A crater discovered in the newly imaged portion of Mercury’s surface
during MESSENGER’s second Mercury flyby has uncommonly dark material
within and surrounding the crater. The material is darker than the
neighboring terrain such that this crater with a diameter of 180
kilometers (110 miles) is easily identified even in a distant global image
of Mercury; it is located just south of the equator near the limb of the
planet in this previously released Wide Angle Camera (WAC) image (PIA11245).
The dark halo may be material with a mineralogical composition different
from the majority of Mercury’s visible surface. Craters with similar dark
material on or near their rims were seen on the floor of the Caloris basin
during MESSENGER’s first flyby (PIA10603). Images acquired though the
11 different narrow-band color filters of the WAC during MESSENGER’s
second flyby will be crucial to an understanding of the nature of this
newly seen, unusual feature.
Date Acquired: October 6, 2008
Image Mission Elapsed Time (MET): 131774051
Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS)
Resolution: 540 meters/pixel (0.34 miles/pixel)
Scale: This image is about 550 kilometers across (340 miles)
Spacecraft Altitude: 21,000 kilometers (13,000 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.
