MSL DAN Passive Data and Interpretations

Friday, 19 December 2014
Christopher Tate1, Jeffrey Moersch1, Insoo Jun2, Douglas W Ming3, Igor G. Mitrofanov4, Maxim L Litvak4, Alberto Behar2, William V Boynton5, Darrel Drake6, Denis Lisov4, Michael A Mischna2, Craig J Hardgrove7, Ralph Milliken8, Anton B. Sanin4, Richard D Starr9, Javier Martín-Torres10, Maria-Paz Zorzano11, Fedor Fedosov4, Dmitry Golovin4, Karl Harshman5, Alexander Kozyrev4, Alexey Malakhov4, Maxim Mokrousov4, Sergey Nikiforov4 and Aleksey Varenikov4, (1)University of Tennessee, Knoxville, TN, United States, (2)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (3)NASA Johnson Space Center, Houston, TX, United States, (4)Space Research Institute RAS, Moscow, Russia, (5)Univ Arizona, Tucson, AZ, United States, (6)TechSource, Inc, Los Alamos, NM, United States, (7)Arizona State University, Tempe, AZ, United States, (8)Brown University, Providence, RI, United States, (9)Catholic University of America, Washington, DC, United States, (10)Instituto Andaluz de Ciencias de la Tierra, Granada, Spain, (11)INTA-CSIC, Madrid, Spain
In its passive mode of operation, The Mars Science Laboratory Dynamic Albedo of Neutrons experiment (DAN) detects low energy neutrons that are produced by two different sources on Mars. Neutrons are produced by the rover's Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and by interactions of high energy galactic cosmic rays (GCR) within the atmosphere and regolith. As these neutrons propagate through the subsurface, their energies can be moderated by interactions with hydrogen nuclei. More hydrogen leads to greater moderation (thermalization) of the neutron population energies. The presence of high thermal neutron absorbing elements within the regolith also complicates the spectrum of the returning neutron population, as shown by Hardgrove et al. DAN measures the thermal and epithermal neutron populations leaking from the surface to infer the amount of water equivalent hydrogen (WEH) in the shallow regolith. Extensive modeling is performed using a Monte Carlo approach (MCNPX) to analyze DAN passive measurements at fixed locations and along rover traverse segments. DAN passive WEH estimates along Curiosity's traverse will be presented along with an analysis of trends in the data and a description of correlations between these results and the geologic characteristics of the surfaces traversed.