Mini-RF X/C-Band Bistatic Synthetic Aperture Radar: Architecture, Polarimetric Observations, and Implications for Future Systems

Synthetic aperture radars (SAR) have a significant heritage in terrestrial applications and have demonstrated new scientific opportunities in planetary missions. Here, we present the technical details of the Mini-RF bistatic SAR architecture and experiment, which utilizes the DSS-13 (X/C-Band) radio telescope as a transmitter and the Mini-RF instrument onboard the Lunar Reconnaissance Orbiter (LRO) as the receiver. We first analyze the X/C-Band bistatic radar system performance and describe the polarimetric channel calibration process. Next, we outline the image processing technique that leverages hybrid-polarimetry and time-domain backprojection processing (TDBP) to focus and normalize polarimetric bistatic SAR images.We also demonstrate the effectiveness of the bistatic radar technique by presenting primary and derived data products, including Stokes parameters and Circular Polarization Ratios (CPR). We further highlight the importance of precise lunar surface imaging in this bistatic radar configuration, as the Mini-RF experiment represents the first implementation of X/C-Band polarimetric bistatic SAR in planetary science to image the lunar surface. We conclude by discussing the advantages and challenges of future bistatic radar architectures, with the goal of inspiring cost-effective polarimetric SAR systems for planetary exploration.