The interferometric cartwheel: a multi-purpose formation of passive radar microsatellites

The interferometric cartwheel (CNES patent) is composed of three passive identical microsatellites set in a particular orbital geometry and flying behind or ahead of an active synthetic aperture radar (SAR) satellite. This satellite illuminates a ground swath and the reflected signals are received by the microsatellites with specific viewing configurations. The obtained data are mainly used for the computation of a Digital Elevation Model (DEM). This paper details first the across-track interferometry principle specific to the cartwheel geometry. General system and satellite characteristics are then presented as well as their main constraints. Finally, a performance budget based on a typical satellite configuration is carried out and leads to the topographic accuracy of the DEM.