Gamma Ray Spectrometer (GRS) Raw Data
MESSENGER Mission to Mercury

This bundle contains the following collections:

data_edr - raw GRS data products
document - the GRS EDR Software Interface Specification and other relevant documents
miscellaneous - the PDS3 index table for this archive

This PDS4 bundle has been migrated from a PDS3 data volume. For details, see the document
geo_notes_and_errata.pdf in the document collection.

Each document and data product in this bundle is described by a PDS4 label in a separate file with 
the same name but with the extension XML. PDS4 labels are XML (eXtended Markup Language) files that 
conform to the PDS4 Information Model XML schema at https://pds.nasa.gov/pds4/schema/released/. 
They are best viewed in an XML-aware text editor, and may be used by software that can manipulate 
XML documents.

The MESSENGER GRS raw product collection consists of uncalibrated observations from the GRS
instrument. There are ten standard product types associated with the GRS sensor. Six product types
contain spectra from either the high-purity germanium or scintillator detector. The remaining raw
product types pertain to the operation of the GRS instrument, including a time-tagged list of
commands executed. A single raw product typically contains data collected over one Earth day. A
description of each product type is given in the table below. Code refers to the product type
abbreviation used in the file name.


Code     Product Type        Description                                             Storage Format

ADC      FPGA ADC            This product type contains diagnostic information       Binary Table  
         Diagnostic          about the state of the instrument, with parameters                    
         Information         associated with the Analog-to-Digital Converter (ADC)                 
                             processing in the field-programmable gate array                       
                             (FPGA).                                                               

ANC      Anti-Coincident     This product type contains high-purity germanium        Binary Table  
         Spectra             (HPGe) Anti-Coincident (AC) spectra collected by the                  
                             MESSENGER Gamma Ray Spectrometer (GRS).                               

CMD      Command             The GRS Command product contains the set of commands    ASCII Table   
                             executed by the GRS instrument.                                       

MID      Microphonics        The Microphonics product contains time series data of   Binary Table  
                             fluctuations generated electronically due to                          
                             cryocooler vibrations. These data help determine if                   
                             the cooler is developing vibration issues. The                        
                             cryocooler failed on June 15, 2012.                                   

RAW      HPGe Spectra        This product type contains raw spectra collected from   Binary Table  
                             the high-purity germanium (HPGe) detector.                            

SCR      Anti-Coincidence    This product type contains high-resolution count rate   Binary Table  
         Shield              data of events registered by the GRS Anti-Coincidence                 
                             shield in 10 ms increments.                                           

SHI      Shield Spectra      This product type contains raw spectra collected from   Binary Table  
                             the GRS shield detector prior to September 17, 2010.                  

SHI2     Shield Spectra 2    The GRS flight software was changed on September 17,    Binary Table  
                             2010 to detect fast neutrons in the shield sensor.                    
                             The shield-2 products are formatted to provide data                   
                             on thermal and fast neutrons.                                         

STA      Telemetry Status    These products monitor engineering parameters, such     ASCII Table   
                             as voltages, currents, temperatures, and modes in raw                 
                             units.                                                                

SWC      Software            This product type contains software rate counter        ASCII Table   
         Telemetry           telemetry information of events measured by GRS.                      

GRS Raw products have the following file names:
grs_zzzyyyydddwww.dat
where:
zzz  = Product Type (Code)
yyyy = 4-digit year corresponding to the start time of the first record in the Raw data file
ddd  = 3-digit day of year corresponding to the start time of the first record in the Raw data file
www  = reserved 3-character string to use during the course of the mission as necessary to
       identify “special” data products; nominal data products will be identified with “ZZZ”

This bundle was created and archived by the Geosciences Node of the Planetary Data System. 
Questions about this bundle may be directed to geosci@wunder.wustl.edu.