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Stability of perchlorate hydrates and their liquid solutions at the Phoenix landing site, Mars
Author(s) -
Chevrier Vincent F.,
Hanley Jennifer,
Altheide Travis S.
Publication year - 2009
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 - 10.1029/2009gl037497
Subject(s) - perchlorate , phoenix , eutectic system , mars exploration program , magnesium , evaporation , sodium perchlorate , chemistry , materials science , thermodynamics , astrobiology , metallurgy , ion , physics , organic chemistry , electrochemistry , geography , archaeology , metropolitan area , alloy , electrode
We studied the low‐temperature properties of sodium and magnesium perchlorate solutions as potential liquid brines at the Phoenix landing site. We determined their theoretical eutectic values to be 236 ± 1 K for 52 wt% sodium perchlorate and 206 ± 1 K for 44.0 wt% magnesium perchlorate. Evaporation rates of solutions at various concentrations were measured under martian conditions, and range from 0.07 to 0.49 mm h −1 for NaClO 4 and from 0.06 to 0.29 mm h −1 for Mg(ClO 4 ) 2 . The extrapolation to Phoenix landing site conditions using our theoretical treatment shows that perchlorates are liquid during the summer for at least part of the day, and exhibit very low evaporation rates. Moreover, magnesium perchlorate eutectic solutions are thermodynamically stable over vapour and ice during a few hours a day. We conclude that liquid brines may be present and even stable for short periods of time at the Phoenix landing site.