Advances in multiple spacecraft operations require precise determination of the relative kinematic state of the platforms involved. Such knowledge - above all in case of non-cooperative approaches - can be usefully attained by means of imaging. However, the extremely varying light conditions in the orbital environment do not allow for extended operations in the visible spectrum. The paper investigates the possible coupling of thermal imagery with visible one in order to have a continued relative tracking even during eclipse. The focus is on simple camera devices, suitable for mounting onboard microsatellites, and on the combined (visual and infrared) image processing and data fusion helped by the purposeful modeling of the spacecraft dynamics and bus signature.