MESSENGER MDIS Wide-angle Map-projected 5-Color Multispectral RDR (MAPMD5)

MAPMD5 – Wide-angle Map-projected 5-Color Multispectral RDR

Instrument: MESSENGER Mercury Dual Imaging System

PDS Data Set ID: MESS-H-MDIS-5-RDR-MP5-V1.0DOI: 10.17189/1520308

For more information about MDIS MAPMD5 products, see the CDR/RDR Product SIS.

The Mercury Dual Imaging System (MDIS) Wide-angle Map-projected 5-Color Multispectral Reduced Data Record (MAPMP5) data product is a 5-color map of northern latitudes acquired during MESSENGER’s Extended Mission. This product has higher spatial resolution than, and complements, an 8-color multispectral map acquired during the primary mission (RDRMDR). It has better spectral sampling and the same spatial resolution, and complements, a 3-color multispectral map also acquired during the Extended Mission (MDRWAC). It is intended to search for spatial variations in color properties of the northern volcanic plains.

This product is photometrically normalized to a solar incidence angle, i=30°, emission angle, e=0°, and phase angle, g=30°, at a spatial sampling of 128 pixels per degree. The map consists of a single tile composed of 5 bands corresponding to 5 of the 11 WAC filters. The tile also contains 6 backplanes describing ancillary information. The subset of 5 of 11 available multispectral filters samples albedo and spectral slope over MDIS’s wavelength range. Unlike the 3- and 8-color products, which were acquired with the WAC pointed near nadir, the 5-color map was acquired pointed at a nearly uniform phase angle near 30 degrees to minimize shadowing at the high latitudes of the Northern Volcanic Plains.

MDIS 5-color imaging of Mercury is mosaicked into a single 128 pixel/degree tile. This tile corresponds to the pre-existing Mercury chart H01, plus the northern part of the chart to the immediate south, H02-H05.

Mercury Charts overlapped by the MAPMP5, as named at the end of mission delivery:


Filename Identifier

Latitude (degrees)

Longitude (degrees east)

H-1 Borealis


65 to 90

0 to 360

H-2 Victoria


22.5 to 65

270 to 360

H-3 Shakespeare


22.5 to 65

180 to 270

H-4 Raditladi


22.5 to 65

90 to 180

H-5 Hokusai


22.5 to 65

0 to 90

MDIS observing variables pertaining to the MAPMP5 are the following:

  • Pixel Binning: Some images are unbinned and 1024 x 1024 pixels. Some images are 2x2 pixel binned in the focal plane hardware (also known as “on-chip” binning), resulting in 512 x 512 images. Images can be further compressed 2x2 using the Main Processor (MP), in addition to Data Processing Unit (DPU) binning, yielding 256 x 256 images. Images used in 5-color MAPMP5 products are mostly not binned although some taken at the lowest altitudes are binned 2x2 “on-chip”. This less aggressive binning strategy than in the 8-color map results in nearly a 2.5x reduction in the average native pixel scale of the data.

  • 12-8 bit compression: Images are read off the detector in 12-bit format. 12 bit images may be converted to 8-bit images using one of eight lookup tables (LUTs). All WAC images collected as part of the 5-color multispectral map have been converted to 8 bits.

  • FAST/DPCM compression: All images are compressed losslessly using FAST/DPCM compression as they are read out of the DPU, to conserve recorder space. Once the data are written to the recorder, they can be uncompressed and recompressed more aggressively in the spacecraft MP.

  • Wavelet compression: Images may be integer wavelet transform-compressed in the MP, typically at 3:1 for color data. Color imaging was taken losslessly compressed when downlink volume permitted it.

  • Exposure Control: The exposure time of MDIS images can be set manually by command, or automatically by the software. In manual mode, exposure times from 1-989, 1001-1989, …, to 9001-9989 ms are available. In autoexposure mode the exposure time of the next image is computed by the DPU software, and cannot exceed 989 ms in duration. If the time of the next image occurs before the calculation can be completed, and pixel binning or filter position change, then the algorithm compensates for predicted changes in scene brightness and filter transmission using an onboard data structure. All images in the MAPMP5 were acquired using automatic exposure.

  • Pointing: The MDIS imagers are mounted on a pivot platform, which is itself mounted to the MESSENGER spacecraft deck. The pivot platform is controlled by a stepper motor, which is controlled by the DPU. The pivot platform can move in either direction. The total range of motion is 240 degrees, limited by mechanical “hard” stops, and is further constrained by “soft” stops applied by the software. The nominal pointing position for MDIS is defined as 0 degrees, aligned with the spacecraft +Z axis and the boresight for several other instruments. The range of the soft stops is set to 40 degrees in the spacecraft –Y direction (toward the MESSENGER sunshade) and +50 degrees in the +Y direction (away from the sunshade). The pivot position can be commanded in intervals of 0.01 degrees within this range. During acquisition of the 5-color multispectral map, the pivot was used to point the WAC to low emission angles on the surface, at times when the solar incidence angle was close to the lowest values possible at that latitude.

  • Filter selection: The WAC imager contains a 12-position filter wheel to provide spectral imaging over the spectral range of the CCD detector. Five of the filters were chosen for the map and appear in the MAPMP5 in order of increasing wavelength:

    • WAC filter 6 (filter F), 430 nm, BP 40

    • WAC filter 4 (filter D), 560 nm, BP 5

    • WAC filter 7 (filter G), 750 nm, BP 5

    • WAC filter 12 (filter L), 830 nm, BP 5

    • WAC filter 9 (filter I), 1000 nm, BP 15

The MAPMP5 product is named MDIS_MP5_128PPD_H01NP1.IMG, with its corresponding label file.

In ODE, the MAPMP5 product has the following product ID: