| Autor: |
R. D. Starr, Denis Lisov, Jeffrey E. Moersch, Craig Hardgrove, A. V. Malakhov, Cary Zeitlin, William V. Boynton, Insoo Jun, Donald M. Hassler, F. Fedosov, Michael A. Mischna, D. M. Drake, Ralph E. Milliken, Maxim Mokrousov, Ruslan O. Kuzmin, D. W. Ming, A. B. Sanin, A. Varenikov, Bent Ehresmann, Andrey Vostrukhin, Sergey Nikiforov, M. L. Litvak, I. G. Mitrofanov, Alberto Behar, Lauren DeFlores, K. Harshman, Dmitry Golovin, C. Tate, A. S. Kozyrev |
| Rok vydání: |
2015 |
| Předmět: |
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| Zdroj: |
Icarus. 262:102-123 |
| ISSN: |
0019-1035 |
| DOI: |
10.1016/j.icarus.2015.09.002 |
| Popis: |
The Dynamic Albedo of Neutrons (DAN) experiment on the Mars Science Laboratory (MSL) rover Curiosity is designed to detect neutrons to determine hydrogen abundance within the subsurface of Mars (Mitrofanov, I.G. et al. [2012]. Space Sci. Rev. 170, 559–582. http://dx.doi.org/10.1007/s11214-012-9924-y ; Litvak, M.L. et al. [2008]. Astrobiology 8, 605–613. http://dx.doi.org/10.1089/ast.2007.0157 ). While DAN has a pulsed neutron generator for active measurements, in passive mode it only measures the leakage spectrum of neutrons produced by the Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) and Galactic Cosmic Rays (GCR). DAN passive measurements provide better spatial coverage than the active measurements because they can be acquired while the rover is moving. Here we compare DAN passive-mode data to models of the instrument’s response to compositional differences in a homogeneous regolith in order to estimate the water equivalent hydrogen (WEH) content along the first 200 sols of Curiosity’s traverse in Gale Crater, Mars. WEH content is shown to vary greatly along the traverse. These estimates range from 0.5 ± 0.1 wt.% to 3.9 ± 0.2 wt.% for fixed locations (usually overnight stops) investigated by the rover and 0.6 ± 0.2 wt.% to 7.6 ± 1.3 wt.% for areas that the rover has traversed while continuously acquiring DAN passive data between fixed locations. Estimates of WEH abundances at fixed locations based on passive mode data are in broad agreement with those estimated at the same locations using active mode data. Localized (meter-scale) anomalies in estimated WEH values from traverse measurements have no particular surface expression observable in co-located images. However at a much larger scale, the hummocky plains and bedded fractured units are shown to be distinct compositional units based on the hydrogen content derived from DAN passive measurements. DAN passive WEH estimates are also shown to be consistent with geologic models inferred from other MSL instruments, which indicate that fluvial/lacustrine activity occurred at certain locations ( e.g. , Yellowknife Bay). |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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Full Text from ScienceDirect