First mid-infrared light observations of Mercury

This greyscale part of this image shows the first-ever measurement by a spacecraft of how Mercury radiates in mid-infrared light. It was measured by the MERTIS instrument on the ESA/JAXA BepiColombo mission on 1 December 2024, as the spacecraft flew past the planet for the fifth time. The MERTIS data is overlaid on the global mosaic of a topography map based on data from NASA's Messenger mission.

MERTIS, short for Mercury Radiometer and Thermal Infrared Spectrometer, will be a key tool for BepiColombo to uncover what Mercury's surface is made of. The brightness in this image indicates how much Mercury's surface radiates with a wavelength of 8.45 micrometres. This radiance depends on what minerals the cratered surface is made of, the surface roughness and the temperature. The regularly appearing gaps on the map are due to the calibration cycle on the instrument. 

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