Joshua M. Block, Air Force Institute of Technology; David H. Curtis, Air Force Institute of Technology; Robert A. Bettinger, Air Force Institute of Technology; Adam P. Wilmer, Air Force Institute of Technology
Keywords: space domain awareness; space situational awareness; space traffic management; cislunar; uncertainty
Abstract:
With an increased interest in the cislunar domain for both civilian and military applications comes a need for Space Domain Awareness (SDA) of objects in cislunar space. Space-based SDA in cislunar space is challenging in part due to difficulties associated with accurately estimating the position of the observer satellite, which is a requirement for effectively performing the SDA mission. Using multiple observation satellites with lower-fidelity equipment may be able to help alleviate these concerns by aggregating together multiple datasets with higher variance to achieve the same level or better accuracy as compared to fewer higher-quality measurement systems. This research investigates the advantages of using multiple observation satellites to improve the accuracy of orbit estimation for target satellites in cislunar space.
For this research, all spacecraft dynamics will be modeled utilizing the Circular Restricted Three-Body Problem (CR3BP). The observer spacecraft will be placed in one of two selected Earth-Moon periodic orbits. These spacecraft will be observing a target object in an L1 Halo orbit as its proximity to the Moon makes it an ideal location both for communications platforms and a staging location for lunar operations. The Earth-Moon periodic orbits were chosen based on its long-term orbital stability, close sweeps back to the Earth for better command and control, and previous analysis of SDA feasibility. Another advantage of these orbits are their large coverage of cislunar space sweeping all the way out to L3. While this research focuses on their use for observing L1, it is worth noting that the contents of this research could be further applied to a larger application of SDA and Space Traffic Management across the Cislunar domain.
To accomplish the goals of this research, the observer and target spacecraft will be modeled in the synodic reference frame of the CR3BP as described above. The observing spacecraft will simulate optical sensors to generate measurements with the use of Systems Tool Kit. With both the orbits and sensors modeled, the experiment will focus on comparing the effectiveness of a different number of spacecraft needed in the observing constellation to generate the same or less uncertainty than a tradition SDA network. Each spacecraft will have varying levels of both positional and measurement noise. The measurement data will then be processed utilizing optimal filtering techniques to generate the future positional data of the target spacecraft. Comparing estimated state data to the truth data generated by the model, each set of data will be assigned an error value which will be the primary metric used to contrast the different initial conditions set for each simulation.
It is expected that the error values corresponding to some of the observer constellations tested will match or exceed that of a single traditional high-performance SDA spacecraft. This would allow for more flexibility when it comes to the utilization of multiple orbital regimes for conducting SDA missions and has the potential to decrease overall mission cost due to cheaper and standardized components that would be used for each spacecraft. The ability to track objects with less uncertainty in cislunar space, specifically around the moon, would allow for safer operations of both manned and unmanned missions in the region as it becomes more contested and congested and proof new techniques for both Space Domain Awareness and Space Traffic Management.
Date of Conference: September 27-20, 2022
Track: Cislunar SSA