Tory Smith, USSF/MIT; Zachary Folcik, MIT Lincoln Laboratory; Richard Linares, Massachusetts Institute of Technology
Keywords: NASA Standard Break-up Model (SBM), Space Fence Radar, Population Modeling, Orbital Capacity
Abstract:
This paper presents case studies of the area-to-mass ratio distributions and delta velocity distributions estimated by the NASA Standard Break-up Model when compared against empirical data. We use data collected by the Space Fence phased array radar and gathered by MIT Lincoln Laboratory (MIT/LL) for five recent break-up events before simulating the same events with the NASA SBM and comparing the resulting distributions.
NASA developed their model for satellite break-ups in the 1990s with hypervelocity ground tests and radar observation data of on-orbit break-ups. The model has since become the go-to for orbital capacity and long-term population environment models such as NASA’s own EVOLVE 4.0, and the MIT Orbital Capacity and Analysis Tool (MOCAT). Its ease of implementation and low computational cost makes it an attractive option for modeling fragmentation events within these environment models.
With the limited availability of empirical data at the time of development, assumptions were made in the original model that do not accurately take into account certain factors, such as the arbitrary assignment of large fragments to model conservation of mass, and thus the model produces inaccurate debris cloud estimations. Recent ground-based hypervelocity impact experiments such as DebrisSat have highlighted the model’s underestimation of debris generation. This study further explores the NASA SBM by analyzing recent on-orbit debris-creation incidents with data from the Space Fence radar. Before Space Fence was operational, the detection of small debris pieces from such incidents relied on high-resolution, but narrowly focused, radars like the Haystack Ultrawideband Satellite Imaging Radar (HUSIR) — the radar technology that initially informed the SBM. The advent of the next-generation phased array radar technology used by the Space Fence, combined with its high-power capabilities, enables the simultaneous monitoring of a much broader area of the sky. This advancement significantly enhances our ability to comprehensively track and catalog debris clouds compared to the limited scope of previous narrow FOV radar systems.
Now that the Space Fence has been operational for several years and has observed on-orbit break-up events, opportunities have emerged to further investigate and characterize any discrepancies that may exist between the current NASA break-up model and new empirical data.
The SBM is broken into three parts: size distributions, area-to-mass distributions, and delta velocity distributions. In a previous study, we compared the size distributions estimated by the NASA SBM when simulating five known break-up events against the empirical data from the debris cloud of the same events captured by Space Fence. These five break-up events included the following: COSMOS 1408 anti-satellite (ASAT) missile test, Chang Zheng 6A, H-IIA Launch Vehicle, COSMOS 2499, and Orbcomm FM36.
In this paper, we will continue our investigation of the NASA SBM by comparing the results of the SBM’s area-to-mass distributions and ejection velocity distributions against the data collected by Space Fence for the same events studied previously. We expect to find similar discrepancies between the model estimates and the empirical data as we found in our investigations of the size distributions.
When making determinations about orbital capacity and modeling long-term population evolution, it is extremely important to model fragmentation events as these are the largest contributors to space debris. The NASA SBM has been the standard because of its ease of use and low computational cost. However, perhaps in the pursuit of its ease of use and the age of the model, it has lost some of its general applicability as it is unable to account for all of the complexities involved in fragmentation events. With our findings from this paper, we hope to motivate future areas for research, such as introducing new satellite break-up models using modern statistical techniques.
Date of Conference: September 17-20, 2024
Track: Space Debris