Mapping and Analysis of Sulfates at Gale Crater from Orbital Data Sets and Preparing for Future Rover Exploration

Sulfates are a common mineral identified from orbital remote sensing data of Mars with several locations having large deposits, such as Meridiani Planum, Valles Marineris, and the central mound in Gale crater (Aeolis Mons). The Gale sulfates lie above a phyllosilicate unit and below a spectrally bland, possible aeolian deposit. Both monohydrated and polyhydrated sulfates have been identified within Aeolis Mons. Additionally, a dark-toned marker bed is observed within the sulfates at Gale, but its extent and origin are unknown. In preparation for the sulfate investigation by the Curiosity rover, we intend to perform a detailed study of the sulfates across Aeolis Mons using orbital remote sensing data sets. For this project, we have outlined several tasks that will characterize and interpret the sulfates and marker bed within Aeolis Mons to provide additional insights into the geologic history of Gale crater and the formation of sulfates on Mars.

Task 1 will use CRISM images to determine the composition of the sulfates, in particular distinguishing between monohydrated and polyhydrated sulfates, as well as other minerals mixed with the sulfates. These CRISM images, combined with visible images from HiRISE, CTX, and HRSC images, will be used for geologic mapping of the sulfates and marker bed across the entire mound, extending the mapping currently being performed at 1:60,000 scale of western Aeolis Mons by Co-I Thomson.

Task 2 will produce 8 new HiRISE-derived Digital Terrain Models (DTMs) and then measure bedding orientation and thickness of the sulfates and marker bed from these DTMs. We will create detailed stratigraphic sections at approximately 8-12 locations across Aeolis Mons that encompass the sulfates and the marker bed. The results will enhance our understanding of the vertical and lateral variability of the sulfates, and determine if the sulfates that will be explored by the Curiosity rover are representative of all the sulfates seen from orbit across Aeolis Mons. For the marker bed, we will utilize the DTMs to determine if the bed always occurs between the same sulfate layers, measure its elevation and thickness across Aeolis Mons, and look for variations in slope and dip of the bed. We will then use these measurements to suggest the most plausible formation mechanism(s) for the marker bed, as well as identify the key questions about the marker bed that could be addressed by the MSL rover instruments as part of Task 4.

Task 3 will compare our results from the Gale sulfates to other sulfates found on Mars, especially those in Meridiani Planum and Valles Marineris where team members have already conducted previous analyses. The goal is to learn if the Gale sulfates are similar in their composition and morphology to other martian sulfate deposits. Formation scenarios for the sulfates within the Gale mound will be investigated in relation to others on Mars using previously published chemical modeling and laboratory studies of sulfate deposition.

Task 4 will look specifically at orbital data of the sulfates that are likely to be traversed by the Curiosity rover in order to relay our findings from this investigation and provide key questions to the MSL science team that could be investigated by the rover once it reaches the sulfates and marker bed based upon our results from Tasks 1-3.