Valentin Eder, Space Analyses GmbH; Christian Unfried, Space Analyses GmbH
Keywords: Outer space, Sustainability, Risk Management, Data Analytics, Applied System Theory
Abstract:
Understanding the probability and the impact of cascading collisions in outer space orbits around the earth turns out to be one of the more controversial topics in outer space sustainability and risk management. A lot of work invested over the past decades and especially in the last years has led to a better understanding of fragmentation and collision processes, and the fragmentations and collisions which actually took place during that time served as real-life examples to validate or falsify model approaches, and to refine them. We have not seen cascading collisions leading to what has been described as the “Kessler syndrome” decades ago. And like in climate change, we don’t know beforehand when exactly we pass the tipping point, but we know we are moving closer to it every day. Using a systems theory approach, the goal of our research was to enable a perspective which is not meant to be contrary, but rather complementary to existing astrophysics and astrodynamics approaches which mostly care about conjunctions and collisions as risks for single objects, their dynamics and interaction with other single-object items. We show how we can learn from available data and its correlations rather than feeding Monte-Carlo method results into theoretical models. We show how we can use traffic lane analogies from a system traffic point-of-view rather than from a moving-object perspective only. We show how understanding impacts of internal and external changes to orbital shell systems can provide added value for decision-makers that designing better-than-required criteria as thresholds for space sustainability awards on a per-object basis cannot yield. We use existing measurement data, collected and assigned to altitude- and time-based systems of space objects, for analyzing the interactions of space objects and the evolution over time. This leads us to parameters describing the risk and the potential of cascading collisions. Other than the collision risk obtained by traditional astrophysics and astrodynamics methods, this cascading potential does not tell something about single object risks, but says something about the overall system, about the likelihood an “infected” object can “infect” further objects. Such potential analyses can be performed for different orbital shells and object types with the cascading potential change over time allowing an interpretation of the past, of the current situation and for future scenarios. We show that for the calculation of the cascading potential, there is a difference between an object repeatedly meeting the same other object, and an object meeting many different other objects on its daily journey. Like in epidemiology, the risk of spreading an infection in a population is much bigger if there is a bigger exchange between many. (Note that this is different from the other perspective of the individual risk of getting infected.) The resulting parameters and their variation over altitude and time can be used to identify trends, to assign priorities and, therefore, to support decisions e.g., in Active Debris Removal (ADR) planning, but also for life-time extension and Post-Mission Disposal (PMD) considerations. All of these are important tasks on the way to a sustainable use of outer space by our and future generations, which is the guiding vision to which we dedicate our efforts.
Date of Conference: September 27-20, 2022
Track: Space Debris