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MSL - SAM and CHEMIN, Discussion of the science/results from these instruments
Astro0
post Nov 21 2012, 11:46 AM
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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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pospa
post Nov 21 2012, 05:24 PM
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MSL Status Report 11.20.2012:
"... Although Curiosity has departed the Rocknest patch of windblown sand and dust where it scooped up soil samples in recent weeks, the sample-handling mechanism on the rover's arm is still holding some soil from the fifth and final scoop collected at Rocknest. The rover is carrying this sample so it can be available for analysis by instruments within the rover if scientists choose that option in coming days."

If the latest SAM analysis result IS "one for the history books" then I would expect repeated measurement of the same sample.
Is there any indication of such a plan for upcoming days (in addition to first drilling)?


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Fran Ontanaya
post Nov 21 2012, 06:45 PM
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Something for reference: http://proceedings.spiedigitallibrary.org/...rticleid=786403


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Don1
post Nov 22 2012, 06:23 AM
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SAM is of course capable of detecting gases evolved from heated samples, and measuring the isotope ratios. Such gases would be expected to include CO2 and water, and possibly HCl or Cl2.
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nprev
post Nov 22 2012, 06:34 PM
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Mod note: Two posts discussing rule 1.3 changes moved here.


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RonJones
post Nov 22 2012, 07:35 PM
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I have not seen any specific statements from the Curiosity science team regarding the ability of SAM to detect organics if perclorates are present in a soil/rock sample. Since SAM first heats the sample up to a high termperature (e.g., 1000 deg.) to vapaorize the sample, would this not destroy organics if perclorates are also present in that sample? Since we have known about the potential for perclorates in the Martian soil since the Pheonix results reported in 2008, I asume this has been considered in some detail by the Curiosity team. Anyone have any information on what level of perclorates would be sufficient to cause significant problems for SAM being able to detect organics (I assume that would also depend on the level of organics in the sample)?
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mcaplinger
post Nov 22 2012, 07:43 PM
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QUOTE (RonJones @ Nov 22 2012, 12:35 PM) *
I have not seen any specific statements from the Curiosity science team regarding the ability of SAM to detect organics if perclorates are present in a soil/rock sample.

Have you read http://link.springer.com/article/10.1007/s11214-012-9879-z ?
QUOTE
The presence of perchlorates and other oxidants, if present in the martian soil and
rocks at Gale crater, could have implications for the SAM search for organics as some of
these compounds could be transformed to CO2 in the oven. If perchlorates are present, a small amount of the organics may form chlorohydrocarbons that could be detected by the SAM GCMS experiment. The presence of perchlorates
may also be indicated by O2 , HCl, or Cl2 evolution in a SAM EGA experiment or these
compounds may be detected by the ChemCam instrument. Similarly,
the presence of high concentration H2 O2 in sediments could manifest itself in the form of
formaldehyde or methanol, species that are potentially detectable by SAM.



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Disclaimer: This post is based on public information only. Any opinions are my own.
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nprev
post Nov 22 2012, 07:44 PM
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One fascinating finding would be if perchlorates are not present in these first samples.

I rather suspect that there is considerable diversity in the composition of martian soil at the regional scale once you get beneath the ubiquitous wind-deposited global dust layer. Recall the serendipitous exposure of subsurface chemical deposits at Gusev by Spirit from the dragging wheel.


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Burmese
post Nov 22 2012, 08:55 PM
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No data yet to work with until they present their findings in Dec, however the news so far out of JPL is illustrative:

I think this announcement will be of relatively mild significance here, the fact that the scientists are even dropping hints at this stage is an indication that is the case. There have been elements and compounds that we are pretty certain are there on Mars and these are simply the 1st instruments capable of definitive proof. It is a feather in Curiosity's hat(hopefully the 1st of many), but just that, not a turkey on the table. That they plan to present the data at a science forum, and not at the typical news conference is simply intelligent planning. The audience will be of a caliber to hear the word 'organic' and understand the nuances inherent in that whereas, if they 1st say that word at a news conference full of reporters, that would be tantamount to yelling 'fire' in a theater and likely induce spontaneous combustion in the room.

If they ever encounter anything more significant, we won't hear word one coming from JPL for a long time, as the watchword would undoubtedly be one of Carl Sagans' better known pronouncements: "Extraordinary claims require extraordinary proof"
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nprev
post Nov 22 2012, 09:11 PM
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Very good comment, Burmese; thank you!

In general, findings of scientific significance tend to be deeply underwhelming to the general public. Strongly advise our members not to be swayed by the usual mass media sensationalism; they are, after all, trying to sell a product and therefore marketing takes precedence over accuracy and critical thinking.

We will find out what it is in due course. In the meantime...the journey continues!!! And it's barely begun. wink.gif

EDIT: Also, a word about organics.

It is overwhelmingly likely that at some point organic molecules will be detected by Curiosity. However, it is also overwhelmingly likely that most if not all of same came from carbonaceous meteorites, and we have seen both direct evidence of recent impacts on Mars from the orbiters as well as iron-nickel meteorites from the MERs. Bear in mind that compounds up to and including amino acids have been found in terrestrial meteorites; therefore, it is reasonable to expect the same sorts of findings from Curiosity as, over time, these objects have weathered and become incorporated into the martian soil.

Bottom line is that ANY discovery of organics means just that: Discovery of organics. Nothing less...and nothing more.


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RonJones
post Nov 23 2012, 01:56 AM
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I suspect that if any new finding by MSL would be of significant interest to the general public it would be announced at a NASA press conference rather than just with paper to a science conference. The findings expected to be disclosed in a couple of weeks may be very interesting to planetary scientists, but may be not be of such a nature to be understood or appreciated by the general public. Let's wait and see if NASA schedules a press conference before the start of the conference.
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Astro0
post Nov 23 2012, 02:30 AM
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ADMIN NOTE: Can I remind everyone that this thread is for "Discussion of the science/results from these instruments" and not for debating why, how or when information will be/should be released, etc. This thread was opened with some very specific rules put in place and if it goes off-topic, will result in its closure and Rule 1.3 changed again. This was an attempt by the Admin Team to allow for discussion on a topic that has been 'out of bounds' in the past. It's up to members to make it work - if it doesn't then it's off the agenda forever.
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marsophile
post Nov 23 2012, 03:54 AM
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QUOTE (RonJones @ Nov 22 2012, 12:35 PM) *
...would this not destroy organics if perclorates are also present in that sample?


All you have to do is wash the sample in water before pyrolyzing it. That would remove water-soluble components like perchlorate while retaining hydrophobic organic substances if any are present. I was under the impression that Curiosity has this capability or something like it.
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mcaplinger
post Nov 23 2012, 06:49 AM
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QUOTE (marsophile @ Nov 22 2012, 08:54 PM) *
All you have to do is wash the sample in water before pyrolyzing it...I was under the impression that Curiosity has this capability or something like it.

Not that I'm aware of. SAM has its wet chemistry cells but the SAM instrument paper referenced above doesn't indicate that this is their purpose -- see section 4.6, "Solid Sample Measurements Based on Wet Chemical Processing".

Note that Springer-Verlag has made all of the MSL instrument papers free-access until the end of the year, so there's no excuse not to read up if you're interested -- http://link.springer.com/journal/11214/170/1/page/1


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MrNatural
post Nov 23 2012, 03:08 PM
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Can we discuss SAM's stereochemistry capabilities? I believe that SAM can sort out chirality, but I have seen very little written about this. As we all know, stereochemistry would allow us to help us determine, ah I hesitate to say this, the genesis of some organics. As far as I can tell, SAM can determine if a peak is chiral, but I am not sure if it can tell if there is a preponderance of L- versus D- for a particular organic chemical.
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