"Space capacity allocation for the sustainability of space activities"

Several members and collaborators of Team Space Enabled are presenting as part of a workshop hosted by the Politecnico di Milano in Italy from June 6 to 8, 2023. The workshop is called "Space capacity allocation for the sustainability of space activities," and it explores questions drawing from engineering, business and policy to determine what range and types of satellite operations can be consistently and safely operated in Earth's orbit. The topic of the workshop is closely linked to the work of Team Space Enabled as key contributors to the Space Sustainability Rating. The conference is co-hosted by Professor Camilla Colombo of the Politecnico di Milano who studies orbital dynamics, trajectory design and optimization, dynamical system analysis and control, and space mission analysis and design. Prof Colombo has been a consistent collaborator with Prof Wood since 2018. Prof Wood and Prof Colombo have co-mentored two Master of Science students based at Politecnico di Milano: Daniele Leuteri Costanzo and Sina es Haghi. Other co-organizers for the workshop include Francesca Letizia and Stijn Lemmens, members of the Space Sustainability Rating design team from the European Space Agency.

Team Space Enabled is leading or co-authoring in three presentations during the workshop. Postdoctoral scholar, Dr. Scott Dorrington, of Team Space Enabled is participating in the meeting in person and giving a presentation. Prof Danielle Wood is also a co-author for presentations lead by Emmanuelle David of the Space Sustainability Rating and Sina es Haghi of Politecnico di Milano. Prof Wood serve as the co-advisor for Sina's thesis along with Prof Colombo. Below is a summary of each paper. In addition, Will Parker of MIT's ARCLab under Prof Richard Linares, presents on "Impacts of Thermosphere Contraction on Debris Accumulation and Orbital Capacity." Prof Wood serves on Will's doctoral thesis committee.

"Quantifying Satellite Impacts on the Space Debris Environment using Density Distribution Metrics in Specific Orbital Angular Momentum Space"

Authors: Scott Dorrington, Danielle Wood

Abstract: In previous work by the authors, we demonstrated that the cartesian components of satellites’ specific orbital angular momentum vectors provide an effective parameter space in which to characterize the distribution of the space object catalog. We applied Kernel Density Estimation methods to produce a density distribution that effectively identifies high density clusters of space objects associated with known debris-generating events. The goal of this work was to develop new metrics for the Space Sustainability Rating (SSR) that quantify how identifiable individual satellites are from their neighbouring objects. In this paper, we extend this work to investigate the applicability of the density distribution in specific orbital angular momentum space for measuring the impact new satellite missions have on the space debris environment. We define a reference density distribution p(x) computed from the sum of contributions from all satellites in the space object catalog, and an incremental density distribution Δp(x) due to new satellites for which we wish to measure the impact. We then compute the fractional increase in density with respect to the existing catalog Δp(x)/p(x), and integrate it over the entire parameter space. This gives a measure of the impact that these new satellites have in increasing the density distribution relative to the existing population. This method can also measure the effectiveness of active debris removal missions, by computing the total relative reduction in the density distribution caused by removing specific space objects. To assess the effectiveness of this method in quantifying the impact that adding or removing satellites has on the space debris environment, we conduct numerical experiments by adding or removing new satellites from a reference catalog. We test different numbers of satellites (single satellites and small and large constellations) being added or removed from different orbital regions.

"Decision Support System for Space Collision Avoidance using the  ENVIRONMENT-VULNERABILITY-DECISION-TECHNOLOGY Framework"

Authors: Sina es Haghi, Scott Dorrington, Jackie Smith, Camilla Colombo, Danielle Wood

Abstract: Recently, the number of Anthropogenic Space Objects (ASOs) orbiting the Earth has increased significantly, and the space environment has become congested. As of 2023, more than 27,000 ASOs with dimensions larger than a smartphone are being tracked by the US Space Surveillance Network and with the launch of mega-constellations, this number will grow. From a Space Traffic Management (STM) and Space Situational Awareness (SSA) perspective, the workload heavily increases as the number of probable collisions between these ASOs rises. To choose an optimal architecture for STM operations in the future, a need for Decision Support System (DSS) is unavoidable. This paper outlines the first application of the Environment-Vulnerability-Decision-Technology (EVDT) framework in the space domain, to develop a prototype DSS for Collision Avoidance (COLA) operations, called COLA-EVDT. EVDT is a modeling framework that takes into account the interdependent relationships and feedback loops within complex systems to promote sustainable development. The framework considers social, environmental, and economic factors and aims to create a DSS for high uncertainty and multi-stakeholder scenarios. While EVDT has been successfully demonstrated previously using Earth-observation systems for terrestrial applications, this paper will present the first application of the framework to a non-terrestrial environment. The authors use EVDT to model the main stages of COLA operations and analyze how collision avoidance operators can be affected by the space environment. The modularity of the developed COLA-EVDT allows the possibility of modifying each component of the framework, such as the space environment component or the socioeconomic impact component, to trial different architectures depending on the required application in space sustainability. As a case study of an affected conjunction assessment team, the authors consider the publicly documented operations of the NASA Conjunction Assessment Risk Assessment (CARA). CARA provides conjunction and risk analysis services to NASA’s uncrewed spacecraft. The algorithm downloads space catalogs from Space-Track, geometrically filters irrelevant ASOs, propagates the remaining objects, and performs volumetric screening to detect conjunction events. By utilizing publicly released CARA software, the model generates conjunction data messages and values based on their socioeconomic impact in the event of a collision. The results presented in the paper show that interactive data-driven DSS through the use of EVDT can help with illuminating the effects of using different risk mitigation strategies or SSA suppliers. This paper represents the first step in the development of a comprehensive EVDT framework for space that simultaneously considers physical and socioeconomic factors informing collision avoidance

"An application of a debris index and its complementarity with standard compliance-based approach: the Space Sustainability Rating"

Authors: Emmanuelle David, Adrien Saada, Francesca Letizia, Dennis Weber, Danielle Wood, Minoo Rathsnasabapathy

Abstract: Long-term simulations of the space environment predict an exponential increase in collision rates due to the current launch rate and implementation of space debris mitigation measures. An acceptable level of risk must be maintained to ensure a stable space environment, requiring strict compliance with existing guidelines and best practices. However, current compliance assessment approaches have limitations, such as obsolete disposal criteria due to increasing launch traffic and difficulty accounting for the current aggregated compliance levels. An alternative is a risk-based approach, which was formulated under the appellation of “debris index”. A derived version of the index was developed, tested, and implemented for the Space Sustainability Rating (SSR). Based on ratings successfully used in other industries, the SSR was first conceptualised in 2016 within the World Economic Forum’s Global Future Council on Space as a tool to assess and quantify sustainable design and operational decisions taken by operators. The SSR is now operational, rating missions as part of its core activities. Whereas global regulatory changes enforcing the utilisation of a capacity-based approach is unlikely to happen in the coming years, the SSR is in a unique position to test such implementation. Additionally, strategic advantages of using a risk based approach for rating satellite missions rather than for regulatory purposes exists and will be listed. Whereas the SSR is operational since 2022, difficulties arose from the utilisation of debris indices. From past use cases, the description of the technical challenges of applying this approach to complex and operating missions will be provided, as well as the unique opportunities to deliver positive change in the space sector that can be harnessed. Additionally to the risk-based part of the SSR, other aspects of sustainability need to be introduced in a rating methodology to develop a comprehensive and complete assessment. In June 2019, the United Nations (UN) adopted twenty-one Long Term Sustainability (LTS) guidelines. While not legally binding under international law, they reflect the latest global consensus on what responsible and sustainable space activities are in practice. The presentation will describe the parallels between the SSR methodology and the UN LTS guidelines, as well as the opportunities for the SSR to enforce it using a compliance-based approach. The compatibility and complementarity of risk-based and compliance-based approaches will be discussed. To conclude, the presentation will introduce and analyse incentives identified by the SSR allowing actors to demonstrate their adherence to sustainability practices and ESG measures.

The organizers of the event, describe it as follows. 

Workshop topics and outcome

Space, as any other ecosystem, has a finite capacity. The continuous growth of space activities, due to our increasing reliance on services from Space, the privatisation of the space market and the lower cost of deploying smaller and distributed missions in orbit, is from one side improving human-life quality and, however, it is also contributing to overloading this delicate system. International discussion is ongoing at the Inter Agency Debris Coordination Committee and at COPUOS on how to measure the overall capacity of the space environment and assess the impact that individual missions have on it.

The “Space capacity allocation for the sustainability of space activities” workshop will be held in Politecnico di Milano (Italy) on 6-8 June 2023, in Piazza Leonardo Campus.

The workshop is organised by Politecnico di Milano, the European Space Agency Space and the Italian Centre of Research (CNR). The workshop is sponsored by the GREEN SPECIES project funded by the European Research Council lead by Politecnico di Milano and co-sponsored by Secure World Foundation.

This workshop is open to all researchers, space operators and regulators working in the space debris field. The aim is not only to present current advances in research on space capacity modelling and management, but above all to offer a constructive and interdisciplinary framework to discuss and work collaboratively to advance the discussion on space sustainability and space capacity management.

In this view, the following topics will be addressed and discussed during the workshop:

• Modelling the long-term evolution of the space debris environment,
• Defining indices to assess the impact of missions to the space environment,
• Measuring and defining thresholds for the overall space carrying capacity,
• Proposals to manage the space environment on the long-term,
• Policy and economic studies on space debris mitigations and applicability of capacity management strategies.

As outcome of the workshop, a special issue of a journal might be initiated with invited publications. In addition, a report and statement of the outcome to be shared with the outcome of the discussion will be prepared.