So, to your judgement, that line of reasoning (which provides no adverse effects on the results and is more practical) is flawed?
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.
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.
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?
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!
Huh? Clean instruments are not that important?
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 point is: why this interest with trying to imply negligence in a project many professionals have spent years carefully working with?
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.
Finding unusual isotopic variations of methane is a key experiment. Invalid readings in this experiment would be undesirable.
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"?
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?
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.
Quote from: fthurber on 11/12/2012 11:15 pmCan 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.
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.