This image was recently featured in an article in Science magazine about
the evolution of Mercury’s crust. The top mosaic (A) is an enhanced-color
view (PIA12051) of the planet created from images taken through the WAC’s
eleven color filters during MESSENGER’s first and second flybys of Mercury.
White areas are those that MESSENGER has not yet observed. The bottom half
of this image (B) is a map of major terrain types on Mercury. It was made
by examining enhanced-color WAC mosaics (as shown at the top) that
highlight color and compositional differences on the surface as well as
higher-resolution Narrow Angle Camera (NAC) mosaics (PIA11767) that provide
information about the surface texture and relationships among surface
features.
On the geologic map, the pale yellow and darker yellow areas represent
different types of smooth plains. The Caloris basin (PIA10359), for example,
appears all in the pale yellow color, while the area around it is a darker
yellow, indicating two different types of smooth plains in these
neighboring areas. This global mapping study has indicated that smooth
plains are widespread and cover about 40% of Mercury’s surface. Many
large areas of smooth plains also show evidence for a volcanic origin,
leading to the conclusion that volcanism may have been extensive in
Mercury’s history. The light and dark blue colors highlight areas of the
surface that have a lower reflectance and different composition than the
smooth plains. The black areas on this map represent other kinds of
terrain. The crosshatched areas were not included in the map because the
high Sun angle during the flybys made them unsuitable for interpreting
surface texture.
Credit: Figure 4 from Denevi et al., Science, 324, 613-618, 2009.
Date Acquired: January 14, 2008, and October 6, 2008
Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Scale: Mercury’s diameter is 4880 kilometers (3030 miles)