On board of Mars rover Curiosity and as part of a X-ray spectrometer, KETEK’s Silicon Drift Detectors have arrived on the Red Planet. The X-ray instrument, again part of an onboard science laboratory, irradiates a rock or soil target with X-rays. The irradiation results in the target giving off own characteristic X-ray radiation, which is collected and understood by KETEK’s Silicon Drift Detector at the spectrometer head. Quality and quantity of chemical elements in the target are revealed. A significant improvement to Curiosity’s X-ray instrument compared to those of previous Mars rover X-ray spectrometers is the Silicon Drift Detector’s cooling system. Instruments of previous Mars laboratories could only measure during the night when temperatures are low. The advanced cooling also allows measurements at day.