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Selfsim
2013-Sep-20, 09:59 AM
Life on Mars hopes fade after methane findings (Update) (http://phys.org/news/2013-09-nasa-rover-hint-methane-mars.html)


Hopes of finding life on Mars suffered a setback after new findings from NASA's Curiosity rover detected only trace amounts of methane gas in the Red Planet's atmosphere, a study said Thursday.
...
Scientists said Curiosity's findings indicated that the maximum level of methane was 1.3 parts per billion by volume—about six times lower than previous estimates.

The low atmospheric methane level greatly reduces chances that Martian soil contains living microbes or organic fossil materials that would produce the gas, scientists said.
...
Previously identified methane plumes may have been the result of misinterpretation of observations, including those made from Earth-based telescopes, according to the researchers.The most interesting aspect for me, was the conclusion of: misinterpretation of (previous) observations.

Apparently we are unable to reliably and accurately remotely detect the so-called methane 'bio-sign', even in a neighbouring planet's atmosphere.

I'd imagine that might come as a surprise for some folk(??)

Selfsim
2013-Sep-20, 10:12 AM
PS: By means other than by remote interplanetary probe based equipment, that is.

iquestor
2013-Sep-20, 11:04 AM
comes as a big surprise to me; and its disheartening. :(

Paul Wally
2013-Sep-20, 01:14 PM
Why can't the ground based stations look again to see whether they find the same levels of methane as they found that time? Obviously, we ought to compare current measurements with current measurements. Perhaps the methane release is only episodic.

kzb
2013-Sep-20, 03:48 PM
It's only a factor of six. Why is six times this level a sign of life, whereas this is a sign of no life? Where's the dividing line?

iquestor
2013-Sep-20, 04:00 PM
6x is a LOT to be wrong by. Much less methane would seem to point to a non-biological source. My reasoning is that there would either be a lot of methane producing microbes, or none. not "a few" which would results in really low levels of methane.

Current theories on martian methane is that its produced by the effects of radiation on meteoric dust while temperatures are within a set range, which would explain the seasonal variations.

Don J
2013-Sep-20, 07:49 PM
From the article:
http://phys.org/news/2013-09-nasa-rover-hint-methane-mars.html


Michael Meyer, NASA's lead scientist for Mars exploration, did not definitively rule out the possibility of finding life in the planet's soil following the methane findings.

"This important result will help direct our efforts to examine the possibility of life on Mars," he said.

"It reduces the probability of current methane-producing Martian microbes,but this addresses only one type of microbial metabolism. As we know, there are many types of terrestrial microbes that don't generate methane."

Colin Robinson
2013-Sep-20, 08:42 PM
Life on Mars hopes fade after methane findings (Update) (http://phys.org/news/2013-09-nasa-rover-hint-methane-mars.html)


Previously identified methane plumes may have been the result of misinterpretation of observations, including those made from Earth-based telescopes

Note the word "including". Findings re methane on Mars didn't only come from Earth-based telescopes, they also came from an orbiting space probe, the Mars Express Orbiter.


The most interesting aspect for me, was the conclusion of: misinterpretation of (previous) observations.

Apparently we are unable to reliably and accurately remotely detect the so-called methane 'bio-sign', even in a neighbouring planet's atmosphere.

Especially if we're talking about a planet where any methane is at a level of no more than 10 parts per billion, according to the highest finding. The challenge is to distinguish between a very small trace and none at all.

Selfsim
2013-Sep-20, 09:45 PM
Note the word "including". Findings re methane on Mars didn't only come from Earth-based telescopes, they also came from an orbiting space probe, the Mars Express Orbiter.Yep .. I added post#2, following the same lines of thought.

Interestingly, and somewhat introspectively speaking, I must admit, personally, I'm generally somewhat more skeptical of ESA's announcements than NASA's. :surprised: ESA seems to hype the 'wow' more, whereas NASA seems more acutely aware of its more negative impacts and, at least, is aware of the need for 'a good measure' of scrutiny, prior to announcements, (I think).


Especially if we're talking about a planet where any methane is at a level of no more than 10 parts per billion, according to the highest finding. The challenge is to distinguish between a very small trace and none at all... Especially so from inside an atmosphere having 1% water vapour. From memory, absorption windows made the remote detection from ground-based scopes very 'challenging'(?)
From: "Detection of methane in the martian atmosphere: evidence for life?" (http://www.sciencedirect.com/science/article/pii/S0019103504002222) (the original ground-based detection announcement):

Using the Fourier Transform Spectrometer at the Canada–France–Hawaii Telescope, we observed a spectrum of Mars at the P-branch of the strongest CH4 band at 3.3 μm with resolving power of 180,000 for the apodized spectrum. Summing up the spectral intervals at the expected positions of the 15 strongest Doppler-shifted martian lines, we detected the absorption by martian methane at a 3.7 sigma level which is exactly centered in the summed spectrum. The observed CH4 mixing ratio is 10±3 ppbWhich turns out to be about 10nmol/mol. A 3.7 sigma level wasn't all that entirely convincing, either, I suppose(?) The paper Abstract seems to be more concerned with the implications of the measured value, rather than defending its accuracy(?)

The original ESA announcement is here (http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Mars_Express_confirms_methane_in_the_Martian_atmos phere). If ya ask me, the 'spin' in this announcement, (at the end), is more about how 'good' their detection technique is/was, generating 'excitement', and doesn't attempt to dispel skepticism about the possibility of false positives(?) .. (All easy to say in retrospect admittedly, I might add ..).

Selfsim
2013-Sep-20, 09:50 PM
Why can't the ground based stations look again to see whether they find the same levels of methane as they found that time? Obviously, we ought to compare current measurements with current measurements. Perhaps the methane release is only episodic.Not sure if it'd be worth the observation time … ie: why bother when SAM can do it more accurately .. and rule out Earth atmospheric effects at the same time ?

The issue seems to be more how everyone succumbed to the 'hype' about the possibility that methane could mean microbial life on Mars .. rather than dwelling on the measurement credibility itself.

... A good lesson to learned from the experience, wouldn't you say?

Selfsim
2013-Sep-20, 09:51 PM
I wonder whether the same will happen when Webb starts seeing exo-atmospheric spectra?

iquestor
2013-Sep-21, 01:43 AM
Not sure if it'd be worth the observation time … ie: why bother when SAM can do it more accurately .. and rule out Earth atmospheric effects at the same time ?

The issue seems to be more how everyone succumbed to the 'hype' about the possibility that methane could mean microbial life on Mars .. rather than dwelling on the measurement credibility itself.

... A good lesson to learned from the experience, wouldn't you say?


yes, it does say a lot about hindsight being 20/20, and a good lesson. and a dissapointing one, for me.

Colin Robinson
2013-Sep-21, 02:07 AM
Why can't the ground based stations look again to see whether they find the same levels of methane as they found that time? Obviously, we ought to compare current measurements with current measurements. Perhaps the methane release is only episodic.

Yes. The results from Curiosity are for a particular location on Mars' surface and a particular period of time. Is it perhaps a little hasty to conclude that there is no truth at all in the results that came from the ESA orbiter as well as from the Earth-based observations?

iquestor
2013-Sep-21, 02:25 AM
Yes. The results from Curiosity are for a particular location on Mars' surface and a particular period of time. Is it perhaps a little hasty to conclude that there is no truth at all in the results that came from the ESA orbiter as well as from the Earth-based observations?

I dont think they would call into question the results of all those ground based surveys if they werent sure about it...

Colin Robinson
2013-Sep-21, 02:47 AM
I dont think they would call into question the results of all those ground based surveys if they werent sure about it...

The quote in the OP uses the word "may"


Previously identified methane plumes may have been the result of misinterpretation of observations

The linked article does say that the NASA researchers have high confidence in their results, and see them as inconsistent with the plumes of methane reported by the ESA orbiter and the Earth based studies. However, the inconsistency depends on assumptions about the rate at which methane would break down in Martian conditions. Is enough really known about chemistry on Mars to be certain these assumptions are right?

Regarding NASA and ESA, I respect the scientific work of both space agencies. That is why I am disinclined to jump to the conclusion that the Mars Express orbiter got it completely wrong.

Selfsim
2013-Sep-21, 04:47 AM
The quote in the OP uses the word "may"
...
The linked article does say that the NASA researchers have high confidence in their results, and see them as inconsistent with the plumes of methane reported by the ESA orbiter and the Earth based studies. However, the inconsistency depends on assumptions about the rate at which methane would break down in Martian conditions. Is enough really known about chemistry on Mars to be certain these assumptions are right?
...

"There's no known way for methane to disappear quickly from the atmosphere," Atreya said. "Methane is persistent. It would last for hundreds of years in the Martian atmosphere.Ok .. so if there's, 'maybe', a new way' for methane to appear and disappear quickly from an atmosphere, (ie: another possibility other than 'observation misinterpretation' issues), then what does that then tell us about its usefulness for reliably inferring remotely detectable exo-life?

Don J
2013-Sep-21, 06:51 AM
...
Ok .. so if there's, 'maybe', a new way' for methane to appear and disappear quickly from an atmosphere, (ie: another possibility other than 'observation misinterpretation' issues),

There is effectively another possibility.
The possibility is that the methane is not consumed at all, but rather condenses and evaporates seasonally from clathrates.
http://en.wikipedia.org/wiki/Atmosphere_of_Mars


Research suggests that the implied methane destruction lifetime (on Mars) is as long as ~4 Earth years and as short as ~0.6 Earth years.[30][34] This lifetime is short enough for the atmospheric circulation to yield the observed uneven distribution of methane across the planet. In either case, the destruction lifetime for methane is much shorter than the timescale (~350 years) estimated for photochemical (UV radiation) destruction.[30] The rapid destruction of methane suggests another process must dominate removal of atmospheric methane on Mars and it must be more efficient than destruction by light by a factor of 100 to 600.[30][34] This unexplained fast destruction rate also suggests a very active replenishing source.[35] A possibility is that the methane is not consumed at all, but rather condenses and evaporates seasonally from clathrates.[36]

On the other hand the Journal Nature dated 19 September 2013 ,said that several mechanisms for such rapid decomposition have been proposed — including oxidation by soil chemicals called perchlorates — but there is no hard evidence for any of them.
Interesting article.
http://www.nature.com/news/missing-methane-gas-mystifies-mars-scientists-1.13779


Plume today, gone tomorrow

Mumma, too, has failed to see strong methane signals in recent measurements. That might be because atmospheric methane is destroyed much more quickly than expected, in mere weeks or months. Several mechanisms for such rapid decomposition have been proposed — including oxidation by soil chemicals called perchlorates — but there is no hard evidence for any of them. “It’s a puzzle,” says Mumma. “I haven’t yet heard a convincing geochemical explanation.”

Colin Robinson
2013-Sep-21, 07:13 AM
...
Ok .. so if there's, 'maybe', a new way' for methane to appear and disappear quickly from an atmosphere, (ie: another possibility other than 'observation misinterpretation' issues), then what does that then tell us about its usefulness for reliably inferring remotely detectable exo-life?

Who has said that methane is useful "for reliably inferring remotely detectable exo-life"? It is a simple compound of two of the commonest elements in the universe, hydrogen and carbon. Its significance in a given chemical environment depends on what else is in that environment. One reason why scientists are specifically interested in its presence or absence on Mars, is that the overall chemistry of Mars is dominated by oxygen compounds rather than by hydrogen compounds. So, the reported observation of methane there (e.g. by the ESA orbiter) has raised questions as to why the methane hasn't all been oxidized to water plus carbon monoxide and/or carbon dioxide, unless it is being actively replenished.

iquestor
2013-Sep-21, 12:18 PM
Who has said that methane is useful "for reliably inferring remotely detectable exo-life"? It is a simple compound of two of the commonest elements in the universe, hydrogen and carbon. Its significance in a given chemical environment depends on what else is in that environment. One reason why scientists are specifically interested in its presence or absence on Mars, is that the overall chemistry of Mars is dominated by oxygen compounds rather than by hydrogen compounds. So, the reported observation of methane there (e.g. by the ESA orbiter) has raised questions as to why the methane hasn't all been oxidized to water plus carbon monoxide and/or carbon dioxide, unless it is being actively replenished.

my understanding is that methane is primarily produced by volcanism or biology, and Mars, as far as we know isnt volcanically active. So we got excited, envisioning underground vats of methane producing alient microbes.

However recently it has been proposed that the Mars Methane is produced by the effects of radiation on meteoric dust when the temperatures are in a given range, which would explain the presense, some of the volume, as well as the seasonal fluctuations. Now that we have deduced the volume may be much lower than recorded, I dont know how it affects this theory.

Paul Wally
2013-Sep-21, 10:32 PM
Yes. The results from Curiosity are for a particular location on Mars' surface and a particular period of time. Is it perhaps a little hasty to conclude that there is no truth at all in the results that came from the ESA orbiter as well as from the Earth-based observations?

I think it is a little hasty, especially because both ESA and Earth-based independently arrived at about 10ppb.

neilzero
2013-Sep-22, 12:37 AM
If the methane is from 1000 randomly located far below the surface bio masses, then I would expect zero most days with a few hundred farts per century, some of which only last seconds. The half life of methane in Earth's atmosphere is 16 days according to one source of unknown validity. Do we have any guestimates for the half life of methane in the atmosphere of Mars? I suppose it matters (at least slightly) how many millimeters above the surface you are measuring. Neil

kzb
2013-Sep-23, 05:23 PM
Selfsim wrote:

Interestingly, and somewhat introspectively speaking, I must admit, personally, I'm generally somewhat more skeptical of ESA's announcements than NASA's. ESA seems to hype the 'wow' more, whereas NASA seems more acutely aware of its more negative impacts and, at least, is aware of the need for 'a good measure' of scrutiny, prior to announcements, (I think).

Anyone else remember the president of the USA being wheeled out to announce NASA finding martian fossils? What was that arsenic-based lifeform announced by NASA.....?

However I do remember there were impressive false colour contour maps of the methane concentration, and how it varied with the seasons. How would you reconcile those maps and the seasonal variations with a cosmic-ray/soil interaction mechanism of methane production ?

iquestor
2013-Sep-23, 05:30 PM
kzb said:
However I do remember there were impressive false colour contour maps of the methane concentration, and how it varied with the seasons. How would you reconcile those maps and the seasonal variations with a cosmic-ray/soil interaction mechanism of methane production ?

Here is a link to one article I read: "Methane on Mars not an indication of Life (http://www.mpg.de/5825479/mars_methane_life)"



Since the temperature on the red planet varies from minus 143 degrees Celsius at the poles to plus 17 degrees Celsius at Mars’ equator, the scientists also investigated the meteoritic samples at appropriate temperatures. The warmer it became, the more methane was released by the meteoritic fragments. This temperature dependence also agrees with the different methane concentrations at different locations in the Martian atmosphere. In infrared spectra, the largest concentration of methane was found in the equatorial region, the warmest place on Mars, relatively speaking.

Selfsim
2013-Sep-23, 10:33 PM
Anyone else remember the president of the USA being wheeled out to announce NASA finding martian fossils? What was that arsenic-based lifeform announced by NASA.....? 'Twas Richard Hoover who made that announcement (as I recall). NASA almost instantly distanced itself from it .. and him as well(?)
This is exactly why I think NASA is now a more reliable announcer that ESA is. ESA doesn't seem to have experienced the consequences of a massive public debacle of such proportions.
Except for, perhaps, the FT neutrinos/CERN announcement. They should've learned form that experience I suppose .. (no national leaders were invoked in that one though ..).


However I do remember there were impressive false colour contour maps of the methane concentration, and how it varied with the seasons. How would you reconcile those maps and the seasonal variations with a cosmic-ray/soil interaction mechanism of methane production ?The dynamics of the perceived phenomenon would be subject to seasonal and geographical variability, regardless of ambient gas concentrations (non-zero)?

Cosmic ray/soil interaction is an attempt at explaining a formation mechanism under certain base conditions. The insight in the OP, suggests that the original observations might have been inaccurate, therefore the base condition criteria for the explanation may not have been satisfied(?)

Selfsim
2013-Sep-23, 10:42 PM
Since the temperature on the red planet varies from minus 143 degrees Celsius at the poles to plus 17 degrees Celsius at Mars’ equator, the scientists also investigated the meteoritic samples at appropriate temperatures. The warmer it became, the more methane was released by the meteoritic fragments. This temperature dependence also agrees with the different methane concentrations at different locations in the Martian atmosphere. In infrared spectra, the largest concentration of methane was found in the equatorial region, the warmest place on Mars, relatively speaking.
See, this sustains the idea that the original measurements by ground-scopes and Mars Express were not in error.

Rather than conducting the ground-based observations again (as Paul W suggests), I think the upcoming MAVEN mission might have the right equipment on board to resolve the matter(?) Perhaps these announcements are just to stir up support/interest in MAVEN(?)

iquestor
2013-Sep-23, 11:40 PM
See, this sustains the idea that the original measurements by ground-scopes and Mars Express were not in error.

Rather than conducting the ground-based observations again (as Paul W suggests), I think the upcoming MAVEN mission might have the right equipment on board to resolve the matter(?) Perhaps these announcements are just to stir up support/interest in MAVEN(?)

Maybe; probably a good idea. I for one would like to see its resolution.

kzb
2013-Sep-24, 05:37 PM
[QUOTE=Selfsim;2158338]'Twas Richard Hoover who made that announcement (as I recall). NASA almost instantly distanced itself from it .. and him as well(?)
This is exactly why I think NASA is now a more reliable announcer that ESA is. ESA doesn't seem to have experienced the consequences of a massive public debacle of such proportions.
Except for, perhaps, the FT neutrinos/CERN announcement. They should've learned form that experience I suppose .. (no national leaders were invoked in that one though ..).

QUOTE]

Hoover as well? So Clinton was not the first?

http://www.marsnews.com/focus/life/

kzb
2013-Sep-24, 05:47 PM
kzb said:

Here is a link to one article I read: "Methane on Mars not an indication of Life (http://www.mpg.de/5825479/mars_methane_life)"

OK that is a possible mechanism that could fit the bill. It is based on solar uv not cosmic rays. However, if this mechanism is operating then we still have the measurement discrepancies.

Before we know if it is truly plausible, we need a mass balance. Can the amount of organic meteoric material on the surface, under the level of uv irradiation on Mars, account for the rate of methane production? Bearing in mind that Viking did not apparently detect any organic material in the soil.

Don J
2013-Sep-24, 06:37 PM
OK that is a possible mechanism that could fit the bill. It is based on solar uv not cosmic rays. However, if this mechanism is operating then we still have the measurement discrepancies.

Before we know if it is truly plausible, we need a mass balance. Can the amount of organic meteoric material on the surface, under the level of uv irradiation on Mars, account for the rate of methane production? Bearing in mind that Viking did not apparently detect any organic material in the soil.
http://spie.org/x41481.xml?pf=true&ArticleID=x41481


Abstract
Assuming a gas detected in the Viking Labeled Release experiment was methane, the extrapolated size, soil density, and aqueous requirements of a microbial population are large enough to produce that gas.
......
see description
.....
Conclusion
The remarkable result is that a population of methanogens existing at depths from the surface to no more than 10m below the surface on average, and in a low concentration of Mars water similar to the Viking LR experiments, could easily replenish the methane content of the Martian atmosphere on the timescale required. These estimates are global averages by necessity. If methanogens exist, they may be concentrated in geologically restricted patches or oases.


Possible adaptability of Martian microbes based on new interpretation of Viking datas
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=1183396
Abstract


The adaptability of extremophiles on Earth raises the question of what strategies putative life might have used to adapt to the present conditions on Mars. Here, we hypothesize that organisms might utilize a water–hydrogen peroxide (H2O–H2O2) mixture rather than water as an intracellular liquid. This adaptation would have the particular advantages in the Martian environment of providing a low freezing point, a source of oxygen and hygroscopicity. The findings by the Viking experiments are reinterpreted in light of this hypothesis. Our conclusion is that the hitherto mysterious oxidant in the Martian soil, which evolves oxygen when humidified, might be H2O2 of biological origin. This interpretation has consequences for site selection for future missions to search for life on Mars.

Full free paper
http://arxiv.org/pdf/physics/0610093

ESA -2013- about the low level of methane detected by Curiosity instruments.
http://meetingorganizer.copernicus.org/EPSC2013/EPSC2013-988.pdf
They take into account the fact that the measurements were made at night at sol 79,81 and 106...

Colin Robinson
2013-Sep-24, 08:59 PM
'Twas Richard Hoover who made that announcement (as I recall). NASA almost instantly distanced itself from it .. and him as well(?)
This is exactly why I think NASA is now a more reliable announcer that ESA is. ESA doesn't seem to have experienced the consequences of a massive public debacle of such proportions.
Except for, perhaps, the FT neutrinos/CERN announcement. They should've learned form that experience I suppose .. (no national leaders were invoked in that one though ..).



Hoover as well? So Clinton was not the first?

http://www.marsnews.com/focus/life/

Depends which meteorite we're talking about...

In 1996, following a study of Meteorite Alan Hills 84001 (https://en.wikipedia.org/wiki/Allan_Hills_84001), David McKay of NASA published in the journal Science about features interpreted as microbial fossils, and President Clinton made his announcement.

Richard Hoover (https://en.wikipedia.org/wiki/Richard_B._Hoover) published articles about micro fossils in meteorites in 1997, 2007 and 2011. His 2011 paper in the Journal of Cosmology got a lot of publicity but was not supported by NASA.

Selfsim
2013-Sep-24, 09:11 PM
'Twas Richard Hoover who made that announcement (as I recall). NASA almost instantly distanced itself from it .. and him as well(?)
This is exactly why I think NASA is now a more reliable announcer that ESA is. ESA doesn't seem to have experienced the consequences of a massive public debacle of such proportions. Hoover as well? So Clinton was not the first?Ooops! I got my announcements a bit mixed up ..

'Twas David McKay who 'fired' Clinton up about ALH84001 (1996) (http://en.wikipedia.org/wiki/ALH84001#Hypothetical_biogenic_features). NASA has however subsequently distanced itself from the technique of relating structures to fossilised exo-life, on the basis of morphology alone.

Hoover has made subsequent announcements (http://en.wikipedia.org/wiki/Richard_Hoover#Carbonaceous_meteorites) about structures which resemble fossilised bacteria in 1997 (the Murchison), 2007 (the Orgueil) and 2011 (cyanobacteria in C11 carbonaceous meteorites). NASA has distanced itself from his latest claims, and lack of peer reviews.

Felisa Wolfe-Simon (http://en.wikipedia.org/wiki/Felisa_Wolfe-Simon) started the ball rolling, (2010), on the Arsenic based life idea, based on Mondo lake samples, which has also subsequently been refuted in peer reviewed published material (2012).

So, its looks like McKay beat Clinton … but only just … :)

Selfsim
2013-Sep-24, 09:13 PM
Depends which meteorite we're talking about...

In 1996, following a study of Meteorite Alan Hills 84001 (https://en.wikipedia.org/wiki/Allan_Hills_84001), David McKay of NASA published in the journal Science about features interpreted as microbial fossils, and President Clinton made his announcement.

Richard Hoover (https://en.wikipedia.org/wiki/Richard_B._Hoover) published articles about micro fossils in meteorites in 1997, 2007 and 2011. His 2011 paper in the Journal of Cosmology got a lot of publicity but was not supported by NASA.Yep .. agreed.

Your above post just sneaked in ahead of my own (below) .. (just like McKay vs Clinton :))

Apologies for any confusion ..

kzb
2013-Sep-25, 12:53 PM
http://spie.org/x41481.xml?pf=true&ArticleID=x41481


Possible adaptability of Martian microbes based on new interpretation of Viking datas
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=1183396
Abstract

Full free paper
http://arxiv.org/pdf/physics/0610093

ESA -2013- about the low level of methane detected by Curiosity instruments.
http://meetingorganizer.copernicus.org/EPSC2013/EPSC2013-988.pdf
They take into account the fact that the measurements were made at night at sol 79,81 and 106...

Don J thanks for all the interesting articles. These argue that biology is a plausible explanation of the rate of methane production seen on Mars. Further, one article points out potential low biases in the Curiosity measurements of the methane concentration (taken only at night, and in the dry location of Gale crater). The mass balance question is explicitly addressed for the biological process.

The question I was asking was about the mass balance of the proposed abiological process. Specifically, is there enough organic material on the surface to account for the rate of methane production, using the proposed UV reaction mechanism? This part of the argument has not been addressed for the abiological process.

iquestor
2013-Sep-25, 01:19 PM
Don J thanks for all the interesting articles. These argue that biology is a plausible explanation of the rate of methane production seen on Mars. Further, one article points out potential low biases in the Curiosity measurements of the methane concentration (taken only at night, and in the dry location of Gale crater). The mass balance question is explicitly addressed for the biological process.

The question I was asking was about the mass balance of the proposed abiological process. Specifically, is there enough organic material on the surface to account for the rate of methane production, using the proposed UV reaction mechanism? This part of the argument has not been addressed for the abiological process.

Im not sure - they can make some educated guesses based on the rate of bombardment, etc as to how much of the dust is lying around, and maybe take a percentage of the methane detected and attribute it to this process, then work backwards to see if it the numbers are reasonable, but I doubt they would be anywhere close to a reasonable degree of error. Too many variables.

kzb
2013-Sep-25, 05:47 PM
Im not sure - they can make some educated guesses based on the rate of bombardment, etc as to how much of the dust is lying around, and maybe take a percentage of the methane detected and attribute it to this process, then work backwards to see if it the numbers are reasonable, but I doubt they would be anywhere close to a reasonable degree of error. Too many variables.

Yes but this is what is needed to be done in order to assess the plausibility of the abiological production rate of methane.

The conclusion has been put forward that less methane means less chance of life. Point number one, the recent methane measurements which set this off seem to be questionable. Point number 2, even if the lower methane production is confirmed, there are still thousands of tonnes per year of methane being produced on Mars. The logic chain of the conclusion is not clear to me.

A meteoric organic matter-UV reaction is proposed as the origin of this methane. If this cannot account for the order of magnitude of methane production then the door is open for alternative mechanisms, including biological ones.

iquestor
2013-Sep-25, 07:27 PM
Yes but this is what is needed to be done in order to assess the plausibility of the abiological production rate of methane.

The conclusion has been put forward that less methane means less chance of life. Point number one, the recent methane measurements which set this off seem to be questionable. Point number 2, even if the lower methane production is confirmed, there are still thousands of tonnes per year of methane being produced on Mars. The logic chain of the conclusion is not clear to me.

A meteoric organic matter-UV reaction is proposed as the origin of this methane. If this cannot account for the order of magnitude of methane production then the door is open for alternative mechanisms, including biological ones.

The researchers who supplied the non-biological argument factored in what they thought would be a reasonable rate of methane production for this process, but by no means tried to account for all of it.
However since the amount is in question we would need to answer "how Much" then see if its reasonable that their process could reasonable account for all of it, or not. I dont how accurate they can be in estimating how much methane would be contributed by this process, so I doubt we are close to an answer.

Don J
2013-Sep-27, 05:51 AM
Don J thanks for all the interesting articles. These argue that biology is a plausible explanation of the rate of methane production seen on Mars. Further, one article points out potential low biases in the Curiosity measurements of the methane concentration (taken only at night, and in the dry location of Gale crater). The mass balance question is explicitly addressed for the biological process.

The question I was asking was about the mass balance of the proposed abiological process. Specifically, is there enough organic material on the surface to account for the rate of methane production, using the proposed UV reaction mechanism? This part of the argument has not been addressed for the abiological process.
This document estimate the organic matter contributed to the surface of Mars by the accretion of interplanetary dust,meteorites,comets and asteroids.
http://www.lpi.usra.edu/meetings/earlymars/pdf/3044.pdf

Potential Sources and Sinks of Methane on Mars
http://en.wikipedia.org/wiki/File:PIA16461-MarsMethane-20121102.jpg

Methane on Mars
http://shelf3d.com/i/Atmosphere%20of%20Mars
Excerpts


Because methane on Mars would quickly break down due to ultraviolet radiation from the Sun and chemical reactions with other gases, its reported persistent presence in the atmosphere also necessitates the existence of a source to continually replenish the gas.
Current photochemical+ models alone can explain neither the fast appearance nor the disappearance of the methane, or its reported variations in space and time. It had been proposed that the methane might be replenished by meteorites entering the atmosphere of Mars, but researchers from Imperial College London+ found that the volumes of methane released this way are too low to sustain the measured levels of the gas.
--------------------------------------------------------------------------------------------------------------------------
The methane occurs in extended plumes, and their profiles imply that the gas was released from sources in three discrete regions. In northern midsummer, the principal plume contained 19,000 metric tons of methane, with an estimated source strength of 0.6 kilogram per second. and the second near . It is estimated that Mars must produce 270 tons/year of methane. Link: Planetary Fourier Spectrometer website (ESA, Mars Express)

Research suggests that the implied methane destruction lifetime is as long as ~4 Earth years and as short as ~0.6 Earth years. This lifetime is short enough for the atmospheric circulation to yield the observed uneven distribution of methane across the planet. In either case, the destruction lifetime for methane is much shorter than the timescale (~350 years) estimated for photochemical (UV radiation+) destruction. The rapid destruction of methane suggests another process must dominate removal of atmospheric methane on Mars and it must be more efficient than destruction by light by a factor of 100 to 600. This unexplained fast destruction rate also suggests a very active replenishing source. A possibility is that the methane is not consumed at all, but rather condenses and evaporates seasonally from clathrates+. Scientist Michael Mumma also argued in 2009 that the evidence suggests that methane plumes are a seasonal event.

Although the methane could stem from a geological source, the lack of current volcanism+, hydrothermal activity+ or hotspots+ are not favorable for a geological explanation. Living microorganism+s, such as methanogen+s, are another possible source, but no evidence exists for the presence of such organisms anywhere on Mars. Roscosmos+ and ESA+ are planning to look for companion gases that may suggest which sources are most likely. In the Earth's oceans, biological methane production tends to be accompanied by ethane+, whereas volcanic methane is accompanied by sulfur dioxide+.

The principal candidates for the origin of Mars methane include non-biological processes such as water+–rock reactions, radiolysis+ of water, and pyrite+ formation, all of which produce H2+ that could then generate methane and other hydrocarbons via Fischer–Tropsch synthesis+ with CO+ and CO2. It was also recently shown that methane could be produced by a process involving water, carbon dioxide, and the mineral olivine+, which is known to be common on Mars. The required conditions for this reaction (i.e. high temperature and pressure) do not exist on the surface, but may exist within the crust. To prove this process is occurring, serpentinite+, a mineral by-product of the process would be detected. An analog on Earth suggests that low temperature production and exhalation of methane from serpentinized rocks may be possible on Mars. Another possible geophysical source could be clathrate hydrates+.

The European Space Agency+ (ESA) found that the concentrations of methane in the Martian atmosphere were not even, but coincided with the presence of water vapor. In the upper atmosphere these two gases are uniformly distributed, but near the surface they concentrate in three equatorial regions, namely Arabia Terra+, Elysium Planitia+, and Arcadia Memnonia+. Planetary scientist David H. Grinspoon+ of the Southwest Research Institute+ believes the coincidence of water vapor and methane increases the chance that the methane is of biological origin, but he cautions that it is uncertain how life could have survived so long on a planet as inhospitable as Mars. It has been suggested that caves may be the only natural structures capable of protecting primitive life forms from micrometeoroids, UV radiation, solar flares and high energy particles that bombard the planet's surface.

Don J
2013-Sep-27, 06:25 AM
Martian methane and stability of clathrates in the crust of Mars
http://meetingorganizer.copernicus.org/EPSC2013/EPSC2013-896.pdf

iquestor
2013-Sep-27, 01:57 PM
This document estimate the organic matter contributed to the surface of Mars by the accretion of interplanetary dust,meteorites,comets and asteroids.
http://www.lpi.usra.edu/meetings/earlymars/pdf/3044.pdf

Potential Sources and Sinks of Methane on Mars
http://en.wikipedia.org/wiki/File:PIA16461-MarsMethane-20121102.jpg

Methane on Mars
http://shelf3d.com/i/Atmosphere%20of%20Mars
Excerpts

great links and papers, DonJ. Very interesting reading. :)

crosscountry
2013-Sep-27, 02:08 PM
Why can't the ground based stations look again to see whether they find the same levels of methane as they found that time? Obviously, we ought to compare current measurements with current measurements. Perhaps the methane release is only episodic.

They have.


It's only a factor of six. Why is six times this level a sign of life, whereas this is a sign of no life? Where's the dividing line?

The *reported* level was already low and decreasing.


Note the word "including". Findings re methane on Mars didn't only come from Earth-based telescopes, they also came from an orbiting space probe, the Mars Express Orbiter.



Especially if we're talking about a planet where any methane is at a level of no more than 10 parts per billion, according to the highest finding. The challenge is to distinguish between a very small trace and none at all.


That was the problem all along. We are guilty of wanting something to be true. The original studies found transient methane on the planet.

http://www.sciencemag.org/content/323/5917/1041.short
http://adsabs.harvard.edu/abs/2004DPS....36.2602M

There were several problems with these studies. First, they have never been repeated successfully, even with the same data. Their processing gave a result that was interpreted to indicate the presence of methane. Several other, subsequent, groups found alternative interpretations that were more likely.

Second, even using their process, the group that published the results did not find methane later. Remember, the original observations were from 2003 (*discovered* in 2009). We've had 10 years to find methane - with no luck.

Methane is known to dissipate or break down in an atmosphere, but it cannot do so at the speed this finding would indicate. Basically, there was a *release* of methane that was quickly broken down - faster than any known processes can do so.

So, we build instruments to test for methane and send them to Mars. This is all based in hope. The low methane result is not a surprise in reality, just a reason to lower our hopes.


That sucks, the way I wrote all of that. It is only my POV. Some of that comes with meeting and speaking to the first author on those reports. Some comes from talking with my atmospheric colleagues. I'm sure that others would see it different if you asked them.

iquestor
2013-Sep-27, 03:20 PM
They have.



The *reported* level was already low and decreasing.




That was the problem all along. We are guilty of wanting something to be true. The original studies found transient methane on the planet.

http://www.sciencemag.org/content/323/5917/1041.short
http://adsabs.harvard.edu/abs/2004DPS....36.2602M

There were several problems with these studies. First, they have never been repeated successfully, even with the same data. Their processing gave a result that was interpreted to indicate the presence of methane. Several other, subsequent, groups found alternative interpretations that were more likely.

Second, even using their process, the group that published the results did not find methane later. Remember, the original observations were from 2003 (*discovered* in 2009). We've had 10 years to find methane - with no luck.

Methane is known to dissipate or break down in an atmosphere, but it cannot do so at the speed this finding would indicate. Basically, there was a *release* of methane that was quickly broken down - faster than any known processes can do so.

So, we build instruments to test for methane and send them to Mars. This is all based in hope. The low methane result is not a surprise in reality, just a reason to lower our hopes.


That sucks, the way I wrote all of that. It is only my POV. Some of that comes with meeting and speaking to the first author on those reports. Some comes from talking with my atmospheric colleagues. I'm sure that others would see it different if you asked them.

So basically, you feel that the initial reports of Methane were erroneous and that thiere isnt anything there now to get excited about regarding methane on Mars. :(

If its really that low then Id guess probably what Methane we do see can be explained by the meteoric dust theory?

It must have been cool to talk with the author though; I'd love to have discussions with those guys!

crosscountry
2013-Sep-27, 10:03 PM
So basically, you feel that the initial reports of Methane were erroneous and that thiere isnt anything there now to get excited about regarding methane on Mars. :(

If its really that low then Id guess probably what Methane we do see can be explained by the meteoric dust theory?

It must have been cool to talk with the author though; I'd love to have discussions with those guys!

He is a good guy and forthcoming about how his process to get the results wasn't straightforward or even reproducible for most people.

I do feel that the original report was erroneous. I also think that the author published it even though there was a very high uncertainty. That wasn't necessarily the biggest problem. I think folks at NASA wanted it to be true. It doesn't matter though. We've got a good null result and a lot of other instruments performing beautifully on the Martian surface.

Selfsim
2013-Sep-27, 10:24 PM
.. We've got a good null result and a lot of other instruments performing beautifully on the Martian surface.Hi crosscountry;

I sense a certain amount of frustration that the definitive detection of the much sort after soil organics is proving so elusive, given the technology deployed with SAM?

Whilst one might be able to show that the QMS/GCMS/TLS suite is performing 'beautifully', the combination of these instruments is still apparently only suited to detecting organics at concentration levels which may well exceed the levels actually present (and ubiquitous) on the surface(?)

The lack of discussion about the MTBSTFA contamination in the GCMS train appears to speak volumes. Have you heard why they think this contamination has happened, why its viewed as a constant, and what impacts this may have on results interpretation when it actually comes to using the wet front end?

Don J
2013-Sep-28, 03:35 AM
He is a good guy and forthcoming about how his process to get the results wasn't straightforward or even reproducible for most people.

I do feel that the original report was erroneous. I also think that the author published it even though there was a very high uncertainty. That wasn't necessarily the biggest problem. I think folks at NASA wanted it to be true. It doesn't matter though. We've got a good null result and a lot of other instruments performing beautifully on the Martian surface.
A good null result?
Here a report published in 2004 by ESA who establish a spatial correlation between water vapour and methane more concentrated in three broad equatorial regions which seems to point to a common underground source in the same regions..-
20 September 2004
http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Water_and_methane_maps_overlap_on_Mars_a_new_clue2


ESA PR 51-2004. Recent analyses of ESA’s Mars Express data reveal that concentrations of water vapour and methane in the atmosphere of Mars significantly overlap.

This result, from data obtained by the Planetary Fourier Spectrometer (PFS), gives a boost to understanding of geological and atmospheric processes on Mars, and provides important new hints to evaluate the hypothesis of present life on the Red Planet.
PFS observed that, at 10-15 kilometres above the surface, water vapour is well mixed and uniform in the atmosphere. However, it found that, close to the surface, water vapour is more concentrated in three broad equatorial regions: Arabia Terra, Elysium Planum and Arcadia-Memnonia.

Here, the concentration is two to three times higher than in other regions observed. These areas of water vapour concentration also correspond to the areas where NASA’s Odyssey spacecraft has observed a water ice layer a few tens of centimetres below the surface, as Dr Vittorio Formisano, PFS principal investigator, reports.

New in-depth analysis of PFS data also confirms that methane is not uniform in the atmosphere, but concentrated in some areas. The PFS team observed that the areas of highest concentration of methane overlap with the areas where water vapour and underground water ice are also concentrated. This spatial correlation between methane and water vapour seems to point to a common underground source in the same regions.

Selfsim
2013-Sep-28, 06:11 AM
What a classic!

The original paper which announced the detection of atmospheric methane by the PFS aboard the ESA Mars Express Orbiter was:

"Detection of methane in the atmosphere of Mars"
Authors: Formisano, V, Atreya, S, Encrenaz, T, Ignatiev, N, Giuranna, M
Journal: SCIENCE, Volume: 306, Page: 1758-1761, Year: 2004

Ok, so now for a chuckle ... this paper has been ranked by "Science Watch" as the ninth (9th) most cited paper over the last 10 years, (http://archive.sciencewatch.com/ana/st/planet/papers10yr/) in all of planetary exploration, (with 193 cites). It has spawned a vast number of explanatory hypotheses, models and explanations, for what now appears to have been met with 'a good null result', courtesy of Curiosity/SAM TLS.

This is going to get interesting ...

crosscountry
2013-Sep-29, 03:24 PM
What a classic!

The original paper which announced the detection of atmospheric methane by the PFS aboard the ESA Mars Express Orbiter was:

"Detection of methane in the atmosphere of Mars"
Authors: Formisano, V, Atreya, S, Encrenaz, T, Ignatiev, N, Giuranna, M
Journal: SCIENCE, Volume: 306, Page: 1758-1761, Year: 2004

Ok, so now for a chuckle ... this paper has been ranked by "Science Watch" as the ninth (9th) most cited paper over the last 10 years, (http://archive.sciencewatch.com/ana/st/planet/papers10yr/) in all of planetary exploration, (with 193 cites). It has spawned a vast number of explanatory hypotheses, models and explanations, for what now appears to have been met with 'a good null result', courtesy of Curiosity/SAM TLS.

This is going to get interesting ...

I need to do a better literature review. The Mumma paper was the first that I know about to discuss methane. Those are the results people have had trouble reproducing. I'll need to read more on the Mars Express detection.



A good null result?
Here a report published in 2004 by ESA who establish a spatial correlation between water vapour and methane more concentrated in three broad equatorial regions which seems to point to a common underground source in the same regions..-
20 September 2004
http://www.esa.int/Our_Activities/Space_Science/Mars_Express/Water_and_methane_maps_overlap_on_Mars_a_new_clue2

I am just starting my post doc at a lab that focuses on atmospheres. My previous work was in geology, so what I'm reporting is second hand.

The conversations I've had to date all tell me that methane does break down, but not at the rates required for the current level to be expected. In other words, the methane that was positively detected has either 1) broken down much faster than expected, or 2) the levels reported were higher than reality. #2 seems to be the consensus, but I will ask some more questions.

crosscountry
2013-Sep-29, 07:20 PM
Just to support what I was saying earlier


Methane breaks up in the presence of ultraviolet solar radiation. Based on photochemical models and on the current understanding of the composition of the Martian atmosphere, methane has a chemical lifetime of about 300-600 years, which is very short on geological time scales. This implies that the methane that is observed today cannot have been produced 4.5 billion years ago, when the planets formed. So what can explain the presence of this gas on the Red Planet?

From here
http://exploration.esa.int/mars/46038-methane-on-mars/

Of course this page was written before the Curiosity results. I bring it up because it shows how methane *detected* in 2003 or 2004 should still be around. It is possible that fundamental processes are different on Mars, but that is a bad assumption to start with.

Don J
2013-Sep-29, 07:56 PM
Just to support what I was saying earlier



From here
http://exploration.esa.int/mars/46038-methane-on-mars/

Of course this page was written before the Curiosity results. I bring it up because it shows how methane *detected* in 2003 or 2004 should still be around. It is possible that fundamental processes are different on Mars, but that is a bad assumption to start with.
Here a 2013 ESA paper which take into account the low methane concentration detected by Curiosity instruments.It point out the fact that the measurements were taken at night. A mechanism is also proposed for the rapid destruction of methane in the reference section..
http://meetingorganizer.copernicus.org/EPSC2013/EPSC2013-988.pdf

crosscountry
2013-Sep-29, 10:01 PM
Thanks, I'll read it when I get a chance.

Don J
2013-Sep-30, 05:07 AM
Thanks, I'll read it when I get a chance.

You're welcome.
Here the paper (size 997k)
Atreya, S., P.R. Mahaffy, and Ah-San Wong, Methane and related trace species on Mars: Origin, loss, implications for life, and habitability, Planetary and Space Science 55, 358-369 (2006).

http://www-personal.umich.edu/~atreya/Articles/Atreya_Mars_CH4.pdf
The proposed mechanism explaining the accelerated methane destruction process is summarized in the abstract page 1:
see page 5 section 2.5
Loss processes, surface oxidants ,and organics. (for detailed explanation).

Selfsim
2013-Sep-30, 07:40 AM
You're welcome.
Here the paper (size 997k)
Atreya, S., P.R. Mahaffy, and Ah-San Wong, Methane and related trace species on Mars: Origin, loss, implications for life, and habitability, Planetary and Space Science 55, 358-369 (2006).

http://www-personal.umich.edu/~atreya/Articles/Atreya_Mars_CH4.pdf
The proposed mechanism explaining the accelerated methane destruction process is summarized in the abstract page 1:
see page 5 section 2.5
Loss processes, surface oxidants ,and organics. (for detailed explanation).This paper, published in 2006, precedes the discovery of surface perchlorates, by the Phoenix Lander (in 2008).
The above process is focussed on the, (speculated at the time - ie: 2006), production of Hydrogen Peroxide (H2O2) .. which has never been measured in any samples thus far taken.

Figure #5 may look pretty, but I can't relate this with what is presently known about Mars, based on the evidence of perchlorates, whose natural processes differ from the peroxide case, because of the presence and effects of the chlorine component. Methane and chlorine produce chloromethane, but this requires temperatures of 400 degrees C, and is hardly applicable for the surface of Mars! The presence of H2O probably changes things .. like producing HCl, but this hasn't been detected either(?)

The paper also talks about SAM being able to detect chirality of long chain organic molecules. To the best of my knowledge, SAM does not have this capability.

Interestingly, the ESA-led Mars rover, 'Exo-Mars' (http://www.lpi.usra.edu/meetings/lpsc2013/pdf/2004.pdf) will either pyrolize the sample, (in an oven), to 1000 degrees C, or volatilize it using a UV laser. A GCMS will then analyse the products. They have figured out that if the perchlorate and organics can be kept separate, more chlorinated methane derivatives like (di, tri) chloromethanes will be produced, than if they are mixed. Careful sample preparation may help to localize where the organics are actually coming from (ie: terrestrial contaminants or the martian sample). SAM may be able to follow a similar sample preparation technique(?)

As an aside: I don't believe any (di, tri)chloromethanes have ever been detected in Mars' atmosphere, either(?) (http://www.lpi.usra.edu/meetings/lpsc2013/pdf/2077.pdf)

crosscountry
2013-Sep-30, 09:38 AM
Here a 2013 ESA paper which take into account the low methane concentration detected by Curiosity instruments.It point out the fact that the measurements were taken at night. A mechanism is also proposed for the rapid destruction of methane in the reference section..
http://meetingorganizer.copernicus.org/EPSC2013/EPSC2013-988.pdf

This is an interesting idea. Methane is produced in the day but removed at night. Of course much of this gas would leave the surface and be undetectable by Curiosity, but then wouldn't it be detectable by remote sensing?

I like the idea of testing in the day time. It would be a cheap way to answer this question. I'm not sure if it will get done, but I suspect the results would not vary much from those already announced.

Selfsim
2013-Sep-30, 10:21 AM
This is an interesting idea. Methane is produced in the day but removed at night. Of course much of this gas would leave the surface and be undetectable by Curiosity, but then wouldn't it be detectable by remote sensing?

I like the idea of testing in the day time. It would be a cheap way to answer this question. I'm not sure if it will get done, but I suspect the results would not vary much from those already announced.The PFS instrument aboard Mars Express broke in July 2005 (http://www.nature.com/news/2005/050905/full/news050905-10.html). Curiosity is the only chance at the moment of remotely detecting any methane emissions (if present).

The PFS also gave dodgy past readings for formaldehyde:

In February of this year, Formisano said that the PFS had found large quantities of formaldehyde around Mars (see '"Formaldehyde claim inflames martian debate": http://www.nature.com/news/2005/050221/full/050221-15.html'). This implied that millions of tonnes of methane were being released by the planet each year: much, much more than thought. Encrenaz says most scientists now agree that these claims about formaldehyde were incorrect.

Without nailing the methane numbers, it will be hard for all scientists to agree on a source for the gas. For now, many say it is probably due to heating of water and carbon dioxide with a mineral called olivine, rather than life, says Sushil Atreya, a member of the PFS team from the University of Michigan in Ann Arbor.A chequered career has PFS had, (so it seems).

Don J
2013-Sep-30, 07:20 PM
This is an interesting idea. Methane is produced in the day but removed at night. Of course much of this gas would leave the surface and be undetectable by Curiosity, but then wouldn't it be detectable by remote sensing?

What we need is new analysis by Earth based instruments to see if it match Curiosity methane detection at ground level.Because as pointed out by Selfsim'-The PFS instrument aboard Mars Express broke in July 2005.


I like the idea of testing in the day time. It would be a cheap way to answer this question. I'm not sure if it will get done, but I suspect the results would not vary much from those already announced.

They envision that possibility, that is why they call also for measurements at a season when there is more moisture in the atmotsphere at Gale crater.

Don J
2013-Oct-04, 07:09 AM
This paper, published in 2006, precedes the discovery of surface perchlorates, by the Phoenix Lander (in 2008).
The above process is focussed on the, (speculated at the time - ie: 2006), production of Hydrogen Peroxide (H2O2) .. which has never been measured in any samples thus far taken.

Hydrogen Peroxide was detected on Mars in 2004
http://irtfweb.ifa.hawaii.edu/research/science/32.Encrenaz.H2O2_on_Mars.pdf
Atreya, A. Wong, S. Lebonnois, F. Lefevre, F. Forget. 1Observatoire de Paris. Encrenaz, Th. et al. 2004, Icarus, 170, 424. “Hydrogen peroxide on. Mars: evidence ...


Figure #5 may look pretty, but I can't relate this with what is presently known about Mars, based on the evidence of perchlorates, whose natural processes differ from the peroxide case, because of the presence and effects of the chlorine component. Methane and chlorine produce chloromethane, but this requires temperatures of 400 degrees C, and is hardly applicable for the surface of Mars! The presence of H2O probably changes things .. like producing HCl, but this hasn't been detected either(?)

Remember that in that case the reference is about a mechanism proposed for the fast destruction of methane not for the creation of it.
Here the details explaining how they theorically get to to fig#5
http://pocarisweat.umdl.umich.edu/bitstream/handle/2027.42/63407/ast.2006.6.451.pdf?sequence=1


The paper also talks about SAM being able to detect chirality of long chain organic molecules. To the best of my knowledge, SAM does not have this capability.

I was very astonished by that declaration...and that is not surprising that Nasa have abandon the idea.Remember the Nasa letmotiv life detection equipments were prohibited after Viking's....


Interestingly, the ESA-led Mars rover, 'Exo-Mars' (http://www.lpi.usra.edu/meetings/lpsc2013/pdf/2004.pdf) will either pyrolize the sample, (in an oven), to 1000 degrees C, or volatilize it using a UV laser. A GCMS will then analyse the products. They have figured out that if the perchlorate and organics can be kept separate, more chlorinated methane derivatives like (di, tri) chloromethanes will be produced, than if they are mixed. Careful sample preparation may help to localize where the organics are actually coming from (ie: terrestrial contaminants or the martian sample). SAM may be able to follow a similar sample preparation technique(?)

Interestingly Levin think that this is the case....note that (di, tri) chloromethanes were effectively find and analysed by SAM .Note also that Levin say that perchlorate was not detected at the 2 Viking landing sites
http://www.gillevin.com/Mars/SPIE_2013_Revised.pdf


As an aside: I don't believe any (di, tri)chloromethanes have ever been detected in Mars' atmosphere, either(?) (http://www.lpi.usra.edu/meetings/lpsc2013/pdf/2077.pdf)

Can you give a reference about someone ho have said that tri-chloromethanes have been detected in the atmosphere of Mars? It was rather discovered (trace of it ) in the analysis made by the SAM GCMS.

Selfsim
2013-Oct-05, 08:08 AM
The above process is focussed on the, (speculated at the time - ie: 2006), production of Hydrogen Peroxide (H2O2) .. which has never been measured in any samples thus far taken.Hydrogen Peroxide was detected on Mars in 2004
http://irtfweb.ifa.hawaii.edu/resear...O2_on_Mars.pdf (http://irtfweb.ifa.hawaii.edu/research/science/32.Encrenaz.H2O2_on_Mars.pdf)
Atreya, A. Wong, S. Lebonnois, F. Lefevre, F. Forget. 1Observatoire de Paris. Encrenaz, Th. et al. 2004, Icarus, 170, 424. “Hydrogen peroxide on. Mars: evidence ...Yep .. although I was speaking of direct samples .. (at the surface).

According to current photolysis models* the photochemical lifetime of peroxide is about six hours (during the day). Once photodissociated, the models have it rapidly reforming from its photolysis products again. When it gets particularly cold, the models also indicate it may condense at the surface at night. If this is the case, then how come no surface probe has detected it?

Its absence on the surface makes it a lot like the (thus far absent) methane, eh?

Having said this, I also acknowledge the 'dust devil' model/mechanism (see below response).

* Reference here. (http://www-personal.umich.edu/%7Eatreya/Articles/2012_Encrenaz_Mars_H2O2.pdf)

Remember that in that case the reference is about a mechanism proposed for the fast destruction of methane not for the creation of it.
Here the details explaining how they theorically get to to fig#5 http://pocarisweat.umdl.umich.edu/bi...pdf?sequence=1 (http://pocarisweat.umdl.umich.edu/bitstream/handle/2027.42/63407/ast.2006.6.451.pdf?sequence=1)




Hmm .. dust devils in the Southern Hemisphere during Southern Spring(?).
I think the other report I posted (above) recommended that the best way to detect peroxide is from orbit.
I'd still like to know why some trace of it couldn't be detected at the surface (if it was present ... and in quantities comparable with Perchlorates ..)


I was very astonished by that declaration...and that is not surprising that Nasa have abandon the idea.Remember the Nasa letmotiv life detection equipments were prohibited after Viking's....I'm not even sure SAM could distinguish amino acids(?) I've quoted Mahaffy (somewhere way back) saying he could stretch the QMS/GCMS to detect amines .. (but not aminos).





Interestingly Levin think that this is the case....note that (di, tri) chloromethanes were effectively find and analysed by SAM .Note also that Levin say that perchlorate was not detected at the 2 Viking landing sites.Are you suggesting peroxide might have been present at the Viking sites?
That's also not what Mahaffy et al infer in the conclusion of this report (http://www.lpi.usra.edu/meetings/lpsc2013/pdf/1395.pdf)(??):
The Rocknest EGA-TLS-GCMS data set is consistent with perchlorate detection by Phoenix and chloromethane and dichloro methane by Viking ...They go on to say:
It is significant that while derivatized water is detected, no complex derivatized organics, chlorinated organic compounds that might have been produced from a perchlorate, or other organic compounds were detected by the GCMS experiment. UV radiation, high energy cosmic particles, degradation by H2O2 or other oxidants are among the processes that may have conspired to remove organic componds from surface exposed materials such as the fines of Rocknest.(My underlines and emboldenments).

Can you give a reference about someone ho have said that tri-chloromethanes have been detected in the atmosphere of Mars? It was rather discovered (trace of it ) in the analysis made by the SAM GCMS.No-one suggested it .. it was just a thought I had (which is why I made it an 'Aside' comment, only ... don't worry 'bout it ... :)-default ).

Don J
2013-Oct-05, 06:37 PM
Note also that Levin say that perchlorate was not detected at the 2 Viking landing sites.

Are you suggesting peroxide might have been present at the Viking sites?
That's also not what Mahaffy et al infer in the conclusion of this report (http://www.lpi.usra.edu/meetings/lpsc2013/pdf/1395.pdf)(??):They go on to say:(My underlines and emboldenment

The point i try to make is: the fact that perchlorate was not detected at the 2 Viking landing sites mean that the chloromethanes and di-chloromethanes detected by Viking GCMS was not caused by the effect of perchlorate when heated at 400 +degree celsius.

Now here something about the possible adaptability of Martian microorganisms explaining the Viking LR ,PR and Gex results and possibly the Viking GCMS results.
A possible biogenic origin for hydrogen peroxide on Mars: the Viking results reinterpreted
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=1183396
Abstract


The adaptability of extremophiles on Earth raises the question of what strategies putative life might have used to adapt to the present conditions on Mars. Here, we hypothesize that organisms might utilize a water–hydrogen peroxide (H2O–H2O2) mixture rather than water as an intracellular liquid. This adaptation would have the particular advantages in the Martian environment of providing a low freezing point, a source of oxygen and hygroscopicity. The findings by the Viking experiments are reinterpreted in light of this hypothesis. Our conclusion is that the hitherto mysterious oxidant in the Martian soil, which evolves oxygen when humidified, might be H2O2 of biological origin. This interpretation has consequences for site selection for future missions to search for life on Mars.

Full free paper:
http://arxiv.org/pdf/physics/0610093

Selfsim
2013-Oct-06, 06:43 AM
The point i try to make is: the fact that perchlorate was not detected at the 2 Viking landing sites mean that the chloromethanes and di-chloromethanes detected by Viking GCMS was not caused by the effect of perchlorate when heated at 400 +degree celsius.
http://www.gillevin.com/Mars/SPIE_2013_Revised.pdfMan, this report by Levin is misleading!
Firstly he says (see Figure#6):
Countering that possibility, Figure 6 shows that the amounts of chlorohydrocarbons detected were less in the pre-sample blank runs than in the first sample. This would seem to rule out terrestrial contamination, at least as a major contributor.It has been stated previously that the blank SAM runs by Curiosity didn't involve materials handled by the CHMIRA device. I thnk he's jumping to uninformed conclusions when ruling out terrestrial contamination ..

Then he makes a quantum leap by introducing triflouromethane and carbon tetraflouride:
There is also a problem with respect to the synthesis of the chlorohydrocarbons from indigenous ingredients in the sample. As seen in the Figure Note, the suggested synthesis process also produces trifloromethane and carbon tetrafloride. This complete suite of products was not detected in the sample. Thus, a case can be made that the organic compounds were indigenous to the sample.Now he hasn't said where the flourinated compounds come from .. (we know they suspect MTBSTFA .. but he hasn't even mentioned this).
So I found this (http://webcache.googleusercontent.com/search?q=cache:wo8BnUT6zogJ:publications.agu.org/files/2013/09/jgre20144.pdf+&cd=9&hl=en&ct=clnk&gl=au) (its one of the better explanations of the SAM Rocknest results):
Several chlorinated hydrocarbons including chloromethane, dichloromethane, trichloromethane, a chloromethylpropene, and chlorobenzene were identified by SAM above background levels with abundances of ~0.01 to 2.3 nmol. The evolution of the chloromethanes observed during pyrolysis is coincident with the increase in O2 released from the Rocknest sample and the decomposition of a product of N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA), a chemical whose vapors were released from a derivatization cup inside SAM. The best candidate for the oxychlorine compounds in Rocknest is a hydrated calcium perchlorate (Ca(ClO4)2·nH2O), based on the temperature release of O2 that correlates with the release of the chlorinated hydrocarbons measured by SAM, although other chlorine-bearing phases are being considered.

Laboratory analog experiments suggest that the reaction of Martian chlorine from perchlorate decomposition with terrestrial organic carbon from MTBSTFA during pyrolysis can explain the presence of three chloromethanes and a chloromethylpropene detected by SAM.


Chlorobenzene may be attributed to reactions of Martian chlorine released during pyrolysis with terrestrial benzene or toluene derived from 2,6-diphenylphenylene oxide (Tenax) on the SAMhydrocarbon trap. At this time we do not have definitive evidence to support a nonterrestrial carbon source for these chlorinated hydrocarbons, nor do we exclude the possibility that future SAM analyses will reveal the presence of organic compounds native to the Martian regolith.

Now here something about the possible adaptability of Martian microorganisms explaining the Viking LR ,PR and Gex results and possibly the Viking GCMS results.

A possible biogenic origin for hydrogen peroxide on Mars: the Viking results reinterpreted
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=1183396
Abstract

Full free paper:
http://arxiv.org/pdf/physics/0610093Man, does it ever end? .. More stories dreaming up exotic combinations, just to keep the idea of life on Mars alive? Whilst I commend the recognition of life's adaptability, methinks invoking such exotica is not warranted, given that simple calcium perchlorate seems to do the trick just fine. (As per the above paper/quote).

Selfsim
2013-Oct-06, 07:01 AM
An even better report on Rocknest SAM analysis is:

"Volatile, Isotope, and Organic Analysis of Martian Fines with the Mars Curiosity Rover" (http://mars.nasa.gov/msl/files/msl/Science-2013-Leshin-.pdf), L.A. Leshin etal, Science, Sept 2013.

PS: (See Table #4, page #7 for a breakdown of compounds detected and their possible source explanations).

Don J
2013-Oct-06, 06:26 PM
Now here something about the possible adaptability of Martian microorganisms explaining the Viking LR ,PR and Gex results and possibly the Viking GCMS results.

A possible biogenic origin for hydrogen peroxide on Mars: the Viking results reinterpreted
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=1183396
full paper
http://arxiv.org/pdf/physics/0610093

Man, does it ever end? .. More stories dreaming up exotic combinations, just to keep the idea of life on Mars alive? Whilst I commend the recognition of life's adaptability, methinks invoking such exotica is not warranted, given that simple calcium perchlorate seems to do the trick just fine.
http://webcache.googleusercontent.com/search?q=cache:wo8BnUT6zogJ:publications.agu.org/files/2013/09/jgre20144.pdf+&cd=9&hl=en&ct=clnk&gl=au
(As per the above paper/quote).

Your above paper/quote may only explain the SAM GCMS datas.
As far as i know Curiosity does not have life detection equipments like the Viking's LR,PR and GEX so your above explanation do not explain the Viking's life detection datas .Add to that that perchlorate was not detected at the Viking's landing sites located 4,000 miles apart.

crosscountry
2013-Oct-06, 08:54 PM
I applaud people who want to find life, but sometimes I think they want it for personal reasons more than scientific ones. That's how I explain this stupefying fascination with dreaming up more exotic ways for it to live. Life is remarkable and adaptable, but some people want to find it too badly.

also, this thread is about methane.

Selfsim
2013-Oct-06, 09:41 PM
The case for Viking's indirect detection of perchlorates from its reaction products, is discussed in Section 4.1 (Page 15) of the first report I posted, (here again (http://webcache.googleusercontent.com/search?q=cache:wo8BnUT6zogJ:p-defaultublications.agu.org/files/2013/09/jgre20144.pdf+&cd=9&hl=en&ct=clnk&gl=au)). It also make the case for global distribution of perchlorates. Interestingly, the absence of chloromethanes in the blank Viking runs, done in interplanetary space on the way to Mars, can be explained by an automatic valve closure in the Viking GCMS. This would mean that Viking could well have been carrying terrestrial contaminants all along, and this explanation could then account for the chloromethanes later (detected at the surface).

Whilst this thread may be about low/no methane, the report is also relevant to how SAM goes about detecting methane on Mars. Page 12 (Section 3.3) points out that the SAM GCMS cannot be used to distinguish methane from other volatiles (CO2, CO, SO2, CH2O and CH3Cl).

The TLS laser required for methane detection was not in operation at the time the Rocknest analysis was performed, so unfortunately, no useful information about martian methane could be deduced from the Rocknest fines results (which might also have been a reasonable thing to have done, considering the fines have been blown about and intermixed considerably with the atmosphere).

Don J
2013-Oct-06, 10:40 PM
I applaud people who want to find life, but sometimes I think they want it for personal reasons more than scientific ones. That's how I explain this stupefying fascination with dreaming up more exotic ways for it to live. Life is remarkable and adaptable, but some people want to find it too badly.

also, this thread is about methane.
Living microorganism produce methane....and it is still a potential source for the methane detected on Mars.And as pointed out in the article below-An apparent absence of Martian volcanic activity precludes one explanation for the presence of methane.-
http://spie.org/x41481.xml?pf=true&ArticleID=x41481


The discovery of methane in the Martian atmosphere,3 and its steady replacement from equatorial sites that seem to host substantial subsurface ice deposits,4 suggests a possible biological origin, methanogenic microbes. An apparent absence of Martian volcanic activity precludes one explanation for the presence of methane. These findings suggest that methane, in addition to CO2, was evolved in the LR experiment.5 Here, we consider how much LR gas could have been methane and whether extrapolation of the amount released per gram of Martian soil could produce the measured levels of methane in its atmosphere. Finally, assuming terrestrial rates of methane production by methanogens, we estimate the necessary size of the microbial population and the amount of water necessary to maintain that population in an aqueous state.

Selfsim
2013-Oct-06, 10:57 PM
Living microorganism produce methane....and it is still a potential source for the methane detected on Mars.And as pointed out in the article -An apparent absence of Martian volcanic activity precludes one explanation for the presence of methane.-
http://spie.org/x41481.xml?pf=true&ArticleID=x41481Yet another model (to support/justify the martian life speculation(??) ).

Interestingly, isotopic measurement of any methane (or evolved CO2, where detected) would give us a clue as to the origin of the Carbon component. The only thing functional, which can do this is Curiosity/SAM. The martian atmospheric CO2 contains isotopically a very different carbon 13 ratio from terrestrial carbon (delta C13 ~ +40 ppb). The Rocknest fines evolved CO2, kind of straddled terrestrial atmospheric and terrestrial carbonates unfortunately, (which adds to the ambiguity) (~-15 to ~+22 ppb).

If Curiosity could find some measurable methane, it might be interesting ..

Don J
2013-Oct-06, 11:17 PM
The case for Viking's indirect detection of perchlorates from its reaction products, is discussed in Section 4.1 (Page 15) of the first report I posted, (here again (http://webcache.googleusercontent.com/search?q=cache:wo8BnUT6zogJ:p-defaultublications.agu.org/files/2013/09/jgre20144.pdf+&cd=9&hl=en&ct=clnk&gl=au)). It also make the case for global distribution of perchlorates.

No,Levin points out clearly that if perchlorates were present at the Viking landing sites the LR control tests at 160 degree celsius destined to kill the microorganims was not hot enough to destroy other chemicals.Thus if chemicals like perchlorate were present in the samples it would have been detected.
http://www.gillevin.com/Mars/SPIE_2013_Revised.pdf


Interestingly, the absence of chloromethanes in the blank Viking runs, done in interplanetary space on the way to Mars, can be explained by an automatic valve closure in the Viking GCMS.

How do you explain the same absence of chloromethanes in the blank Viking runs, done in interplanetary space on the way to Mars on the other Viking probe with the automatic valve working correctly in the Viking GCMS.?


This would mean that Viking could well have been carrying terrestrial contaminants all along, and this explanation could then account for the chloromethanes later (detected at the surface).

Wrong again, due to the extreme measures taken to avoid terrestrial contamination the instruments used in pre-flight condition ie (used to make tests with Earth samples) were not those used for the Viking's mission.A second set of the same kind of instruments LR,PR,GEX and GCMS were used onboard the Viking probes for the mission on Mars surface...

Selfsim
2013-Oct-07, 12:08 AM
No,Levin points out clearly that if perchlorates were present at the Viking landing sites the LR control tests at 160 degree celsius destined to kill the microorganims was not hot enough to destroy other chemicals.Thus if chemicals like perchlorate were present in the samples it would have been detected.Well there's water present in the soil too, eh? When the sample is heated, the water and perchlorate can react producing things like HCl and CH3Cl even at temps below 160 degrees (see the Figure #1 in Leshin's paper (http://mars.nasa.gov/msl/files/msl/Science-2013-Leshin-.pdf)). There's still active chemistry going on at these lower temperatures which might also consume any perchlorates. It seems the SAM detected Ca perchlorate at sub 160 degrees, but it used the QMS to do it. (Did Viking have a QMS?).


How do you explain the same absence of chloromethanes in the blank Viking runs, done in interplanetary space on the way to Mars on the other Viking probe with the automatic valve working correctly in the Viking GCMS.?I don't think the valve closure was a fault. I think it was designed to do exactly what it did:
The absence of chloromethane in the VL blank runs was recently attributed to venting to space because so much adsorbed water was expelled from the ovens after heating to 500°C that the effluent divider went into a 1:8000 split ratio mode causing the mass spectrometer valve to close. (Biemann and Bada, 2011).


Wrong again, due to the extreme measures taken to avoid terrestrial contamination the instruments used in pre-flight condition ie (used to make tests with Earth samples) were not those used for the Viking's mission.A second set of the same kind of instruments LR,PR,GEX and GCMS were used onboard the Viking probes for the mission on Mars surface…One of the so-called 'contaminants' in the SAM was 'TEnax TA', which is a polymer resin used for molecular separation of hydrocarbons. Did Viking use this material in its separator columns? Also what cleaning products were used during the construction of the Viking GCMS train?

Don J
2013-Oct-07, 12:57 AM
Well there's water present in the soil too, eh? When the sample is heated, the water and perchlorate can react producing things like HCl and CH3Cl even at temps below 160 degrees (see the Figure #1 in Leshin's paper (http://mars.nasa.gov/msl/files/msl/Science-2013-Leshin-.pdf)). There's still active chemistry going on at these lower temperatures which might also consume any perchlorates. It seems the SAM detected Ca perchlorate at sub 160 degrees, but it used the QMS to do it. (Did Viking have a QMS?).

No.That is a novelty added for Curiosity SAM suite instruments.


One of the so-called 'contaminants' in the SAM was 'TEnax TA', which is a polymer resin used for molecular separation of hydrocarbons. Did Viking use this material in its separator columns?

No....The Viking GCMS used of a novel(at the time) hydrogen separator (Figure 4) to remove hydrogen carrier gas from thermally evolved organics without removing the organic compounds themselves prior to their entry into the ion source.
http://www.gillevin.com/Mars/Reprint115-2000SPIEFinal_files/Reprint115-2000SPIEFinal.html
See detailed info about Viking GCMS
2.1.1 The Viking GCMS detection of organic compounds


Also what cleaning products were used during the construction of the Viking GCMS train?

Don't know for now i am working on that.
ETA
Still cannot find the specific cleaning products used during the construction of the Viking GCMS train.
They must have been cleaned and sterilised following the Sterilization and cleaning method protocol for Viking.
CLEANING AND STERILIZATION STANDARDS
http://www.nap.edu/openbook.php?record_id=9895&page=17

Selfsim
2013-Oct-08, 10:39 PM
No.That is a novelty added for Curiosity SAM suite instruments.

No....The Viking GCMS used of a novel(at the time) hydrogen separator (Figure 4) to remove hydrogen carrier gas from thermally evolved organics without removing the organic compounds themselves prior to their entry into the ion source.Hmm .. interestingly the palladium surface of the hydrogen separator reacts with chlorine. If perchlorate was present, then I wonder how the reaction with the palladium surface might effect the detection of perchlorates?


2.1.1 The Viking GCMS detection of organic compounds

Don't know for now i am working on that.
ETA
Still cannot find the specific cleaning products used during the construction of the Viking GCMS train.
They must have been cleaned and sterilised following the Sterilization and cleaning method protocol for Viking.
CLEANING AND STERILIZATION STANDARDSThe leak of MTBSTFA into the pyrolizing cup is one thing .. but the other 'contaminants' seem to be specifically 'by design'. The fact that this 'Tenax' has been detected by SAM's GCMS seems, at present, to be claimed as a triumph of the GCMS' detection capability, (and a testament to GCMS' successful functioning). But its ability to virtually disguise whatever might be present in the sample, and whether or not it was such a good choice from this perspective, is left up to the reader to decide, (Which is kind of frustrating). Whilst the appropriateness of the selection of certain materials (including cleaning products) might not have been possible in the light of no prior data about the martian surface composition, some open discussion about this might help to resolve further ambiguiites as far as the Viking results go(?) After all, this is what Navaro-Gonzales did .. (albeit to explain why organics couldn't detected). I wonder whether a rethink of the design of the Hydrogen separator/GCMS might provide some other explanatory clues about non-detection of perchlorates by Viking?

Don J
2013-Oct-09, 02:28 AM
Hmm .. interestingly the palladium surface of the hydrogen separator reacts with chlorine. If perchlorate was present, then I wonder how the reaction with the palladium surface might effect the detection of perchlorates?

You will have to digg a little to find an answer because i don't thing there is any study about that.Meanwhile can you show a study showing how the palladium surface of the hydrogen separator used by the Viking GCMS reacts with chlorine?



The leak of MTBSTFA into the pyrolizing cup is one thing .. but the other 'contaminants' seem to be specifically 'by design'. The fact that this 'Tenax' has been detected by SAM's GCMS seems, at present, to be claimed as a triumph of the GCMS' detection capability, (and a testament to GCMS' successful functioning). But its ability to virtually disguise whatever might be present in the sample, and whether or not it was such a good choice from this perspective, is left up to the reader to decide, (Which is kind of frustrating).

It is frustrating but this is a problem specific for the Curiosity mission which have no effect for Viking datas.


Whilst the appropriateness of the selection of certain materials (including cleaning products) might not have been possible in the light of no prior data about the martian surface composition,

Things that Curiosity conceptors should have know with all the previous missions to Mars.


some open discussion about this might help to resolve further ambiguiites as far as the Viking results go(?) After all, this is what Navaro-Gonzales did .. (albeit to explain why organics couldn't detected). I wonder whether a rethink of the design of the Hydrogen separator/GCMS might provide some other explanatory clues about non-detection of perchlorates by Viking?

As explained before (by Levin) if perchlorates was present in the Martian soil samples analysed at the Viking landing sites it would have been detected by the Viking GCMS because the temperature of 160 degree celsius of the LR control destined to kill Living microorganisms was not hot enough to destroy the perchlorates..(Details post 65)

Selfsim
2013-Oct-09, 03:21 AM
You will have to digg a little to find an answer because i don't thing there is any study about that.Meanwhile can you show a study showing how the palladium surface of the hydrogen separator used by the Viking GCMS reacts with chlorine?Well, from the Levin report you posted (ie: "Approaches to Resolving the Question of Life on Mars"):
Although the use of the separator generally provided excellent sensitivity, the reactivity of its palladium surface was a potential disadvantage to the integrity and survival of some vaporized species for detection. Thus, the construction and performance of the Viking GCMS need to be considered before interpreting its performance for any given organic compound. .. and then from Wiki on Palladium: (http://en.wikipedia.org/wiki/Palladium#Compounds)
Elemental palladium reacts with chlorine to give palladium(II) chloride .. which is the entry point of lots of palladium based chemistry ..


It is frustrating but this is a problem specific for the Curiosity mission which have no effect for Viking datas.Everything learned from successive missions is relevant to our interpretation of the Viking data. Clearly GCMS sensitivity including and subsequent to Viking, has highlighted that these instruments are detecting compounds at extremely low levels, which can in turn, react with a hypothesised very low level of organics thought to be present in the martian soil, (when it is taken above martian ambient temperatures).

Sorry, but its all relevant to the Viking interpretation, because almost none of this chemistry was even suspected to be relevant when Viking was designed. We now know otherwise .. a lot more cards are now on the table (and I suspect, there'll be even more to come). Tenax & MTBSTFA, (etc) may not be specifically relevant .. but is there something else that is, which has never before been considered to be relevant (in the light of the recent SAM experiences)?


Things that Curiosity conceptors should have know with all the previous missions to Mars.Hmm .. do ya reckon someone should've foreseen how MTBSTFA, (which was sealed in a bunch of non-relevant cups), could've masked the detection of low level soil organics, resulting in ambiguity as to the primary cause of detected chlorinated hydrocarbons?


As explained before (by Levin) if perchlorates was present in the Martian soil samples analysed at the Viking landing sites it would have been detected by the Viking GCMS because the temperature of 160 degree celsius of the LR control destined to kill Living microorganisms was not hot enough to destroy the perchlorates..(Details post 65)And as I responded in post #66:
Well there's water present in the soil too, eh? When the sample is heated, the water and perchlorate can react producing things like HCl and CH3Cl even at temps below 160 degrees (see the Figure #1 in Leshin's paper (http://mars.nasa.gov/msl/files/msl/Science-2013-Leshin-.pdf)). There's still active chemistry going on at these lower temperatures which might also consume any perchlorates. It seems the SAM detected Ca perchlorate at sub 160 degrees, but it used the QMS to do it. (Did Viking have a QMS?).If free chlorine and water was released in the Viking oven at temperatures below 160 degrees, what effect would the palladium reaction then have had on any perchlorates which may have still been present in the sample? Would such a reaction have consumed all chemical signatures of perchlorate by the time it reached the GCMS detectors?

Don J
2013-Oct-09, 04:26 AM
Well, from the Levin report you posted (ie: "Approaches to Resolving the Question of Life on Mars"): ..



Although the use of the separator generally provided excellent sensitivity, the reactivity of its palladium surface was a potential disadvantage to the integrity and survival of some vaporized species for detection. Thus, the construction and performance of the Viking GCMS need to be considered before interpreting its performance for any given organic compound

Which points out the incapacity of the GCMS on Viking to detect organic compound even on certain Earth samples demonstrated to have a very low population of living microorganisms.
see
2.1.2 Viking GCMS detectability v. sensitivity
2.1.4 EBB/GCMS results with terrestrial soils
http://www.gillevin.com/Mars/Reprint115-2000SPIEFinal_files/Reprint115-2000SPIEFinal.html


and then from Wiki on Palladium: (http://en.wikipedia.org/wiki/Palladium#Compounds) .. which is the entry point of lots of palladium based chemistry ..
Elemental palladium reacts with chlorine to give palladium(II) chloride

At what temperature does the reaction occurs?
and note that palladium(II) chloride was not detected by the Viking GCMS even if the Martian soil is know to contain chlorine.


And as I responded in post #66: If free chlorine and water was released in the Viking oven at temperatures below 160 degrees, what effect would the palladium reaction then have had on any perchlorates which may have still been present in the sample? Would such a reaction have consumed all chemical signatures of perchlorate by the time it reached the GCMS detectors?
Still an open question till it is not tested.

Don J
2013-Oct-11, 03:54 AM
About a mechanism explaining the fast destruction of methane on Mars.

From Post #56:
According to current photolysis models* the photochemical lifetime of peroxide is about six hours (during the day). Once photodissociated, the models have it rapidly reforming from its photolysis products again. When it gets particularly cold, the models also indicate it may condense at the surface at night. If this is the case, then how come no surface probe has detected it?

Its absence on the surface makes it a lot like the (thus far absent) methane, eh?

Having said this, I also acknowledge the 'dust devil' model/mechanism (see below response).

* Reference here. (http://www-personal.umich.edu/%7Eatreya/Articles/2012_Encrenaz_Mars_H2O2.pdf)


If you read page 12 chapter 6.1 of your link you will notice that the lifetime of 6 hours is valid for the gaseous form of H2O2.See the description of the triboelectric model about the lifetime of -one hundred to several millions of years- of the H2O2 bound to Martian regolith.
http://www-personal.umich.edu/%7Eatreya/Articles/2012_Encrenaz_Mars_H2O2.pdf
Page 12
Chapter 6.1 origin of localised H2O2
Now consider what the effect of 10 years(since the last measurements of methane) of triboelectric effect caused by dust devils and dust storms (which contain H2O2 bound to the regolith with a lifetime of -one hundred to several millions of years- )must have to the Methane of the Martian atmotsphere.

Here a report which show how heavily the Martian atmotsphere react with the Martian -surface soil- as the dust is moving around the planet via dust storms.
http://news.xinhuanet.com/english/sci/2013-09/27/c_125455251.htm


In addition to determining the amount of the major gases released, SAM also analyzed ratios of isotopes of hydrogen and carbon in the released water and carbon dioxide. Isotopes are variants of the same chemical element with different numbers of neutrons, and therefore different atomic weights.

[b]The analysis found that the ratio of isotopes in the soil is similar to that found in the atmosphere analyzed earlier by Curiosity, indicating that the surface soil has interacted heavily with the atmosphere.

"The isotopic ratios, including hydrogen-to-deuterium ratios and carbon isotopes, tend to support the idea that as the dust is moving around the planet, it's reacting with some of the gases from the atmosphere," Leshin said.

Selfsim
2013-Oct-12, 08:14 PM
If you read page 12 chapter 6.1 of your link you will notice that the lifetime of 6 hours is valid for the gaseous form of H2O2.See the description of the triboelectric model about the lifetime of -hundred to several million years- of the H2O2 bond to Martian regolith.
http://www-personal.umich.edu/%7Eatreya/Articles/2012_Encrenaz_Mars_H2O2.pdf
Page 12
Chapter 6.1 origin of localised H2O2
Now consider what the effect of 10 years(since the last measurements of methane) of triboelectric effect caused by dust devils and dust storms (which contain H2O2 bond to the regolith with a lifetime of -hundred to several million years- )must have to the Methane of the Martian atmotsphere.Sorry .. I'm not sure what your point is here(?) :confused: Are you suggesting that H2O2 formed by dust devils reacts with the methane

Presumably the 'hundreds-to-millions of years lifetime' of H2O2 refers to the end products of the suface mineral-to-atmospheric H2O2 condensate reaction(?) Clearly most of the surface of Mars is oxidised. Is this oxidised layer not what they're referring to when they talk about 'hundreds-to-millions of years lifetime'? If H2O2 is condensing and reforming during night, then there should be some detection of this condensate on the surface by SAM, no? Surely it exists for a finite period as condensation before it forms more stable compounds?


Here a report which show how heavily the Martian atmotsphere react with the Martian -surface soil- as the dust is moving around the planet via dust storms.
http://news.xinhuanet.com/english/sci/2013-09/27/c_125455251.htmYep .. the drift sample of Rocknest should be a good indicator of what is in the atmosphere.

There's lots of rather complex things happening during these dust storms (http://en.wikipedia.org/wiki/Dust_storms_on_Mars#Effect_of_dust_storms). They also seem to cause (water) rain cloud formation.

Don J
2013-Oct-13, 03:37 AM
Sorry .. I'm not sure what your point is here(?) :confused: Are you suggesting that H2O2 formed by dust devils reacts with the methane

The hydrogen peroxide(H2O2) is known to destroy the methane.(see post #50 for details)
http://www-personal.umich.edu/~atreya/Articles/Atreya_Mars_CH4.pdf
The proposed mechanism explaining the accelerated methane destruction process is summarized in the abstract page 1:
see page 5 section 2.5
Loss processes, surface oxidants ,and organics. (for detailed explanation).
------------------
So imagine the destructive effect on the methane when the production of hydrogen peroxide is enhanced by a factor of 10,000 -in the atmosphere- compared to classical values.



Presumably the 'hundreds-to-millions of years lifetime' of H2O2 refers to the end products of the suface mineral-to-atmospheric H2O2 condensate reaction(?)[b] Clearly most of the surface of Mars is oxidised. Is this oxidised layer not what they're referring to when they talk about 'hundreds-to-millions of years lifetime'?

No. That is why they talk about "detectability of localized H2O2(hydrogen peroxide)sources on Mars".


If H2O2 is condensing and reforming during night, then there should be some detection of this condensate on the surface by SAM, no? Surely it exists for a finite period as condensation before it forms more stable compounds?

The problem is that the spots of precipitated H2O2 formed during dust devils is hard to locate.As explained in
Page 12 section 6.1- 6.2 here:
http://www-personal.umich.edu/%7Eatreya/Articles/2012_Encrenaz_Mars_H2O2.pdf

Don J
2013-Nov-05, 08:09 PM
The PFS instrument aboard Mars Express broke in July 2005 (http://www.nature.com/news/2005/050905/full/news050905-10.html). Curiosity is the only chance at the moment of remotely detecting any methane emissions (if present).

There is hope to have a direct analysis from Martian orbit to see if the level of methane detected at ground level by Curiosity is the same amount higher in the atmosphere.India have launched a mission to Mars, arrival in September 2014,
http://spaceflightnow.com/pslv/c25/131105launch/


The mission carries a color imaging camera to return medium-resolution pictures of the Martian surface, a thermal infrared spectrometer to measure the chemical composition of the surface, and instruments to assess the Mars atmosphere, including a methane detector.