The Multibeam Radar Sensor BIRALES: Performance Assessment for Space Surveillance and Tracking

Near-Earth space has become progressively more crowded in active satellites, inactive spacecraft and debris. Consequently, an international effort is currently being devoted to improving the performance of the network of optical and radar sensors for space objects monitoring. In this regard, the use of the Italian novel BIstatic RAdar for LEo Survey (BIRALES) is investigated in this work. BIRALES sensor exploits a bistatic configuration in which the Radio Frequency Transmitter (RFT) located at Salto di Quirra (Cagliari) plays the role of the transmitter, whereas a portion of the UHF Northern Cross antenna (Bologna) is used as the receiver. The first part of the paper is dedicated to the illustration of the sensor, with a detailed analysis of the multibeam receiver gain pattern. The tailored orbit determination algorithm is described, and a detailed analysis of the algorithm for the reconstruction of the trace of the transiting object within the receiver field of view is offered. The second part of the work illustrates the results achieved with both numerical simulations and observation campaigns. The sensor performance is assessed considering both cases of known and unknown objects, and the results in terms of number of observed objects, as well as accuracy in position and velocity are shown. For all cases, the effect of measurement noise on each single available measurement is investigated. The final part of the paper illustrates the results obtained during the observation campaign of space station Tiangong-l re-entry. An analysis of the accuracy of the obtained results is carried out, and the potential of BIRALES sensor is highlighted.