THE OBJECTIVES OF THE PROPOSED WORK ARE TO 1) EXPLORE THE LIKELY FORMATION PATHWAYS FOR AMORPHOUS NANOCRYSTALLINE AND/OR POORLY CRYSTALLINE SULFATE CHLORIDE OXYCHLORINE AND MULTICOMPONENT SALTS 2) CHARACTERIZE THE HYDRATION STATE XRD AND SPECTRAL PROPERTIES OF AMORPHOUS SALTS EXPECTED FOR MARS AND 3) DESCRIBE THE THERMODYNAMIC PROPERTIES OF THESE SALTS AND THE SOLUTIONS AND/OR CRYSTALLINE MATERIALS FROM WHICH THEY FORM OVER A WIDE RANGE OF CONDITIONS. RECENT DISCOVERIES OF HYDRATED AMORPHOUS MATERIALS FROM THE MARS SCIENCE LABORATORY MISSION AS WELL AS DETECTIONS OF HYDRATED AMORPHOUS PHASES FROM ORBIT AND FROM OTHER LANDING SITES HAVE HIGHLIGHTED A NEED TO BETTER UNDERSTAND THE POSSIBLE PHASES THAT COULD COMPRISE THESE MATERIALS. FUNDAMENTAL QUESTIONS REMAIN ABOUT THE AMORPHOUS CONSTITUENTS IN MARTIAN SOILS AND IN PARTICULAR THE EXISTENCE AND PROPERTIES OF AMORPHOUS SALTS. THERE ARE A NUMBER OF MARS-RELEVANT PROCESSES THAT COULD LEAD TO AMORPHOUS OR NANOPHASE SALTS AND PREVIOUS STUDIES HAVE SUGGESTED THAT THEY COULD BE IMPORTANT CONSTITUENTS OF MARTIAN SURFACE MATERIALS. YET LITTLE IS KNOWN ABOUT THE FORMATION MECHANISMS STABILITY OR SPECTRAL PROPERTIES OF THESE PHASES. THERE ARE SEVERAL OUTSTANDING QUESTIONS RELATED TO AMORPHOUS SALTS LINKED UNDER THREE MAJOR OBJECTIVES. THE FIRST SET OF QUESTIONS RELATES TO FORMATION PATHWAYS FOR AMORPHOUS SALTS AS A FUNCTION OF COMPOSITION TEMPERATURE AND HUMIDITY CONDITIONS. THOUGH SOME SALTS HAVE BEEN INVESTIGATED ALREADY UNDER VARIOUS PATHWAYS OTHERS REMAIN UNEXPLORED. IMPORTANT TO UNDERSTANDING AMORPHOUS SALT FORMATION PATHWAYS IS DETERMINING THE DELIQUESCENCE RELATIVE HUMIDITY (DRH) OF CRYSTALLINE STARTING MATERIALS AT MARS-RELEVANT TEMPERATURES; HENCE THE INCLUSION OF DRH MEASUREMENTS IN THIS OBJECTIVE. THE SECOND SET OF QUESTIONS RELATES TO THE VISIBLE SPECTRAL X-RAY AND HYDRATION STATE CHARACTERISTICS OF THESE SALTS WHICH ARE IMPORTANT FOR THEIR DETECTABILITY USING PAST CURRENT AND FUTURE INSTRUMENTATION AT MARS. THE THIRD SET OF QUESTIONS RELATES TO THE STABILITY OF AMORPHOUS SALTS. THE RH-TEMPERATURE CONDITIONS UNDER WHICH AMORPHOUS SALTS FORM AND ARE STABLE AS WELL AS THE RATES OF TRANSFORMATIONS ARE NOT WELL CONSTRAINED PARTICULARLY FOR TEMPERATURES<25 C. THUS WE PROPOSE TO SYNTHESIZE A RANGE OF AMORPHOUS SALTS THROUGH MULTIPLE MARS-RELEVANT FORMATION PATHWAYS EXPLORING THE EFFECT OF BRINE/SALT CHEMISTRY AND TEMPERATURE ON THE RESULTING PRODUCT THROUGH EACH PATHWAY. WE WILL ACQUIRE XRD PATTERNS TGA/DSC DATA AND VNIR TIR AND RAMAN SPECTRA OF EACH PRODUCT. LAST WE WILL USE TIME-RESOLVED X-RAY DIFFRACTION AND DIFFERENTIAL SCANNING CALORIMETRY TO PROVIDE A CRITICAL SOURCE OF FUNDAMENTAL MEASUREMENTS AND EXPERIMENTS THAT WILL YIELD THERMODYNAMIC QUANTITIES OF AMORPHOUS SOLIDS CRYSTALLIZATION PRODUCTS AND SOLUTIONS. THESE EXPERIMENTAL RESULTS WILL BE USED TO DEVELOP THERMODYNAMIC MODELS OF MINERAL/AMORPHOUS SOLID STABILITY AT THE MARTIAN SURFACE. UNDERSTANDING THE CONDITIONS UNDER WHICH AMORPHOUS SALTS FORM STABILIZE AND DELIQUESCE IS KEY TO BETTER UNDERSTANDING THE PRESENT DAY H2O CYCLE ON MARS. FURTHERMORE PUTTING CONSTRAINTS ON WHICH PHASES ARE LIKELY FOR MARTIAN SOILS AND THEIR STABILITY AND THERMODYNAMIC PROPERTIES WILL HAVE BROADER SIGNIFICANCE AS IT RELATES TO BIOCHEMICAL AVAILABILITY/ENERGY SOURCES BIOSIGNATURE PRESERVATION POTENTIAL SAMPLE RETURN IN-SITU RESOURCE UTILIZATION AND THE GEOCHEMICAL ENVIRONMENT FOR MISSION HARDWARE. THE PROPOSED INVESTIGATION USES LABORATORY STUDIES AND DATA SYNTHESIS THAT WILL IMPROVE UNDERSTANDING OF PHYSICAL AND CHEMICAL PROCESSES ON MARS AND THEREFORE IS RELEVANT TO THE SOLAR SYSTEM WORKINGS PROGRAM.