advanced Space; Patrick Miga, Advanced Space; Brighton Smith, Advanced Space; Karina Rivera Lopez, Advanced Space
https://doi.org/10.64861/PHQR4236
Keywords: low-lunar orbit, LLO, optical, cislunar, cone of shame, exclusion zone, orbit determination, navigation, tracking, PNT, timing, SDA, catalog, hybrid, architecture, maintenance, custody
Abstract:
As international presence at the Moon expands, proliferation of Lunar orbits poses a large challenge for traditional detection and cataloging methods and their efforts to mitigate risk of conjunctions and collisions. Existing and planned sensors intended for cislunar space situational awareness concern an incredibly large and important domain, but all lack capability in arguably the most critical subset: Low-Lunar Orbit (LLO). Observing non-transmitting objects and debris in LLO poses unique challenges caused by the Lunar exclusion zone or “Cone of Shame”; sunlight reflected off the regolith washes out sensors pointed at or near the Moon, rendering non-transmitting objects in Low-Lunar Orbit all but undetectable by any passive methods. This poses a critical safety problem as the volume of Low-Lunar orbit is quite small relative to Low-Earth orbit, markedly increasing the probability of conjunctions and collisions, reduced orbital traffic notwithstanding. Additionally, this domain is the gateway to landing humans back on the moon, as well as a valuable scientific outpost to help further study our nearest celestial neighbor and gateway to the rest of the solar system. For these reasons, ensuring the safety of this domain by closing our current sensor gap is tantamount to the safety of future Lunar exploration.
To address the Low-Lunar Orbit detectability issue suffered by existing and planned methods, Advanced Space has proposed the use of in-situ sensors to track and catalog non-transmitting objects in this domain. Placing sensors in-situ with wide field-of-view optical instruments permits meaningful detections of non-transmitting objects in LLO by leveraging a hybrid system of LLO and Lunar surface-based observers that can look both “up” and “sideways” while avoiding the Moon, effectively circumventing the dreaded cone-of-shame. Obtaining metric observations of Low-Lunar orbiting objects is only the beginning of the chain; the end state must leverage those observations to track and catalogue debris and non-transmitting objects in the domain to facilitate safe and secure LLO operations for all parties.
Transmuting metric observations into actionable data necessitates an undergirding architecture of LLO object detection, detection track association, orbit determination of both detected targets and orbiting observers, a robust timing system to maintain accuracy in the former and finally catalog generation and maintenance. This work focuses mainly on detection network formulation and its supporting positioning, navigation, and timing system necessary to support such a network in facilitating accurate tracking and custody maintenance of target non-transmitting spacecraft in Low-Lunar Orbit. An exploration of a hybrid orbital and Lunar surface-based system of sensors given realistic operational constraints on visibility and detectability is performed to provide a basis for sensor placement. From resulting detections, orbit evolution characterization of different LLO domains is used to formulate custody maintenance metrics based on the evolution of state dispersions. These metrics help define acceptable orbit determination performance for tracking non-transmitting objects to ensure that coverage granted by the sensor architecture is capable of maintaining custody of said objects during observation gaps. Target orbit determination performance will in turn help inform required navigation and timing performance for the sensor architecture itself, in which autonomous navigation methods are explored to further aid in the architecture’s accuracy and autonomy. Linking the findings through each thread of analysis helps to frame a system capable of detecting, tracking, and eventually cataloging the LLO domain to ensure safe operations for all future Lunar missions to come.
Date of Conference: September 15-18, 2026
Track: Cislunar SDA