Simulation and observational evaluation of space debris detection by Sanya incoherent scatter radar

The Sanya incoherent scatter radar (SYISR) is a newly built active digital phased array, all solid-state transmitting and digital receiving incoherent scatter radar in Sanya (18.3°N, 109.6°E). The radar frequency band is from 430 to 450 MHz. The Sanya site is a low latitude station in China dedicated for ionospheric investigation. Meanwhile, SYISR is also suitable for detecting a wide range of space debris because of its high power and flexible beam steering ability. In this paper, we first calculate the detectable lower limit size of space debris with respect to integration time and range based on SYISR parameters through theoretical simulation. Then, we selected several typical space debris, with a size near the theoretical detectable lower limit, to perform the experiment. We found that the estimated radar cross section versus range accorded well with the theoretical curve, which confirmed our simulation. Specifically, the detectable lower limit size of space debris is ∼8 cm in a range of 1,000 km given a threshold signal-to-noise ratio of 14 dB. This value decreases to ∼3 cm if a 200-ms coherent integration is implemented. We further performed several experiments on objects with different inclinations using signals with 0.3 and 4 MHz under both static staring and tracking modes. In comparison with the two-line element file predicted raw orbit, the tracking error of 0.3 and 4 MHz are 7 km and 400 m, respectively, without coherent integration in the processing. The study expands the function of the SYISR and should be beneficial to our ionospheric data inversion given the frequent occurrence of space debris around the SYISR.