June 16, 2014
Visible and Infrared Spectrograph (VIRS) of the Mercury Atmosphere and Surface Composition Spectrometer (MASCS)and Mercury Dual Imaging System (MDIS)
VIRS Color Composite Wavelengths:
575 nm as red, 415 nm/750 nm as green, 310 nm/390 nm as blue
Hesiod crater (lower, with smaller inset crater) is about 100 km (62 mi.) in diameter
The top image is a MASCS
VIRS color composite
of several large craters including Hesiod
(lower middle, with smaller crater inside) and smaller Kuniyoshi
to the west. The bottom image is a monochrome MDIS mosaic of the same area. The craters host a series of pyroclastic vents
. The vents and the material erupted from them are brighter than the surrounding cratered plains and appear red in the VIRS composite, attesting to a difference in composition.
The VIRS composite shows hundreds of individual footprints tracks (minimum 100-200 m across and 3-4 km long) taken from different directions and altitudes. In locations where multiple footprints cover the same area, the footprint with the best illumination for mineralogical interpretation (usually the lowest incidence angle where shadows are minimized) is used for making the map. Due to the nature of MESSENGER's orbit, the VIRS coverage of the southern hemisphere is greater than the north. In the MDIS, mosaic some brightness variations are due to tiling of images taken at different illuminations.
The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation
are unraveling the history and evolution of the Solar System's innermost planet. During the first two years of orbital operations, MESSENGER acquired over 150,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
For information regarding the use of MESSENGER images, see the image use policy.