PDS_VERSION_ID          = PDS3
LABEL_REVISION_NOTE     = "2018-10-16 GEO:SHS Added pointer to README.TXT
                           for the PDS4 archive"
RECORD_TYPE             = STREAM
OBJECT                  = TEXT
  PUBLICATION_DATE      = 2017-05-12
  NOTE                  = "AAREADME.TXT describes this volume."
END_OBJECT              = TEXT
END

PLEASE NOTE: This archive has been migrated from PDS3 to PDS4. The
contents and directory structure of the PDS3 archive have not changed, 
but PDS4 metadata in the form of XML files have been added. 
The file README.TXT in the root directory has more information.
The file you are now reading, AAREADME.TXT, was written for the original
PDS3 archive and does not have information about the PDS4 additions.

---- Original contents of AAREADME.TXT are below this line. ----

MESSENGER Mercury Laser Altimeter Calibrated Reduced (RDR) and
Gridded (GDR) Data Archive

Prepared for the Geosciences Discipline Node of the Planetary Data System

========================================================================
Introduction
========================================================================

This volume contains Reduced Data Records (RDR), Gridded Data Records (GDR),
and associated ancillary files and documentation from the MESSENGER Mercury
Laser Altimeter (MLA) instrument.

The Reduced Data Record (RDR) contains the time-of-flight altimetric data
merged with the Spacecraft, Planet, Instrument, C-matrix and Events (SPICE)
archives of instrument orientation, spacecraft orbit position and pointing,
timing, planetary orientation and ephemerides to locate the MLA ranges in a
planetocentric center-of-mass coordinate system as well as inertial
coordinates tied to a celestial frame. One or more records are generated for
each laser shot due to noise concerns.

The Gridded Data Record (GDR) contains the binned, interpolated planetary
shape and planetopotential topography at appropriate sampling intervals. These
products are also sometimes referred to as the MLA Digital Elevation Model
(DEM) products or "MLA DEMs," but they are not to be confused with the
MESSENGER MDIS DEMs provided in another volume).

The RDRs are generated from the CDRs in V1.0 of this data set, and the GDR
from these RDRs (with some data taken from the V1.0 RDR data set as well).

A complete description of these products and the design of this volume is
given in the MLA CDR/RDR/GDR Software Interface Specification, "MESSENGER
Software Interface Specification for the Mercury Laser Altimeter Calibrated,
Reduced and Gridded Data Records." An electronic copy of this document is
located on this volume in DOCUMENT/MLA_RDRSIS.PDF. A description of the
processing that produced these products and how they relate to each other is
given in this volume in the document "MESSENGER MLA EDR-to-CDR-to-RDR/GDR
Processing" in DOCUMENT/MLA_EDR_TO_CDR_TO_RDR-GDR.PDF.

This volume is intended for the use of scientists and students in the
study of the geography and geochemistry of the planet Mercury. The data
may be used for research and publication.

Versions of This Data Set
----------------------------
The RDRs in this volume are derived from Calibrated Data Records (CDR) in
version 1.0 (data set ID: MESS-E/V/H-MLA-3/4-CDR/RDR-DATA-V1.0) of this data
set. The earlier, but still useful, versions of the RDRs are also found in the
V1.0 data set along with still fully valid corresponding RADR products and
GDRs.

The CDRs, RADRs, and pre-orbit RDRs in the V1.0 data set are still fully
valid. The on-orbit RDRs in the V1.0 data set are superseded by the ones in
this V2.0 data set, but are retained as they are still scientifically useful.

The GDRs in the MESS-E/V/H-MLA-4-GDR-V1.0 data set remain fully valid. The GDR
in this V2.0 data set complements, but does not replace any in the other set.
The GDR in this version of the data set is produced from the V2.0 RDR data.

The RDRs and GDR in the V2.0 data set were produced using spacecraft ephemeris
kernels (SPK) produced by the MLA team at Goddard Space Flight Center (GSFC).
These SPKs may be found in the PDS NAIF data archive at
https://naif.jpl.nasa.gov/pub/naif/pds/data/mess-e_v_h-spice-6-v1.0/ in
data set MESS-E/V/H-SPICE-6-V1.0. In the NAIF archive, these kernels are:
data/spk/msgr_<yymmdd>_<yymmdd>_recon_gsfc_<n>.bsp.

The RDRs and GDRs in the previous version (V1.0) of this data set were
produced using the mission spacecraft SPK
msgr_040803_150430_150430_od431sc_2.bsp also in the NAIF data set.

========================================================================
Volume Format
========================================================================

All science data are located in the CDR, RDR_RADR, and GDR directories. The 
INDEX directory contains a listing of all of the data products included on 
the volume. The CATALOG directory contains PDS documentation describing the
mission, spacecraft, instrument, and data set. These include:

  MISSION.CAT                   MESSENGER mission description
  INSTHOST.CAT                  MESSENGER spacecraft description
  MLAINST.CAT                   MLA instrument description
  CDR_RDR_DS.CAT                MLA calibrated and reduced data set
                                description
  GDR_DS.CAT                    MLA gridded data set description
  REF.CAT                       MESSENGER mission reference information,
                                including MLA references
  PERSON.CAT                    MLA personnel contact information

Additional information on volume organization is given in the CDR/RDR/GDR
SIS (described above), and in section the "Volume Contents" below.

========================================================================
File Formats
========================================================================

The RDR data files on this volume are provided in ASCII table format
(extension .TAB). The GDR data file is provided in binary image format
(extension .IMG). Each data file is also accompanied by a detached PDS label
file (extension .LBL), which is an ASCII file containing information
describing the data file and data record format.

Catalog files (extension .CAT) are provided in ASCII format.

Document files describing the volume and the data are given in ASCII and PDF
formats.

Text files and detached label files contain ASCII records, with a
carriage-return character (ASCII 13) and a line-feed character (ASCII 10) at
the end of the record. This format allows the files to be read on all major
contemporary operating systems. Note that while both label and catalog files
are ASCII, some operating systems will not recognize the .LBL and .CAT
extensions as ASCII types. It may be necessary to either remap these
extensions as ASCII in the system or text browser, or else to open the files
from within the text browser.

========================================================================
Volume Contents
========================================================================

Directory Structure and Contents for MLA RDR/GDR Data Archive Volume
data set ID MESS-E/V/H-MLA-3/4-CDR/RDR-DATA-V2.0.

The following illustration shows the directory structure overview for the
MLA CDR/RDR/RADR/GDR Data Archive Volume, which bears the PDS-assigned
volume ID MESSMLA_2101. This volume contains the MLA RADR and GDR data
products, supporting documentation, and any additional files required for the
volume to be compliant with PDS standards.

Directory Structure Overview

                                <ROOT>
                                  |
                                  |
   _______________________________|______________________________________
   |        |         |           |                 |         |         |
   |        |         |           |                 |         |         |
<LABEL>   <INDEX>  <CATALOG>  <DOCUMENT>        <RDR_RADR>  <GDR>   <EXTRAS>
                                  |                 |         |        |
                              <NAVASSMT>            |    _____|_       |
                    ______________|_______          |    |     |   <BROWSE>
                    |           |        |          |  <IMG>  <JP2>    |
              <RDR_PLTS>  <SPK_PLOTS>  <SPK>        |                <GDR>
                  |                                 |
             _____|_____         _______________|_________
             |         |         |       |      |        |
          <2014>     <2015>   <2011>  <2012>  <2013>   <...>
             |                                  |
        _____|_________                     ____|__________
        |      |      |                     |       |      |
     <MAY>   <JUN>  <...>                 <JAN>   <FEB>  <...>


Directory Contents:

<ROOT> Directory
   This is the top-level directory of the data volume. The following are
   files contained in the root directory.

AAREADME.TXT: General information file. Provides users with information
   about the MESSENGER MLA data products. Directs user to other documents on
   the volume containing more detailed information. This file.

VOLDESC.CAT: PDS file containing the VOLUME object. This gives a high level
   description of the contents of the volume. Information includes:
   production date, producer name and institution, volume ID, etc.

ERRATA.TXT: Text file for identifying and describing errors and/or anomalies
   found in the current volume. Any known errors for the associated volume
   will be documented in this file. Also contains any general release notes.

<DOCUMENT> Directory
   This subdirectory contains the documentation that will be needed in order
   to understand and analyze the MLA data products. Documents will be stored
   in PDF and TXT formats.

DOCINFO.TXT: Identifies and describes the function of each file in the
   DOCUMENT directory.
   
   <DOCUMENT/NAVASSMT> Subdirectory
      Contains a set of files that support the documentation of the navigation
      ephemeris correction measurements performed by the MLA team using MLA
      data from the low-altitude campaign conducted during the final months of
      the mission.

      NAVINFO.TXT: Describes the files in the navigation assessment
      documentation set.

      MLATRACKADJUSTMENTS_SUMMARY.PNG: Summary plot of the low-altitude
      campaign adjustments made to the spacecraft track based on MLA data.

      MLATRACKADJUSTMENTS_SUMMARY.LBL: Label for the summary plot file.

      MLATRACKADJUSTMENTS.TAB: A summary file of the adjustments made to the
      spacecraft position using nav orbits and MLA data
      
      MLATRACKADJUSTMENTS.LBL: Label for the summary file.
      
   <DOCUMENT/NAVASSMT/RDR_PLOTS> Subdirectory
      Contains plots of the MLA RDRs before and after corrections. This
      subdirectory is organized by year and month.
      
   <DOCUMENT/NAVASSMT/SPK_PLOTS> Subdirectory
      Contains plots of the corrections made to the spacecraft positions.

   <DOCUMENT/NAVASSMT/SPK_> Subdirectory
      Contains SPICE SPK kernels that contain fragments of the navigation
      team's predicted orbit solutions that were relevant to the time periods
      over which MLA data were used to evaluate spacecraft position.

MLA_RDRSIS.PDF: Specification For The Mercury Laser Altimeter CDR, RDR, RADR,
   and GDR products provided in Adobe PDF (.PDF) format.

MLA_RDRSIS.TXT: Specification For The Mercury Laser Altimeter Calibrated,
   Reduced and Gridded Data Records, provided in plain text (.TXT) format.
   Only the text is provided; for illustrations, tables, etc. the PDF
   version of the document should be consulted.

MLA_RDRSIS.LBL: The detached label for the MLA_RDRSIS files.

MLA_EDR_TO_CDR_TO_RDR-GDR.PDF: MESSENGER MLA EDR-to-CDR-to-RDR/GDR Processing
   document. This document describes the conversion of MLA EDR data to CDR,
   RDR (including radiometry [RADR]) and GDR data in Adobe PDF format.

MLA_EDR_TO_CDR_TO_RDR-GDR.TXT: MESSENGER MLA EDR-to-CDR-to-RDR/GDR Processing
   document. This document describes the conversion of MLA EDR data to CDR,
   RDR (including radiometry [RADR]) and GDR data in ASCII text format. Only
   the text is provided; for illustrations, tables, etc. the PDF version of
   the document should be consulted.

MLA_EDR_TO_CDR_TO_RDR-GDR.LBL: The detached label for the
   MLA_EDR_TO_CDR_TO_RDR-GDR files.

JP2INFO.TXT: Informational file that describes the JPEG 2000 versions of the
   GDR image products. Contains an attached PDS label. 


<CATALOG> Directory
   This subdirectory contains the catalog object files for the entire volume.
   The following files are included in the catalog subdirectory.

CATINFO.TXT: Identifies and describes of function of each file in the catalog
   directory.

DSMAP_POLAR.CAT: Parameter description for the polar stereographically
   projected gridded data.

RDR_DS.CAT: Describes the general content of the CDR/RDR dataset and
   includes information about the duration of the mission and the person or
   group responsible for producing the data.

GDR_DS.CAT: Describes the general content of the GDR dataset and includes
    information about the duration of the mission and the person or group
    responsible for producing the data.

MLAINST.CAT: Describes physical attributes of the MLA instrument and
    provides relevant references to published literature.

INSTHOST.CAT: Describes the MESSENGER spacecraft.

MISSION.CAT: Describes the scientific goals and objectives of the MESSENGER
   program. It also identifies key people and institutions.

REF.CAT: Contains the reference objects. These reference additional documents
   that may be useful to the person using the MLA products.

PERSON.CAT: Lists and provides contact information for the people involved
   with the MLA instrument.


<INDEX> Directory
   This subdirectory contains the indices for the MLA CDR, RDR, RADR, and GDR
   products. The following files are contained in the index subdirectory.

INDXINFO.TXT: Identifies and describes the function of each file in the
   index subdirectory. This includes a description of the structure and
   contents of each index table in the subdirectory and usage notes.

INDEX.TAB: The CDR/RDR/GDR index file is organized as a table; there is one
   entry for each of the product label files included in the MLA data sets;
   the columns contain parameters that describe the data as well as instrument
   and spacecraft parameters.

INDEX.LBL: Detached PDS label for INDEX.TAB.

MD5.TAB: Contains an MD5 hash table of all files in the archive volume.

MD5.LBL: Detached PDS label for MD5.TAB.


<LABEL> Directory
   This subdirectory contains the format files for each of the different
   CDR, RDR and RADR product types in the volume (GDRs do not have format
   files). The format file describes the format of the table object in the
   CDR, RDR, or RADR data file.

LABINFO.TXT: Identifies and describes the function of each file in the
   label subdirectory.

MLASCIRDR.FMT: Format of this table contains one set of Reduced MLA Science
   values, as reported by the MESSENGER Mercury Laser Altimeter.


<RDR_RADR> - Data Directory
   The RDRs are stored in this directory with the same subdirectory
   organization as the CDRs (in the V1.0 data set) from which they derive.
   This directory only contains on-orbit RDR altimetry products. The directory
   name, RDR_RADR, is a parallel to that in the verion V1.0 of this data set,
   but does not include RADR products.


<GDR> - Data Directory
   The GDR products are stored in this directory. They are provided both in
   IMG raster and JPEG2000 formats in respective IMG and JP2 subdirectories.


<EXTRAS> - Extras directory for supplemental files.
    <BROWSE> - Directory within EXTRAS for viewable reduced-size browse
               images.
       <GDR> - Directory within EXTRAS/BROWSE for the GDR browse images in
               JPEG format. These are the only browse images provided in this
               volume. There is only one such image in this data set.


========================================================================
Related PDS Products
========================================================================

1. The MLA CDR products from which this data set is derived
(MESS-E/V/H-MLA-3/4-CDR/RDR-DATA-V1.0, volume ID MESSMLA_2001) are themselves
derived from the MLA EDR data set
(PDS Data Set ID MESS-E/V/H-MLA-2-EDR-RAWDATA-V1.0, volume ID MESSMLA_1001).
The MLA EDR and CDR/RDR/GDR data sets are available from the Planetary Data
System (http://pds.nasa.gov).

2. The SPICE kernels used in the processing of the products in this volume are
located at the PDS NAIF node in data set MESS-E/V/H-SPICE-6-V1.0, volume ID
MESSSP_1000.

3. A larger set of DEM products related to the GDR provided in this volume
is archived at the PDS Imaging Node in the
"MESSENGER MDIS DIGITAL ELEVATION MODEL ARCHIVE" Volume (MESSDEM_1001),
DATA_SET_ID = "MESS-H-MDIS-5-DEM-ELEVATION-V1.0". These products are produced
from data from the MESSENGER MDIS instrument. More information about these
products is available at the PDS Imaging Node (http://img.pds.nasa.gov/).


========================================================================
Errata
========================================================================

Every effort has been made to ensure that the data and documentation are of
the best possible quality. However, all users are encouraged to verify the
correctness of the data prior to submitting any publications or other work
based on these data.

The file ERRATA.TXT at the root level of this volume contains a list of known
deficiencies or caveats associated with data on this volume at the time it was
published. It also lists any revisions that have been made to the data set as
a whole or to individual products.

If you find an error on this volume, please report the error to the PDS
Geosciences Node at geosci@wunder.wustl.edu.


========================================================================
Contacts
========================================================================

For questions concerning these data products and documentation, contact:

          PDS Geosciences Node
          Washington University
          Dept. of Earth and Planetary Sciences
          1 Brookings Drive
          St. Louis, MO 63130
          314-935-5493

          WWW Site:  http://pds-geosciences.wustl.edu
          Electronic mail address:  geosci@wunder.wustl.edu


For questions regarding PDS Standards or other archive volumes available
from the PDS, please contact PDS Operator at the PDS Central Node (at JPL):


    Internet            pds_operator@jpl.nasa.gov
    Telephone           (818) 354-4321
    U.S. Mail           Planetary Data System, PDS Operator
                        Jet Propulsion Laboratory
                        Mail Stop 202-101
                        4800 Oak Grove Dr.
                        Pasadena, CA 91109-8099