Pole-Sitter Based Space Domain Awareness for Cislunar Objects

Modern space missions are increasingly venturing across cislunar space, requiring expansion of space awareness functions. Legacy space domain awareness (SDA) systems were not originally built to detect and track cislunar objects, and this could require acquisition of new sensor systems. There are numerous parameters, including sensing type, altitude, and number of platforms that could be varied for each system. One of the proposed options is a pole-sitter satellite located at 2.5 million km above either the North or South Pole. One key advantage to any “pole-sitter” is that it has a position well outside the ecliptic plane and offers a unique, in some cases orthogonal viewing geometry that here to fore have not been developed for operational deployment. Such orbits offer continuous watching and tracking of candidate objects with the advantages of efficiency and characterization. The efficiency results from not having to repeatedly reacquire the object due to blockage by Earth eclipse; and once detected and continuously tracked, any behavior of the object begins to reveal its characteristics, pattern of life, and potential intents. In this paper, the physics of the pole-sitter trajectory, the trade of fuel usage against altitude, and updates in required technology are discussed. All these elements point towards the feasibility of demonstrating a pole-sitter SDA capability in the near term. In addition, this paper devises a proposed prototype using small spacecraft in conjunction with ground-based sensors along with descriptions of current technology ready for deployment.