The Mercury Dual Imaging System on the MESSENGER Spacecraft |
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Authors: | S Edward Hawkins III John D Boldt Edward H Darlington Raymond Espiritu Robert E Gold Bruce Gotwols Matthew P Grey Christopher D Hash John R Hayes Steven E Jaskulek Charles J Kardian Jr Mary R Keller Erick R Malaret Scott L Murchie Patricia K Murphy Keith Peacock Louise M Prockter R Alan Reiter Mark S Robinson Edward D Schaefer Richard G Shelton Raymond E Sterner II Howard W Taylor Thomas R Watters Bruce D Williams |
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Institution: | (1) The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA;(2) Applied Coherent Technology, Herndon, VA 20170, USA;(3) School of Earth and Space Exploration, Arizona State University, Box 871404, Tempe, AZ 85287-1404, USA;(4) Center for Earth and Planetary Studies, National Air and Space Museum, Smithsonian Institution, Washington, DC 20013, USA |
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Abstract: | The Mercury Dual Imaging System (MDIS) on the MESSENGER spacecraft will provide critical measurements tracing Mercury’s origin
and evolution. MDIS consists of a monochrome narrow-angle camera (NAC) and a multispectral wide-angle camera (WAC). The NAC
is a 1.5° field-of-view (FOV) off-axis reflector, coaligned with the WAC, a four-element refractor with a 10.5° FOV and 12-color
filter wheel. The focal plane electronics of each camera are identical and use a 1,024×1,024 Atmel (Thomson) TH7888A charge-coupled
device detector. Only one camera operates at a time, allowing them to share a common set of control electronics. The NAC and
the WAC are mounted on a pivoting platform that provides a 90° field-of-regard, extending 40° sunward and 50° anti-sunward
from the spacecraft +Z-axis—the boresight direction of most of MESSENGER’s instruments. Onboard data compression provides capabilities for pixel
binning, remapping of 12-bit data into 8 bits, and lossless or lossy compression. MDIS will acquire four main data sets at
Mercury during three flybys and the two-Mercury-solar-day nominal mission: a monochrome global image mosaic at near-zero emission
angles and moderate incidence angles, a stereo-complement map at off-nadir geometry and near-identical lighting, multicolor
images at low incidence angles, and targeted high-resolution images of key surface features. These data will be used to construct
a global image base map, a digital terrain model, global maps of color properties, and mosaics of high-resolution image strips.
Analysis of these data will provide information on Mercury’s impact history, tectonic processes, the composition and emplacement
history of volcanic materials, and the thickness distribution and compositional variations of crustal materials. This paper
summarizes MDIS’s science objectives and technical design, including the common payload design of the MDIS data processing
units, as well as detailed results from ground and early flight calibrations and plans for Mercury image products to be generated
from MDIS data. |
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Keywords: | MESSENGER Mercury Imaging Camera Imager CCD Heat pipe Wax pack Photometry Stereo |
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