Abstract: There is provided a device for detection of undesired objets on surfaces, for example airport runways. The device co-ordinates sensed data from a plurality of sensor units. With radar sensors, synthetic aperture radar processing is found to be advantageous. A vehicle configured with a plurality of sensors is described. The vehicle may be either remotely controlled or autonomous. The vehicle may also be provided with debris retrieval apparatus and communication equipment. A debris detection system incorporating both mobile sensing devices and fixed installations is also considered. A suitable mobile sensing device and a method for operating the debris detection system are also described.