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Magnesium Sulfate as a Key Mineral for the Detection of Organic Molecules on Mars Using PyrolysisPyrolysis of soil or rock samples is the preferred preparation technique used on Mars to search for organic molecules up today. During pyrolysis, oxichlorines present in the soil of Mars release oxidant species that alter the organic molecules potentially contained in the samples collected by the space probes.This process can explain the difficulty experienced by in situ exploration probes to detect organic materials in Mars soil samples until recently. Within a few months, the Curiosity rover should reach and analyze for the first time soils rich in sulfates which could induce a different behavior of the organics during the pyrolysis compared with the types of soils analyzed up today. For this reason, we systematically studied the pyrolysis of organic molecules trapped in magnesium sulfate, in the presence or absence of calcium perchlorate. Our results show that organics trapped in magnesium sulfate can undergo some oxidation and sulfuration during the pyrolysis. But these sulfates are also shown to protect organics trapped inside the crystal lattice and/or present in fluid inclusions from the oxidation induced by the decomposition of calcium perchlorate and probably other oxychlorine phases currently detected on Mars. Trapped organics may also be protected from degradation processes induced by other minerals present in the sample, at least until these organics are released from the pyrolyzed sulfate mineral (700C in our experiment). Hence, we suggest magnesium sulfate as one of the minerals to target in priority for the search of organic molecules by the Curiosity and ExoMars 2018 rovers.
Document ID
20180001599
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Francois, P. (Centre National de la Recherche Scientifique Paris, France)
Szopa, C. (Universite de Versailles Saint-Quentin-en-Yvelines Versailles, France)
Buch, A. (Ecole Centrale de Paris France)
Coll, P. (Centre National de la Recherche Scientifique Paris, France)
McAdam, A. C. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Mahaffy, P. R. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Freissinet, C. (Maryland Univ. Baltimore County Baltimore, MD, United States)
Glavin, D. P. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Navarro-Gonzalez, R. (Universidad Nacional Autonoma de Mexico Mexico City, Mexico)
Cabane, M. (Universite de Versailles Saint-Quentin-en-Yvelines Versailles, France)
Date Acquired
March 5, 2018
Publication Date
January 26, 2016
Publication Information
Publication: Journal of Geophysical Research: Planets
Volume: 121
Issue: 1
ISSN: 2169-9097
Subject Category
Space Sciences (General)
Geophysics
Report/Patent Number
GSFC-E-DAA-TN40584
Distribution Limits
Public
Copyright
Other