Discipline: Chemistry and Chemical Sciences
Subcategory: Geosciences and Earth Sciences
Lucas Reynoso - Arizona State University
Co-Author(s): Dr. Maitrayee Bose, Arizona State University, Tempe, AZ; Dr. Julie Castillo-Rogez, NASA Jet Propulsion Laboratory, Pasadena, CA
Ceres shows geophysical evidence for the existence of sub-surface brines in its past and present, at least locally. Vast salt deposits detected in Occator crater (e.g., Ceralia and Vinalia Faculae) were likely formed by the extrusion of salty water through fractures created by an impact from depths of >35 km . Ceres’ reflectance spectra are consistent with minerals resulting from aqueous alteration, such as sodium carbonate (Na2CO3) and ammonium (NH4+) bearing phyllosilicates [2-3]. That material is intimately mixed with dark floor material rich in organic matter, likely with high concentrations of carbon [4-5]. As Ceres’ environment contains the three prerequisites for life: water, carbon, and a source of energy, Vinalia Faculae represents a viable candidate location to sample both bright and dark material. This research presents laboratory analyses on Ceres analogs, specifically the synthesis of sodium chloride (NaCl) salts with the addition of the amino acid glycine (C2H5NO2), to better understand carbon incorporation into salt evaporates at Vinalia Faculae. The changes in the chemical, physical, and optical properties of salts are documented in the study and are important to designing a robust sample collection system for a future sample return mission from Ceres. Sodium chloride crystals were synthesized from a supersaturated solution (40 g of NaCl powder per 100 ml of reverse osmosis (RO) water) in a clean laboratory setting. The resulting solution was filtered and distributed into several petri dishes to allow NaCl crystals to grow under equilibrium. Next, sets of crystals were grown incorporating the amino acid glycine at varying concentrations (500 mg, 1 g, and 10 g per 100 ml of RO water). Optical images were taken of both crystals. Pure NaCl crystals appeared predominantly white with distinct growth layers, while the NaCl crystals with glycine showed 2 separate features in reflected light, namely (a) blebs of dark material scattered heterogeneously and (b) a dark hue over the entire crystal. Secondary Ion Mass Spectrometry (SIMS) measurements were also completed on the crystals, measuring 12C+ and 23Na+. Pure NaCl crystals show an average 12C/23Na ratio of 4.59⨉10-8. The NaCl crystals with blebs within them show a 12C/23Na ratio that is >50 times the ratio in the blank. These results confirm the inclusion of carbon-bearing materials during the growth of NaCl. Further exploration will be completed to understand how amino acids, if present in the muddy layer of Ceres crust, can be captured by the salt crystals. References:  De Sanctis M. C. et al. (2020), Nat. Ast., 4. 786-793.  Milliken R., Rivkin A., (2009) Nat. Geosci., 2, 258-261.  Ammannito E. et al. (2016) Sci., 353, aaf4279.  De Sanctis M. C. et al. (2017) Sci., 355, 719-722.  Prettyman T. H. et al. (2017) Sci., 355, 55-59.
Funder Acknowledgement(s): I would like to thank Dr. Bose for her continued support with this project and Dr. Castillo-Rogez for her generously provided knowledge and expertise. This research is supported by the Western Alliance to Expand Student Opportunities (WASEO), Louis Stokes Alliance for Minority Participation (LSAMP), National Science Foundation (NSF) Cooperative Agreement No. HRD-1619524. This work was also supported through a NASA grant awarded to the Arizona/NASA Space Grant Consortium.
Faculty Advisor: Dr. Maitrayee Bose, firstname.lastname@example.org
Role: I synthesized all the salt samples in a laboratory environment analyzed in this study. I also assisted and observed the various measurement techniques (optical microscopy, secondary ion mass spectrometry, and elemental analyzer) on the crystals. To culminate my work, I analyzed the data and presented my findings in various abstracts/posters.