Premium
Low temperature aqueous ferric sulfate solutions on the surface of Mars
Author(s) -
Chevrier Vincent F.,
Altheide Travis S.
Publication year - 2008
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 - 10.1029/2008gl035489
Subject(s) - sulfate , evaporation , mars exploration program , ferric , eutectic system , aqueous solution , sulfur , geology , chemistry , mineralogy , inorganic chemistry , materials science , astrobiology , thermodynamics , metallurgy , alloy , physics
We have studied the low‐temperature properties of ferric sulfate Fe 2 (SO 4 ) 3 solutions as a model for potential liquid brines on the surface of Mars. Geochemical modeling demonstrates that concentrated ferric sulfate brines form through sulphur‐rich acidic evaporation processes in cold oxidizing environments. Experiments and thermodynamic calculations show that the Fe 2 (SO 4 ) 3 eutectic temperature is 205 ± 1 K for 48 ± 2 wt% concentration. As a result of low water activity, these solutions exhibit evaporation rates ranging from 0.42 mm h −1 (29.1 wt%) to 0.03 mm h −1 (58.2 wt%), thus down to 20 times lower than pure water. The combination of extremely low eutectic temperature and evaporation rates allow subsurface liquids to be stable at high latitudes, where the majority of gullies and viscous flow features are located. Therefore, we conclude that episodic releases of highly concentrated ferric sulfate brines are a potential agent for the formation of recent and present‐day gullies on Mars.