Craters in Caloris
27 Feb 2008
(Source: Johns Hopkins University Applied Physics Laboratory)
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 released at MESSENGER's NASA press conference on January 30, 2008. 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, 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. 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.
Additional information and features from MESSENGER's first flyby of Mercury are online at http://messenger.jhuapl.edu/mer_flyby1.html
MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. The MESSENGER spacecraft launched on August 3, 2004, and after flybys of Earth, Venus, and Mercury will start a yearlong study of its target planet in March 2011. Dr. Sean C. Solomon, of the Carnegie Institution of Washington, leads the mission as Principal Investigator. The Johns Hopkins University Applied Physics Laboratory built and operates the MESSENGER spacecraft and manages this Discovery-class mission for NASA.