Backscattering Characteristics of Millimeter Wave Landing Radar on Mars Surface

Abstract:
During the EDL (entry, descent and landing) prcess of the TianWen-1 Mars probe, the millimeter wave landing radar provides the GNC (Guidance, Navigation and Control) sub-system with high-precision ranging and velocity measurement data between the landing rover and the Martian surface to ensure the landing rover landing safely. The radar backscattering coefficient of Mars surface is the key characteristic parameter of the target detection, which directly affects the radar detection range and measurement accuracy, and is the most critical and uncertain parameter in the design process of millimeter wave landing radar. This paper proposes a method to calculate the radar scattering coefficient of Martian surface. This method, through setting up the mathematical model for radar scattering coefficient with incident angle, relief, and the components of the Martian surface. This radar scattering coefficient, is very important input for millimeter wave landing radar for range and precision analysis. At the same time, the backscattering coefficients obtained by electromagnetic calculation and in-orbit telemetry data inversion are compared and analyzed, which effectively verifies the correctness of the electromagnetic modeling of the radar backscattering coefficients of Mars surface, and provides a theoretical basis for the design and improvement for the deep-space landing radar.