MSL - SAM and CHEMIN, Discussion of the science/results from these instruments |
MSL - SAM and CHEMIN, Discussion of the science/results from these instruments |
Nov 21 2012, 11:46 AM
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Senior Member Group: Admin Posts: 3108 Joined: 21-December 05 From: Canberra, Australia Member No.: 615 |
ADMIN NOTE: Hi All, a new topic for the discussion of the science from the SAM and Chemin instruments.
There has been a very important amendment to Rule 1.3 which is explained here. Please remember Rule 1.3 at all times when discussing matters in this section. |
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Nov 27 2012, 06:21 AM
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#2
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Senior Member Group: Members Posts: 2542 Joined: 13-September 05 Member No.: 497 |
http://www.lpi.usra.edu/meetings/lpsc2012/pdf/2008.pdf and various other abstracts coming up with a google search for "sam msl perchlorate" may be of interest.
QUOTE The parent salts of the perchlorate on Mars are unknown, but geochemical models using WCL data support the possible dominance of Mg-perchlorate salts. Mg(ClO4)2•6H2O is the stable phase at ambient martian conditions, and breaks down at lower temperatures than carbonates giving off Cl2 and HCl gas. Devlin and Herley report two exotherms at 410-478°C and 473-533°C which correspond to the decomposition of Mg(ClO4)2. They support a two-stage process:
(1) 2Mg(ClO4)2 = [MgO•Mg(ClO4)2] + Cl2 + 3.5O2 (2) [MgO•Mg(ClO4)2] = 2MgO + Cl2 + 3.5O2 If the chlorine gas produced reacts with moisture in the system or if the magnesium perchlorate has not fully dehydrated, then HCl gas can form and react with a carbonate phase to evolve CO2: (3) CaCO3 + 2HCl = CaCl2 + CO2 + H2O -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Nov 27 2012, 11:18 PM
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#3
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Senior Member Group: Members Posts: 1056 Joined: 17-February 09 Member No.: 4605 |
http://www.lpi.usra.edu/meetings/lpsc2012/pdf/2008.pdf and various other abstracts coming up with a google search for "sam msl perchlorate" may be of interest. Thanks for the link and as expected I stand corrected on the Ca perchlorate decomposition products. The sheer volume of information on the web is daunting but I couldn't find anything on analysis of mixed samples reflecting candidate martian perchlorates/soil compositions? I seem to remember that the thermal stablility of a mix of perchlorates is lower than that of the pure components and the initial endothermic reaction in the figure 1 Wicked Witch sample seems closer to that for Ca perchlorate. Curiosity's investigative capability is remarkable and I can't wait for the next LPSC. |
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