Moon-based Synthetic Aperture Radar: Review and challenges

Based on a recent renewed interest in the utilization of Moon as a platform for Earth remote sensing, this paper reviews the concept of a Moon-based Synthetic Aperture Radar (SAR). Such a system presents some features, which differentiate it from a conventional spaceborne SAR. Indeed process of antenna synthesis and the observation geometry are quite different. The platform, on which the observatory shall be build up, is not an orbiter or a space formation, but a whole celestial body. Earth-Moon relative motion generates the synthetic aperture and the properties of such a motion allow for the exploitation of very long synthetic antennas. Moreover two or more antennas can be located over lunar surface realizing a distributed SAR and enabling single-pass interferometric SAR applications, e.g. cross-track interferometry and tomography. System parameters and technological challenges of such a Moon-based observatory are also discussed.