Management of Radar Resources for Space Debris Tracking
Tens of thousands of debris are expected in the near future in the most critical Low Earth Orbit (LEO) regimes, hence representing a serious threat for European space assets. In the frame of the Space Situational Awareness Preliminary Programme of the European Space Agency, the design for a ground-based phased array radar - aimed at debris detection and tracking - has been proposed. Track-while-Scan (TwS) survey is combined with Active Tracking (AT) tasks in order to achieve the required performance. A managing strategy for TwS/AT radar resources is analysed versus the accuracy requirements dictated by collision warning services.
Radar sensors, devoted to Space Situational Awareness (SSA), support the identification of close conjunctions between space debris (or other spacecrafts) and valuable space assets. Ground-based radar data allow refreshing and maintaining the orbital parameters for the catalogued objects in Low Earth Orbit (LEO) regimes. The availability of accurate and up-to-date orbital data is fundamental for achieving a good probability of early detecting a potential collision with low false alarm rate. However, the multitude of required observations (tens of thousands of debris expected in 2040 in the same LEO regimes of most civilian satellites) and the scarceness of SSA-devoted sensors lead to complex optimization issues.
In the frame of the European Space Agency SSA Preliminary Programme, the design for a ground-based phased array radar - aimed at LEO surveillance - has been proposed. A fence-shaped volume of the sky is routinely, electronically scanned by the radar beams in order to feed the Track-while-Scan (TwS) processor - an L-band radar breadboard is currently under development following this approach. The actuation of Active Tracking (AT) tasks is also considered, in parallel with the use of dedicated tracking radars for orbit refinement. The optimal strategy for managing the TwS/AT resources of the phased array radar is hereafter derived from the accuracy requirements dictated by the collision warning services. Resource savings is addressed in terms of observation time for target acquisition, track confirmation and track refinement. Simulation results over a representative debris population dataset are presented in order to support the analysis.