Speaker
Mr
Vitali Braun
(IMS Space Consultancy GmbH)
Description
ESA’s space debris mitigation policy has come into force in March 2014 and adopts the space debris mitigation technical requirements from the ECSS adoption notice of ISO 24113. Those requirements include recommendations on the disposal of systems that have reached the end of their useful life, and were driving the development of OSCAR (Orbital SpaceCraft Active Removal). Specifically, OSCAR is the component of DRAMA designed to address disposal manoeuvres at end-of-life and assess the compliance of the later stages of a mission with the mitigation requirements, where mission planners have to decide on their implementation at early stages in the project (typically around SRR/PDR).
In its current version, published and freely available within the DRAMA software suite, OSCAR allows for the analysis of the orbit evolution subject to different possible future scenarios for solar and geomagnetic activity, which are the main drivers in the estimation of the residual lifetime for a specific orbit.
Based on standardised and widely accepted methods for the prediction of those scenarios, the remaining orbit lifetime is computed via a semi-analytical propagation taking into account all relevant perturbations.
However, long-term forecasts of the orbit evolution are very sensitive to several quantities, most of them very difficult to forecast, including the solar and geomagnetic activity, the object’s cross-section, its attitude state and mass, the drag and solar radiation pressure coefficient of the object, as well as physical model limitations. Moreover, the uncertainties in the injection manoeuvre transferring the spacecraft into its disposal orbit and uncertainty in the disposal epoch cannot be neglected.
With OSCAR being used in the compliance verification process with respect to the mitigation requirements, the current approach to also assess the uncertainty associated with a lifetime estimate shall be discussed. By accounting for the various sources of uncertainty, OSCAR will allow for a more probabilistic and thus more realistic estimate, which is beneficial in the compliance analysis.
This paper will give a brief overview on the core functionalities of OSCAR and then focus on the uncertainties considered in the latest update of OSCAR. The propagation of the uncertainties results in a probabilistic assessment of the orbit lifetime. For example, the 25-year-rule compliance can then be based on an assessment in how many cases the orbit lifetime would be below or above 25 years.
Finally, some exemplary results will be provided, addressing different orbital regimes.
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Primary author
Mr
Vitali Braun
(IMS Space Consultancy GmbH)
