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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#1
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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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Dec 4 2012, 04:43 PM
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#2
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Member Group: Members Posts: 507 Joined: 10-September 08 Member No.: 4338 |
For some context, we had the following results from the Viking GCMS.
Sample T Compound Abundance (ppb) VL1 Blank Test 500 CH3Cl Not Detected Sample 1 200 CH3Cl 15 VL-2 Blank Test 500 CH2Cl2 Not Detected Sample1 500 CH2Cl2 2-6 Sample2 500 CH2Cl2 20-40 For a discussion, see this paper: http://www.agu.org/pubs/crossref/2010/2010JE003599.shtml The original Viking GCMS results were published in this Ph.D. thesis: http://dspace.mit.edu/bitstream/handle/172...69/07517313.pdf See for example, Pages 203 and 204 for VL-1 and VL-2 chlorinated hydrocarbon results. (Methyl Chloride = Chloromethane, Methylene Chloride = Dichloromethane) Also chlorinated hydrocarbon results from Antarctic soils Pp 233,242,250,258. |
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Dec 5 2012, 04:03 PM
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#3
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Member Group: Members Posts: 507 Joined: 10-September 08 Member No.: 4338 |
Also chlorinated hydrocarbon results from Antarctic soils Pp 233,242,250,258. What I find fascinating is that chloromethanes were detected by tests of the Viking GCMS in Antarctic soils. Apparently these soils do also contain perchlorate: http://pubs.acs.org/doi/abs/10.1021/es9033606 If this hint had been followed up, we might have hypothesized the presence of perchlorate in Martian soils a lot earlier. |
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Dec 5 2012, 04:59 PM
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#4
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
...If this hint had been followed up, we might have hypothesized the presence of perchlorate in Martian soils a lot earlier. Well... perchlorate was one of the options that was being discussed at the time of the original GCMS experiments on Viking. The phrasing I recall is that the time-release experiment data fit well with a Martian soil rich in "super-oxidants," and one of the super-oxidants that headed the list was perchlorate. I believe the presence of chlorine in some of the evolved gasses seen in the Viking results is what led to that speculation, 36 years ago. I don't have any articles of the time in front of me, but I am very confident of my memory of the "super-oxidant" reports. -the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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Dec 5 2012, 07:51 PM
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#5
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Senior Member Group: Members Posts: 2517 Joined: 13-September 05 Member No.: 497 |
Well... perchlorate was one of the options that was being discussed at the time of the original GCMS experiments on Viking. The phrasing I recall is that the time-release experiment data fit well with a Martian soil rich in "super-oxidants," and one of the super-oxidants that headed the list was perchlorate. I don't think so. At the time H2O2 or superoxides were used as explanations for the O2 release seen after wetting in the GEx experiment, and CO2 release in the LR experiment. I'm no chemist but I don't think perchlorates alone explain these results; see http://www.lpi.usra.edu/meetings/lpsc2011/pdf/2003.pdf for example. And I don't think that perchlorates are technically superoxides. I'd be happy to be proved wrong but it would take an actual reference from pre-Phoenix to convince me that anyone had mentioned perchlorates in the context of Viking. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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Dec 5 2012, 08:59 PM
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#6
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Senior Member Group: Members Posts: 2517 Joined: 13-September 05 Member No.: 497 |
...it would take an actual reference from pre-Phoenix to convince me that anyone had mentioned perchlorates in the context of Viking. For example, Zent and McKay's 1994 Icarus paper "The Chemical Reactivity of the Martian Soil and Implications for Future Missions" http://www.sciencedirect.com/science/artic...019103584710475 says nothing about perchlorates that I can see. -------------------- Disclaimer: This post is based on public information only. Any opinions are my own.
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