Parameter Assumption Source/basis Implication/sensitivity Satellite cross-section3 m2SSA/LeoLabs baseline for operational payloads Simplified geometry; deviations in real dimensions will proportionally alter the collision probabilities Rocket-body cross- section and mass 8 m2 and 1,400 kg Historical mean for SL-8 and similar rocket bodies Larger derelicts dominate collision energy and debris-generation risk Fragment area 0.04 m2Derived from LeoLabs catalogue statisticsInfluences detection thresholds and debris-count estimates Relative velocity 12 km/s Standard LEO average Approximation; orbital-inclination variations slightly adjust outcomes Fragment ratio 90 lethal plus 250 hazardous per catalogued objectNASA MASTER 826If underestimated, total cost is conservative Constellation plans All major systems proceed per International Telecommunication Union (ITU) filingsITU filings Cancellations or delay would lower congestion Launch upper-stage abandonment rates50% rocket-body abandonment 2025– 2030; 0% rocket-body abandonment 2030–2040 due to lower altitude targets (~500–650 km, where atmospheric drag plays a role) Based on 10-year average mid-LEO launches Operator discipline strongly affects outcomes Satellite failure rate 0.5% declining to 0.25% from 2030–2040 Observed performance of large constellations Operator discipline strongly affects outcomes Rocket-body explosions2029, 2033 and 2037 Historical recurrence rate More explosions will increase collision probabilities Atmospheric drag Removes debris < 600–700 km Empirical decay threshold Solar activity variations can temporarily enhance decay No active debris removalADR effects excluded before 2040 Pending business case Including ADR could reduce modelled lossesB2 Core modelling assumptions The model relies on a defined set of simplifying assumptions summarized in Table 5, where each parameter’s technical basis and potential influence on results are outlined for transparency. Simplified core modelling assumptions TABLE 5 Clear Orbit, Secure Future: A Call to Action on Space Debris 26

Clear Orbit Secure Future 2026