The ultra-compact imaging spectrometer is a miniature imaging spectrometer that has been designed for compatibility with operation in a Martian environment. The spectrometer can be mated to a variety of front optics, both telescopic and microscopic. With a miniature telescope, it can serve as a rover mast instrument that surveys the surrounding area from a distance of to infinity and produces full spectral data (500 to 2500 nm) of a wide panoramic scene in order to find the most mineralogically promising targets for further analysis and for directing subsequent rover activities. With a microscopic front lens, it can serve as an analytical tool for determining types of minerals in a rock and their spatial relations at a scale of tens of micrometers in order to make detailed interpretations of geological history. A realization of the instrument, adapted for operation in the Earth’s atmosphere, has been produced and tested both in the laboratory and in the field. The results prove the ability of the instrument to detect and map minerals of interest in both modes of operation.