Contribution from SSA data to the definition of a Space Sustainability Rating

Sept. 16, 2020


Letizia, Francesca, Stijn Lemmens, Danielle Wood, Minoo Rathnasabapathy, Miles Lifson, R. Steindl, Moriba Jah, Nikolai Khlystov, Maksim Soshkin, and Simon Potter. "Contribution from SSA data to the definition of a space sustainability rating." In Proceedings of the Advanced Maui Optical and Space Surveillance Technologies (AMOS) Conference, p. 12. September 2020.


In 2018, the Word Economic Forum issued a call for proposal to develop a so-called “Space Sustainability Rating” to capture the debris risk associated to a mission. Following this call, the European Space Agency, Massachusetts Institute of Technology, University of Texas at Austin, and Bryce Space and Technology have formed a consortium to design a rating able to encourage behaviours that are more responsible by promoting mission designs and operational concepts that are compatible with a stable evolution of the environment. The approach adopted for this initiative is to combine, in a composite indicator, different components, related to both short-and long-term effect, considering the impact on other operators, and on the environment globally. The identified components include a metric of the fragmentation risk associated to an object in orbit, an evaluation of the collision avoidance process adopted by a mission operator, the steps to ease the detectability, identification, and tracking of the mission, the level of data sharing implemented, the adoption of international standards related to debris mitigation measures, and the readiness of a mission with respect to on-orbit servicing. The paper will discuss the direct and indirect contribution coming from Space Situational Awareness (SSA) data in the definition, assessment, and verification of such a rating. The direct contribution refers to how a given mission deals with SSA data and considerations. The evaluation of the aspects related to collision avoidance, detectability, identification, and tracking will be discussed, together with the definition of the levels of data sharing implemented. The rationale behind the proposed classification is to identify and promote actions that are effective in reducing the collision avoidance efforts for other operators and the burden on space surveillance system (e.g. in the case of a launch with multiple similar shaped satellites). Some examples will be presented to answer the questions: What happens to the mission rating if one acquires additional tracking data? And what if one adopts design features to enhance trackability? The indirect contribution refers instead to how SSA data can support the effective adoption and credibility of the proposed rating. For example, the rating will be computed based on operator-provided data (e.g. on the adopted disposal and collision avoidance strategies), so there is operator-provided data (e.g. on the adopted disposal and collision avoidance strategies), so there is an interest in developing reliable approaches to perform independent assessment and validate such inputs. In addition, the current rating formulation requires the number of objects able to trigger a catastrophic collision, the evaluation of the manoeuvre capabilities of an object (also as a proxy of its operational status), the estimation of the relevant properties for lifetime assessment. Finally, the availability of independent data sources will also allow the evaluation of the rating (or at least of some of its components) also for non-participating actors. In this way, a global representation of the level of adoption of mitigation measures can be achieved and the performance of the rating is promoting such measures can be assessed. Therefore, a discussion on the potential sources of the different parameters that are used in the rating evaluation will be presented, discussing their reliability and the availability of independently verifiable data accepted.

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