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- Title
Depth Distribution of Chlorine at Gale Crater, Mars, as Derived From the DAN and APXS Experiments Onboard the Curiosity Rover.
- Authors
Litvak, M. L.; Mitrofanov, I. G.; Gellert, R.; Djachkova, M. V.; Lisov, D. I.; Vasavada, A. R.; Czarnecki, S.
- Abstract
The subsurface chlorine depth distribution at Gale crater has been studied using measurements from the Alpha Particle X‐ray Spectrometer (APXS) and Dynamic Albedo of Neutrons (DAN) instruments onboard NASA's Curiosity Mars rover. These measurements have been acquired at or near ∼30 drill holes made by Curiosity along its 30 km drive. APXS measured a ∼15 micron surface layer of bedrock and shallow depth of ∼5 cm of drill tailings. DAN is sensitive to the bulk (∼50 cm depth) chlorine abundance and that of other neutron absorbing elements. Joint analysis of APXS and DAN data shows that the chlorine distribution at Gale crater consists of two components: surficial chlorine with concentrations >1 wt.%, possibly controlled by aeolian deposition of Cl‐rich dust and surface alteration, and subsurface chlorine with concentrations <1 wt.%, likely a result of groundwater activity in the past. Plain Language Summary: The Curiosity rover has been exploring layered sediments enriched with hydrated mineral phases which were formed in past epochs due to the interaction with fluids in Gale crater, Mars. Curiosity carries 10 science instruments to conduct remote and contact measurements and has already made ∼30 drill holes along its 30 km drive, testing samples of Martian soils and rocks. One of Curiosity's science tasks is to measure the elemental composition of the Martian surface and chlorine is considered here as an important chemical component that could tell us what has occurred on Mars in the past. Several instruments aboard Curiosity are capable of estimating the concentration of chlorine and we selected two of them (Dynamic Albedo of Neutrons and Alpha Particle X‐ray Spectrometer) to evaluate how chlorine is distributed with depth using data acquired at drill locations. We found that the chlorine distribution at Gale crater consists of two components: surficial chlorine with concentration >1%, possibly controlled by wind‐driven deposition of Cl‐rich dust and surface alteration, and subsurface chlorine with concentration <1%, likely a result of groundwater activity in the past. Key Points: A correlation between Alpha Particle X‐ray Spectrometer drill tailings and Dynamic Albedo of Neutrons measurements of subsurface chlorine was foundChlorine depth distribution consists of surficial chlorine (>1 wt.%) and bulk chlorine (<1 wt.%) componentsThe surficial Cl is controlled by Aeolian deposition and surface alteration, and bulk Cl is a result of groundwater activity
- Subjects
GALE Crater (Mars); MARS rovers; NEUTRON measurement; CHLORINE; MARTIAN surface; LUNAR craters; IMPACT craters
- Publication
Journal of Geophysical Research. Planets, 2023, Vol 128, Issue 5, p1
- ISSN
2169-9097
- Publication type
Article
- DOI
10.1029/2022JE007694