PDS_VERSION_ID                  = PDS3 



RECORD_TYPE                     = STREAM

SPACECRAFT_NAME                 = "CLEMENTINE 1"

TARGET_NAME                     = MOON

OBJECT                          = TEXT

  PUBLICATION_DATE              = 1996-01-01

  NOTE                          = "CLEMENTINE GRAVITY AND TOPOGRAPHY

                                    DATA ARCHIVE"

END_OBJECT                      = TEXT

END





              CLEMENTINE GRAVITY AND TOPOGRAPHY DATA ARCHIVE







1.  Introduction



This archive contains gravity and topography data from the Clementine

Mission to the Moon.  The gravity products resulted from the

processing of radio tracking data of the spacecraft, and topographic

information was acquired by a laser ranging instrument (LIDAR).



The topographic data products were produced by Maria T. Zuber,

Massachusetts Institute of Technology, Cambridge, MA, David E. Smith,

NASA/Goddard Space Flight Center, Greenbelt, MD, and Gregory A.

Neumann, John Hopkins University, Baltimore, MD.  The gravity data

were produced by Frank G. Lemoine, NASA/Goddard Space Flight Center,

Greenbelt, MD.



Supporting documentation and label files conform to the Planetary Data

System (PDS) Standards, Version 3.0, Jet Propulsion Laboratory (JPL)

document JPL D-7669.







2.  File Formats



The data files are in three formats:  array, image, and tabular.  The

array formats are 2-dimensional ASCII global grids of 180 lines by 360

samples (i.e. 1 degree resolution) or 720 lines by 1440 samples (i.e.

0.25 degree resolution).  These files are described by detached PDS

labels.



There are also images of each of the gridded ASCII data files. 

Each image is 180 lines by 360 samples or 720 lines by 1440 samples,

with one byte per sample.  The images are described by detached PDS

labels.



Tabular files are formatted so that they may be read directly into

many software analysis systems on various computers.  All fields are 

separated by commas, and character fields are enclosed in double

quotation marks (").  Character fields are left justified, and numeric 

fields are right justified.  The "start byte" and "bytes" values

listed in the labels do not include the commas between fields or the

quotation marks surrounding character fields.  The records are of

fixed length, and the last two bytes of each record contain the ASCII

carriage return and line feed characters.  This allows a table to be

treated as a fixed length record file on computers that support this

file type and as a normal text file on other computers.



All document files and detached label files contain stream format

records, with a carriage return character (ASCII 13) and a line feed

character (ASCII 10) at the end of each line.  This allows the files

to be read by the MacOS, DOS, Unix, and VMS operating systems.  All

tabular files are also described by PDS detached labels.  The detached

PDS label file has the same name as the data file it describes, with

the extension .LBL; for example, the file GLGM2.TAB is accompanied by

the detached label file GLGM2.LBL in the same directory.



PDS labels are object-oriented.  The object to which the label refers

(e.g., IMAGE, TABLE, etc.) is denoted by a statement of the form:



       ^object = location



in which the carat character (^, also called a pointer in this

context) indicates that the object starts at the given location.  In

an attached label, the location is an integer representing the

starting record number of the object (the first record in the file is

record 1).  In a detached label, the location denotes the name of the

file containing the object, along with the starting record or byte

number.  For example:



       ^IMAGE = "THICKGRD.IMG" 



indicates that the IMAGE object points to the file THICKGRD.IMG, in

the same directory as the detached label file.  Below is a list of the

possible formats for the ^object keyword.



       ^object = n

       ^object = n<BYTES>

       ^object = "filename.ext"

       ^object = ("filename.ext",n)

       ^object = ("filename.ext",n<BYTES>)



where



       n         is the starting record or byte number of the object,

                 counting from the beginning of the file (record 1,

                 byte 1)

       <BYTES>   indicates that the number given is in units of bytes

       filename  is the upper-case file name

       ext       is the upper-case file extension







3.  Archive Contents



The files in this archive are organized in one top-level directory

with several subdirectories.  The following table shows the structure

and content of these directories.  In the table, directory names are

enclosed in square brackets ([]), upper-case letters indicate an

actual directory or file name, and lower-case letters indicate the

general form of a set of directory or file names.





   FILE                  CONTENTS



Top-level directory

    |

    |- AAREADME.TXT       The file you are reading.

    |

    |- VOLDESC.CAT        A description of the archive contents.

    |

    |- [CATALOG]          A directory containing PDS catalog objects,

    |   |                 and information about the gravity and

    |   |                 topography data sets.

    |   |

    |   |- CATINFO.TXT    Description of files in the CATALOG

    |   |                 directory.

    |   |

    |   |- DSMAP.CAT      A description of the simple cylindrical

    |   |                 map projection.

    |   |

    |   |- MISSION.CAT    A brief description of the mission.  It

    |   |                 includes a chronology of events, definition

    |   |                 of mission phases, and science objectives.

    |   |

    |   |- INSTHOST.CAT   A description of the Clementine spacecraft

    |   |                 and a very brief overview of the NASA Deep

    |   |                 Space Network.

    |   |

    |   |- RSSINST.CAT    An overview of the spacecraft radio science

    |   |                 system on Clementine, and a summary

    |   |                 description of the Deep Space Network

    |   |                 instrumentation which support radio science

    |   |                 experiments.

    |   |

    |   |- LSRINST.CAT    An overview of the Laser Rangefinder (LIDAR)

    |   |                 instrument used for obtaining topographic

    |   |                 data.

    |   |

    |   |- RSSDS.CAT      PDS data set catalog object.  A description

    |   |                 of the gravity data set, parameters,

    |   |                 processing, data coverage/quality.

    |   |

    |   |- LSRDS.CAT      PDS data set catalog object.  A description

    |   |                 of the topography data set, parameters,

    |   |                 processing, data coverage/quality.

    |   |

    |   |- REF.CAT        A listing of references used elesewhere in

    |   |                 the catalog objects and of references

    |   |                 that might be generally useful in working

    |   |                 with these data.

    |   |

    |   |- PERSON.CAT     A listing of key people involved in

    |                     generating and processing the archival data

    |                     set.

    |

    |- [DOCUMENT]         A directory containing document files

    |   |                 relating to this archive.

    |   |

    |   |- DOCINFO.TXT    Description of files in the DOCUMENT

    |   |                 directory.

    |   |

    |   |- VOLINFO.TXT    A description of the format and content 

    |                     of each of the data sets, and background

    |                     information and references needed to

    |                     understand the data set processing

    |                     histories.

    |

    |- [GRAVITY]          A directory containg gravity data files

    |   |                 and PDS detached labels.

    |   |

    |   |- BOUGGRD.DAT    A 180 line by 360 sample ASCII array of

    |   |                 Bouguer gravity anomalies.

    |   |

    |   |- BOUGGRD.LBL    A PDS detached label describing BOUGGRD.DAT.

    |   |

    |   |- FAIRGRD1.DAT   A 180 line by 360 sample ASCII array of

    |   |                 free-air gravity anomalies.

    |   |

    |   |- FAIRGRD1.LBL   A PDS detached label describing

    |   |                 FAIRGRD1.DAT.

    |   |

    |   |- FAIRGRD2.DAT   A 720 line by 1440 sample ASCII array of

    |   |                 free-air gravity anomalies.

    |   |

    |   |- FAIRGRD2.LBL   A PDS detached label describing

    |   |                 FAIRGRD2.DAT.

    |   |

    |   |- FAIRERR1.DAT   A 180 line by 360 sample ASCII array of

    |   |                 free-air gravity anomaly errors.

    |   |

    |   |- FAIRERR1.LBL   A PDS detached label describing

    |   |                 FAIRERR1.DAT.

    |   |

    |   |- FAIRERR2.DAT   A 720 line by 1440 sample ASCII array of

    |   |                 free-air gravity anomaly errors.

    |   |

    |   |- FAIRERR2.LBL   A PDS detached label describing

    |   |                 FAIRERR2.DAT.

    |   |

    |   |- GEOIDGRD.DAT   A 180 line by 360 sample ASCII array of

    |   |                 Geoid anomalies.

    |   |

    |   |- GEOIDGRD.LBL   A PDS detached label describing

    |   |                 GEOIDGRD.DAT.

    |   |

    |   |- GEIODERR.DAT   A 180 line by 360 sample ASCII array of

    |   |                 Geoid anomaly errors.

    |   |

    |   |- GEOIDERR.LBL   A PDS detached label describing

    |   |                 GEOIDERR.DAT.

    |   |

    |   |- GLGM2SH.TAB    A 70-th degree and order spherical

    |   |                 harmonic gravitational field model.

    |   |

    |   |- GLGM2SH.LBL    A PDS detached label describing GLGM2SH.TAB.

    |   |

    |   |- THICKGRD.DAT   A 180 line by 360 sample ASCII array of

    |   |                 effective crustal thicknesses.

    |   |

    |   |- THICKGRD.LBL   A PDS detached label describing

    |                     THICKGRD.DAT.

    |

    |- [IMAGES]           A directory containing byte-scaled images

    |   |                 of the data files in the GRAVITY and

    |   |                 TOPO directories, and PDS detached labels.

    |   |

    |   |- BOUGGRD.IMG    A 180 line by 360 sample image of

    |   |                 Bouguer gravity anomalies.

    |   |

    |   |- BOUGGRD.LBL    A PDS detached label describing

    |   |                 BOUGGRD.IMG.

    |   |

    |   |- FAIRGRD1.IMG   A 180 line by 360 sample image of

    |   |                 free-air gravity anomalies.

    |   |

    |   |- FAIRGRD1.LBL   A PDS detached label describing

    |   |                 FAIRGRD1.IMG.

    |   |

    |   |- FAIRGRD2.IMG   A 720 line by 1440 sample image of

    |   |                 free-air gravity anomalies.

    |   |

    |   |- FAIRGRD2.LBL   A PDS detached label describing

    |   |                 FAIRGRD2.IMG.

    |   |

    |   |- FAIRERR1.IMG   A 180 line by 360 sample image of

    |   |                 free-air gravity anomaly errors.

    |   |

    |   |- FAIRERR1.LBL   A PDS detached label describing

    |   |                 FAIRERR1.IMG.

    |   |

    |   |- FAIRERR2.IMG   A 720 line by 1440 sample image of

    |   |                 free-air gravity anomaly errors.

    |   |

    |   |- FAIRERR2.LBL   A PDS detached label describing

    |   |                 FAIRERR2.IMG.

    |   |

    |   |- GEOIDGRD.IMG   A 180 line by 360 sample image of

    |   |                 Geoid anomalies.

    |   |

    |   |- GEOIDGRD.LBL   A PDS detached label describing

    |   |                 GEOIDGRD.IMG.

    |   |

    |   |- GEOIDERR.IMG   A 180 line by 360 sample image of

    |   |                 Geoid anomaly errors.

    |   |

    |   |- GEOIDERR.LBL   A PDS detached label describing

    |   |                 GEOIDERR.IMG.

    |   |

    |   |- THICKGRD.IMG   A 180 line by 360 sample image of

    |   |                 effective crustal thicknesses.

    |   |

    |   |- THICKGRD.LBL   A PDS detached label describing

    |   |                 THICKGRD.IMG.

    |   |

    |   |- TOPOGRD1.IMG   A 180 line by 360 sample image of

    |   |                 topography.

    |   |

    |   |- TOPOGRD1.LBL   A PDS detached label describing

    |   |                 TOPOGRD1.IMG.

    |   |

    |   |- TOPOGRD2.IMG   A 720 line by 1440 sample image of

    |   |                 topography.

    |   |

    |   |- TOPOGRD2.LBL   A PDS detached label describing

    |                     TOPOGRD2.IMG.

    |

    |- [TOPO]             A directory containing topographic data

        |                 and PDS detached labels.

        |

        |- GLTM2BPR.TAB   A file containing topographic profiles

        |                 and related data along each orbit.

        |

        |- GLTM2BPR.LBL   A PDS detached label describing

        |                 GLTM2BPR.TAB.

        |

        |- GLTM2BSH.TAB   A 70-th degree and order spherical

        |                 harmonic topographic field model.

        |

        |- GLTM2BSH.LBL   A PDS detached label describing

        |                 GLTM2BSH.TAB.

        |

        |- TOPOGRD1.DAT   A 180 line by 360 sample ASCII array of

        |                 topography.

        |

        |- TOPOGRD1.LBL   A PDS detached label describing

        |                 TOPOGRD1.DAT.

        |

        |- TOPOGRD2.DAT   A 720 line by 1440 sample ASCII array of

        |                 topography.

        |

        |- TOPOGRD2.LBL   A PDS detached label describing

                          TOPOGRD2.DAT.







4.  Ancillary Data



A useful product for understanding the errors in the gravity solution

is the gravity field covariance matrix.  The gravity field covariance

represents the complete error description for the GLGM-2 gravity field

solution, including the coefficient variances (sigmas^2), and the

correlations between all the coefficients.  It is a product of the

least squares solution that derived GLGM-2.  The covariance provides a

more complete description of the error associated with the GLGM-2

gravity field solution, than would be available from the sigmas alone.

The covariance matrix is large (311 MB) since it contains the

correlations of each of the solution parameters with all the other

parameters. (GLGM-2 solved for 5106 spherical harmonic coefficients,

and the lunar GM value). The full covariance matrix was used to

compute the error maps for the gravity anomalies, and geoid anomalies

that are associated with this archive. The covariance matrix is

available on request from the PDS Geoscience Node (contact Jim

Alexopoulos at 314-935-8152 or jim@wuzzy.wustl.edu) or NASA Goddard

Space Flight Center (contact Frank G. Lemoine at

301-286-2460 or flemoine@olympus.gsfc.nasa.gov).







5.  Whom to Contact for Information



     For questions concerning this archive, data products, associated

     PDS labels and documentation:



              Jim Alexopoulos

              Washington University

              Dept. of Earth and Planetary Sciences

              1 Brookings Drive

              Campus Box 1169

              St. Louis, MO 63130

              314-935-8152 



              Electronic mail address:

              Internet:  jim@wuzzy.wustl.edu





     For questions about the gravity data set:



              Frank G. Lemoine

              NASA Goddard Space Flight Center

              Code 926, Space Geodesy Branch

              Greenbelt, MD 20771

              301-286-2460



              Electronic mail address:

              Internet:  flemoine@olympus.gsfc.nasa.gov





     For more information about the topography data set:



              Maria T. Zuber

              Massachusetts Institute of Technology

              Department of Earth, Atmospheric and 

                Planetary Sciences

              54-518

              Cambridge, MA 02139-4307

              617-253-6397



              Electronic mail address:

              Internet:  zuber@mit.edu





              David E. Smith

              NASA Goddard Space Flight Center

              Laboratory for Terrestrial Physics

              Greenbelt, MD 20771

              301-286-8671



              Electronic mail address:

              Internet:  dsmith@tharsis.gsfc.nasa.gov





              Gregory A. Neumann

              John Hopkins University

              Dept of Earth and Planetary Sciences

              Baltimore, MD 21218

              410-516-4236



              Electronic mail address:

              Internet:  gregory.neumann@jhu.edu







 This archive was produced by Jim Alexopoulos.