The nature of Mars’s surface hydration: converging views from satellite (MEX), surface (MSL) and meteorite (NWA 7034 / 7533 and co) observations.
Pierre Beck1, Antoine Pommerol2, B Zanda3, Laurent Remusat4, Jean-Pierre Lorand5, Christa H Gopel6, Roger Hewins7,8, Sylvain Pont9, Eric Lewin10, Eric Quirico11, Bernard Schmitt12, German Montes-Hernandez10, Alexandre Garenne11, Lydie Bonal13, Olivier Proux14, Jean-Louis Hazemann15, Vincent F Chevrier16, Javier Martín-Torres17, María-Paz Zorzano17, Olivier Gasnault18, Sylvestre Maurice19 and Roger C Wiens20, (1)Univ. Grenoble Alpes, CNRS, CNES, IPAG, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), Grenoble, France, (2)University of Bern, Space Research & Planetary Sciences, Bern, Switzerland, (3)Museum National d'Histoire Naturelle, paris, France, (4)Muséum National d´Histoire Naturelle, Laboratoire de Minéralogie et Cosmochimie du Muséum, Paris, France, (5)LPGN Laboratoire de Planétologie et Géodynamique de Nantes, Nantes Cedex 03, France, (6)Institut de Physique du Globe de Paris, Paris, France, (7)Rutgers University, Department of Earth and Planetary Sciences, Puscataway, NJ, United States, (8)Institut de Minéralogie, de Physique des matériaux et de Cosmochimie (IMPMC), Sorbonne Université, CNRS, MNHN, Paris, France, (9)MNHN National Museum of Natural History Paris, IMPMC, Laboratoire de Minéralogie et Cosmochimie du Muséum, Paris, France, (10)UJF-Grenoble 1 / CNRS-INSU, Institut des Sciences de la Terre (IsTERRE), Grenoble, France, (11)UJF-Grenoble 1 / CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), Grenoble, France, (12)Univ. Grenoble Alpes, CNRS, CNES, IPAG, 38000 Grenoble, France, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), Grenoble, France, (13)IPAG, Univ. Grenoble Alpes, Grenoble, France, (14)Observatoire des Sciences de l’Univers de Grenoble (OSUG), Grenoble, France, (15)Institut Néel, Grenoble, France, (16)University of Arkansas, Department of Geosciences, Fayetteville, United States, (17)Centro de Astrobiologia, Madrid, Spain, (18)IRAP, CNRS, Université de Toulouse, UPS-OMP, Toulouse Cedex 4, France, (19)IRAP, CNRS, Université de Toulouse, UPS-OMP, Toulouse, France, (20)Space Science and Applications, Los Alamos, United States
Abstract:
Early infrared observations of the Martian surface have revealed the presence of a deep absorption between 2.6 and 3.5 µm usually referred to as the 3-µm band. Two non-exclusive explanations have been formulated to account for this 3-µm band. The first possibility is that it relates to the presence of some amount of adsorbed atmospheric water, water that would be exchangeable and could play a role in present day Mars water cycle. The alternative is that this absorption is due to an –OH or H2O bearing mineral component within the Martian dust, which would imply that water is involved at some stage of the dust production mechanism. Several lines of evidences seem to converge toward the second hypothesis.
First, after 10 years of mapping of the martian surface with OMEGA (MEX), the lack of variation of the 3-µm feature with surface relative humidity suggests that the surface hydration does not exchange with the atmosphere. This is in agreement with laboratory adsorption experiments under Mars conditions.
More recently the Mars Science Laboratory with unprecedented payload has provided some crucial constraints on the nature of surface hydration. The ChemCam instrument onboard MSL has detected hydrogen in dust and soil, and revealed the lack of variation of H concentration with surface humidity, including nighttime measurements. Also, evolved gas analysis by SAM of Gale crater soils shows that water is released at relatively high-temperature and suggest that –OH or H2O bearing phases are trapped in the amorphous component of soils.
Finally, the exceptional “black beauty” meteorite might also provide clues to the nature of Mars’s surface hydration. This Martian breccia shows elevated amount of water with respect to any other Martian meteorite. By studying the spectral properties of NWA 7533, we were able to show the presence of a 3-µm band and a small red-slope; this Martian breccia seems to contain a fine-oxidized-H-bearing component, possibly similar to that present in the Martian dust.
