This paper presents proof-of-concept methods and results on a passive synthetic aperture radar for surface change monitoring. The bistatic topology comprises navigation satellites (such as Global Positioning System, GLObal Navigation Satellite System (GLONASS), Galileo, or Beidou) as transmitters of opportunity and a fixed receiver on the ground. Surface monitoring is to be provided through coherent change detection. An experimental test bed built to confirm the concept of the system is described, and the appropriate experimental program is presented. Preliminary signal processing algorithms for change detection are derived. Experimentally measured changes are compared to the theoretical predictions, and the obtained results are discussed.