MERTIS is an imaging spectrometer combined with a radiometer. The instrument is characterised by its compact design measuring 18 by 18 by 13 centimetres, a weight of only 3.3 kilograms and its low power consumption. The sensors built into MERTIS are unique: The imaging channel uses a so-called uncooled microbolometer - the first to be space-qualified in Europe. The radiometer uses a sensor measuring only three by one millimetres, which has been made from silicon and also serves as a slit for the spectrometer. Using MERTIS, the mineralogical composition of Mercury’s surface as well as the rock-forming minerals will be investigated. At the same time, the integrated micro-radiometer will measure the temperature and thermal conductivity of Mercury. From the data, the scientists hope to learn about the formation and evolution of the planet.