Rachel M. Derbis, Air Force Institute of Technology; Bryan D. Little, Air Force Institute of Technology; Joshuah A. Hess, Air Force Institute of Technology; David W. Meyer, Air Force Institute of Technology
Keywords: space domain awareness, cislunar, modeling and simulation
Abstract:
The number of objects on orbit has continued to grow at an increasing rate with more countries developing space capabilities and commercial space endeavors. Space Domain Awareness (SDA) is foundational to the ability to operate in space. As the domain becomes more congested, it is critical to be able to sense small objects accurately at higher altitudes. Impact of a spacecraft with orbital debris or micro-meteors can cause significant damage. Small explosions on orbit or on orbit spacecraft collisions result in additional debris that must be tracked to avoid future mishaps.
The desire is to identify which on-orbit sensing constellations provide the best performance for SDA beyond Geostationary Orbit (GEO). For this work, the authors use Systems Tool Kit (STK) to model the orbits considered for notional sensing constellations at varying altitudes versus orbital debris beyond GEO. The initial SDA constellation considered has an altitude which places it above GEO but below the GEO disposal belt to avoid having to maneuver in a region with a high resident space object (RSO) population. Sensors point to maximize the region that can be accessed by a given spacecraft allowing the constellation to have coverage with a reasonable number of spacecraft to minimize cost. The sensors on the satellites are modeled as optical systems. Optical sensors can refine the state (position and velocity) of an object of interest to millimeter accuracy. This will be important when conjunctions are forecast or repositioning maneuvers are being monitored. The range, line of sight, and relative attitude can be used to identify vehicle status. The vehicle image can be processed, evaluating the signature to determine an objects status (i.e. operational, recently damaged, etc.). However, image processing is complex requiring additional time to provide results.
With the interest in cislunar missions, higher altitudes need to be considered. SDA constellations are modeled with spacecraft in orbits at higher altitudes above the GEO disposal belt extending the initially evaluated SDA constellation and targets to consider objects up to 8 times GEO altitude. The higher altitude resident space objects are affected by three body effects.
For a space-based SDA constellation mean range to resident space objects is smaller than the altitude from earth to GEO so resolution of small objects will be better than sensing from ground sensors. Constellation cost and potential for dual use satellites may be significant for design trades. Continued research in space domain awareness is critical to ensure safe operation for all spacecraft at GEO and beyond.
Date of Conference: September 27-20, 2022
Track: Space-Based Assets