Data Set Information
DATA_SET_NAME MESSENGER E/V/H MLA 4 GDR DATA V1.0
DATA_SET_ID MESS-E/V/H-MLA-4-GDR-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION Resampled (binned), interpolated altimetry data products from the MESSENGER mission.
DATA_SET_DESCRIPTION
Data Set Overview
   =================
     The data set consists of gridded, resampled shape maps known as GDRs.
     The data product is an image object contained in a data file,
     and a detached PDS label file with a pointer to the data file
     as well as meta-data information.

     The values are planetary radii relative to a sphere with a defined
     offset, and counts giving the number of observations in each individual
     pixel, or zero where values are interpolated.

     The label file that accompanies each GDR defines the timespan over which
     the data values were collected, as well as the product creation time.

     The shape models are provided in PDS compliant IMG format at
     resolutions of 2^n pixels per degree in cylindrical equidistant
     projection, and in north polar stereographic projection at resolutions
     of integral numbers of meters, typically 250-1000, and a map at 64
     pixels per degree at the north pole, or 665.24 m. Pixels represent
     finite areas rather than discrete points, as scan-line raster images.
     The center of the upper left pixel is defined as line 1 and sample 1.
     Simple cylindrical images may extend from -180 to 180 degrees longitude
     or from 0 to 360 degrees longitude, positive East. A polar model is a
     square raster image whose four central pixels surround the north pole.
     The [LINE,SAMPLE]_PROJECTION_OFFSET elements are the pixel offset from
     line and sample (1.0, 1.0) to the map projection origin defined by the
     CENTER_LATITUDE and CENTER_LONGITUDE elements.

     The design of the MESSENGER mission [SOLOMONETAL 2007] and the ranging
     distance of the MLA allow for data collection primarily in the northern
     hemisphere, while sparse data were collected from the equator to 18 S.

     Dataset projections are given in DSMAP.CAT and DSMAP_POLAR.CAT.

     A geospatially labeled, JPEG2000 format product is additionally produced
     with accompanying XML and LBL files as an alternate format to the PDS
     IMG format. Pixel level information can be read from these files using
     an appropriate reader. The data providers do not provide support for
     commercially available data analysis products. Additionally, internally
     produced software for the visualization or interpretation of data
     products is not provided. Attention must be paid to the 0.5 scale factor
     that must be applied to digital numbers to obtain meters.

     A JPG file of the data product is also provided for user convenience.

     The density of observations accumulates over time, and warrants gridding
     at increasing resolution as coverage improves. As of the end of the
     nominal mapping mission, more than 50% of pixels at 1 x 1 degree
     resolution in the northern hemisphere had one or more data values.
     Orbital phases where ranging could reach below the equator provided
     some measurements to as far as 16.7 degrees south, and offnadir
     slews reached as far north as 89.98 degrees north. The density of
     observations is given in the accompanying altimetry counts images,
     where values greater than 0 indicate the number of successful ranges.

     The vertical resolution of the laser is approximately 30 cm. Horizontal
     resolution varies due to factors such as surface slope and roughness,
     the distance between the spacecraft and the surface, and the pointing
     angle of the altimeter.

     The lowest point observed is 2433.598 km, or -5.802 km relative to a
     2439.4 km datum at 28.104N, 56.349E in Rachmaninoff crater. The polar
     crater inside Prokofiev at 85.5N, 63.87E is nearly as deep (-5.64 km)
     although at a higher equipotential level.

     The highest area is 4.743 km, at 116.84 to 116.89 E, 30.31 to 30.34 N,
     on the rim crest surrounding Raditladi Crater.
DATA_SET_RELEASE_DATE 2017-05-12T00:00:00.000Z
START_TIME 2008-01-14T12:00:00.000Z
STOP_TIME 2015-04-30T12:00:00.000Z
MISSION_NAME MESSENGER
MISSION_START_DATE 2004-08-03T12:00:00.000Z
MISSION_STOP_DATE 2015-04-30T12:00:00.000Z
TARGET_NAME MERCURY
TARGET_TYPE PLANET
INSTRUMENT_HOST_ID MESS
INSTRUMENT_NAME MERCURY LASER ALTIMETER
INSTRUMENT_ID MLA
INSTRUMENT_TYPE LASER ALTIMETER
NODE_NAME Geosciences
ARCHIVE_STATUS ARCHIVED - ACCUMULATING
CONFIDENCE_LEVEL_NOTE
Data Confidence Note
     ====================

     As GDR products are constructed using RDR and CDR data records, the
     Data Confidence Notes in CDR_RDR_DS.CAT should be consulted.

     GDR topographic products have a data span from -18 to 89.98 degrees N
     latitude. This data release (entire mission through 04/30/2015)
     incorporates 27 million high-quality observations from 3279 orbital
     profiles for which values for topography range from -5.8 km to 4.75 km
     relative to a sphere of radius 2439.4 km.
CITATION_DESCRIPTION G. A. Neumann (GSFC), MESSENGER E/V/H MLA 4 GDR DATA V1.0, NASA Planetary Data System, 2013.
ABSTRACT_TEXT This data set contains gridded data products from the MESSENGER mission [SOLOMONETAL2007].
PRODUCER_FULL_NAME GREGORY A. NEUMANN
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