MESSENGER MDIS Map-projected Multispectral Reduced Data Record (RDRMDR)

RDRMDR – Map-projected Multispectral Reduced Data Record

Instrument: MESSENGER Mercury Dual Imaging System

PDS Data Set ID:MESS-H-MDIS-5-RDR-MDR-V1.0DOI: 10.17189/1520178

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

The Mercury Dual Imaging System (MDIS) Map-projected Multispectral Reduced Data Record (RDRMDR) data products comprise a global color map of I/F in the 8 filters used for multispectral mapping during the primary mission, photometrically normalized to a solar incidence angle, i=30°, emission angle, e=0°, and phase angle, g=30°, at a special sampling of 64 pixels per degree. The map is divided into 54 non-overlapping segments or “tiles”. Each tile is composed of 8 bands corresponding to 8 of the 11 Wide-angle camera (WAC) filters and contains backplanes describing ancillary information. The subset of 8 of 11 available multispectral filters was selected on account of limitations in MESSENGER Solid-State Recorder (SSR) space, and more or less evenly samples the spectral range of MDIS.

MDIS 8-color imaging of Mercury is mosaicked into tiles that correspond to the NW, NE, SW, or SE quadrants of one of the 13 non-polar, or one of the 2 polar quadrangles or “Mercury charts” already defined by the U.S. Geological Survey (USGS), shown in the table below.

Mercury Charts, 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

H-6 Kuiper


-22.5 to 22.5

288 to 360

H-7 Beethoven


-22.5 to 22.5

216 to 288

H-8 Tolstoj


-22.5 to 22.5

144 to 216

H-9 Eminsecu


-22.5 to 22.5

72 to 144

H-10 Derain


-22.5 to 22.5

0 to 72

H-11 Discovery


-65 to -22.5

270 to 360

H-12 Michelangelo


-65 to -22.5

180 to 270

H-13 Neruda


-65 to -22.5

90 to 180

H-14 Debussey


-65 to -22.5

0 to 90

H-15 Bach


-90 to -65

0 to 360

MDIS observing variables pertaining to the RDRMDRs 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. Some images are further compressed 2x2 using the spacecraft Main Processor (MP), yielding 256 x 256 images. Images taken at lower altitude have more pixel binning, to control the volume of data collected for the global map.

  • 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 8 lookup tables (LUTs). All images collected as part of the global basemap 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 Data Processing Unit (DPU), to conserve recorder space. Once the data are written to the recorder, they may have been uncompressed and recompressed more aggressively in the MP.

  • Wavelet compression: Images may be integer wavelet transform-compressed in the MP, typically at 3:1 for color data and 8:1 for monochrome data. The wavelet compression ratio for color images is 3:1 for global mapping. 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.

  • 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 global 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. Eight of the filters were chosen for the map and appear in the RDRMDR in order of increasing wavelength:

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

    • WAC filter 3 (filter C), 480 nm, BP 10

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

    • WAC filter 5 (filter E), 630 nm, BP 5

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

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

    • WAC filter 10 (filter J), 900 nm, BP 5

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

MDIS RDRMDR products have the following file names:

MDIS_MDR_064PPD_Hxxddv.IMG (with detached PDS label)


MDIS = instrument = Mercury Dual Imaging System

BDR = product type = Basemap Reduced Data Record

064PPD = resolution in pixels/degree

Hxx = Mercury chart designation

dd = quadrant within Mercury chart (NW, NE, SW, or SE), or a polar chart (NP, SP)

v = version number

Additionally, there is a redundant tile covering the south polar region that has a modified nomenclature, reflecting that it includes reduced-resolution (to 2700m/pixel) images in order to fill a coverage gap in the nominal tile. It is named MDIS_MDR_064PPD_2700_H15SP4.IMG, with corresponding label file.

In ODE, RDRMDR products have the following product IDs: