Matt Schierholtz, Trusted Space, Inc; Thomas Kubancik, Trusted Space, Inc; Kyle Charles, Trusted Space, Inc; Islam Hussein, Trusted Space, Inc.; Erin Griggs, Trusted Space, Inc.; Blair Thompson, United States Air Force Academy; Elvis Silva, Blue Canyon Technologies;
Keywords: GEO, Patrol Orbit, SSA, SDA, Orbital Phasing, Constellation, Optical Sensor, Maneuvering, SNR Analysis
Abstract:
Using inclined, eccentric geosynchronous (GEO) orbits allows monitoring of a single target or longer-term full in-plane coverage of multiple targets in the GEO belt. This is due to the eccentricity-produced motion of such an orbit relative to objects that are stationary with respect to earths longitude. Previously, Geosynchronous Patrol Orbit for Space Situational Awareness (SSA) by Thompson (2017) analyzed two classes of patrol orbits: (1) an asynchronous or drifting orbit that visits all longitudes, and (2) a patrol orbit that will focus on SSA around a resident space object (RSO). A delta-v budget was developed for station-keeping, maneuvering, plane changing, and orbit insertion.
This paper adds a delta-v analysis for switching between orbit classes over a year. Different concepts of operations (CONOPS) are explored, such as optimized pointing, ground site considerations, and careful phasing of patrol orbits. Pointing for different desired lighting conditions can be applied to gain continuous custody of an object with low or zero associated delta-v cost. This is especially true if a well-matched payload is chosen for this mission. The considered payload is visible band in nature, as the visible band is best suited to SSA missions. Analysis is performed for both the RSO and modeled threats that could come in close proximity with the RSO from a set of diverse and potentially difficult-to-predict orbits.
This paper will, for the first time, also explore the effects of phasing for patrol orbits. Phasing the patrol and drift orbit classes in predetermined ways is shown to provide more complete coverage of RSO and threat orbits with high diversity of measurement geometries. When employing phased patrol orbits in conjunction with ground sites, a command center may attain more complete custody of an RSO. We conduct a ground site analysis to determine the rarity of coinciding ground site blackouts and patrol orbit blackouts, as well as the frequency of excellent viewing conditions from ground coinciding with an earth exclusion from the patrol satellite. This capability would augment a GEO space domain awareness regime.
For our analysis we considered a range of inclinations and number of satellites. Multiple pointing Concepts of Operations (CONOPS) were modeled to evaluate performance against mission objectives. These include 1) solar opposition pointing, which optimizes for the best possible lighting conditions, 2) fixed-nadir-offset pointing, which is closer to a typical pointing CONOPS for GEO SSA missions, and (3) a four-pi-steradian scan, which sweeps the full sky, modeled as a sphere of Fibonacci points, over a set period of time. We analyze whether these CONOPS are adequate to monitor the modeled RSO or incoming threats.
We describe and demonstrate a tool to create the orbital elements for such orbital phasing in a Modeling and Simulation environment. We discuss the considerations necessary when designing CONOPS optimized to meet more complex mission objectives. We explore two, three, four, six, and eight-satellite constellations for their respective performance at different combinations of phasing and longitude at all times of the year.
Date of Conference: September 19-22, 2023
Track: Space-Based Assets