Author Topic: Has Curiosity detected methane on Mars?  (Read 38127 times)

Offline JohnFornaro

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Re: Has Curiosity detected methane on Mars?
« Reply #100 on: 11/12/2012 03:58 pm »
So, to your judgement, that line of reasoning (which provides no adverse effects on the results and is more practical) is flawed?

I have no idea.  My question has not been answered.

Quote
The problem with the "obvious" solutions is that they may bring more problems than just risking a very minor contamination that can be easily flushed and accounted for upon landing. Inert fillup with Earth's ambient pressure will lead to overpressurization and an energetic gas release at the instrument's first use.

So generally true.  There's no information on this thread regarding whether or not the device could maintain Earth's ambient pressure thruout the journey, even if filled with Ar.  Neither has the starting pressure been specified.  All that's been unofficially mentioned is that terrestrial methane was clearly present in the chamber, and that four on-site purges have been made.

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Filling up with Mars' pressure will be almost the same than [as?] leaving it in vacuum (which again may or may not be unfeasible or have other ill-effects with this instrument) and may impede good ventilation to the outside in the first few measurements. I would be very interested in knowing about the calibration safeguards agains Earth gas contaminants too, and I don't intend to have a blind trust in the builders, but I don't think suggesting somebody overlooked something pretty basic as adsorption or eliminating the problem with a simple Ar flush is the proper way of asking for details.

It's a shame that there are so many tender egos which must be assuaged.  Mea culpa on my intial tone of voice, which I acknowledged already in the thread above.  Can we move beyond a discussion about me? 

From what hasn't been said on the thread, there was no Ar flush.  There's no need to be coy about it.

Quote from: JF
IDK.  If you're looking for a flu virus, you generally sterilize your instruments before looking.  ...  I mean, when you're building the device, why get all dolled up in these suits?

Quote from: eergo
Equipment sterilization ... is not comparable to completely eliminating a ubiquotous atmospheric gas... in addition to all the mechanisms I suggested, even the rover may be outgassing some of it!

To illustrate, an experiment I work with is contaminated with 85Kr, a much rarer gas than CH4 created mainly during the Cold War nuclear tests (and to some extent by nuclear reactors), even though it has been isolated under a mountain and flushed innumerable times with special (unbreathable) synthetic air, during more than 3 years. And it still gives problems analyzing the signal we're looking for!

Finding unusual isotopic variations of methane is a key experiment.  Invalid readings in this experiment would be undesirable.

Quote from: JF
Huh?  Clean instruments are not that important?

Quote from: eergo
Perhaps my wording is confusing: I meant it's not reasonable to be that picky and assume somebody has made a major mistake, with something as basic, obvious and important as proper cleaning in a cutting-edge instrument.

My mistake is "loaded" wording in the first asking.  Still a valid, unanswered question.  Leave me out of the question.  Nice to have the background perspective you bring.  But... why not purge the methane before ya leave?  Sheesh.

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My point is: why this interest with trying to imply negligence in a project many professionals have spent years carefully working with?

Classic response.  It's not about me, remember?  When this question is asked, they seem to get all sensitive all of a sudden.

Why not purge the methane before ya leave?

[Ominous pause.  Dark music.] [Colon. Right paren.]
« Last Edit: 11/12/2012 04:02 pm by JohnFornaro »
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Offline kevin-rf

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Re: Has Curiosity detected methane on Mars?
« Reply #101 on: 11/12/2012 04:28 pm »
A better way to have dealt with out gassing would be during the long cruise to mars baking the unit in hard vacuum.. But would they have been able to bake the entire lander? As eergo pointed out, they may be detecting methane out gassing from other rover parts. Ie in methane speak, she is smelling herself ::)

You are up against several different factors here, Al was used to save weight, Stainless is a much better vacuum metal. Stainless is not as porous. I am assuming the Gold Plating was ment to try to counter some of this. Though, can you imaging the outcry if they had plated the entire rover in gold? Or the size of LV if the entire rover had instead been made out of Stainless.

I wonder if you grasp how sensitive working in vacuum can be. On Ultra High Vac systems, the oil in one mis-placed finger print can keep you from ever achieving the desired level of Vac. The fact that the level has started to drop below the detection threshold says they invested in making sure they have a very clean system. 

The problem with purging with an inert gas it it often pushes the gasses into all the nooks and crannies and does not actually remove it from the system. I can tell horror stories from back in the 90's when doing UV spectroscopy with N2 purged systems became all the rage. Positive pressure and increasing flow the rate of N2 actually made the problem worse (O2 blocking light below 200nm). That and everyone switched from hard vac. stainless to N2 purged Al chambers.
« Last Edit: 11/12/2012 04:36 pm by kevin-rf »
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Offline eeergo

Re: Has Curiosity detected methane on Mars?
« Reply #102 on: 11/12/2012 04:38 pm »

There's no information on this thread regarding whether or not the device could maintain Earth's ambient pressure thruout the journey, even if filled with Ar.  Neither has the starting pressure been specified.  All that's been unofficially mentioned is that terrestrial methane was clearly present in the chamber, and that four on-site purges have been made. [...] From what hasn't been said on the thread, there was no Ar flush.  There's no need to be coy about it.


This is a thread in an Internet forum (whose main focus of interest isn't unmanned probe scientific instruments), it wouldn't be the most ideal place to find those technical specifications. It could happen however that someone who knows may stumble upon this thread and answer to the very reasonable question, but the forms (talking about egos, impling gross overlooks and negligences) are what I'm saying is not so reasonable, especially after generic technical issues have been hypothesized by other people.

By the way, the four runs were not described as purges, just initial measurements.

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Finding unusual isotopic variations of methane is a key experiment.  Invalid readings in this experiment would be undesirable.

This I agree completely and it would be very enlightening to know how they have safeguarded against contaminated measurements.

Quote
It's a shame that there are so many tender egos which must be assuaged. [...] It's not about me, remember?  When this question is asked, they seem to get all sensitive all of a sudden.

Why not purge the methane before ya leave?

Who is "they"? I clearly said I don't have any involvement with this instrument, but as a scientist try to give a vote of confidence to the professionals while keeping a critic and inquisitive attitude to find out possible flaws. However, you keep asking with an accusatory tone, even though you say you dropped it after the first answer... and you don't know if it was indeed purged to the lowest possible level!

In any case, I agree given the high interest in the result it would be nice if somebody could give a more technical insight into the purging procedures and contamination detection!
« Last Edit: 11/12/2012 04:40 pm by eeergo »
-DaviD-

Offline JohnFornaro

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Re: Has Curiosity detected methane on Mars?
« Reply #103 on: 11/12/2012 04:45 pm »
Who is "they"?

Thanks for your input about some of the difficulties surrounding this issue.
Sometimes I just flat out don't get it.

Offline fthurber

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Re: Has Curiosity detected methane on Mars?
« Reply #104 on: 11/12/2012 11:15 pm »
Can I change the subject just a bit and talk about the other gases detected by SAM?  I noticed that oxygen and carbon dioxide were detected in small amounts but it is my understanding that these gases are not stable over geological timescales suggesting they are being replenished.  What is this mechanism?  Photo or UV disassociation of carbon dioxide?

Offline Tetrakis

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Re: Has Curiosity detected methane on Mars?
« Reply #105 on: 11/13/2012 05:40 am »
Can I change the subject just a bit and talk about the other gases detected by SAM?  I noticed that oxygen and carbon dioxide were detected in small amounts but it is my understanding that these gases are not stable over geological timescales suggesting they are being replenished.  What is this mechanism?  Photo or UV disassociation of carbon dioxide?

First of all, CO2 is by and large the principal component of the Martian atmosphere. The question of it's stability is a good one; it is cleaved to form carbon monoxide and oxygen photochemically surprisingly quickly on geological time scales. It turns out that carbon dioxide regeneration is catalyzed by hydrogen originating from atmospheric water (Parkinson, T. D., D. M. Hunten, 1972: Spectroscopy and Acronomy of O2 on Mars. J. Atmos. Sci., 29, 1380–1390.); the real question here is why the carbon monoxide to oxygen ratio isn't stoichiometric. From what I can tell, that problem has yet to be solved... perhaps MSL can have a hand in its solution.
« Last Edit: 11/13/2012 05:41 am by Tetrakis »

Offline RigelFive

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Re: Has Curiosity detected methane on Mars?
« Reply #106 on: 11/13/2012 05:48 am »
Can I change the subject just a bit and talk about the other gases detected by SAM?  I noticed that oxygen and carbon dioxide were detected in small amounts but it is my understanding that these gases are not stable over geological timescales suggesting they are being replenished.  What is this mechanism?  Photo or UV disassociation of carbon dioxide?
Carbon dioxide comprises 95.32% of the Martian atmosphere, and oxygen is 0.13%.  Methane is believed to be at 10.5 x 10-9 mol/mol.  Which means that the sheets of paper that the Martian methane articles are published on likely have a greater concentration of methane within its fibrous pores than can be found on Mars.

The origin and mechanisms of Martian carbon dioxide has had me perplexed long nigh for 43 Earth years...

As can be told by many geologists, steam is the key ingredient to make the grand volcano events on Earth.  But on Mars and Venus, the largest volcanoes very likely used carbon dioxide as their generated gas.  The CO2 on Venus creates a thermal greenhouse,  at the moment Mars does not.  If pressure is trapped under the surface of Mars, there could be a tremendous explosion of carbon dioxide AT ANY MOMENT just waiting to occur.   The surface could be consumed in clouds as the atmospheric thickness increases and the greenhouse effect becomes so potent on Mars, the surface temperature becomes hot enough to melt the Martian polar ice caps.  As the white dry ice sublimes into the atmosphere, the planet is propelled to an even closer solar orbit.  The planet surface temperature increases from the solar radiation, and additional subsurface minerals begin to outgas violently.  The surface cracks under the stress and fissures in the surface yield gas vents that make the planet spin wildly.  The added centrifugal motion causes the wind speeds to increase to near sonic conditions.  Violent degradation of the Martian surface begins, and the runaway sublimation, erosion and evaporation begins to make the planet unstable.  At the moment the center of gravity of Mars begins to bifurcate - the planet breaks apart into asteroids and assorted space debris particles.  The radiation from the sun is blocked to the outer planets.  Jupiter and Saturn collapse under the cooler conditions and each go into a pre-ignition state.  As the moons and rings of Jupiter and Saturn are scattered like a grenade over the solar system, the primary sequence occurs.  Our solar system becomes a trinary star system like the Centauri system with cataclysmic debris all over the place. 
« Last Edit: 11/13/2012 06:09 am by RigelFive »

Offline KelvinZero

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Re: Has Curiosity detected methane on Mars?
« Reply #107 on: 11/13/2012 06:08 am »
And this is why no one should ever take a Mentos to mars.  8)

http://en.wikipedia.org/wiki/Diet_Coke_and_Mentos_eruption

Offline JohnFornaro

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Re: Has Curiosity detected methane on Mars?
« Reply #108 on: 11/13/2012 01:10 pm »
The origin and mechanisms of Martian carbon dioxide has had me perplexed long nigh for 43 Earth years...

Our solar system becomes a trinary star system like the Centauri system with cataclysmic debris all over the place. 

Okayyyyyy..... Maybe you could take two of these, and call me in the morning.
Sometimes I just flat out don't get it.

Offline fthurber

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Re: Has Curiosity detected methane on Mars?
« Reply #109 on: 11/13/2012 03:15 pm »
Can I change the subject just a bit and talk about the other gases detected by SAM?  I noticed that oxygen and carbon dioxide were detected in small amounts but it is my understanding that these gases are not stable over geological timescales suggesting they are being replenished.  What is this mechanism?  Photo or UV disassociation of carbon dioxide?

First of all, CO2 is by and large the principal component of the Martian atmosphere. The question of it's stability is a good one; it is cleaved to form carbon monoxide and oxygen photochemically surprisingly quickly on geological time scales. It turns out that carbon dioxide regeneration is catalyzed by hydrogen originating from atmospheric water (Parkinson, T. D., D. M. Hunten, 1972: Spectroscopy and Acronomy of O2 on Mars. J. Atmos. Sci., 29, 1380–1390.); the real question here is why the carbon monoxide to oxygen ratio isn't stoichiometric. From what I can tell, that problem has yet to be solved... perhaps MSL can have a hand in its solution.

ACK!!!  I had a typo. My question was about carbon monoxide.  I was asking about O2 and CO.  They are unstable and must be generated from CO2 photo-dissociation...

Sorry, but the CO2 answer is also very interesting...
« Last Edit: 11/13/2012 03:18 pm by fthurber »

Offline Tetrakis

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Re: Has Curiosity detected methane on Mars?
« Reply #110 on: 11/14/2012 12:20 am »
The paper is really interesting. It's amazing how it was possible for chemists to solve a catalysis problem through terrestrial telescopic spectroscopy. They were even able to localize the altitude at which the chemistry takes place.

It might have been mentioned in another thread, but for what it's worth the instrument suite can definitely route thermally evolved gasses from solids (like CO2 from carbonates) to it's various other analytical tools (TLS, GCs, QMS).
« Last Edit: 11/14/2012 01:16 am by Tetrakis »

Offline Mader Levap

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Re: Has Curiosity detected methane on Mars?
« Reply #111 on: 11/14/2012 08:59 pm »
If pressure is trapped under the surface of Mars, there could be a tremendous explosion of carbon dioxide AT ANY MOMENT just waiting to occur. (...) Our solar system becomes a trinary star system like the Centauri system with cataclysmic debris all over the place.
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Offline MP99

Re: Has Curiosity detected methane on Mars?
« Reply #112 on: 11/14/2012 10:13 pm »
+1

cheers, Martin

Offline Dalhousie

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Re: Has Curiosity detected methane on Mars?
« Reply #113 on: 11/14/2012 11:40 pm »
There seem to be suggestions that improper procedure was carried by supposedly not purging the instrument beforehand.

The fact is no matter how certain you were the system was clean before it left Earth you would still want to purge it with ambient air on Mars several times and track what is happening.

I am constantly amazed at the ability for good procedure to be interpreted as signs of incompetance. 
Apologies in advance for any lack of civility - it's unintended

Offline RigelFive

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Re: Has Curiosity detected methane on Mars?
« Reply #114 on: 11/21/2012 09:26 pm »
Rumored news from MSL SAM.  Oh boy, this rediscovery might just get in under the wire for congressional budget season!!  Very exciting!

http://news.discovery.com/space/mars-mystery-what-has-curiosity-discovered-121120.html


Offline kevin-rf

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Re: Has Curiosity detected methane on Mars?
« Reply #115 on: 11/22/2012 12:43 pm »
Been covered multiple times in the other threads
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