October 6, 2008
Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS)
Mercury's diameter is 4880 kilometers (3030 miles)
The Mercury Dual Imaging System (MDIS) has 11 narrow-band spectral filters covering visible and near-infrared wavelengths (400 to 1050 nm). The specific colors of the filters were selected to discriminate among common minerals. Three-color images (480 nm, 560 nm, 630 nm) were combined to produce an approximation of Mercury's true color as might be seen by the human eye
(left). From this rendition of Mercury it is obvious that color differences on the surface are slight. Statistical methods that utilize all 11 filters in the visible and near-infrared highlight subtle color differences (right) and aid geologists in mapping regions of different composition. What do the exaggerated colors tell us about Mercury? The nature of color boundaries, color trends, and brightness values help MESSENGER geologists understand the discrete regions (or “units”) on the surface. From the color images alone it is not possible to determine unambiguously the minerals that comprise the rocks of each unit. During the brief flybys, MESSENGER's other instruments sensitive to composition lack the time needed to build up adequate signal or gain broad areal coverage, so only MESSENGER's cameras were able to acquire comprehensive measurements. Once in orbit about Mercury, MESSENGER's full suite of instruments will be brought to bear on the newly discovered color units to unlock their secrets.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
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