Perchlorate induced low temperature carbonate decomposition in the Mars Phoenix Thermal and Evolved Gas Analyzer (TEGA)

• Published in: Geophysical research letters 2012-07, Vol.39 (13), p.np-n/a
• Main Authors: Cannon, K. M., Sutter, B., Ming, D. W., Boynton, W. V., Quinn, R.
• Format: Article
• Language: English
• Subjects: Analyzers; Calcite; Carbon dioxide; Carbonates; Earth sciences; Earth, ocean, space; Exact sciences and technology; Magnesium perchlorates; Mars; MSL; perchlorate; Perchlorates; Soils; TEGA
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2012GL051952

Simulated Thermal Evolved Gas Analyzer (TEGA) analyses have shown that a CO2 release detected between 400°C and 680°C by the Phoenix Lander's TEGA instrument may have been caused by a reaction between calcium carbonate and hydrated magnesium perchlorate. In our experiments a CO2release beginning at 385 ± 12°C was attributed to calcite reacting with water vapor and HCl gas from the dehydration and thermal decomposition of Mg‐perchlorate. The release of CO2 is consistent with the TEGA detection of CO2 released between 400 and 680°C, with the amount of CO2increasing linearly with added perchlorate. X‐ray diffraction (XRD) experiments confirmed CaCl2 formation from the reaction between calcite and HCl. These results have important implications for the Mars Science Laboratory (MSL) Curiosity rover. Heating soils may cause inorganic release of CO2; therefore, detection of organic fragments, not CO2 alone, should be used as definitive evidence for organics in Martian soils. Key Points Hydrated magnesium perchlorate decomposes to release HCl gas when heated Evolved HCl reacts with carbonates to evolve carbon dioxide Carbon dioxide releases are not proof of organic molecules in Martian soils