Speaker
Description
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.
| Which section would you like to submit your abstract to? | Session 5: “How to assess the impact of space missions onto the space environment?” |
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