MARS SAMPLE RETURN MISSIONS. David Vaniman (Los ... 100. 90. 80. 70. 60. 50. 0. 100. 200. 300. 400. 500. 600 temperature ( C) w e ig h t. / in itia lw e ig h.
SALT-HYDRATE STABILITIES AND MARS SAMPLE RETURN MISSIONS David Vaniman (Los Alamos National Laboratory) David Bish (Indiana University) Steve Chipera (Chesapeake Energy Corp.)
Case histories • Meteorites: Epsomite in primitive CI1 chondrites has been been cited as evidence of late-stage oxidation of the CI1 parent body but there is strong evidence that epsomite has formed in these meteorites after they were placed in humid terrestrial museums.
• Lunar Samples: Goethite (FeOOH) “rust” observed in Apollo 16 rocks stimulated great interest but was eventually found to have formed by hydration-oxidation of lawrencite (FeCl2).
Mg-sulfates – Many variants, especially in cold, water-poor environments Formula MgSO4 anhydrous MgSO4·1H2O MgSO4·1H2O type 2 MgSO4·2H2O MgSO4·2.4H2O
Mineral name none (reagent) kieserite none (reagent) sanderite none
MgSO4·4H2O
starkeyite
MgSO4·5H2O
pentahydrite
MgSO4·6H2O
hexahydrite
MgSO4·7H2O
epsomite
MgSO4·11H2O
meridianiite
MgSO4·nH2O
amorphous (n variable)
TGA data
Ca sulfate forms: Gypsum CaSO4·2H2O
Bassanite CaSO4·0.5H2O
Anhydrite CaSO4
weight / initial weight (%)
Gypsum is relatively resistant to dehydration 100 90
