PDS_VERSION_ID          = PDS3
RECORD_TYPE             = STREAM
OBJECT                  = TEXT
  PUBLICATION_DATE      = 2000-02-07
  NOTE                  = "Description of the RS directory contents"
END_OBJECT              = TEXT
END



     The RS directory contains archival radio science results from the
Mars Global Surveyor (MGS) mission.  Data products in this directory
contain results from radio occultation and gravity investigations
carried out by members of the MGS Radio Science Team (RST).  

     The Mars gravity field was derived from radio tracking data
collected through March 1999.  The model derived under the direction
of W.L. Sjogren at the Jet Propulsion Laboratory (file JGM75B01.SHA in
the SHA directory) includes coefficients to degree and order 75; it is
based on Viking Orbiter 1 and 2 data as well as MGS.  The model
derived under the direction of D.E. Smith at Goddard Space Flight
Center (file GGM0964A.SHA in the SHA directory) includes coefficients
to degree and order 70; it is based solely on MGS data.  The JPL group
has also provided their model in binary format with covariances (SHB
directory).

     There are several different radio science data types included on
this volume including gravity determinations derived from radio
tracking data and atmospheric temperature-pressure profiles from radio
occultation observations.  Each data type is stored in a separate
subdirectory as listed below.  Each data product has a detached PDS
label.

BRO

     Files in the BRO directory are snapshots of gravity products
included in this volume.  The BRO directory contains PostScript
representations of both gridded products from the Goddard group.

IMG

     Both gravity investigation teams have provided gridded products (IMG
directory) showing gravity anomaly referenced to their model evaluated to
degree and order 50.  The Goddard group has also provided a grid of gravity
anomaly uncertainties.  The JPL group has provided a grid of geoid height
above a reference ellipsoid.  All grids have one degree point spacing and
use a simple cylindrical projection. 

OCS

     Files in the OCS directory are occultation summary files for
standard resolution.  These data products contains information
extracted from the temperature-pressure profile data products (TPS).

SHA

     Files in the SHA directory contain spherical harmonic models of
the gravity field in ASCII format.

SHB

    Files in the SHA directory contain spherical harmonic models of
the gravity field in binary format.

TPS_xxxx

    Files in the TPS_1001 and TPS_1003 directory are atmospheric
temperature-pressure profiles at standard resolution derived from
radio occultation observations.  Files in the TPS_1001 directory were
taken from Radio Science volume MORS_1001, whereas files in the
TPS_1003 directory were originally found on Radio Science volume
MORS_1003.  Radio occultation profiles of temperature and pressure
derived from data collected in 1998.