Speaker
Description
Recent long-term simulations of the space environment extrapolating the current launch rate under present space debris mitigation measures suggests that the space environment will become unstable, leading to an exponential increase of the collision rate. The analysis of the extrapolation scenarios defines an acceptable level of risk (i.e., an orbital capacity) that is compatible with a stable evolution of the space environment, this risk level can however only be achieved under strict compliance to existing guidelines and best-practices for every mission. As current guideline compliance assessment approaches comport limitations such as obsolescence of disposal criteria due to an increasing launch traffic or the impossibility to account for the current aggregated level of compliance of space missions, an alternative risk-based approach was formulated under the appellation of “debris index”. A derived version was tested, and implemented under the operation of the Space Sustainability Rating (SSR).
This presentation depicts the process applied by the SSR to use a risk-based approach for quantifying the sustainability level of space missions: the mission index. As a first step in the assessment, the SSR uses parameters provided by satellite operators in order to perform an evaluation. The required parameters for computing an index value are listed, allowing to demonstrate the possibility to define precise and quantified impact assessments based on high level parameters. The accessibility of the required parameter list is discussed. The formulation of the index metric as a risk-based approach is then described, using the collision probability and severity terms at a given epoch. The index value integration process is explained, allowing to demonstrate the usability of the index metric over the entire lifetime of an object, also considering different trajectory evolution scenarios based on the disposal strategy. The presentation especially highlights the importance of implementing a post mission disposal strategy through the comparative analysis of mission disposed and not disposed, at different altitudes and with different disposal success rate values. Finally, the presentation focusses on how a tool such as the SSR can leverage the risk metric defined and incentivize satellite operators to implement more sustainable end-of-life practises.
