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Foto Originale fatta dalla N.A.S.A.
http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?page=1&gallery_id=2&image_id=289
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)
Of Interest: 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 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, where other dark surface material, as well as patches of
light-colored rocks, can be seen.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie
Institution of Washington
