In The Netherlands a demonstration small SAR instrument mission is prepared under the ESA Prodex program. Its launch is expected in 2017. The overall objective of this project is to demonstrate an alternative means to systematically assess the structural health of large volumes of infrastructure (built environment), in order to avoid hazardous situations. The assessment is based on an X-band interferometric Synthetic Aperture Radar with high resolution in the order of 2 meter. The radar system will be using the FMCW principle and will be realized within stringent Size, Weight and Power (SWAP) requirements in order to allow future missions of this type to be flown on small satellites. These future missions will possibly exploit the full FMCW capability in a formation flying sensor suite. The current demonstrator will consist of one platform with the instrument operating in Interrupted FMCW mode. This back-up mode is foreseen also for the future missions, in order to keep imaging capability in case one of the instruments in the formation has a serious malfunction. The paper describes the mission goal, the radar instrument and its performance.