Second Space Capacity Allocation For The Sustainability Of Space Activities Workshop

3 Jun 2026, 09:00 → 5 Jun 2026, 18:00 Europe/Amsterdam

Politecnico di Milano

Camilla Colombo, Emma Stevenson (IMS Space Consultancy GmbH at ESA), Francesca Letizia, Francesco De Bortoli (Politecnico di Milano), Martina Rusconi (Politecnico di Milano), Stijn Lemmens

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  2nd Space capacity allocation for the sustainability of space activities workshop will be held in Politecnico di Milano (Italy) on 3-5 June 2026, in Bovisa Campus at the Department of Aerospace Science and Technology.

The workshop is organised by Politecnico di Milano, the European Space Agency, Consiglio Nazionale delle Ricerche (CNR) and EUCASS. 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 space operators, regulators, researchers working in the space debris field and in space law. The aim is:

• to discuss and compare current advances in research on space capacity modelling and management towards reaching an international agreement on modelling the Space capacity and defining an accepted threshold.
• to offer a constructive and interdisciplinary framework to advance the discussion on space sustainability and space capacity management, including from a legal and economic perspective.
• to engage among the different factors that affect space sustainability at large such-as: long-term orbital capacity, short term slotting for space traffic management, emission into the atmosphere at re-entry and launch, integration between re-entry and air traffic control, light pollution by orbiting spacecraft.

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

• Modelling of the long-term evolution of the space object population environment  and challenges in the forecast of the future launch traffic and technology development scenarios;
• Analysis on how mitigation guidelines can adapt to the change in the launch trend and the increase of large constellations;
• Comparing indices to assess the impact of missions to the space debris environment;
• Measuring and defining thresholds for the overall space carrying capacity;
• Proposals to manage the space environment on the long-term;
• In additional to orbital pollution, discuss how to integrate different indicators such as light pollution, atmosphere emissions, casualty risk at re-entry, etc.;
• Policy studies on space debris mitigations and applicability of capacity management strategies;
• Economic studies on space debris mitigations and applicability of capacity management strategies.

As outcome of the workshop, a special issue of the Journal of Space Safety Engineering will be initiated with invited publications. In addition, a report and statement to be shared with the outcome of the discussion will be prepared. EUCASS will sponsor the best space sustainability student award for PhD students.

Workshop organisation

The workshop will be organised in presence only, with presentations by participants alternating with working sessions and discussions. Some presentations will be also broadcasted for remote participants.

Please find practical information about accommodations and public transport in Milan in the uploaded files section below.

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Agenda 

Wednesday, June 3^rd 

09:00-09:30: Registration 

09:30-11:30: Session 1: “Is Space debris an environmental problem?” 

•     Introduction 
•     Keynote: "Control of climate and space capacity allocation: what are the commonalities"
•     Discussions on similarities and differences with space debris 

 

11:30-13:00: Session 2: “Challenges of space debris modelling” 

Presentations:

Covered topic: Modelling of the long-term evolution of the space object population environment and challenges in the forecast of the future launch traffic and technology development scenarios. 

13:00-14:30: Lunch 

14:30-16:00: Session 3: Exercise “Space debris modelling exercise”

16:00-17:30: Session 4: “How space debris mitigation can adapt to the space environment?” 

Presentations:

Covered topic: Analysis on how mitigation guideline can adapt to the change in the launch trend and the increase of large constellations. 

18:00-20:00: Opening buffet 

 

Thursday, June 4^th

09:00-10.30: Session 5: “How to assess the impact of space missions onto the space environment?” 

Presentations:

Covered topic: Comparing indices to assess the impact of missions to the space debris environment. 

10:30-12:00: Session 6: “How to measure the space capacity?” 

Presentations: 

Covered topic: Measuring and defining thresholds for the overall space carrying capacity. 

12:00-13:00: Session 7: Exercise: “Space capacity exercise”

13:00-14:30: Lunch 

14:30-16:00: Session 8: Workshop: “How technical mitigation actions can be translated in policies?”

16:00-17.30: Session 9: “Space debris mitigation policies” 

Presentations:

Covered topic: Policy studies on space debris mitigations and applicability of capacity management strategies. 

17:30-18:00: Wrap up 

19:30-21:00: Dinner (upon registration) 

 

Friday, June 5^th

09:00-10:30: Session 10: Panel “Space debris and space capacity measures in the EU space act and international cooperation” 

10:30-11:00: Discussion 

11:00-12:30: Session 11: “Space capacity management” 

Presentations:

Covered topics:

• • Proposals to manage the space environment on the long-term,
  • Economic studies on space debris mitigations and applicability of capacity management strategies. 

 

12:30-14:00: Lunch 

14:00-15:30: Session 12: “Towards the integration of all the open aspects in space sustainability” 

Presentations:

Covered topics:

• • Integrate different indicators such as light pollution, atmosphere emissions, casualty risk at re-entry, etc. 
  • Life cycle assessment of space missions 

 

15:30-17:00: Session 13: “Conclusions and next steps”

 

 

Practical Information

• Accomodations.pdf
• Detailed Agenda.pdf
• Transport_and_maps.pdf

Wednesday 3 June

09:00 → 09:30 Registration

09:30 → 12:15 Is Space debris an environmental problem?

10:00 Space debris as an environmental stressor: analogies and insights from Planetary Boundary-based absolute environmental sustainability assessment

Space activities are increasingly facing with sustainability challenges associated with the deployment of large satellite constellations and rapid accumulation of both functional and non-functional objects (i.e. debris), eventually leading to orbital congestion and increased cascading collision risks. Similar to conventional environmental stressors, space debris results from the interaction between human activities, technological development, and increasing societal demand, echoing the well-known IPAT identity where environmental impact (I) is driven by population (P), affluence (A), and technology (T).
While the IPAT framework provides a useful conceptual basis for understanding the drivers of environmental pressure, it does not account for ecological limits or the carrying capacity of natural systems, defined as the maximum continuous burden that the environment can sustain without undergoing critical degradation. To address this limitation, environmental Life Cycle Assessment (LCA) framework increasingly relies on normalization approaches based on carrying capacity also defined as Safe operating Space (SoS) within the well-established Planetary Boundaries framework. The latter provides a science-based representation of global environmental limits beyond which Earth system stability may be compromised.
Building upon this concept, Absolute Environmental Sustainability Assessment (AESA) aims to evaluate whether human activities remain within their allocated share of the SOS by (i) estimating the environmental footprint of an activity and (ii) allocating carrying capacities to the studied activity across regions, countries, and sectors, relying on different ethical principles such as equal per capita, responsibility, ability to pay, or acquired rights.
This keynote explores the analogy between space debris and conventional environmental stressors through the prism of Absolute Environmental sustainability Assessment. Particular attention will be given to methodological developments related to normalization, impact pathways, and carry capacity allocation principles. The presentation will further discuss recent applications on the assessment of the EU Consumption Footprint against Planetary Boundaries, illustrating how AESA can support the transition from relative environmental performance to absolute sustainability considerations.

Speakers: Esther Sanyé-Mengual (Joint Research Centre (JRC)), Thibaut Maury (Directorate General for Defence industry and Space (DEFIS), European Commission)

01_integration_maury.pptx

12:15 → 13:30 Lunch

13:30 → 14:45 Challenges of space debris modelling

Covered topics:
- Modelling of the long-term evolution of the space object population environment and challenges in the forecast of the future launch traffic and technology development scenarios.

13:30 New modelling approaches for defining environment evolution scenarios

Environment evolution models are important scientific tools to study on-orbit population dynamics over long time scales. While such tools are based on intrinsic physical models, i.e. the computation of collision rates, they equally rely on external scenario assumptions, i.e. the future evolution of launch traffic. As such tools are already being used to carry out sustainability analyses, evaluate mitigation measures and derive guidelines for a sustainable use of outer space, it is important to conduct such studies under realistic assumptions regarding the underlying long-term evolution scenarios.
Using the LUCA2 simulation tool as an example, we demonstrate how scenario assumptions can be derived from publicly available data sources. In this context, the extrapolation of launch traffic and explosion rates, as well as the configuration of satellite constellations, are considered. First, a generic model for extrapolating event rates has been developed to define launch traffic and explosion rate scenarios based on historic events. The new model enables the definition of more complex scenarios compared to commonly employed approaches, such as the repetition of previous launch cycles. Second, a dedicated model has been developed to derive key operational and orbital parameters of satellite constellations that are currently active or under deployment from orbital data. This allows constellations to be simulated based on their current on-orbit configuration, which may differ from public reports or initially filed plans. Based on these two modelling approaches, various evolution scenarios have been defined, simulated using the LUCA2 tool, and analysed in terms of the temporal and spatial distribution of object populations.

Speaker: Lorenz Böttcher

lorenz_boettcher_space_capacity_workshop_tubs.pdf

13:45 ESMILE: An Ensemble-Driven Particle-in-a-Box Model for Efficient Space Debris Scenario Exploration

One of the main challenges in long-term space debris population modelling is the need to explore multiple scenarios in order to assess system evolution under varying conditions and to evaluate different “what-if” situations. However, traditional approaches rely on sequential simulations, making this process time-consuming and computationally inefficient, as they are typically designed to explore single fixed-parameter scenarios.

Inspired by ensemble techniques widely adopted in the space weather domain, and building upon the promising results of The Aerospace Corporation’s ADEPT work, Politecnico di Milano, in collaboration with Telespazio and GMV under ESA’s EXPRO+ contract (“Ensemble and surrogate modelling for debris environment long-term simulation”), introduces ESMILE: an ensemble-driven Particle-in-a-Box model designed for efficient and automated multi-scenario exploration. The model generates artifacts that serve as interpolating weights for a surrogate model, which is made available through a graphical interface.

This presentation focuses on the architecture of the Particle-in-a-Box model and its ability to maximise computational efficiency through reusability across the simulation campaign. The input parameter space is sampled efficiently to enhance domain exploration, while stochastic events are fully decoupled from the population evolution dynamics. These dynamics are computed once and reused whenever possible across the sampled parameter space.

The model incorporates also techniques to perturb and aggregate data from different modelling methods, in order to add variability and explore the uncertainties and errors in the simulations.

Finally, stochastic processes are handled using a layer-based approach combined with a branch-and-bound strategy that enables the exploration of multiple statistically driven evolutions without repeating the propagation step. This significantly reduces the computational overhead associated with scenario analysis.

As a result, the proposed framework enables the execution of many simulations in significantly less time required by traditional sequential models, providing stakeholders with a powerful tool to assess the impact of mitigation strategies and fragmentation events on the long-term evolution of the space debris environment.

Speaker: Francesco De Bortoli (Politecnico di Milano)

02_ESMILE_DeBortoli.pptx

14:00 An Overview of Innovative Optical Observation Techniques Applied to Daytime and Cislunar Orbits and Real-Time Tracking

The growing population of Resident Space Objects (RSOs) poses increasing challenges for Space Surveillance and Tracking (SST) and, more broadly, for Space Situational Awareness (SSA). The Low Earth Orbit (LEO) environment is already highly congested, and the rapid deployment of commercial mega-constellations is expected to further increase the number of active and inactive objects requiring monitoring. At the same time, renewed lunar exploration initiatives, including the Artemis program, are extending operational activity beyond traditional Earth orbits into cislunar space, introducing new observational and tracking requirements. In this context, optical observations provide a cost-effective and scalable solution for tracking space objects. Although optical systems are constrained by visibility conditions and by the availability of priori information for target acquisition. However, they remain the most practical and, in some regimes, the only feasible option for observing objects in high-altitude Earth orbits and cislunar and lunar space.
This work investigates innovative strategies for two particularly challenging observational scenarios: daylight optical observations and observations of objects above the GEO region up to lunar distances. It investigates the adopted sensor configuration for daytime observations, which enables clear object detection over most of the pass for several LEO targets. A detailed assessment of the operational viability of the proposed approach is performed by presenting different observational cases with different illumination conditions. The work also reports observation tests carried out in very high elliptical orbits and cislunar regime, aimed at evaluating the feasibility of detecting and measuring objects at distances exceeding 40,000 km.
A further contribution to this work concerns the tracking of uncatalogued objects in the absence of reliable a-priori orbital information. While optical survey observations often allow only the detection of unknown targets, they do not always provide sufficient measurements for orbital determination and cataloguing. To address this limitation, a stare-and-chase strategy is proposed, enabling real-time tracking immediately after detection and thus improving data collection for subsequent orbit determination. These approaches expand the operational capabilities of optical sensors and support future SSA/SST needs in increasingly complex framework around the Earth.

Speaker: Matteo Rossetti (Sapienza University of Rome)

Presentation_Matteo_Rossetti.pptx

14:15 KESSLER SYNDROME ANALYSIS VIA A MULTI-SHELL MACROSCOPIC MODEL

The rapid proliferation of satellites and the continuous accumulation of space debris in Low Earth Orbit (LEO) pose a significant threat to the long-term sustainability of space activities, raising concerns about the potential onset of the Kessler syndrome. This work presents a comprehensive analysis of the future LEO environment through a modified and expanded version of the one-dimension particle-in-a-box model proposed by Lafleur (J.M. Lafleur, 2011). To accurately capture spatial dynamics, the LEO region is discretized into a selected number of orbital shells ranging from 200 km to 2000 km in altitude. The system's evolution is governed by a set of coupled ordinary differential equations tracking four distinct object populations: active satellites, inactive satellites, Starlink satellites (explicitly modeled as a standalone evolutionary class to enhance the model's predictive accuracy), and trackable debris larger than 10 cm.

Crucially, parameters used to model phenomena such as the solar cycle-dependent atmospheric drag, explosion rates, and collision probabilities, are consistently derived from scientific literature, ensuring a solid physical basis without relying on artificial curve fitting for validation. The methodology has been validated against historical SATCAT data spanning from 1960 to 2025, demonstrating strong agreement with observed population growth.

Building upon this validated baseline, the study projects the orbital environment up to the year 2125 under varying launch traffic models. The analysis systematically evaluates scenarios ranging from current launch rate extrapolations to significant increases in space traffic. Furthermore, a parametric sensitivity analysis is conducted to assess the effectiveness of technological advancements and operational mitigation strategies. The impacts of improved collision avoidance capabilities, enhanced post-mission disposal compliance, and active debris removal implementations are evaluated. The findings provide a structured approach to assess divergence in long-term debris evolution, highlighting the critical thresholds of launch activities and the mandatory mitigation compliance levels required to stabilize the LEO environment and prevent a runaway collisional cascade.

This work is performed within the GREEN SPECIES project funded by the European Research Council (ERC) under the European Union’s Horizon Europe research and innovation program (Grant agreement No - 101089265).

Speaker: Luca Di Gregorio (Politecnico di Milano)

Presentazione_DiGregorio2.pdf

14:30 The MOCAT Ecosystem: An Overview of the MIT Orbital Capacity Assessment Tool Suite

The recent surge in commercial space activity in Low-Earth Orbit (LEO) has led to increased interest in understanding the complex dynamics of space debris, estimating their long-term evolution, and defining an upper limit on sustainable satellite activity. The open-source MIT Orbital Capacity Assessment Tool (MOCAT) tackles this challenge through an integrated suite of models that offer varying levels of fidelity and computational efficiency.

MOCAT Monte Carlo (MOCAT-MC) represents the high-fidelity model that propagates individual space objects (SOs), models their interactions in terms of collisions and explosions, and is computationally efficient to predict millions of SOs over a 200-year period. MOCAT-MC has been validated against the Inter-Agency Space Debris Coordination Committee (IADC) study, which in 2013 had several space agencies use their MC tools to compare the performance for a strict future scenario.

MOCAT Source-Sink Evolutionary Model (MOCAT-SSEM) is the low- to medium-fidelity model that makes use of differential equations for the representation and evolution of the number of SOs, evolving distributions over orbital shells and species rather than propagating individual objects. The reduction of the fidelity of the model leads to large speed-ups with century scale simulations running in seconds. The original SSEM adopts two simplifying assumptions: all objects are on circular orbits, and fragments generated by collisions are retained within the altitude shell in which the collision occurs. Recent developments include debris fragment spreading, where fragment ejection velocities are used to redistribute collision fragments across neighboring altitude shells while retaining a circular orbit assumption, and an elliptical model that introduces explicit semi-major axis and eccentricity bins for the inclusion of elliptical orbits and extending fragment redistribution to operate across both altitude and eccentricity bins. Moreover, MOCAT-SSEM incorporates a feedback proportional-derivative controller and a nonlinear model predictive controller to optimize Active Debris Removal (ADR) subject to a defined cost objective, a constrained nonlinear programming optimization framework to compute the optimal orbital capacity of the low region of LEO, and several Integrated Assessment Models (IAMs) to support techno-economic analysis of debris-mitigation policies and ADR strategies. MOCAT-SSEM has recently undergone a cross-fidelity verification and benchmark-based validation study against MOCAT-MC by using a composite metric.

MOCAT Machine Learning (MOCAT-ML) is a surrogate model of MOCAT-MC with significantly reduced computational cost. By utilizing a Convolutional Gated Recurrent Unit (ConvGRU) architecture, the model captures complex spatiotemporal patterns to forecast the evolution of space object density maps. Recent advancements have extended this framework to provide accurate 100-year predictions in seconds, offering a scalable and efficient alternative to traditional physics-based simulators for long-term orbital capacity assessment.

MOCAT Quasi-Deterministic (MOCAT-QD) proposes an alternative to MOCAT-MC: a quasi-deterministic all-vs-all evolutionary model whose variance is greatly reduced, requiring much fewer simulations than traditional Monte Carlo evolutionary models. MOCAT-QD offers solutions that are almost unbiased with respect to the original corresponding all-vs-all simulator, and reduce the variance by a factor of up to 1,500, with computational cost only about 1.5 times larger. MOCAT-QD is augmented to be able to provide not only the mean, but also a user-defined standard deviations from the mean, with a single run.

Together, these open-source multi-fidelity tools establish MOCAT as a comprehensive and versatile framework for characterizing LEO capacity and supporting the implementation of data-driven space sustainability strategies.

Speaker: Dr Giovanni Lavezzi (Massachusetts Institute of Technology)

Workshop_MOCAT_MIT.pptx

14:45 → 15:30 Exercise: “Space debris modelling workshop”

15:30 → 16:00 Coffee Break

16:00 → 17:45 How space debris mitigation can adapt to the space environment?

Covered topics:
- Analysis on how mitigation guideline can adapt to the change in the launch trend and the increase of large constellations.

16:00 GREEN SPECIES: Active control of the space debris population to define optimal mitigation policies to target a sustainable development of space activities

Space assets offer services of social and economic benefit for humankind and enable monitoring the condition of our planet. As recognised by the UN and space agencies, space missions for Earth observation, geolocation, telecommunication, science, and technology contribute to the achievement of the Sustainable Development Goals. As our lives become more and more interconnected thanks to satellites and space is more easily accessible, Space can be seen as the extension of our planet biosphere. As such, long-term sustainability of space activities will be possible only if a change of behaviour is put in place by space faring nations. The growth of space debris is following an exponential trend, which is typical of many other environmental stressors of Earth system trends. Immediate actions are needed to mitigate the increasing risk of collisions and enable the future use of Space as a common.

The GREEN SPECIES project is devising an interdisciplinary framework for the modelling of the space debris population, and the forecast of its evolution. A probabilistic space debris model is proposed for the overall space debris environment. All uncertainties of physical, economic, and political nature are modelled, and the forecast of future launch traffic and compliance to guidelines included via economic approaches. The project incorporates the management of the debris environment through a robust time-delayed controller, applied to the space debris model, described as a complex dynamical system. Ideal feedback control actions will be transformed into policies and guidelines, via quantitative indicators, assessing both the environmental impact and the social and economic benefit of space missions.

Speaker: Camilla Colombo (Politecnico di Milano)

01_Colombo_GREEN_v01.pptx

16:30 A Tiered Approach to Space Debris Mitigation Policy

There are numerous space debris mitigation policy documents around the world, ranging from national and international policy to agency-level policy. In most cases, rules designed to mitigate the impacts of debris are “one-size-fits-all” rules applying to all operators equally. As traffic levels grow and space becomes more congested, current rules may not suffice and will need to be made more stringent. The effects of such rule changes would not impact all operators equally and applying them as such would not be necessary to achieve the desired outcomes. A tiered approach to space debris mitigation policy is presented along with a simple framework for setting tier thresholds that would only require the most stringent rules for those operators that would otherwise contribute the most to space debris risk.

Speaker: Gregory Henning (The Aerospace Corporation)

ADEPT Tiered Policy.pptx

16:45 Development of risk assessment tools at the University of Padova

In recent years, the problem of space debris has reached a critical level, requiring new and continuously updated mitigation tools. It is essential to develop impact risk assessment methodologies supported by accurate physical models, enabling more reliable satellite platform design. At the same time, up-to-date environmental models are crucial to provide realistic, high-resolution risk analyses. Furthermore, the capability to analyze orbital fragmentation events within a few hours is becoming increasingly important in order to better understand failure dynamics and respond promptly to changes in the orbital environment.
In this context, the Space Debris Group of the University of Padova is working in parallel on these three topics. Thanks to a hypervelocity facility, impacts at speeds comparable to orbital velocities can be replicated on advanced materials and complex components. Based on these experiments, the group has developed the Collision Simulation Tool Solver (CSTS), an updated semi-empirical tool for simulating hypervelocity impacts and explosions of orbital objects. The software can be used both during the design phase, to study interactions with different orbital environments and optimize system performance, and after a collision event, to reconstruct the underlying dynamics.
Starting from its outputs, in fact, it is possible to transition from the local reference frame, in which the event occurs, to the orbital reference frame, thereby characterizing how the resulting debris cloud disperses around the Earth. Recent developments also include the evaluation of how spacecraft attitude at the time of impact influences the spatial distribution of the generated fragments.
Finally, the team is developing different debris sensor prototypes, both integrated into satellite platforms currently under development within student projects at the University of Padova (CubeSats and PicoSats) and through the exploration of novel sensing technologies.

Speaker: Stefano Lopresti (CISAS/UniPd)

03_development_lopresti.pptx

17:00 Autonomous collision avoidance algorithms as enablers for space congestion management

Even with the adoption of increasingly more demanding regulations to curb the generation of debris by space missions, both during operations and at end-of-life, the congestion of commercially relevant orbital regions such as LEO is expected to increase due to two main drivers. First, the existing population of debris will continue to pose a threat, and their number can keep increasing through collisional and fragmentation events. Second, the adoption of large constellations as technological solution for certain uses such as broadband internet access increases the number of active objects, clustered in specific regions of space. Therefore, collision avoidance remains a key pillar in space debris mitigation activities.

A promising approach to deal with this growing congestion is autonomous collision avoidance, where the satellite has the capability to plan and design a collision avoidance manoeuvre based on SSA information received from external sources and its own navigation data. However, this requires algorithms that are both robust, so a valid solution is always reached, and algorithmically lightweight, so they can be executed on board.

In this talk, recent advances in impulsive and low-thrust collision avoidance models suitable for autonomous on-board execution are presented. The trade-off between accuracy, optimality, and robustness is discussed, considering also the key feature of being flexible enough to accommodate the main operational constraints. We will also show an overview or recent projects where these models have been used as part of autonomous collision avoidance pipelines, and how this application has driven the development roadmap. The performance of the models will be shown through sample cases, discussing their current limitations and way forward for development.

Speaker: Dr Juan Luis Gonzalo (Universidad Rey Juan Carlos)

Autonomous_COLA_algorithms_for_space_congestion.pdf

17:15 Operational Long Term Assessment of Periodic Satellite Conjunctions

Periodic encounters arise from repeated close approaches between the same pair of objects, driven by their relative orbital geometry, and represent one of the main causes of Conjunction Data Messages. Due to their recurrent nature, these events can generate multiple conjunction notifications over extended time intervals, making their early identification particularly important for long term conjunction monitoring.
This study is conducted within the ESA project “Orbital Neighbourhood Awareness”, funded by the ESA Space Safety Office, developed in collaboration with GMV France, GMV Romania, and Politecnico di Milano, which aims to provide an orbital neighbourhood monitoring tool for predicting potential conjunctions several months in advance. Within this framework, periodic encounters constitute a specific and operationally relevant class of events and are the focus of the present work.
The proposed methodology is based on analytical formulations designed to efficiently process Two Line Element sets of objects within a given orbital region, such as Low Earth Orbit. For a selected primary object, a screening procedure compares it with the surrounding population to identify orbital configurations leading to periodic close approaches. The population is classified into active satellites and inactive objects. For active satellites, an orbit maintenance assumption constrains the long-term evolution of orbital elements, enabling more reliable estimates of conjunction recurrence. For inactive objects, the framework is complemented by limited orbit propagation to account for secular drift, at the expense of increased computational cost.
For the screened pairs, the model estimates the expected number of encounters within a given time interval with low computational burden. The methodology is validated using Conjunction Data Messages associated with known periodic encounters. Results show good performance over short and medium time horizons, with a gradual degradation for longer predictions due to cumulative perturbations and modelling uncertainties. The approach is less effective in the Geostationary Earth Orbit regime, where station keeping manoeuvres introduce kilometre scale orbital displacements, significantly altering the orbital geometry and dominating the encounter dynamics
An extension of the methodology is introduced to analyse constellation crossing scenarios, accounting for slowly varying semi major axis profiles associated with low thrust manoeuvres, thus enabling the assessment of encounter dynamics during gradual orbit changes. In addition, a complementary framework is proposed to evaluate the impact of new constellation deployments on the orbital corridor of a target satellite, providing insight into the evolution of the local encounter environment.

Speaker: Achraf Mizmizi (Politecnico di Milano)

Presentation Conjunctions v2.pptx

17:30 Space Debris Characterization Through Multiband Photometry

Space debris are an increasing hazard for every kind space activities and a growing source of pollution. To date, research has primarily focused on a quantitative approach, monitoring the number and orbits of debris. However, characterizing individual objects could prove equally valuable — enabling the study of re-entry trajectories, associated risks, and, most importantly, the study of their origin and of the causes of the fragmentation events that generated them.
This presentation will illustrate our research on space debris, presenting the instrumentation available at the Astronomical Observatory of Palermo and at GAL-Hassin observatory in Sicily for the observation and analysis of space debris and showing how multiband photometry can play a crucial role in debris characterization and in determining their origin.

Speaker: Alfredo Biagini (Osservatorio Astronomico di Palermo - OAPA)

Space_Debris_Characterization_Through_Multiband_Photometry.pdf

17:45 → 18:15 Wrap-up on modelling and mitigations

18:30 → 20:30 Opening buffet

Thursday 4 June

09:00 → 10:45 How to assess the impact of space missions onto the space environment?

Covered topics:
- Comparing indices to assess the impact of missions to the space debris environment.

09:30 The impact of large satellite constellations on astronomy

The exponential increase in the population of satellites in Low Earth Orbit is seriously interfering with optical, infrared and radio astronomical observations. The Centre for the Protection of Dark and Quiet Sky, created by the International Astronomical Union in 2022, is actively engaged in discussions with all concerned stakeholders on possible mitigating measures. While the majority of the current LEO population is represented by communication satellite constellations (Starlink, Amazon/Kuiper, Oneweb, Guowang, Qianfan, etc.), other types of constellations are being planned in LEO, MEO and GEO, especially concerning the transmission of space-collected solar light or solar energy to the ground. The interference of the different types of constellations on astronomy will be discussed, along with possible mitigating measures.

Speaker: Piero Benvenuti (International Astronomical Union)

Benvenuti_june_4.pdf

09:45 Real-time health monitoring for reliable satellite disposal

Post Mission Disposal (PMD) success rates remain well below the levels needed to stabilize the debris population, in both LEO and GEO, and below the thresholds now codified in ISO 24113. Historical analysis of unsuccessful disposal attempts reveals a recurring pattern: spacecraft with sufficient propellant and no single catastrophic failure were nonetheless not disposed of successfully. The causes are well documented: operator decisions taken too late, causing the accumulation of minor failures progressively eroding disposal capability without triggering any single alarm, and reliability models that kept returning a green light while actual spacecraft health silently deteriorated.

The conventional approach, assessing disposal readiness against a reliability model frozen at the Critical Design Review (CDR) and updated only upon confirmed failures, is structurally inadequate for this purpose. CDR models assume constant failure rates calibrated to worst-case environmental conditions. They apply those rates uniformly regardless of how the satellite has actually been operated, sometimes overestimating actual risk, and always blind to the gradual wear-out and performance erosion that accumulates across power, thermal, and attitude control subsystems over extended mission lifetimes. Reassessing compliance with a long-term disposal probability threshold against this model can confirm nominal status even for satellites that are a single additional failure away from losing their disposal capability entirely. ISO 24113 has acknowledged these limits by introducing requirements for periodic spacecraft condition monitoring and for specific, mission-evaluated disposal initiation criteria, but practical implementation remains an open challenge, particularly for small satellite operators.

This work presents a conceptual framework for continuous, telemetry-driven spacecraft health monitoring aligned with ESA's approach methodology for in-orbit reliability updating, developed under the ESA-RISE program. While more advanced prognostic methods, e.g. stochastic wear-out models or data-trend analysis, offer greater predictive depth, they require large amounts of historical failure data that are rarely available for small satellite operators. The approach adopted here offers a practical balance: it improves on static CDR models using already-available telemetry, without demanding data volumes or supplier inputs that are not yet accessible, while remaining fully explainable and interpretable.
Component failure rates across critical subsystems (power storage, solar generation, thermal control, and on-board electronics) are dynamically adjusted using real-time telemetry rather than design-phase assumptions. Preliminary application to operational flight data indicates that actual subsystem stress levels frequently differ substantially from CDR predictions, carrying actionable information for disposal planning that static models cannot provide.

We argue that continuously tracking disposal readiness, rather than periodically reassessing it, is a practical and necessary step toward achieving the PMD success rates required for long-term orbital sustainability. We discuss how this approach can be realistically integrated into the operational workflows of small satellite operators within existing regulatory frameworks.

Speaker: Enza Magaudda

EnzaMagaudda.pdf

10:00 Estimation of the Avoidance Manoeuvre Operational Burden Caused by In-Orbit Fragmentation Events

Given the recent increase in space activity, new interest has been brought on understanding the consequences that in-orbit fragmentations can create to the space environment. In addition to the potential collisions that fragments produced in a breakup could have on the operational population of satellites, it is important to evaluate the increment of operational effort caused by a break-up event. This refers to the assessment of an increased number of conjunction alerts and the eventual execution of Collision Avoidance Manoeuvres (CAMs). Connecting the burden of CAM to possible fragmentation event can provide a quantitative link between short term space traffic management and long-term space sustainability.

Previous works have introduced methods for debris cloud modelling through a continuum-based approach. The STARLING 2.0 suite, developed at Politecnico di Milano, is an example of this. This tool propagates the space distribution of a debris cloud through the method of characteristics (MOC) and then uses the kinetic gas theory analogy, to estimate the impacts of the debris with other targets.

In this research, this technique is employed for propagating and estimating the conjunctions between trackable fragments and active satellites. To do this, the minimum size of modelled fragments is elevated from 1 cm to 10 cm, capturing only fragments that would be trackable. Additionally, an enlarged cross-sectional area for the evaluated targets is taken. With this, instead of detecting the collisions caused by the fragments, an estimation of close encounters is yielded. The selection of the enlarged cross-sectional area is done by defining a threshold on the miss distance. Considerations such as the time delay in the object cataloguing process after a fragmentation, and the fraction of undetected fragments are included in this method. For validation, the Cosmos-1408 fragmentation is included as a test case. The resulting number of conjunctions is used to estimate a monetary operational cost incurred by operators due to the fragmentation. This value is estimated based on an average labour hour cost and the estimated time that operators take to assess conjunction alerts. The proposed methodology, is finally used to build pre-computed consequence maps, showing the different operational consequences that breakups at different orbital bins would cause. This research is part of the TELCOLA project “T509-801SD debris impact assessment to improve collision avoidance metric for telecommunication spacecraft” funded by the European Space Agency Space Safety Programme.

Speaker: Juan Felipe Cabrera (Politecnico di Milano)

04_Presentation_JC.pptx

10:15 Activities on space sustainability within the CNES Ecosystem

CNES, the French space agency, is actively involved in space sustainability efforts, for example through the development and use of environmental indices. Its unique position—as a regulator (through the French Space Operation Act), an operator (notably as the provider of the CAESAR collision avoidance service for EUSST), and a research actor—enables it to address space sustainability from multiple complementary perspectives. This presentation highlights CNES’s activities in the field of space sustainability and environmental indices, as well as how its dual role as both operator and regulator shapes their design and implementation.

Speaker: Francois Vinet (CNES)

Francois_VINET.pptx

10:30 COLLISION AVOIDANCE DECISION MAKING BASED ON RISK AND CONSEQUENCE METRICS

The growth of large constellations and the increasing reliance on multiple SSA providers are pushing current conjunction assessment (CA) and collision avoidance (COLA) practices to their limits. In operational CA, decision criteria are still largely driven by geometrical and/or a probability of collision (PoC) thresholds, while neglecting the environmental and economic consequences of a potential collision. Moreover, current practices struggle when several high-risk encounters must be managed concurrently, highlighting the need for robust event-prioritization strategies.
Within the ESA activity TELCOLA, a decision-support framework that couples refined collision risk metrics with quantitative consequence indicators is currently being developed within the ARCADE (Assessment of Risk and Consequences for Avoidance Decision Endorsement) prototype software.
On the risk side, ARCADE provides a suite of refined metrics, including depth of intrusion, scaled and maximum collision probability estimates and risk and dilution predictions, in addition to classical collision risk metrics.
On the consequence side, ARCADE incorporates fragmentation consequence maps to evaluate both short-term (traffic management) and long-term (space sustainability) effects. Additional operational indicators, such as orbital slot value, the expected number of induced manoeuvres and associated operational costs on third-party operators, are also considered. These metrics are integrated through a utility-based decision framework inspired by general decision and risk theories, where the selection among possible actions (“CAM”, “No CAM”, or “Wait”) is driven by the maximization of expected utility.
This work focuses on the aggregation methodology implemented within the CAM decision logic and on its application to event prioritization in operational environments characterized by multiple concurrent conjunctions. Combining risk and consequence metrics enables more transparent, actionable, and sustainability-oriented collision avoidance decisions for satellite operators.

Speakers: Camilla Colombo (Politecnico di Milano), Diego Ramírez Rodríguez, Eduardo Maria Polli (Politecnico di MIlano), Juan Felipe Cabrera (Politecnico di Milano)

2026_SCAW_Collision_Avoidance_Decision_Making_Based_on_Risk_and_Consequence_Metrics.pptx

10:45 → 11:15 Coffee Break

11:15 → 12:30 How to measure the space capacity?

Covered topics:
- Measuring and defining thresholds for the overall space carrying capacity.

11:15 SDM 6.0: A Modernized Evolutionary Framework for Assessing Long-Term Orbital Capacity and Mitigation Strategies

The rapid expansion of space activities, driven by the deployment of megaconstellations and the diversification of orbital operations, poses an unprecedented challenge to the finite carrying capacity of the near-Earth environment. To effectively manage this delicate ecosystem and establish globally accepted thresholds, robust and adaptable long-term evolutionary models are essential. This study introduces SDM 6.0, a comprehensive modernization of the well-established Space Debris Mitigation (SDM) model, designed to meet the evolving demands of contemporary space traffic management and capacity assessment.
To address the growing complexity of the space environment, the core architecture of SDM has been fundamentally refactored. By implementing scalable, modern data structures and an extensible computational framework, SDM 6.0 offers significantly enhanced adaptability and performance. This software modernization allows for a more flexible and future-proof representation of dynamic orbital operations, enabling researchers to better characterize complex multidimensional space environments.
Utilizing this upgraded framework, we present a comprehensive 50-year evolutionary simulation study, serving both as a rigorous validation of the new architecture and as an exploratory scenario analysis. The simulations are specifically designed to evaluate the long-term impact of critical mitigation and remediation strategies on spatial density and orbital capacity. Key focus areas include evaluating, e.g., variations in post-mission disposal (de-orbit) strategies, the long-term environmental footprint of large-scale constellation planning, the integration of Active Debris Removal (ADR) technologies, and the effectiveness of enhanced collision avoidance capabilities.
Furthermore, to quantitatively assess the environmental impact of these simulated scenarios, the study couples SDM 6.0 outputs with the Criticality of Spacecraft Index (CSI). By translating complex orbital population dynamics into standardized capacity metrics, we aim to provide a more intuitive evaluation of different space management strategies. Ultimately, this work seeks to offer actionable insights to support international dialogues on defining sustainable orbital thresholds and formulating long-term space environment management policies.

Speaker: Xiaoran Yan (IFAC-CNR)

01_SDM6_Yan.pptx

11:30 Advances in Modelling Space Capacity with THEMIS

The THEMIS approach allows modelling consumed space capacity. In the probability-based approach, environmental impact from all major objects (spacecraft, rocket bodies and derelicts) is aggregated. This gives a single value for the consumed space capacity. It can be evaluated for the current space environment and future predictions. Different scenarios or individual events like fragmentations can be evaluated to compare their consumed capacity. This approach cannot yet find an upper limit of the available capacity. Providing only one singular value also makes it difficult to evaluate the effect on individual objects. The evaluation of impacts of tens of thousands of objects is also computationally expensive. Finally, only the direct impact of a fragmentation is evaluated in THEMIS. Fragmentations caused by previous fragmentations are not counted when estimating the environmental impact. This work aims at improving the THEMIS model in these areas to improve interpretability of results, computational speed, modelling accuracy and, eventually, find an upper limit for Capacity.
To improve the interpretability of results, the effect term of the THEMIS space debris index is changed from a single value, average for the entire orbital region, to provide a vector giving the effect for every populated orbital bin ($\vec{EI}$). From this the probability of an impact on individual satellites or their expected number of collision avoidance manoeuvres (CAM) can be derived. This can help set an upper limit based on the maximum acceptable loss rate of satellites or maximum feasible CAM rates. While the current THEMIS approach evaluates the environmental impact for individual satellites, using representative objects like it is already done for the effect term can speed up computation. For each altitude and inclination bin, an average object is defined through mass, area and CAM capabilities. This allows the definition of a Matrix describing the effect of the fragmentation of a representative object on each other representative object $\textbf{e}$. Extracting also collision probabilities for the average objects from MASTER ($\vec{p_c}$) allows a fully matrix-based evaluation of the consumed capacity via:
$\vec{EI} = \textbf{e}\cdot\vec{p_c}$
Finally, to capture the effect of secondary, induced fragmentations, an expression is found using the Matrix of expected number of catastrophic collisions caused by the fragmentation of a representative object $\textbf{E}$:
$\vec{EI} = \textbf{e} \cdot (\textbf{I} - \textbf{E})^{-1} \cdot \vec{p_c}$
This formulation allows to find the point where each fragmentation would cause more than one secondary fragmentation leading to unmitigated growth. Some preliminary results of this approach are presented. This work is performed as part of the ESA Contract No. 4000145375/24/D/BL funded by the ESA safety office.

Speaker: Daniel Lück (Politecnico di Milano)

02_advances_lueck.pptx

11:45 The Criticality of Orbital Regions: from Local Effects to the Global Health of the Space Environment

This paper presents a network-theoretic approach to the analysis of the global health of the space environment. We will first introduce an index measuring the criticality of different orbital regions to the status of the environment.
We will then derive a definition of orbital carrying capacity from the criticality score and relate the region criticality to more common object level risk metrics. The same criticality score will then be used to derive a characteristic time at which effects propagate through the environment.

We will argue that the proposed approach leads to a physically significant and actionable quantification of the status of the environment.
The proposed network-theoretic approach can be shown to provide useful information at both regional and
global level because it captures the inter-dependencies between local events and global evolution. Furthermore, it can differentiate between localised and global-scale widespread growth in space object populations. Simulation results suggest that the proposed criticality score effectively captures the impact of individual missions on the space environment.

Speaker: Prof. Massimiliano Vasile (University of Strathclyde)

03_the_vasile.pdf

12:00 ADEPT as an Analysis Framework for Space Environment Sustainability Indices

As large constellation launch traffic continues to grow and Low Earth Orbit (LEO) becomes more crowded the ability to quantify the effect that space traffic has on operations sustainability in that environment is becoming more important. A variety of indices have been developed or are currently under development to address this problem, each tailored to a specific analytical purpose and conceptual framework. The Aerospace Debris Environment Projection Tool (ADEPT) evaluates the efficacy of different indices by implementing the algorithms to compute them for various scenarios, simulating those scenarios over long time scales, and analyzing the correlation of the indices to resulting metrics like debris object growth, collision rates, and the impact on operations at different orbital altitudes. ADEPT’s ability to quickly compare hundreds or thousands of scenarios enables the demonstration of the correlation of sustainability indices to space environment outcomes. Work is ongoing to improve the process to position ADEPT as a true “testbed”, and to gather available indices from across the international community to implement and evaluate.

Speaker: Gregory Henning (The Aerospace Corporation)

ADEPT Index Framework.pptx

12:15 Fragmentation, Loss-of-control And Other Acute Space-based Hazards Score - FLASH - For Fragmentation Hazard Oriented Ground Based Observations

The expansion of human activity in space has resulted in a substantial increase in the number of objects traveling at high velocities in low Earth orbit. These objects are susceptible to mutual collisions, necessitating continuous and precise monitoring. The resulting cascade of debris from successive collisions, commonly referred to as the
Kessler syndrome, poses a significant long-term threat to the sustainability of orbital operations. To mitigate this risk, space agencies have established debris-mitigation guidelines, including passivation requirements and active debris-removal initiatives. At the level of ground-based Space Situational Awareness (SSA) operations, a critical objective is the development of comprehensive hazard knowledge for all monitored objects. Evaluating probabilities of fragmentation and associated risks is essential for enabling observers to prioritize and optimize observation campaigns in accordance with the threat levels posed by individual objects.

For similar purposes, indices such as the Environmental Consequences of Orbital Break-Ups (ECOB) or Criticality of Spacecraft Index (CSI) have already been created by different organizations. However, they mostly prioritize active debris removal based primarily on intrinsic object properties or collision rather than on explosion behavior. Few of them rely on private databases, long-term space environmental projections, or
parameters that are infrequently updated or not publicly accessible, making their use unpractical. These limitations underscore the need for a more practical index whose computation incorporates a broader assessment of fragmentation risk using regularly updated, publicly available data.

The Fragmentation, Loss-of-control, and other Acute Space-based Hazards (FLASH) Score was therefore developed as a hazard rating system for all tracked objects, intended to support day-to-day observation prioritization within SSA operations by identifying the most hazardous objects in orbit. In this framework, risk is defined as the product of event probability and the associated consequences for the space environment. Building on this premise, a central focus of the work is the characterization of self-fragmentation risk (i.e., explosions rather than collisions).

FLASH can be broadly decomposed into four components: 1) self-explosion
probability, estimated through statistical reliability methods; 2) collision probability, derived from formulations based on the kinetic theory of gases applied to orbital dynamics; 3) fragmentation consequences, quantified using the NASA Standard Breakup Model to estimate the number of generated fragments and their potential to induce catastrophic events; 4) an object-centric component that captures intrinsic properties independently of any fragmentation scenario.

The proposed solution exhibited 28-40% object-level similarity with existing indices in the top 50 rankings. However, the correspondence lies primarily in object categories rather than specific objects, as rankings within categories vary with orbital activity and location. The explosion component proved effective, with many top 200 objects belonging to categories documented in Database and Information System Characterizing Objects in Space (DISCOS) fragmentation. FLASH rankings show strong spatial agreement with Massive Collision Monitoring Activity (MCMA) cluster. While most indices prioritize rocket bodies (60-89% of 50 rankings), FLASH allocates only 49% of its top 200 to rocket bodies, thereby allowing greater diversity in object types.

Speaker: Zoé Medaric

05_fragmentation_medaric.pptx

12:30 → 14:00 Lunch

14:00 → 14:45 Exercise: “Space capacity workshop”

14:00 Review of parameters influencing Orbital Carrying Capacity

The concept of an orbital carrying capacity was introduced relatively recently. It works under the assumption that, like other ecosystems, space in orbit around Earth is a limited resource. Efforts have been made to evaluate the total available space capacity and the share of capacity consumed both by current missions and for different future scenarios. This way the maximum number of missions that could be supported can be estimated and potentially unsustainable scenarios identified. Currently, there is no clear consensus on how these estimations should be made. Several different approaches have been proposed so far. They can be broadly classified in source-sink models, proxy value-based approaches, and risk-based approaches. Those differ significantly in the way the capacity calculation is performed.
Instead of evaluating these approaches directly, this work evaluates the different input parameters that should go into the estimation of the capacity. Parameters are split into mission based, like satellite properties and orbit, Infrastructure based, like tracking and cataloguing performance, and environment based, like space debris background or atmospheric density. For each parameter, the mechanism through which it influences the capacity is discussed. Interactions between different parameters are also evaluated. The sensitivity of the capacity to these parameters is estimated based on the THEMIS approach. This work could help identify parameters that might lack modelling in certain approaches but also understand if different approaches would be equivalent if they model the same parameters with the same or at least similar sensitivities. This work is performed as part of the ESA Contract No. 4000145375/24/D/BL funded by the ESA safety office.

Speaker: Daniel Lück (Politecnico di Milano)

01_review_lueck.pptx

14:45 → 16:00 Exercise: "How technical mitigation actions can be translated in policies?"

14:45 Scenario-based modeling of debris mitigation strategies to support policy and operator decisions

The scale and cadence of space activities today are expected to have long-lasting impacts on the Low Earth Orbit environment. Debris evolution models exist, but there remains a gap between environmental modelling outputs and how they translate to guiding and informing operational and regulatory decision-making. This work, developed as part of the ERC project GREEN SPECIES in a collaboration between Politecnico di Milano and Secure World foundation, addresses this gap by linking orbital environment evolution to decision-relevant objectives that support evidence-based policymaking and operator decision-making.

We leverage an integrated simulation framework to evaluate mitigation strategies as controllable policy levers. A simplified one-dimensional density-based debris evolution model is used to capture the dynamics of active satellites, inactive objects, and fragments across discretised altitude shells. The debris model is combined with a state-dependent linear feedback controller that dynamically optimises debris mitigation measures to achieve prescribed space sustainability targets.

This paper investigates the calibration of Post-Mission Disposal (PMD) measures under different operating scenarios, which are defined by varying assumptions around launch traffic and PMD requirements. For each scenario, the model is used to identify the combination and level of mitigation actions required to achieve defined targets in terms of the cumulative collision probabilities across satellite mission profiles. The aim is to connect technical modelling outputs with practical policy and operational decision-making contexts, and to integrate stakeholder input into model- and evidence-based decision-making to support space sustainability goals.

Speakers: Martina Rusconi (Politecnico di Milano), Qian Shi (Secure World Foundation)

Space capacity workshop - Presentation.pptx

16:00 → 16:30 Coffee Break

16:30 → 18:00 Space debris mitigation policies

Covered topics:
- Policy studies on space debris mitigations and applicability of capacity management strategies.

16:30 Business-as-Usual and Orbital Debris Path

This paper develops a dynamic general equilibrium integrated assessment model of the space economy that explicitly links economic activity on Earth with satellite operations in orbit. The model incorporates a space environmental externality in the form of orbital debris, which accumulates endogenously through launches, on-orbit operations, and collisions, and generates damages to space capital. We characterize the decentralized competitive equilibrium in which economic agents do not internalize the social cost of debris accumulation, corresponding to a business-as-usual (laissez-faire) outcome, and contrast it with the socially optimal allocation chosen by a central planner who internalizes the debris externality. Methodologically, the paper proposes a fixed-point algorithm to compute decentralized equilibria in dynamic growth models with environmental externalities. The decentralized equilibrium is obtained by iterating on the debris stock trajectory while repeatedly solving a nonlinear programming problem in which agents take debris-related damages as exogenous. The framework allows for a quantitative comparison between decentralized and socially optimal outcomes in terms of welfare, orbital environmental quality, and the accumulation of both terrestrial and space capital. The results highlight the magnitude of the inefficiencies generated by unregulated space activity and provide a tractable platform for evaluating policies aimed at preserving the long-run sustainability of the orbital environment.

Speaker: José Luis Torres Chacón (Universidad de Málaga)

01_Business_Torres.pdf

16:45 Space Debris Mitigation Policy in the Context of Deployment of Space Data Centers

This presentation examines the evolving policy and legal requirements associated with the emergence of a new category of space activity, namely space-based data centers designed to support artificial intelligence operations. Initiatives such as Google’s Project Suncatcher, Microsoft Azure Space, Blue Origin’s Orbital Data Centre, Space Exploration Holdings illustrate an accelerating trend toward the deployment of data-intensive infrastructures in orbit, prompting both intensified congestion and a qualitative rethinking of space governance.
Building on the analysis of early-stage projects, the presentation identifies several key dimensions of environmental impact. These include the exponential increase in the number of satellites, adding to an already dense orbital environment, the concentration of such infrastructures in heavily utilized low Earth orbit (LEO) regions, and the emission of heat in near-Earth space. Additional concerns arise from the atmospheric and terrestrial effects of satellite re-entry, including evidence that rocket emissions and re-entry processes may contribute to ozone layer degradation.
The study adopts an interdisciplinary legal approach, combining the analysis of international space law instruments with relevant opinion of the International Court of Justice to assess the broader normative framework governing space activity. It argues that there is a solid legal basis for regulatory responses to these emerging activities, while emphasizing the need to balance environmental safeguards with the avoidance of undue constraints on commercial innovation.
The presentation ultimately aims to contribute to the development of adaptive governance models capable of addressing the environmental externalities of space-based data infrastructures within a rapidly evolving technological landscape.

Speaker: Anna HUROVA (Space Chair, ENS-PSL)

02_Space_Hurova.pptx

17:00 From Policy Assumption to Practical Implementation: Reassessing PMD Policy through Economic Viability, Technology Readiness, and Risk Relevance, with an Illustrative Industry Case

Post-mission disposal (PMD) is increasingly embedded in the policy framework for space debris mitigation. However, the growing expectation that missions should dispose of space objects at end of life does not automatically mean that disposal solutions are practicable at scale. As commercial space activity expands rapidly, the key policy question is no longer only whether PMD is desirable, but whether current PMD policy assumptions are sufficiently grounded in implementation reality. This is particularly important because launch vehicle upper stages and satellites are increasingly expected to undergo PMD at end of life, making the availability of practicable PMD methods a matter of growing importance.

This presentation argues that space debris mitigation policies should be assessed not only in terms of regulatory intent, but also in terms of practical applicability introducing PMD. Rather than relying solely on government spending to advance debris mitigation, it is increasingly important to establish practicable approaches that commercial operators can adopt voluntarily. As commercial missions continue to grow, three considerations are becoming increasingly important to whether PMD policy can work in practice: (i) economic viability, (ii) technology readiness, and (iii) risk relevance. A disposal approach may be conceptually sound, but if it is too burdensome to integrate, too costly to adopt widely, insufficiently mature for near-term deployment, or insufficiently connected to the actual risk environment faced by operators, its practical policy effect may remain limited. If PMD is to function as an effective mitigation measure rather than a formal expectation, policy discussions should place greater emphasis on mission-level implementation conditions, including mass and power constraints, integration simplicity, operational robustness, business-case viability, and practical implications for operator risk.

More specifically, this presentation will show that (i) economic viability is relevant not only because passive PMD can reduce propellant reservation requirements, but also because it may create additional operational lifetime and business opportunity, thereby giving commercial operators a positive incentive to adopt PMD voluntarily. It will further show that (ii) technology readiness should be understood not only in terms of formal mission timing, but also in light of actual engineering progress, test evidence, deployability, and the role of passive PMD as a complementary backup to active disposal approaches. It will also argue that (iii) risk relevance matters not only for compliance-related and collision-related considerations, but also for space insurance, suggesting that risk profile effects and economic viability should be considered together. Finally, through an illustrative industry case, this presentation will show how ongoing efforts by BULL, one of the JAXA Partner Startups and a 3-year-old Japan-originated company that established a European subsidiary in 2025, to deploy passive PMD in actual missions can help bridge the gap between policy ambition and practical implementation.

This presentation therefore proposes that PMD policy should explicitly incorporate economic viability, technology readiness, and risk relevance when evaluating the real applicability of debris mitigation measures. In an environment of rapidly increasing commercial space activity, practicable and scalable PMD solutions will be essential if policy expectations are to translate into meaningful sustainability outcomes.

Speakers: Mr Yasuhito UTO (BULL Co., Ltd.), Mr Masakazu KOYANAGI (BULL SAS)

2026-06-04_BULL_From_Policy_Assumption_to_Practical_Implementation_sent.pptx

17:15 Space Debris Mitigation Policies for Large Constellations: Licensing and Continuing Supervision as Tools of Space Capacity Management

Large-constellation deployment has outgrown a debris-mitigation framework designed for a less congested orbital environment. Standards developed for individual missions and comparatively slow replenishment cycles are under pressure from continuous launch activity, rapid satellite replacement, and disposal practices whose cumulative effects span operators and accumulate over time. The regulatory question is not simply how to secure post-mission disposal in the narrow sense, but whether existing mitigation standards can still preserve long-term orbital usability amid conditions of sustained traffic growth.

At the centre of the issue lies a mismatch between regulatory form and operational reality. Large constellations operate as integrated systems characterised by continual renewal, persistent conjunction exposure, and repeated disposal events. Treating them as discrete missions obscures the aggregate effects of scale, replacement tempo, disposal reliability, and interaction with an increasingly crowded space environment. Formal compliance with existing mitigation guidelines does not, by itself, resolve those cumulative risks.

The paper addresses this problem through a doctrinal and policy analysis of national licensing practice, continuing supervision under Article VI of the Outer Space Treaty, and the emerging shift from debris mitigation toward broader space-capacity governance. It proposes three regulatory adjustments: licensing criteria calibrated to constellation-scale operations rather than single-satellite missions; supervisory review linked to in-orbit performance and disposal outcomes; and accountability mechanisms that evaluate environmental effect in operational terms rather than by reference to design-stage commitments alone.

No wholly new legal order is required. What is required is a stricter and more operational use of existing authorisation and supervision tools, so that debris-mitigation policy remains credible in an orbital environment it was not designed to govern.

Speaker: Raoul Cardellini Leipertz (School of Advanced Defence Studies (CASD-SSU))

04_Space_Cardellini.pptx

17:45 Fostering Space Sustainability: Interdisciplinary Frameworks for Policy and Investment

In 2023, the EPFL Space Center launched the Sustainable Space Hub to pioneer and steward Swiss space sustainability. By fostering interdisciplinary collaborations and building expertise between academic institutions, international organizations, and private actors, the Hub aims to advance the field through constructive dialogue.

This abstract contribution will focus on the workshop discussion point regarding the constructive and interdisciplinary framework to advance the discussion on space sustainability and space capacity management, including from a legal and economic perspective.

During the last two years, the Hub has conducted projects to enhance dialogue between the scientific community, international organizations, and private investors. First, funded by the Geneva Science-Policy Interface, a project explored policy-making challenges at the International Telecommunication Union (ITU). We will present the outcomes and policy recommendations from this work.

Second, addressing economic incentives, a student group performed a qualitative and quantitative analysis on how sustainability considerations influence investment decisions. Utilizing the Environment-Vulnerability-Decision-Technology (EVDT) Framework, this research was awarded the Clearspace Prize.

This presentation will discuss the frameworks resulting from these projects and showcase potential ways to apply the generated knowledge to promote sustainable behavior and improve space capacity management.

Speaker: Emmanuelle David (EPFL)

EPFL_Space_CapacityManagement.pptx

18:00 → 18:30 Wrap-up on space capacity and integration with space traffic management

19:30 → 21:00 Dinner (upon registration)

Friday 5 June

09:00 → 11:00 Space debris and space capacity measures in Europe and international cooperation

09:00 From Chicago to Orbit: Can Space Learn to Fly Together? The 1944 Chicago Convention and the Future Governance of Outer Space

The rapid expansion of space activities, the proliferation of mega-constellations and the growing congestion of Earth orbit are generating unprecedented governance challenges for the long-term sustainability of outer space. The presentation explores a historical parallel between today’s orbital environment and the evolution of international civil aviation in the mid-twentieth century. In 1944, the Chicago Convention established the institutional and regulatory foundations that enabled aviation to evolve into a safe, interoperable and globally coordinated system through the creation of ICAO. Drawing on this precedent, the presentation examines whether similar governance principles could support the future management of outer space activities. Particular attention is devoted to Space Traffic Management (STM), capacity allocation, orbital sustainability and the need for internationally shared operational standards. The talk argues that the sustainability of space activities will depend not only on technological innovation, but also on the timely development of cooperative governance mechanisms capable of balancing commercial growth, strategic competition and the collective interest of preserving the orbital environment for future generations.

Speaker: Giuseppe Sala (Politecnico di Milano)

01_from_sala.pptx

09:15 A European perspective on the legal management of space sustainability: opportunities and Challenges

The proposed EU Space Act, introduced by the European Commission on June 2025, aims to establish a regulatory framework for space activities within the European Union. Anchored in Article 114 TFEU, the regulation seeks to strengthen the internal market by creating a predictable, competitive, and innovation-friendly environment for space operators. It responds to increasing fragmentation across national legislations, the rapid growth of space traffic, and the environmental impact of space activities, while also reinforcing existing European frameworks addressing cybersecurity.

This presentation will first provide an overview and critical analysis of the proposed EU Space Act, focusing on its rationale, structure, and expected implications for the European space sector, as well as its effects on third-country operators.

It will then analyse the core requirements under the three pillars of safety, resilience, and sustainability, highlighting their interaction with existing EU legislation. The principle of proportionality, particularly regarding SMEs and low-risk missions, will also be addressed.

Finally, the presentation will discuss key challenges, gaps, and open questions, including competitiveness, regulatory burden, and the need for complementary industrial policies, before concluding with an assessment of the current status of the draft and next steps.

Speaker: Giulia Pavesi

02_aeuropean_pavesi.pdf

09:30 The joint Call of the Science Academies on the G7 Governments to Manage Large Satellite Constellations

Prior to the G7 Summit of Heads of State and Government, the science
academies of the G7 countries (Canada, France, Germany, Italy, Japan, the
United Kingdom and the United States) met in Paris on May 18 and 19, 2026
for Science 7 (S7). These S7 meetings are designed to inform international
policy decisions with available scientific knowledge. On this occasion, a
joint statement on large satellite constellations was presented by the G7
academies. The present lecture will first summarize the main questions
discussed in this statement, including the pace of evolution of the field,
the promises of these constellations, and the multidisciplinary nature of
the induced risks. It will then review the recommendations jointly made to
the G7 Governments.

Speaker: François Baccelli (Académie des Sciences)

03_thejoint_baccelli.pdf

11:00 → 11:30 Coffee Break

11:30 → 13:00 Space capacity management

11:30 Integration of orbital environmental impacts within the EU Environmental Footprint framework for space: first methodological developments and outlook

Life Cycle Assessment (LCA) is emerging as a key tool to support eco-design and sustainability assessment in the space sector. However, current practices remain fragmented and often limited to upstream phases, with insufficient consideration of in-orbit operations and end-of-life impacts. This gap hinders comparability across studies and prevents a comprehensive evaluation of the environmental footprint of space activities.

The development of Product Environmental Footprint Category Rules for space systems (PEFCR4Space) seek to harmonise LCA practices across the sector. By providing common methodological requirements, system boundaries, and impact assessment approaches, PEFCR4Space aims to ensure consistency, transparency, and comparability of environmental assessments for space missions.

This contribution explores how to extend the PEFCR4Space framework to better integrate in-orbit life cycle stages. It focuses on how concepts such as space capacity and state of the art debris-related indicators can be used to reflect the use and degradation of the orbital environment as a finite resource.

The alignment between current development in the field and the PEFCR4Space methodology is addressed by identifying relevant impact pathways, defining appropriate inventory data, and deriving potential characterisation models in compliance with the Environmental Footprint framework.

This approach supports a shift from partial assessments to a full life cycle perspective, covering all phases of space activities. By bridging environmental footprint methods and space sustainability metrics, this work supports the transition towards more robust, comparable, and policy-relevant environmental footprint assessments for the space sector.

Speaker: Dr Thibaut MAURY-MICOLIER (DEFIS - European Commission)

01_integration_maury.pptx

12:00 Extended capabilities of the THEMIS 2.0 for Tracking the Health of the Environment and Missions in Space and interactions with satellite operators

Space debris indicators are powerful tools for the quantitative evaluation of the environmental impact of space missions towards space debris and the effectiveness of space debris mitigation adoptions. This work presents the advancements of the THEMIS 2.0 software for “Tracking the Health of the Environment and Missions in Space” within the project S2-SD-02 - Extended Methods for Space Debris Consequence and Space Capacity Analyses lead by Politecnico di Milano, in partnership with GMV UK, funded by the ESA Space Safety Programme.
The impact of a space mission is measured in terms of risk that the undeliberate fragmentation of such mission might cause on the overall active spacecraft population. Such formulation is thought to give an estimation of the increased operational effort that all spacecraft operation will have to sustain in case an object fragments in another orbital bin. The THEMIS debris indicator can be then used for evaluating possible mission design options in terms of orbit selection, and spacecraft characteristics. When the THEMIS index of each active object in the population of active satellites is aggregated, it is used as a measure of the overall space carrying capacity. This metric can be exploited to compare various future scenarios of the evolution of the space environment and evaluate the risk of operating in a specific orbital slot.
This work presents the extended capabilities of the THEMIS 2.0 project such as improved PMD modelling, improved constellation design, more precise mapping of the trackability of small debris fragments, possibility to evaluate the risk effect over different time frames etc.
The frontend of the software was opened to the space community of space operators, manufacturer, regulators and space debris experts: 20 spacecraft operator, space debris experts and regulators have been involved in using the software, performing some guided exercises and asked to provide feedback in their use and their applicability to preliminary mission design, space safety operations and end-of-life disposal design. The interaction with the end-used of the tools will be shown to demonstrate its applicability to a sustainable mission design and the evaluation of mitigation guidelines.

Speakers: Andrea Muciaccia (Politecnico di Milano), Mr Diego Ramirez (GMV Spain)

Template_DAER_draft_v1 1.pptx

12:15 A Performance-Based Orbital Slotting Framework for Long-Term Space Sustainability

In the coming years, the Near-Earth orbital environment is expected to undergo a radical transformation, driven by the growing interest in space, the proliferation of mega constellations and the increasing accessibility of space through reusable launch vehicles. As the density of Resident Space Objects (RSOs) rises, the risk of orbital overexploitation and the increasing number of conjunction events threaten the long-term sustainability of space activities. In this context, Space Traffic Management (STM) needs to integrate active and passive coordination. Currently, the problem of space environment congestion is addressed through active coordination among all the operators, who manually handle conjunctions. But this approach can become unsustainable and ineffective. An alternative and scalable method is based on orbital coordination which enables the use of designated slots, optimizing orbital capacity, and minimizing the risk of conjunction and the operational burden associated with coordinating collision avoidance maneuvers. While literature has extensively explored orbital slotting techniques, such as 2D Lattice Flower Constellations for intra-shell coordination and frozen orbits for inter-shell orbital slotting, these models often rely on the theoretical minimum separation distance among satellites. However, the effectiveness of any slotting architecture is strictly bound by the operational capabilities of the satellites (control, measurement, and communication) and the STM tracking and surveillance architecture. In this context, the concept of Required Navigation Performance (RNP), used in Air Traffic Management (ATM), can be extended to STM. By establishing a quantitative link between RNP and orbital slot size, performance-based containment volumes are defined to dictate safe operational boundaries. The spaceborne RNP architecture is governed by two primary factors: the satellite's control capability to maintain a nominal trajectory and the tracking and navigation uncertainty. The proposed RNP framework is classified into three progressive levels of orbital coordination, ranging from basic orbital shell maintenance to full nominal trajectory adherence. A preliminary analysis of required station-keeping and tracking performance across these varying degrees of coordination identifies the critical aspects affecting the orbital slots size. Crucially, investigations into tracking uncertainty reveal that the rapid divergence of in-track errors represents the primary bottleneck for high-density intra-shell coordination, requiring highly accurate sensors and high-frequency measurement updates.
This framework represents a paradigm shift from static geometric allocations to dynamic, performance-based orbital slots. It provides a standardized methodology for operators and STM authorities to systematically determine the minimum slot size a satellite can maintain based on its performance, thereby identifying which assets are eligible for operation in high-density orbital shells. While serving as a tool for orbital coordination, this RNP formulation concurrently establishes the groundwork for future comprehensive studies aimed at directly mapping navigation performance to maximum attainable orbital capacity, which will provide a quantitative foundation for future STM regulations.

Speaker: Pietro Russo (Università degli Studi di Napoli Federico II)

SpaceCapacityWorkshop_PR_UNINA_RNP.pptx

12:30 National Registration as a Tool for Space Sustainability: Lessons from the Philippines

This paper examines the fundamental obligations of authorization and continuing supervision under Article VI of the Outer Space Treaty, viewed through the lens of an emerging space nation. As new actors enter the space domain, distinguishing these two functions is critical for maintaining State responsibility and supporting sustainable space activities. Authorization functions as a prospective regulatory "gatekeeper," while supervision is a dynamic, ongoing obligation ensuring compliance with international safety and sustainability standards.

Using the Philippine experience as a case study, the paper highlights the challenges of supervising space activities that often involve cooperative development and foreign launch services. In this context, the National Registry is more than an administrative list: it is a vital tool for transparency, traceability, and asserting a nation’s role in global orbital capacity management.

By framing these concepts within the discourse on space sustainability, the paper demonstrates how robust domestic legal mechanisms enable emerging nations to participate responsibly in the shared space environment and contribute to the equitable allocation of orbital capacity.

Speaker: christian villanueva (private practitioner)

CHRISTIAN VILLANUEVA.pdf

12:45 Long-term environmental impact mitigation strategies for transatlantic launcher transport

Transatlantic transport constitutes a significant environmental hotspot in the life cycle of launch vehicles. This study evaluates key mitigation strategies for MaiaSpace's logistics operations between Le Havre (Metropolitan France) and Kourou (French Guiana), as projections show that logistics activities will account for approximately 30% of MaiaSpace’s total climate change impact by 2033 (excluding the launch phase). We analyzed the cumulative environmental benefits of rideshare with the Canopée cargo vessel equipped with wind-assisted propulsion, operational speed optimisation & transport planning consolidation, and sustainable biofuel adoption. Avoided impacts from the combined mitigation strategies were calculated using Life Cycle Assessment (LCA) methodologies, accounting for Well-to-Wake emissions, land-use change impacts and biogenic CO₂ treatment.
Four fuel configurations with custom LCA models were evaluated, both in terms of bunkering feasibility and environmental gains: B20 (20% FAME blended with 80% MDO), B100 (100% FAME bio-diesel), HVO30 (30% HVO blended with 70% MDO), and HVO100 (100% Hydrotreated Vegetable Oil).

This study will present the preliminary environmental analysis results (and associated recommendations) put in perspective with the MaiaSpace launcher LCA. We will highlight the GHG reduction potentials associated with transitioning towards biofuel bunkering for Canopée, distinguishing between pure biofuels and blended fuels which offer transitional compatibility advantages. Regulatory compliance considerations (specifically FuelEU Maritime regulation and EU Emissions Trading System) and feedstock competition with other sectors were also taken into account, to evaluate long-term economic viability beyond immediate fuel price comparisons.

While feedstock competition and current pricing constrain near-term deployment, this study finds that waste-based biofuels represent a viable long-term decarbonization pathway for aerospace transatlantic logistics, while remaining increasingly competitive under FuelEU Maritime and EU ETS regulatory frameworks.

Speaker: Marie Delaroche (MaiaSpace)

Marie_DELAROCHE.pdf

13:00 → 14:30 Lunch

14:30 → 16:30 Towards the integration of all the open aspects in space sustainability

14:30 Extending the Polluter Pays Principle to Orbit: The Legal Challenges of Mandatory Life Cycle Assessments in the EU Space Act

The proposed EU Space Act represents a landmark paradigm shift in space governance by importing the so-called Polluter Pays Principle (PPP) from Union environmental law into the regulatory framework of outer space activities. Central to this initiative is the transition from a reactive liability regime to a proactive model of environmental stewardship through mandatory Life Cycle Assessments (LCA) and the submission of Environmental Footprint Declarations (EFDs) for mission authorisation. This contribution explores the legal and structural challenges of integrating diverse indicators - including launch emissions, orbital debris mitigation, and “dark and quiet skies” - into a single regulatory “cradle-to-grave” assessment.
A primary concern addressed is the verification of LCAs for space assets manufactured outside the Union. By employing a “marketplace approach” similar to the General Data Protection Regulation, the EU Space Act mandates that non-EU operators providing services within the Union single market must comply with these sustainability standards. This contribution questions whether such requirements constitute an extraterritorial overreach that conflicts with the Outer Space Treaty’s grant of exclusive jurisdiction to the state of registry. Furthermore, it examines the potential for unfavorable LCAs to serve as de facto evidence of fault under the 1972 Liability Convention; if an operator fails to adhere to the EU Space Act’s mandated sustainable design, could accidental collision be reclassified as negligent conduct?
The analysis also scrutinises the EU Space Act’s bundling of disparate risks, specifically the grouping of “casualty risk at re-entry” with scientific concerns such as light pollution. It argues that while the latter is a legitimate scientific interest, its enforcement through internal market regulations lacks a clear international mandate, potentially leading to regulatory overreach. Finally, the contribution addresses the risk of carbon and economic leakage. While the EU Space Act aims to set a global “gold standard” via the Brussels effect, initial assessments indicate manufacturing costs for satellite platforms could rise by 10%. This contribution investigates whether these high compliance burdens will drive a “race to the bottom” or “forum shopping,” where operators migrate to less regulated jurisdictions, thereby shifting rather than solving the problem of space pollution.
The contribution concludes by situating the EU Space Act as a transformative but contested instrument of industrial policy that seeks to define the technical requirements of responsible behaviour in a congested and contested orbital environment.

Speaker: Cecilia Nota (Università di Torino)

2026 NOTA PRESENTATION Extending the Polluter Pays Principle to Orbit_ The Legal Challenges of Mandatory Life Cycle Assessments in the EU Space Act.pptx

15:00 A payload-aware LCA eco-design tool for iterative launch vehicle development

Integrating environmental considerations into launcher design presents unique challenges due to the iterative nature of development processes, limited production volumes, variety of design versions, and specialized materials involved. This study presents the development and application of an environmental trade-off tool designed to support eco-design for the MaiaSpace launch vehicle. The tool enables engineers to quantitatively compare alternative design solutions across standardized life cycle assessment impact categories while accounting for launcher performance constraints.

Three distinct comparison modes are implemented: (1) direct unitary impact comparison per trade-off alternative; (2) absolute cumulative impacts over a defined operational timeframe, within the scope of the chosen launcher stage (“location” of the trade-off), while incorporating the expendable/reusable vehicle mix; and (3), performance-relative impacts that normalize environmental impact differences against payload capacity changes. A critical feature of the third mode is its ability to identify performance thresholds beyond which design alternatives become environmentally advantageous with regards to the functional unit considered, thereby enabling the consideration of minimizing structural mass as a primary eco-design lever. This is particularly significant for launch systems, as mass reduction limits high-altitude radiative forcing emissions, whose warming effect is potentially several orders of magnitude greater than ground-level equivalents.

A case study comparing aluminum versus carbon fiber reinforced polymer (CFRP) thermal coverings for the Interstage Separation System demonstrated the tool's usability within the MaiaSpace teams. For each trade-off conducted, The tool enables identifying the performance gain threshold required to offset a potential increase in environmental impact.

This eco-design tool makes performance considerations visible when weighing the environmental benefits of a design change. The effects of said changes can be visualized in comparison to the entire projected launcher life cycle. Integrating this tool into early design cycles could systematically reduce the retrospective nature of LCA in launcher design.

Speaker: Marie Delaroche (MaiaSpace)

Marie_DELAROCHE.pdf

15:15 Towards integrated ecodesign of space launch systems: A digital LCA tool for early-stage decision-making

The transition towards more sustainable space activities requires the integration of environmental considerations across all phases of design and operation, as well as the consideration of multiple impact dimensions beyond traditional performance metrics. In this context, this work presents a digital tool based on life cycle assessment (LCA) useful to support ecodesign in space launch systems, enabling the systematic evaluation of environmental impacts from early design stages to more advanced system configurations.
The proposed tool is being developed to address current gaps in the integration of sustainability aspects within the space sector, particularly the need to combine different indicators such as atmospheric emissions, resource consumption, and emerging concerns including re-entry effects. Special emphasis is placed on usability during early design phases, where rapid iteration and limited data availability require simplified, decision-oriented approaches. To this end, the tool incorporates both a detailed LCA framework and a streamlined LCA mode, aligned with established guidelines, allowing fast comparison of alternative technologies and configurations while maintaining methodological robustness.
The applicability of the tool will be demonstrated through two complementary research initiatives. First, within the RELANES project, the environmental performance of alternative launch system scenarios is assessed, including the use of renewable RP-1 fuels and the implementation of reusable first-stage technologies. The results highlight the potential of these strategies to significantly reduce life cycle impacts, particularly through decreased fossil resource use and lower emissions associated with production and launch operations. Second, within the DISAPPEAR project, the tool is applied to evaluate the substitution of conventional metallic materials with fibre-reinforced thermoplastic polymer composites. These lightweight materials enable reduced structural mass, leading to lower propellant demand and associated upstream and operational impacts, while also offering advantages in manufacturing efficiency.
By integrating these use cases, the work illustrates how ecodesign strategies —such as propellant substitution, structural reuse and lightweighting— can be consistently assessed within a unified LCA-based framework. Furthermore, the inclusion of emerging impact categories, such as emissions during re-entry, contributes to advancing a more holistic perspective on space sustainability.
Overall, this contribution demonstrates that digital LCA tools, particularly when adapted to early-stage design needs, can play a key role in embedding sustainability into engineering workflows and supporting the development of next-generation environmentally responsible space systems.

Speaker: Enrique Moliner (Arribes Enlightenment)

Polimi Workshop_Enrique Moliner.pptx

15:30 Satellite Brightness Model

Artificial light pollution in the night sky has increased significantly in recent years, raising growing concern among institutions and the space community. International bodies, including the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) and the International Astronomical Union (IAU), have recognized satellite brightness as a major sustainability challenge. Despite this growing awareness, no formalised framework currently exists to assess and regulate satellite brightness at the pre-launch stage. This work funded by a Global Satellite Operators Association (GSOA) study aims to address that gap.
A method for estimating satellite brightness is proposed, based on the modelling of apparent magnitude through the combined contribution of direct solar flux and Earthshine, i.e., sunlight reflected by the Earth toward the satellite. Earthshine is modelled using a discrete Earth reflectance model, in which the Earth’s surface is subdivided into panels and assigned reflectance properties derived from observational data. In particular, BRDF measurements associated with the different IGBP surface classes are fitted using a Phong reflectance model to obtain a realistic representation of terrestrial reflectivity.
The satellite is represented as a three-dimensional object provided as input by the operator. The geometry is discretised into a triangular mesh, so that the spacecraft is modelled as an agglomeration of multiple two-dimensional surface elements, each contributing to the total reflected flux. This approach makes it possible to capture complex satellite geometries, including appendages and surface orientation effects. In addition, self-shadowing and facet visibility from the observer are explicitly taken into account, enabling the analysis of the impact of spacecraft attitude and orbit on apparent brightness. Material properties can also be assigned to each surface, allowing both diffuse and specular reflectance components to be modelled.
The proposed model has been validated through comparison with publicly available real observations, showing good agreement between estimated and measured brightness. Future developments will integrate the model into an indexing framework for quantifying the optical light pollution generated by a mission, with the goal of providing satellite operators with a practical tool to predict the impact of their design choices on the night sky.

Speaker: Achraf Mizmizi (Politecnico di Milano)

04_brightness_mizmizi.pptx

15:45 Is Active Debris Removal Beneficial? An Environmental Risk Analysis with THEMIS 1.0

In recent years, simulations based on evolutionary models of the space debris population, from many studies in the literature, have shown the need for more actions to mitigate the space debris problem, beyond post-mission disposal of satellites at the end of life. Many derelict objects have been left in orbit since the first space missions and more will inevitably be left in orbit in the future.
Active Debris Removal (ADR) has been proposed as a possible solution to reduce orbital congestion, by removing dangerous derelict objects that would otherwise remain in space for many years and continue to pollute the environment. Even if the technology is not yet mature enough for regular use, some demonstration missions are currently ongoing, showing the growing interest in ADR. It is considered a promising technology for future applications.
With this growing interest, some important questions arise: is ADR really beneficial from an environmental risk perspective? In which situations would debris removal be more beneficial, either alone or together with other mitigation measures?
This paper presents scientific results to help answer these questions. First, an environmental indicator is selected to evaluate the impact of ADR missions and the benefit they can provide, both alone and combined with post-mission disposal. The THEMIS 1.0 software that implements a debris risk metric is used because it can estimate environmental risk during the different phases of a mission.
The index is calculated for different ADR mission profiles and compared with post-mission disposal practices and with cases where no action is taken. Sensitivity analyses are carried out to study how the index changes when targeting satellites at different altitudes in low Earth orbit and with different masses. Moreover, the effect of the success of each mission phase is analysed.
Results are presented and discussed to identify the situations, in terms of mission profiles and parameters, where ADR is beneficial, and where the risk introduced may be higher than that of other mitigation options.

Speaker: Martina Rusconi (Politecnico di Milano)

Space capacity allocation Workshop.pptx

16:00 Integrated Assessment of Satellite Optical Brightness for Preservation of Dark and Quiet Skies

The concern raised by astronomers due to undesired acquisitions of space debris and satellites streaks in astronomical images determined a growing interest in so called Dark and Quiet Skies policies over the last years. Space agencies, international organizations and national governments are issuing new recommendations and laws aimed at ensuring
that the apparent brightness of space objects is below a certain threshold, typically recognized as V magnitude not below 7. Although this common requirement does not take into account the several factors that affect an object brightness, it demands for methods aimed at evaluating an object brightness both in the design and operational phase. Evaluating a satellite brightness in the early design phase enables the implementation of mitigation strategies at material level to reduce brightness, if necessary, whereas an assessment of brightness in the operational phase, once in orbit, allows the scheduling of attitude maneuvers to reflect sunlight towards preferred directions. In any case, the development of tools for evaluating a satellite brightness is required. We present a comprehensive approach to brightness evaluation developed under the ESA contract BILAR, which uses both real optical and simulated measurements to provide an assessment of a material brightness. Real measurements are obtained through observations in different photometric band, from the near ultraviolet to the near infrared. Simulated measurements are obtained through a dedicated digital twin that enables the evaluation of a satellite brightness under several configurations, as a function of different attitudes, materials characteristics and orbital conditions. The latter approach is further improved by the application of experimental BRDF measurements of typical space materials, enhancing the achievable characterization level. The entire approach, including real observations,experimental measurements and the digital twin will be presented in this paper.

Speaker: Lorenzo Cimino (Sapienza University of Rome)

presentation_lorenzo_cimino.pptx

16:15 Storm-Time Geospace Variability and Orbital Sustainability: Why Space Weather Matters for Capacity Management

This contribution explores how geomagnetic storm conditions should be incorporated into discussions on space sustainability and orbital capacity management. While space capacity is often discussed through debris population, launch traffic, and mitigation compliance, disturbed space weather conditions also play a significant role by altering upper-atmospheric density, drag, orbital prediction, conjunction risk assessment, and re-entry modelling. Drawing on a space-weather perspective, the paper argues that sustainable orbital governance should better integrate environmental variability driven by solar and geomagnetic activity. The objective is not to replace debris-based metrics, but to complement them by highlighting how storm-time geospace conditions affect the operational and regulatory understanding of orbital use. The contribution therefore proposes a more interdisciplinary approach to capacity governance, linking physical variability in the near-Earth environment with legal and policy debates on responsibility, thresholds, and sustainable access to orbit.

Speaker: Nouhaila Bouhadi (Universtity Chouaïb Doukkali, Faculty of Sciences)

Geomagnetic Storms and Orbital Capacity Governance.pptx

16:30 → 17:00 Conclusions and next steps