Mercury in mid-infrared light (background)

This coloured 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.

Click here for the complete MERTIS image

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 colours in this image indicate 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. 

The greyscale background image shows the surface of Mercury as observed by NASA’s Messenger mission in visible light. 

MERTIS's view during this flyby covers part of the largest impact crater on Mercury, called the Caloris Basin. The zoom panel shows a close-up of the area around the Bashō impact crater. Messenger's visible light images show that Bashō impact crater exhibits both very dark and very bright material. The MERTIS flyby observations reveal that the crater also stands out in infrared light. 

The lower right shows the flyby coverage projected on the Mercury globe. The flyby MERTIS data shown in grey is overlaid on the global mosaic of a topography map based on Messenger data. 

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