Speaker
Mr
Jan Siminski
(ESA/ESOC)
Description
In order to guarantee safe operation of satellites, space object catalogues must be build-up and maintained. The catalogues should be complete, i.e. contain sufficiently accurate and frequently updated orbital states for all required objects.
In theory, completeness of the catalogue is achieved by designing the radar in a way that a major fraction of the object population is considered detectable, i.e. covered by the sensor’s field-of-regard and within the sensor sensitivity. However, complete coverage does not necessarily guarantee a proper catalogue build-up, yet.
If an object is observed once, it must be re-observed in order to verify its existence and improve the accuracy of the determined state. In a next step, individual observation tracks are combined with each other to further improve the accuracy. Consequently, tracks must be associated to each other, i.e. tested if they originate from the same object or not.
The success rate of the association is dependent on the quality of the tracks, the re-observation time and the re-observation geometry. For surveillance radars, the association performance must be considered as a critical design parameter and can be optimized along with the detection rate during the design process.
We outline the underlying techniques and present a simulation-based framework for assessing the surveillance system design in terms of association performance and achievable accuracy.
In the tool framework phased-array radars are defined with a detection figure-of-merit (i.e. ratio of detectable object size at a certain distance), a field-of-view, a pointing direction, and a noise estimate. Then, observations are generated with a realistic object population, e.g., based on ESA's MASTER model. The resulting tracks are associated to each other using covariance-based distance metrics. We address several difficulties which arise during the association, e.g. proper treatment of state uncertainties and robust initial orbit determination.
The association performance is analysed for different orbital heights and re-observation conditions for a specific radar design concept. Additionally, the typical resulting orbital state accuracies are presented for the initial orbits as well as for the improved ones.
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Primary author
Mr
Jan Siminski
(ESA/ESOC)
