Collaborative Research: Formation, Stability, and Detection of Amorphous Ferric Sulfate Salts on Mars

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An accurate determination of the surface composition of planets is essential for understanding the processes that have shaped our Solar System. Beyond Earth, mineralogy is studied using observations from telescopes, orbiting satellites, and in the case of Mars, landers and rovers. It is essential to have accurate "libraries" of measurements showing how different minerals reflect light of different colors. Without comparison samples, a match cannot be made. Materials that are common on Earth have been well studied. However, the surface of Mars is not yet well described in terms of materials that are common in terrestrial studies. Non-crystalline materials ("amorphous") that are rich in water ("hydrated") are ubiquitous on Mars yet are not well studied on Earth. The investigators propose to create a library of reflectance measurements for hydrated amorphous materials that are likely to be found on Mars. They will study how the light reflectance varies with temperature, and how weathering by acids changes the reflectance of a sample. They will include undergraduate students in the research and expect that at least six undergraduate thesis or independent study projects will emerge from this project. As co-PI Dyar is a faculty member at Mount Holyoke (a women's college) and the Five Colleges Astronomy Consortium, many of the student participants are expected to be women.The objectives of the work are to determine the stability and transformation products of amorphous ferric sulfate salts and salt mixtures, measure the spectra of possible regolith materials a) coated with these materials and b) mixed with these materials; and to use the laboratory spectra to search for and map spectral features of amorphouse ferric sulfates, amorphous mixed salts, and amorphous salt coatings in Mars Reconnaissance Orbiter Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) and Mars Global Surveyor Thermal Emission Spectrometer (TES) data.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.