SCIENCE QUESTIONS/OBJECTIVES:JOHNSON ET AL. 2015 DEMONSTRATED THAT THE MSL CHEMCAM SPECTROMETERS EXHIBIT SUFFICIENT RADIOMETRIC SENSITIVITY IN THE 400 840 NM REGION TO ALLOW COLLECTION OF SURFACE SPECTRAL REFLECTANCE IN PASSIVE MODE I.E. WITHOUT USING THE LASER PORTION OF THE LASER-INDUCED BREAKDOWN SPECTROMETER LIBS INSTRUMENT CF. WIENS ET AL. 2015; MAURICE ET AL. 2016. THE UNPRECEDENTED HIGH SPATIAL 0.65 MRAD FIELD OF VIEW AND SPECTRAL 1 NM RESOLUTIONS OF THESE MEASUREMENTS ALLOW UNIQUE INVESTIGATIONS OF THE SPECTRAL BAND POSITIONS SHAPES DEPTHS AND SLOPES OF SPECTRA COLLECTED OF TARGETS BOTH NEAR AND FAR FROM THE ROVER. ALTHOUGH VARIABLE SURFACE DUST CAN SUBDUE SPECTRAL FEATURES IN THE 400 840 NM WAVELENGTH REGION CHEMCAM PASSIVE SPECTRA TYPICALLY WERE ACQUIRED AFTER THE LIBS LASER SHOTS REMOVED SUBSTANTIAL AMOUNTS OF DUST. ALSO THE ROVER WHEELS DISTURBED SOILS AND ROCKS AND DRILL ACTIVITIES PROVIDED FRESHLY GROUND FINES ALL OF WHICH WERE LESS AFFECTED BY DUST. CHEMCAM PASSIVE SPECTRA THEREFORE PROVIDE THE OPPORTUNITY TO INVESTIGATE SPECTRAL VARIABILITY RELATED TO MINERALS SUCH AS HEMATITE MAGNETITE FERRIC SULFATES NANOPHASE OR PARTIALLY CRYSTALLINE FERRIC OXIDES AND MORE FERROUS MINERALS SUCH AS OLIVINE AND PYROXENE JOHNSON ET AL. 2015 2016 2017 2018). IDENTIFICATION OF THESE SPECIES HELPS CONSTRAINTHE MINERALOGY AND CRYSTALLINITY OF IRON-BEARING MINERALS RELEVANT TO UNDERSTANDING THE MAGMATIC EROSIONAL AQUEOUS AND AEOLIAN HISTORY OF MARS.TO PROVIDE THESE SURFACE SPECTRA DIRECTLY TO THE PLANETARY COMMUNITY WE PROPOSE TO CALIBRATE THE EXISTING CHEMCAM PASSIVE SPECTRA RAW DATA FILES AVAILABLE IN THE PDS THROUGH MISSION SOL 1869 TO BOTH RADIANCE AND RELATIVE REFLECTANCE USING ALGORITHMS DEVELOPED BY THE PI PREVIOUSLY JOHNSON ET AL. 2015. WE WILL DEVELOP AND ARCHIVE NEW SOFTWARE THAT INCORPORATES THESE ALGORITHMS WHILE PROVIDINGOPTIONS FOR USERS TO ALTER SPECIFIC CALIBRATION FILES OR METHODS SHOULD THEY WISH TO INVESTIGATE ALTERNATIVE TECHNIQUES. THE SOFTWARE AND ASSOCIATED DOCUMENTATION INCLUDING A USERS GUIDE WILL BE ARCHIVED IN THE NASA GITHUB SITE. FOR EACH SPECTRUM WE WILL USE INFORMATION CONTAINED IN THE DATA HEADERS AND RELATED CHEMCAM REMOTE MICRO IMAGER RMI AND MASTCAM IMAGES TO PROVIDE METADATA USEFUL IN UNDERSTANDING THE SPECTRUM ACQUISITION E.G. TARGET NAME AND TYPE EXPOSURE TIME RASTER LOCATION ILLUMINATION CONDITIONS LOCAL TIME PHOTOMETRIC ANGLES DEGREE OF TARGET SHADOWING AND INSTRUMENT CONDITIONS DETECTOR TEMPERATURE AS WELL AS ATMOSPHERIC OPACITY.IMPLICATIONS SIGNIFICANCE:BY ARCHIVING CHEMCAM PASSIVE CALIBRATED RADIANCE AND RELATIVE REFLECTANCE SPECTRA IN COMBINATION WITH THE SOFTWARE ALGORITHMS USED IN THEIR GENERATION THE PROPOSED WORK WILL DIRECTLY ADDRESS A NEED IN THE PLANETARY SCIENCE COMMUNITY FOR IN SITU HIGH SPATIAL AND SPECTRAL RESOLUTION VISIBLENEAR-INFRARED DATA OF MARS SURFACE MATERIALS. THE COMBINATION OF FLEXIBLE WELL-DOCUMENTED CALIBRATION SOFTWARE AND THE PRODUCTION OF CALIBRATED SPECTRA WITH SUPPORTING METADATA WILL PROVIDE RESEARCHERS A STRAIGHTFORWARD MEANS TO INVESTIGATE EITHER SPECIFIC TARGETS OF INTEREST OR CONDUCT COMPREHENSIVE STUDIES USING THOUSANDS OF INDIVIDUAL SPECTRA. THE FORMER WILL ASSIST IN DOCUMENTING SPECTRAL FEATURES ASSOCIATED WITH MILLIMETER-SCALE SURFACE TARGETS THEREBY ADDING CONSTRAINTS ON THE MINERAL DIVERSITY ALONG THE ROVERS TRAVERSE. THE LATTER WOULD BE VALUABLE IN UNDERSTANDING SPECTRAL VARIABILITY OF LARGER SURFACE GEOLOGIC UNITS PARTICULARLY WHEN COMPARED TO ORBITAL VISIBLENEAR-INFRARED DATA SETS E.G. CRISM OMEGA HIRISE.