Di Wu, Massachusetts Institute of Technology; Richard Linares, Massachusetts Institute of Technology
Keywords: space debris; physical-economic model; space economy; optimization
Abstract:
The grieving and self-sabotaging call over ultimate tragedy and lost morals has never stopped whenever human beings, horrified, helpless, but excited, enter into a new era. Yet, we tend to forget challenges come with opportunities. The space era is evolving so rapidly that losing the old and familiar imagination over a comfortable grip over an ultimately unrealistically large space for a single object is cracking people’s nerves. For sure, the increasing amount of space objects in circumterrestrial space poses a significant threat to the safety and sustainability of space operations. Yet, it is only true to a limited extent and under circumterrestrial space’s current status – an open-access era. This assumption has been greatly challenged and would naturally be replaced. While this is happening at the moment, still goes the question: What are we replacing this open-access era with?
While physical-economic models have been proposed to address the problem, the ground-breaking improvements in this investigation come in two-fold. Physical sections of existing models are simplified single-shell source-sink models. The substantial heterogeneity in orbital-use values in different spherical or circular shells is inevitable as some orbits are more valuable because of the unique conditions they would offer in space application. Such a multi-shell source-sink model has undergone extensive development in the last couple of years. This generalization foreseen by previous works has, yet, not been implemented and would be part of the investigation in this research. Calibration with historical data comes into deciding parameters for the incorporation of a multi-shell source-sink model. More importantly, it is up to the calibration of the economic values of objects in those different shells that would generate a new multi-shell physical-economic model allowing a finer drawing of the overall area. On top of such a model, we would formulate an incentive design problem, the core of encouraging space operators accounting the costs they impose on each other via collision risk, and solve this problem through a common conceptual “orbital-use fee”, a cost on a single orbit satellite that turned out in literature to “quadruple the long-run value of the satellite industry”.
In addition, these physical-economic models often only focus on active satellites and fail to account for the potential value that space debris can bring to the overall space economy. As the space industry continues to grow and expand, there is a need for new sources of revenue and value. Space debris, which was previously seen as a problem, can now be recognized as a valuable resource simply accounting for the underlying orbits occupied by them, as, in space, orbital space itself is a valuable resource. In this study, we would test the definition of space debris value and transfer model that would incentivize the recognition, ownership, and utilization of space debris. An optimal fleet planner problem is formulated by incorporating the space debris value into a Bellman equation describing the value of the entire fleet (satellites and debris owned by a specific planner) into the infinite future, subject to the laws of satellite motions and debris exchange process. We would investigate how different parameters would affect the optimal policy derived by solving these problems and how this formulation would affect the evolution of space object stocking numbers.
Our model aims to scale up the values of the space industry beyond just active satellites in a more detailed multi-shell source-sink model. By incorporating values for space debris, our model encourages responsible and sustainable space operations, as entities in the space industry would be encouraged to make recognition and ownership of space debris. This can lead to the creation of new business models and revenue streams that ultimately incentivize entities to take more responsible actions in space exploration. In conclusion, our proposed investigation would provide a comprehensive solution to the problem of space debris evolution in the circumterrestrial space.
Date of Conference: September 19-22, 2023
Track: Space Debris