Data Set Overview
  =================
    The Moessbauer spectrometers on the two Mars Exploration rovers
    identified Fe-bearing phases and quantitatively measured the relative
    abundance of Fe (as percentage of total Fe) according to oxidation state
    (e.g., Fe2+ and Fe3+), coordination state (e.g.,
    octahedrally-coordinated), and specific Fe-bearing phases (e.g.,
    percentage of total Fe associated with olivine) at Meridiani Planum
    (Opportunity) and Gusev Crater(Spirit). For more information on the MER
    Moessbauer spectrometers please see mer1_mb_inst.cat and
    mer2_mb_inst.cat.

    This archive contains Percent Total Fe products for both MER-1 and MER-2
    rovers.  The archive consists of one table for each rover. Each table has 
    a detached PDS label that describes the content of the table.

  Processing
  ==========
    The processing of this archive is described in detail in
    [MORRISETAL2006A], [MORRISETAL2006B], and [MORRISETAL2008] listed in
    ref.cat.  The archive  consists of one table each for MER-1 and MER-2
    rovers. Each table contains  the percent Moessbauer areas for component
    subspectra, where subspectral  area is the percentage of total Fe
    associated with specific  Fe-bearing   phases.  Note that subspectral
    areas do not provide information about the  proportion of the
    iron-bearing phases themselves unless the concentration of  Fe in those
    phases is independently modeled.
    
    Subspectral areas were determined using a variety of commercial and
    in-house least-squares fitting computer programs in which peak line
    shape function,  peak center, peak width, and area were adjustable
    parameters. Five double  and four sextet subspectra were required to fit
    the Moessbauer spectra. Note  that not all nine subspectra are present
    in every spectrum. All spectra were  fit independently by at least two
    of the authors of [MORRISETAL2006A],  [MORRISETAL2006B], and
    [MORRISETAL2008], which are listed in ref.cat.  Two  approaches were
    used during fitting procedures. In one approach, spectra  were fit using
    individual peaks, and in the other approach spectra were fit using
    individual subspectra. Values of subspectral areas (percentage of total
    Fe associated with specific Fe-bearing phases) reported are average
    values from independent fits by 2-4 co-authors. The reported error is
    the larger of 2% (absolute) or the deviation from the average value of
    the  independent fits. Fitting constraints included the following:

    (1) The two peaks in doublet subspectra were constrained to have equal
        areas and widths.
    (2) The six peaks in sextet subspectra were often constrained to
        the ratio 3:2:1:1:2:3
    (3) Because of the strong overlap of the innermost two peaks of sextet 
        subspectra with doublet subspectra and other sextet subspectra, their 
        positions were often constrained using the positions of the other four
        peaks and 0.572 for the g-factor ratio of the 14.4 KeV excited state 
        to the ground state of Fe-57.

    The areas include a correction factor (the f-factor) to account for 
    differences in recoil-free fractions according to oxidation state 
    (f(Fe3+)/f(Fe2+)) = 1.21 independent of mineralogical composition.

    Phase identification was done using a combination of literature
    databases of  Moessbauer parameters, intercorrelations of subspectral
    areas, and correlation  of subspectral areas with APXS elemental data.

    Additional processing to improve counting statistics and additional
    constraints imposed on certain targets or for certain phases where the 
    combination of reasonable counting statistics and high subspectral area 
    was not sufficient is described in detail in [MORRISETAL2006A], 
    [MORRISETAL2006B], and [MORRISETAL2008].      

  Data
  ====
    The archive consists of one table each for MER-1 and MER-2 rovers.
    The table MERA_MB_PCT_TOTAL_FE.CSV contains the percentage of total
    Fe in Fe-bearing phases from subspectral areas in Spirit (MER-A)
    Moessbauer Spectra.  The table MERB_MB_PCT_TOTAL_FE.CSV contains
    the percentage of total Fe in Fe-bearing phases from subspectral
    areas in the Opportunity (MER-B) Moessbauer Spectra. In the field
    names, D=Doublet Moessbauer spectrum and S=Sextet Moessbauer
    spectrum, and the phase assignments are OL=Olivine,    
    PX=Pyroxene, ILM=Ilmenite, CHR=Chromite, MT=Magnetite, NPOX=Nanophase 
    Ferric Oxide, FE3SULFATE=Fe3+-bearing sulfate, JAR=Jarosite,
    HM=Hematite, PYR/MAR=Pyrite/Marcasite, GT=Goethite, Tr=Troilite and
    A-FE=Fe/Ni Metal      Alloy (kamacite). Absolute errors are included in
    the tables in fields named *_ERR.  An entry of 0 (zero)
    denotes that the doublet or sextet was not used in the least squares
    fitting procedure. Subspectral areas are f-factor corrected. 
    These comma-separated-value tables are suitable for reading into a 
    spreadsheet program such as Microsoft Excel.

    A detached PDS label accompanies each table that describes the content
    and format of the table. All detached label and document files are in
    stream  format files with a carriage return (ASCII 13) and line feed
    character  (ASCII 10) at the end of each record. This allows files to
    be read by the  MacOS, DOS, Unix, and VMS operating systems.

  Software
  ========
    No software is included in this archive. The data products can be viewed
    in a text editor or in a spreadsheet program such as Microsoft Excel.

Please refer to [MORRISETAL2006A], [MORRISETAL2006B], and 
    [MORRISETAL2008] listed in ref.cat.