MESSENGER VIRS Spectral Cube of Mercury (MEAP-1)

MEAP1 – VIRS Spectral Cube Derived Analysis Product

Instrument: Mercury Atmospheric and Surface Composition Spectrometer

PDS Bundle: urn:nasa:pds:izenberg_pdart14_meapDOI: 10.17189/1518648

PDS Collection: urn:nasa:pds:izenberg_pdart14_meap:data_imagecube

For more information about MEAP products, see the Messenger Advanced Product Specification.

The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) Visible and Infrared Spectrograph (VIRS) Spectral Cube Derived Analysis Product (MEAP1) consists of VIRS spectral data map-projected, photometrically normalized, and mosaicked into hyperspectral map tiles. There are 54 non-overlapping, 64 pixel/degree tiles similar to the Mercury Dual Imaging System (MDIS) 8-color image of Mercury (RDRMDR).

Individual footprint pixels where VIRS data exists are determined by ‘best’ VIRS spectra, determined by a quality factor using favorable geometry [max(cos(e)*cos(i)), e = emission angle, i = incidence angle] and spatial coverage (smaller footprints are given higher quality factor).

Data are corrected photometrically to incidence angle = 45 degrees, emission angle = 45 degrees, phase angle = 90 degrees, at a resolution of 64 pixels per degree (~665 meters per pixel at the equator). Hyperspectral data is composed of up to 105 spectral bands corresponding to 105 binned wavelengths of the VIRS spectrum from 300 to 1450 nm, with ~9.3 nm wavelength bins between 300 and 900 nm and ~14 nm wavelength bands between 900 and 1450 nm.

There are 8 backplanes for the hyperspectral data:

  1. Incidence angle of the original spectrum

  2. Emission angle of the original spectrum

  3. Phase angle of the original spectrum

  4. Observation area of the VIRS spectrum

  5. Temperature of the NIR detector

  6. VIRS Calibrated Data Record (VIRSCDR) date (YYDOY)

  7. VIRSCDR time (HHMMSS)

  8. VIRSCDR spectrum number

The wavelength file is an ASCII file with the layer numbers and wavelengths of the spectral layers of the VIRS Cube. The file is named VIRS_WAVELENGTHS.TAB.

MEAP1 products have the following file names:

VIRS_CUBE_64PPD_Hxxdd.IMG

where:

64PPD = map scale, 64 pixels per degree

Hxx = Mercury chart designation

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

MEAP1 PDS4 Logical Identifiers:

urn:nasa:pds:izenberg_pdart14_meap:data_imagecube:virs_cube_64ppd_hxxdd

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

Quadrangle

Designation

Latitude (degrees)

Longitude (degrees east)

H-1 Borealis

H01

65 to 90

0 to 360

H-2 Victoria

H02

22.5 to 65

270 to 360

H-3 Shakespeare

H03

22.5 to 65

180 to 270

H-4 Raditladi

H04

22.5 to 65

90 to 180

H-5 Hokusai

H05

22.5 to 65

0 to 90

H-6 Kuiper

H06

-22.5 to 22.5

288 to 360

H-7 Beethoven

H07

-22.5 to 22.5

216 to 288

H-8 Tolstoj

H08

-22.5 to 22.5

144 to 216

H-9 Eminescu

H09

-22.5 to 22.5

72 to 144

H-10 Derain

H10

-22.5 to 22.5

0 to 72

H-11 Discovery

H11

-65 to -22.5

270 to 360

H-12 Michelangelo

H12

-65 to -22.5

180 to 270

H-13 Neruda

H13

-65 to -22.5

90 to 180

H-14 Debussey

H14

-65 to -22.5

0 to 90

H-15 Bach

H15

-90 to -65

0 to 360