Velocity calibration for in-situ Mössbauer data from Mars

Beginning in August 2004, raw data acquired by the Mössbauer spectrometers on the Mars Exploration Rovers (MERs) have been released to the science community as Experimental Data Records (EDRs) for each Martian day (sol) on which measurements were made. To provide convenient direct access to the EDR data, to enable independent assessment and analysis, and to allow confirmation of MER-team scientific conclusions, a new Windows-based computer program, MERView, has been developed. Direct inspection of the binary structure of an EDR file, conversion of the binary data to decimal column format for display or export, and full-screen graphical displays are included, allowing, in a highly transparent and user-friendly manner, immediate and thorough overview of the entire EDR data set. MERView also includes automated procedures for velocity calibration. Correction for non-linearity is done using the EDR-provided drive error signal, a phase shift, and the requirement that the two halves of a reference spectrum must overlap exactly when plotted on a correct velocity scale. Absolute velocity calibration (mm/s) is then accomplished by comparing each reference spectrum with known peak positions of standard reference materials.