Methane 'confirmed' on Mars. From Space.com, though. Anyone see the story from a more reliable source?

Hey, did I ToSeek anyone?



CJSF

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They're supposed to be Nasa scientists but nothing on Nasa's or Esa's sites yet.

And nothing on Mauna Kea's site.

Or in their "in the press" section.

From the space dot com article...

Just the way "this" is stated, leads me to believe that the story is factual.

I agree; however, it's bordering on sensationalism to title the article the way they did:

In my opinion, the case for either geologic or biologic sources was presented equally, but Space.com chose to spin it toward biological sources. At least that's how I read the article. It seemed biased that way. Does anyone else feel that way, or am I being to sensitive because it's Space.com?

CJSF

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See the constellation ride across the sky
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'Mars Could be Biologically Alive'. Technically, that's true, isn't it?
Of course, the title implies far more than the article has to show. But then, who told us to read implications in the title instead of looking at the article in full, anyway? :P

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I thought there was a slight bias throughout the article, not just the title. It seemed that the geological explanation was surpressed. Again, that might be my bias against Space.com ... though I enjoy some of their 'SETI Thursday' articles - even when they're fairly off topic, like the 'Vanishing Robbers' articles a few weeks ago.

CJSF

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See the constellation ride across the sky
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At least this was a real talk at a real meeting. http://nai.nasa.gov/nai2005/abstracts.cfm
"Detection and Mapping of Methane and Water on Mars: Evidence for Intense Local Enhancements in Methane." Abstract linked from that site.

Leonard David is one of the good guys.

Jon

Mumma keeps making these claims, but like the ESA methane claims, no one is taking them seriously.

As he says in the article, they had to "invent" new ways to do this. That's because they're trying to detect ~10 ppb of methane while looking through a variable atmosphere containing ~2000 ppb. The methods being used and certainly the interpretation of the results are still very suspect, and I find it funny every time I see these guys "confirm" each other's questionable observations with more questionable observations.

I wondered about that as well. I have done optical spectroscopy professionally for many years, and I know how hard it can be with marginal detections. I am learning X-ray spectroscopy for an exercise we are developing, and I'm finding that it's closer to black magic than real science sometimes. :-?

When someone says they have marginal results in spectroscopy, believe it. Marginal may mean really marginal. So I want to see an actual paper with their analysis in it before I make any judgments. I am not saying they are wrong, I am saying I want to see more data first!

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What would give us a more accurate reading?

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As a very general answer, more signal. The problem with a lot of these methods is that you are close to the detection limit and your signal is buried in the noise. The noise can be electronic/instrumentation or can be interferences from other signals (the peak for methane is close to the peak for something like CO2, where there is a huge signal). Often, the best solution is to change your detection method (different detector, completely different technique).

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Higher signal is part of it. Another problem is simply trying to understand what elements are giving off what lines in the spectrum. The errors are pretty large, meaning it's hard to know what is what. In other words, interpreting the spectrum is the hard part.

Since the methane was detected by three separate teams including one in orbit alot of people take its presence seriously.
There is doubt about the claimed local enhancements.


Bob Clark

Three different teams using four different instruments have reported low levels of methane in the Martian atmosphere. They are: Formisano et al., using Mars Express PFS; Mumma et al., using the IRTF in Hawaii and Gemini South in Chile, and Kransopolsky et al., using the CFHT in Hawaii. This is strong evidence that the observations are real. Results have been presented at conferences and are being published in peer reviewed journals. I would say that lots of people are taking these results very seriously indeed. The debate has been almost entirely over what the results mean, not their veracity.

[quote="Bamf"]As he says in the article, they had to "invent" new ways to do this. That's because they're trying to detect ~10 ppb of methane while looking through a variable atmosphere containing ~2000 ppb.quote]

So scientists should never invent new ways of doing things?

Jon

No, it's not. To borrow a quote: "Three marginal observations don't add up to one good one". As we've already discussed, terrestrial-based telescopic observations have some fundamental problems, and the ESA results are just straight up suspect since they're claiming concentrations at or below their noise level.

One more thing to consider: ESA says "we've seen about 10 ppb but that's near our noise limit", but Mumma previously said "we're seeing as much as 300 ppb" (although the last article just says "strong sources"). If Mumma ever really saw 300ppb or anything one might call "a strong source", then surely the ESA guys would have seen more than just a questionable blip at their detection limits.

Lots of people that don't have the knowledge and skill necessary to interpret the results might be taking them seriously, but many scientists in this field that are actually able to analyize the data and confirm or refute the findings, think this is mostly just hot air.
That of course depends on who you're listening to. The press-releases and reporters on space.com may lead you to believe this, but in the science community, the reality is very different.

I agree that some scientists don't take it seriously. But I think more do rather than not. Especially with the crater counts suggesting that Mars volcanism is geologically recent, which suggests it may still be ongoing.


Bob Clark

Bamf:

As I read it, you are saying three things: 1) The methane results are at the detection limits. 2) The only people taking this seriously are those without the necessary knowledge and skills to interpret the results. 3) My opinion is based on press releases and reporters of space.com, and that perspective presented these sources are the opposite to that of the science community. This is incorrect on all three counts.

1) The ME-PFS results were not near the noise limit but 10 times above background. I don’t have easy access to Kransnopolsky et al.’s Icarus paper, so can’t comment on the details, and the on-line abstracts don’t give the detection limits. Mumma’s team have only published abstracts so far, again without written specification of detection limits. The fact remains that three independent studies using five different instruments including Keck) is four positive tests of the original observation and hypothesis. For cutting edge science this is very encouraging. There have been no negative results.

2) The results of all three teams have been presented at several high level international conferences and well received. For example at the 2005 LPSC every reference to current methane accepted that it had been detected. The reception to the paper by Formisano’s team has also been positive. They first published their results in Science Direct on October 29 last, I have reviewed every issue of Science bar one published from then until April 1 and there have not been any criticism of the paper. There was, however, one favourable op-ed by Kargel in the December 17.

3) I am not basing my opinion on press releases and web reports, I am basing this on the relevant scientific literature. As noted in 2), there has been general acceptance that low levels of methane have been discovered. After all, this is not unexpected, there have been over 140 papers in the last 30 or so years discussing the abundance of methane in the atmosphere of Mars. I have found only one sceptic on the presence of methane – Bruce Jakosky – who made some critical comments to the media when the discovery was first announced but has not published or presented anything on the subject.

The situation is different with formaldehyde, also reportedly detected by the ME-PFS and presented at a number of conferences by Formisano. There has been considerable skepticism of the reports by many people (e.g. Yung, Mancinelli, Anderson, Bailey, Walter) over this. Not that formaldehyde is impossible or unlikely, but that the reported signal to noise ratio is very faint. So the jury is still out on this, and the data has not yet been published, being reported only at conferences. I will be at a conference next week that has a paper on Mars methane by Formisano’s team, so may be able to report on its reception then.

Jon

Can you give me a cite? (volume, year, which is the correct spelling as you've used two different ones) I'd be interested in reading it.

Hi jnik

The reference is: Krasnopolsky, V. A.; Maillard, J. P.; and Owen, T.C. "Detection of methane in the martian atmosphere: evidence for life?" Icarus, Volume 172, Issue 2, p. 537-547 (2004).

Jon

Not all of space.com is sensationalist. Here's a thoughtful article by Greg Little on that very topic as it pertains to the recent Martian methane discoveries. That's meh-thane, not mee-thane, BTW. :wink:

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Right in the abstract: "[w]e detected the absorption by martian methane at a 3.7 sigma level..."

Not a Nature result, but definitely nothing to sneeze at.

To avoid the telluric lines, they observed when the Doppler shift was at its maximum, with high spectral resolution, and at high altitude (Mauna Kea). Basically the Martian lines were Doppler-shifted into the wings of the telluric lines, and as the line profiles are well-known, the telluric lines could be extracted via a fit, leaving the Martian lines.

Looks like pretty solid science to me, and some very clever observational technique with the best intrument available. Unfortunately: "...the Fourier transform spectrometer has been decomissioned at the CFHT, and it is impossible to repeat our observation." So a grain of salt is probably merited.

Just a short word of caution: there seems to be the sense that many observations made at the margins of detectability (with no "negative" results) implies a more robust finding.

This idea is mistaken.

For such a spectacular result as this, there can easily be a lot of overinterpretation going on. The fact that many independent groups are independently overinterpreting doesn't mean that the results become stronger. Ten or even 100 detections at the noise limit of the instruments are still not equal to one solid observation.

[Note that I have no opinion one way or the other on the particulars of the Mars methane story. But we all (especially including the researchers) want it to be true, so we need to be especially disciplined and rigorous about interpretation.]


There's a good Mars example of this: how many independent research groups convinced themselves that they saw canals?

Actually, there have been numerous previous attempts to detect methane on mars that did end with negative results (at least to some maximum possible concentration level). Krasnopolsky stated, "Our measured abundance agrees with the upper limits of 20, 50, and 40 ppb established by three other teams who tried but did not succeed to detect methane on Mars."

So, it's clear that whatever Mumma is seeing, any claims of concentrations greater than about 20ppb should be suspect.