Water and Chlorine in the Martian Subsurface Along the Traverse of NASA's Curiosity Rover: 1. DAN Measurement Profiles Along the Traverse. Issue 11 (22nd November 2022)

• Record Type: Journal Article
• Authors: Mitrofanov, I. G.; Nikiforov, S. Y.; Djachkova, M. V.; Lisov, D. I.; Litvak, M. L.; Sanin, A. B.; Vasavada, A. R.
• Is Part Of: Journal of geophysical research. Volume 127:Issue 11(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-22
• Subjects: Mars -- Mars surface -- neutron spectroscopy -- water; Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1029/2022JE007327
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: This paper presents estimates of the water and chlorine contents in the subsurface of Gale crater based on the measurements by the Dynamic Albedo of Neutrons (DAN) instrument onboard the NASA Curiosity rover. It is Part 1 of a two‐paper series. Data derived both from DAN active and passive measurements are presented in discrete surface areas (pixels) assuming a homogeneous distribution of water within the DAN sensing depth (60 cm) along the traverse of the rover. It is shown that the content of hydrogen, reported as Water Equivalent Hydrogen, varies between almost zero and a maximum of (6.1 ± 0.7) wt.%. The content of absorption equivalent chlorine varies between almost zero and (2.6 ± 0.2) wt.%. Such variations are thought to be related to the different geological processes and environmental conditions present in the strata along the traverse during the evolutionary history of Gale crater. The second paper (Part 2) studies particular properties of water and abundances of neutron absorbing elements at distinct geological regions, that the rover crossed on its way. Plain Language Summary: The Dynamic Albedo of Neutrons (DAN) is a neutron spectrometer that searches for signs of water by measuring the content of neutron absorbing elements in the ground below the NASA's Curiosity rover. Data derived from DAN are presented in discrete pixels along the traverse of the rover. Each pixel contains estimations of water equivalent hydrogen (WEH) and absorption equivalent chlorine (AEC) content from neutron sensing. DAN observations were combined into the two types of 3 × 3 m pixels: Pixel with Active Data includes WEH and AEC content and Pixel of Passive Data includes WEH content. Each pixel has been assigned to the associated geological member of the Mars Science Laboratory stratigraphic column. Full DAN data volume for 27 km of the traverse were formatted as a table with more than 10, 000 pixels. The large fraction of stratigraphic members (Bradbury, Pahrump Hills and others) have the mean WEH values between 2 and 3 wt.%, while other members of the second part of the traverse (Jura, Knockfarrill Hill, Glasgow, Pontours) have the mean values of WEH above 3 wt.%. Mean AEC value has no large variations for all tested stratigraphic members; it is equal to around 1 wt.% for the majority of the pixels. Key Points: Dynamic Albedo of Neutrons (DAN) neutron sensing data were analyzed for 27 km of the Curiosity rover traverse DAN data were derived as single pixels and associated with the Gale crater stratigraphic column divisions DAN measurements indicate area with maximum water content of (6.1 ± 0.7) wt.%