PDS_VERSION_ID                   = PDS3
LABEL_REVISION_NOTE              = "S. SLAVNEY, 2000-05-15" 
RECORD_TYPE                      = STREAM

OBJECT                           = DATA_SET
 DATA_SET_ID                     = "MGS-M-MOLA-5-SHADR-V1.0"

 OBJECT                          = DATA_SET_INFORMATION
  DATA_SET_NAME                  = "MOLA SPHERICAL HARMONICS  
                                   TOPOGRAPHY MODEL"
  DATA_SET_COLLECTION_MEMBER_FLG = "N"
  START_TIME                     = 1997-09-15T19:10:00.000
  STOP_TIME                      = 1999-08-31T23:59:59.999
  DATA_OBJECT_TYPE               = FILE
  DATA_SET_RELEASE_DATE          = 2000-03-31
  PRODUCER_FULL_NAME             = "GREG NEUMANN"
  DETAILED_CATALOG_FLAG          = "N"
  DATA_SET_DESC                  = "


  Data Set Overview
  =================
  The Mars Global Surveyor spacecraft included a laser altimeter
  instrument. The primary objective of the Mars Orbiter Laser
  Altimeter (MOLA) is to determine globally the topography of Mars at
  a level suitable for addressing problems in geology and geophysics.

  The MOLA Spherical Harmonics Topography Model (SHADR) is a numerical
  transform of the MOLA Experiment Gridded Data Record (EGDR), a global
  topography data set. See the MOLA EGDR Software Interface
  Specification [MOLAEGDRSIS1999] and the PDS Catalog entry for the EGDR
  data set (MGS-M-MOLA-5-IEGDR-L3-V1.0) for a description of the EGDRs.

  The MOLA SHADR follows the general format of Spherical Harmonics ASCII
  Data Records defined in the SHADR SIS [SIMPSON1999]. The SHADR was
  defined initially for gravity models derived from Magellan and Mars
  Observer radio tracking data, but the format has been generalized to
  be suitable for spherical harmonic expansions of gravity, topography,
  magnetic, and other fields.

  This Mars topography model was produced by Greg Neumann under the
  direction of David E. Smith, MOLA Principal Investigator.  

  Further improvements to the model are expected as additional MGS data
  are incorporated.


  Data
  ====

  The MOLA SHADR is in the form of two ASCII tables, a header table and
  a coefficients table, contained in a single file with a detached PDS
  label.  The header table consists of a single record of eight data
  columns that contain descriptive information about the coefficients
  table. The columns include the assumed gravitational constant, the
  uncertainty in the constant, the degree and order of the model field,
  the reference longitude and latitude for the spherical harmonic
  expansion, and a normalization indicator. A column for the assumed
  reference radius of the planet is also included for consistency with
  the general SHADR format, but it is not used or needed for the model.

  The EGDR that was the source of the SHADR data set included all MOLA
  nadir observations from the Orbit Insertion phase, plus Mapping Phase
  nadir observations from the beginning of mapping through the end of
  August 1999.  Additionally, off-nadir observations of the north pole
  were included from 87 N latitude and northward, taken during the
  spring of 1998, and of both poles taken in July of 1999, from 87 N and
  S to the poles.  Orbits 355 and 358 of the Orbit Insertion Phase and
  parts of orbits 10709 through 10716, inclusive, of the Mapping Phase
  were excluded because solutions for these orbits were deemed to be
  poor. (Note: subtract 10000 from a MOLA mapping phase orbit number to
  determine the equivalent MGS Project orbit number.)  Also excluded
  were shots more than 1 degree off-nadir (except as noted above),
  channel 4 returns, and any returns not classified as ground returns,
  e.g. clouds or noise, according to the SHOT_CLASSIFICATION_CODE. A
  total of approximately 123 million observations are represented in
  the EGDR.


  Parameters
  ==========
  N/A


  Processing
  ==========
  See the PDS Catalog entries for the MOLA EGDR and PEDR data sets
  for a description of the processing applied to the data from which
  this SHADR is derived.


  Ancillary Data
  ==============
  N/A


  Coordinate System
  =================
  The coordinate system is IAU 1991 (Davies et al., Celestial Mechanics
  and Dynamical Astronomy, 53, 377-397, 1992 [DAVIESETAL1992B]),
  areocentric, with longitudes measured positive east.


  Software
  =======
  N/A


  Media/Format
  ============
  The MGS MOLA SHADR dataset is available on CD-ROM and
  electronically via the PDS Geosciences Node web site at
  http://wwwpds.wustl.edu and the MOLA Science Team web site at
  http://ltpwww.gsfc.nasa.gov/tharsis/mola.html.  Formats are
  based on standards established by the Planetary Data System (PDS). "


  CONFIDENCE_LEVEL_NOTE = "

  See the confidence level notes in the PDS Catalog entries for the MOLA
  EGDR and PEDR data sets, from which this SHADR is derived."

 

 END_OBJECT                      = DATA_SET_INFORMATION

 OBJECT                          = DATA_SET_TARGET
  TARGET_NAME                    = MARS
 END_OBJECT                      = DATA_SET_TARGET

 OBJECT                          = DATA_SET_HOST
  INSTRUMENT_HOST_ID             = MGS
  INSTRUMENT_ID                  = MOLA
 END_OBJECT                      = DATA_SET_HOST

 OBJECT                          = DATA_SET_REFERENCE_INFORMATION
  REFERENCE_KEY_ID               = "DAVIESETAL1992B"
 END_OBJECT                      = DATA_SET_REFERENCE_INFORMATION
 
 OBJECT                          = DATA_SET_REFERENCE_INFORMATION
  REFERENCE_KEY_ID               = "MOLAEGDRSIS1999"
 END_OBJECT                      = DATA_SET_REFERENCE_INFORMATION
 
 OBJECT                          = DATA_SET_REFERENCE_INFORMATION
  REFERENCE_KEY_ID               = "SIMPSON1999"
 END_OBJECT                      = DATA_SET_REFERENCE_INFORMATION
 
END_OBJECT                       = DATA_SET

END