As MESSENGER sped by Mercury on January 14, 2008, the Narrow Angle Camera
(NAC) of the Mercury Dual Imaging System (MDIS) captured this image, which
includes the edge of the planet against the blackness of space. Much of
the foreground shows a portion of Caloris basin, one of the largest impact
basins in the solar system. The two large craters near the bottom of this
image can be identified on the northwestern floor of the basin on the
mosaicked image of Caloris (see PIA10383) released at MESSENGER's
NASA press conference on January 30. The large crater in the bottom middle
of this image has a diameter of about 70 kilometers (40 miles).
Caloris basin is an area of particular interest to the MESSENGER science
team, since understanding its formation can lead to insights about the
nature of large impacts in the early solar system and the results of these
catastrophic events. In a false-color image of Mercury (see PIA10398), also
released on January 30, Caloris basin is visible in the northern
hemisphere of the planet as a large, light-colored, roughly circular
feature; the floor of the basin may have some differences in its
composition compared with the darker surrounding surfaces. The two large
craters shown in today's released image are each surrounded by a "halo" of
dark material, like the craters shown in our release of February 21 (see
PIA10602). The smaller of the two craters has an unusual
pattern of bright, highly reflective material on its floor. The fact that
both of these craters, which show different material characteristics, are
located within Caloris basin provides information about the variety and
complexity of processes that have shaped Mercury's surface.
Image Mission Elapsed Time (MET): 108826622
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.