PDS_VERSION_ID                = PDS3
RECORD_TYPE                   = STREAM
OBJECT                        = TEXT
  PUBLICATION_DATE            = 2000-07-13
  NOTE                        = "Description of the DATA
     directory contents on MGS MOLA PEDR archive volumes"
END_OBJECT                    = TEXT
END


                   DATA Directory Contents

     The DATA directory contains MOLA PEDR, EGDR, and SHADR data 
products in three subdirectories. 

     The EGDR subdirectory contains the MOLA global topographic 
gridded product at two resolutions. IEG100_A.TAB is gridded using
a bin size of 1 degree of latitude by 1 degree of longitude.
IEG050_A.TAB uses a bin size of 0.5 by 0.5 degree. Both files are
in the form of an ASCII table with one line for each bin. Both
are described by detached PDS labels, IEG100_A.LBL and IEG050_A.LBL.
The "A" in the file name represents the version of the product.

     The PEDR subdirectory contains binary data files with attached
PDS labels. The file names have the format APnnnnnv.B, in which
nnnnn is the orbit number and v is a letter representing the product
version. The orbit number is equal to the MGS Project orbit number
plus 10000. (This is done to ensure a unique product ID; MGS orbit
numbers started over at 1 at the beginning of the Mapping Phase, but
MOLA had already acquired data before the Mapping Phase using the
pre-mapping orbit number as part of the product ID.) PEDR data files
acquired during the Mapping Phase are aggregated by day; therefore
one PEDR file contains multiple orbits.

     The SHADR subdirectory contains the MOLA spherical harmonics
topography model. The model is a numerical transform of the MOLA
MOLA 0.5-degree EGDR into spherical harmonics using Simpson's Rule
quadrature. It consists of two ASCII tables, a header table and
a coefficients table, contained in the file GTM070AA.SHA and described
by a detached PDS label in GTM070AA.LBL.