The crater in the lower right-hand corner of this image has a patch of
very dark material located near its center. The region of this image has
been seen only with the Sun high overhead in the sky. Such lighting
conditions are good for recognizing color differences of rocks but not
well suited for ascertaining the topography of surface features from
shadows. The shape of the surface in this area is difficult to resolve
given the lighting angle, but the dark patch is not in shadow. Dark
surfaces have also been seen on other regions of Mercury, including this
dark halo imaged during the second Mercury flyby (PIA11357) and near such
named craters as Nawahi, Atget, and Basho seen during MESSENGER's first
Mercury encounter. The example here is particularly striking, however, and
from this NAC image the material may appear even darker than in other
example areas. The dark color is likely due to rocks that have a different
mineralogical composition from that of the surrounding surface.
Understanding why these patches of dark rocks are found on Mercury's
surface is a question of interest to the MESSENGER Science Team. The right
edge of the image here aligns with this previously released NAC image (see
PIA11763), where other dark surface material, as well as patches of
light-colored rocks, can be seen.
Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131771988
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 260 meters/pixel (0.16 miles/pixel)
Scale: This image is about 270 kilometers (170 miles) across
Spacecraft Altitude: 10,100 kilometers (6,300 miles)
These images are from MESSENGER, a NASA Discovery mission to conduct the
first orbital study of the innermost planet, Mercury. For information
regarding the use of images, see the MESSENGER image use policy.