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Soluble sulfate in the martian soil at the Phoenix landing site
Author(s) -
Kounaves Samuel P.,
Hecht Michael H.,
Kapit Jason,
Quinn Richard C.,
Catling David C.,
Clark Benton C.,
Ming Douglas W.,
Gospodinova Kalina,
Hredzak Patricia,
McElhoney Kyle,
Shusterman Jennifer
Publication year - 2010
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2010gl042613
Subject(s) - phoenix , martian , martian soil , astrobiology , sulfate , mars exploration program , geology , mars landing , environmental science , remote sensing , martian surface , exploration of mars , chemistry , geography , archaeology , physics , metropolitan area , organic chemistry
Sulfur has been detected by X‐ray spectroscopy in martian soils at the Viking, Pathfinder, Opportunity and Spirit landing sites. Sulfates have been identified by OMEGA and CRISM in Valles Marineris and by the spectrometers on the MER rovers at Meridiani and Gusev. The ubiquitous presence of sulfur has been interpreted as a widely distributed sulfate mineralogy. One goal of the Wet Chemistry Laboratory (WCL) on NASA's Phoenix Mars Lander was to determine soluble sulfate in the martian soil. We report here the first in‐situ measurement of soluble sulfate equivalent to ∼1.3(±0.5) wt% as SO 4 in the soil. The results and models reveal SO 4 2− predominately as MgSO 4 with some CaSO 4 . If the soil had been wet in the past, epsomite and gypsum would be formed from evaporation. The WCL‐derived salt composition indicates that if the soil at the Phoenix site were to form an aqueous solution by natural means, the water activity for a dilution of greater than ∼0.015 g H 2 O/g soil would be in the habitable range of known terrestrial halophilic microbes.