This map, by the OMEGA instrument on ESA’s Mars Express, shows the distribution of dust across the suface of Mars. The dust is in the form of ferric oxide nanoparticles (at most a few tens of nm in size). The particles are thought to be the result of chemical reactions with the atmosphere, causing the surface to ‘rust’ slowly over billions of years, giving Mars its distinctive red hue. The degree of rusting is also related to the distinct mineral compositions of the crustal rocks from which the dust derived, and is closely linked to iron-rich terrains (including the volcanic province of Tharsis).
Weathering and erosion from past glacial activity and impact events, as well as dust storms, winds and freezing and thawing cycles today, contribute to the continued production of fine-grained dust.
The colour scale represents the amount of dust present on the surface, from low to high abundance.
This map was released on the occasion of the tenth anniversary of the launch of Mars Express, along with global maps of hydrated minerals, olivine, pyroxene and ferric oxide. Click to access the required image.