Ischia

The Ischia news (which Alex Blackwell has been most kindly feeding into the comments threads) is definitely interesting stuff. At the Mars meeting on Ischia Vittorio Formisano has reported that methane and water vapour are concentrated over the same three parts of Mars -- Arabia, Elysium and Arcadia. The suggestion is obviously that in each place they have a common source. One possibility, presumably, might be igneous activity that both melts ice and releases methane. Another, as Mike Mumma points out on BBC Online, is that the source could be the breakdown of clathrates -- ice with methane already trapped within it.

If you buy into the clathrates, that still leaves the question of where the methane came from open. But here’s a possibility. Imagine that under these regions there are deep aquifers with liquid water, of the sort that Steve Clifford and Tim Parker have written about. Maybe they’re the last remnants of a planet-spanning aquifer. And imagine that in these aquifers there are some jolly little methanogens. This means that in the pore spaces above the aquifers there will be both water vapour and methane. The vapour and the methane will rise up until they reach the cold rocks of the shallow subsurface, at which point they freeze, together, into clathrates. Now imagine that this is happening a little while back, in one of the ice ages when the planet’s obliquity was higher and its lower latitudes colder. Back then, clathrates just below the surface might well have been stable; today, with the lower obliquity and the warmer low latitudes, they might be breaking down.

It’s just a scenario. I’ve no idea if it’s feasible (I don’t know if you can make clathrates out of water vapour and methane in this way: on the earth you start with liquid water). And you can imagine something pretty similar going on with an abiogenic methane source. But it’s kind of fun.

Five thoughts. One is that we have to remind ourselves that this data still hasn’t been published, hasn’t been peer reviewed and hasn’t been made available to the scrutiny of other workers in the field. Doesn’t mean it’s wrong, but it’s worth bearing in mind. (Given that they were writing this up in April, there’s definitely been time for it to be submitted). Leonard David quotes Jim Garvin, NASA’s head of Mars science, saying that widespread inspection of the data will be “the real test”.

Two is that there’s no mention in the reports that I’ve seen of the purported temporal changes in methane concentration mentioned back in Nice. That said, the chart on the ESA page shows a level of 35 parts per billion, which is high. Maybe the temporal differences were actually spatial differences.

Three is that the ESA release also says there is a paper on other trace gases (ammonia? Formaldehyde?) currently in the works.

Four is that all this makes it more important than ever that the Marsis antenna gets deployed. Seeing what the subsurface looks like in these three areas has suddenly become on of the highest priorities.

Five is that I think I’m going to go and get a plane ticket to Naples and hear some more.

Comments

[Alex R. Blackwell]

Nice post, Oliver. I like all five of your "thoughts," especially #5 ;-)

Seriously, though, as you alluded to in the other thread, the terrestrial methane production scenario outlined by Scott et al. in the PNAS paper I linked to is, I agree, fairly implausible for Mars. I linked to the paper primarily because it deals with methane production in the mantle and also because of its coincidental publication today.

Methane hydrates or clathrates, which have long been predicted to be present on Mars, especially in the polar regions, is an attractive abiogenic alternative to explain the (apparent) PFS methane signature; however, I find other features (e.g., thermodynamic stability over geologic time scale at near equatorial latitudes) problematic. Similar concerns were expressed (and published) regarding the plausibility of liquid CO2 sequestration in the martian crust as an alternative source for the erosive agent(s) that formed the martian gullies.

As hard as it is for me to accept, and I'm certainly nowhere near fully on board this option yet, the biogenic explanation for methane is still very viable. If the spatial (and temporal) correlation of the methane with H2O vapor holds up, then that, coupled with an apparent regional correlation to the dark slope streaks (thought by many to be dust avalanche scars) and the high near-surface hydrogen content detected by Mars Odyssey, then subsurface liquid water, perhaps from deep-seated aquifers below the melting isotherm, are, in my opinion, just as plausible.

One thing is clear though, as you point out. The Mars Express MARSIS and MRO SHARAD subsurface soundings of these regions are absolutely imperative to test these hypotheses.

[rupert]

Assuming there is methane, is there any hope of determining the isotopic ratios of the carbon - and if so, is it going to be of any interest in determining whether it's of recent biological origin? With so little atmospheric nitrogen, I don't suppose there's going to be much C14 in the first place - but what there is will find its way into methane if there are bugs pooting it out, right, and not otherwise - or am I missing something?

R

[Oliver Morton]

It's true that there's been speculation about clathrates on Mars since Mariner 9, though it went very quiet during the eighties, but for what it's worth almost all of that was about CO2 clathrates, not methane clathrates. And clathrates don't get you out of the problem of of sourcing the methane—they just let you shift it back in time. How far back we don't know; I agree that its unlikely that equatorial clathrates could have been stable for geological periods of time. But at some time before the clathrates you would have to have a methane source, and there's no a priori way to say whether that would have been abiogenic or not.

[Oliver Morton]

Rupert, I'm afraid your misgivings are correct; I'd imagine the production function for C14 on Mars must be negligible, since the amount of nitrogen is so low. C13/12 ratios may reveal something, if a good mass spec or a really great spectrometer could be brought to bear on the subject.

[blairf]

Hydrogen Flouride - now thats a new one!

The phase diagram here
www.airliquide.com/en/business/products/gases/gasdata/images/VaporPressureGraph/Hydrogen_Fluoride_Vapor_Pressure.GIF">http://www.airliquide.com/en/business/products/gases/gasdata/images/VaporPressureGraph/Hydrogen_Fluoride_Vapor_Pressure.GIF

seems to indicate that at 6-10 mb and 170K - 220K you are right around the boiling point of HF.
Anyone fancy swimming in a Hydroflouric acid lake?

[Bruce Moomaw]

Unfortunately, it's not certain that the mass spectrometer on Phoenix will even be able to detect methane at all, let alone its isotopic ratio -- the decision has not yet been reached as to whether it will include a filter to remove atomic oxygen and allow methane measurements, and even if it is I believe that this MS isn't sensitive enough to allow methane isotopic measurements. The hope there would seem to involve either the 2009 MSL, or the possibility that one of the two 2011 Mars Scouts may be the MARVEL orbiter with its supersensitive IR solar occultation specttrometer, which might be able to detect C-13 methane (although I'm not even sure about that). One thing I DO consider very probable now is that MARVEL (or an equivalent) will be one of the 2011 Scouts.

[Alex R. Blackwell]

Thanks, Oliver. I should have been a little clearer in stating that, indeed, it is CO2 clathrates that have been predicted for Mars, not methane clathrates. At any rate, I do agree that, under such a scenario, a plausible CH4 source(s) for that specific class of clathrates needs to be identified. That said, I have problems reconciling the apparent geology of the "methane regions," particularly Arabia Terra, with putative water and methane chemistry. At the risk of sounding repetitive, subsurface soundings (and perhaps even SAR probings of the dust and sand mantles) are imperative.

As for MARVEL, unlike Bruce I do not think it is at at all clear that this particular mission, one the four finalists in the 2007 Mars Scout competition, and which lost out to the Phoenix lander, is a "lock" for one of the two projected Mars Scouts slots in 2011. Though I would not categorically rule it out, I do not think it is certain that NASA would incorporate some sort of surface-based atmospheric investigation targeted to methane, or modify a planned-for instrument, on the 2009 Mars Science Lander (MSL). Science instrument proposals have already been submitted for MSL and, unless a proposer submitted such a capability, I doubt NASA would insist on one. Though anything is possible, I guess.

At any rate, given that one plausible explanation for a valid methane detectionis extant life, and since NASA appears, at least according to the July meeting of NASA's Solar System Exploration Subcommittee (SSES), to have selected Pathway 1: Search for Evidence of Past Life for the "Next Decade (2009-2020)" of Mars exploration, which kicks off with 2009 MSL, it is entirely conceivable that NASA will not follow up on the PFS data, at least directly. However, judging by Jim Garvin's statements to Leonard David yesterday, I think NASA (as well as the science community) is waiting to see if the PFS claims hold up before altering their fairly detailed Mars exploration strategy, though MEP is, admittedly, "discovery driven" and has some flexibility in switching to one of the three other Pathways (e.g., Pathway 3: Search for Present Life), though there will be some delay due to the required lead time in soliciting and developing instruments.

[Alex R. Blackwell]

Martian methane hints at oases of life
Mark Peplow
news@Nature.com
Published online: 21 September 2004; doi:10.1038/news040920-5
http://www.nature.com/news/2004/040920/full/040920-5.html

[Bruce Moomaw]

Well, David Grinspoon has already said (in "Slate", of all places) that he's submitted a proposal for a methane-detecting atmospheric spectrometer for MSL, although this doesn't prove it will get selected. Personally, I think methane detection is much more sensible for an orbiter than for a lander, since the main purpose is to find out where the biggest concentrations of the stuff are on the planet as a whole.

And so, while MARVEL itself is certainly not assured for the mission, I think it very likely that a trace-gas sniffer like it will be one of the 2011 Scouts. Especially since the National Academy of Sciences, in its 2002 appraisal of possible gaps in the Mars program as it then existed, called seasonal analysis of Martian atmospheric gases (including water vapor) to locate their sources and sinks one of the most important goals unmet in the program at that time, and such an orbital mapper could also do that all over the planet.

[Rick L. Sterling]

The Enterprise Mission published today V. Formisano's abstract from the Ischia Mars Conference. I am posting a link here in case there are some people who didn't see it under the "And No Formaldehyde Either" section. http://www.enterprisemission.com/formisanosAbstract.php

[Alex R. Blackwell]

From the September 23, 2004 issue of Nature:

Acid drops in the martian ocean
http://www.nature.com/nature/links/040923/040923-3.html

See also:

A picture of young Mars
http://www.nature.com/news/2004/040920/full/040920-7.html

Mars, Once Warm and Wet, Left Some Clues
http://www.space.com/scienceastronomy/mars_fizz_040922.html

Also in the September 23, 2004 issue of Nature:

Ecology: Widespread colonization by polar hypoliths
C. S. Cockell and M.D. Stokes
Nature 431, 414, (2004)
doi:10.1038/431414a
First paragraph
http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v431/n7007/abs/431414a_fs.html

See also

Polar microbes get helping hand
http://www.nature.com/news/2004/040920/full/040920-9.html

New signs of life found at the Poles
http://www.eurekalert.org/pub_releases/2004-09/bas-nso092104.php

[Alex R. Blackwell]

Mars Express Instrument Finds Possible New Evidence in Search for Life: Water and Methane Maps Overlap
By A.J.S. Rayl
The Planetary Society
September 22, 2004
http://planetary.org/news/2004/mars-express_pfs-findings_0922.html

[Oliver Morton]

Bruce, Alex -- I don't know about the 2011 scout, but I'm pretty sure that more than one of the proposed instrument packages for MSL (not including Pillinger's...:-)) has methane isotope analysis as an advertised capability. It's not clear to me that that capability fits the scientifc rationale for the mission as originally conceived, which seemed to be focussed on past habitability, but the instruments are apparently on offer should they be wanted.

Also worth bearing in mind that the Discovery program might choose Mike Mumma's OOO proposal, which is an IR spectrometer as good as those at ground based facilities, but in orbit. That wouldn't be able to do delta-13C, but it would be able to detect and map methane on the disc of Mars at accuracies below 1ppb, I think.

As I mentioned a while back, the Canadians have an earth orbiting occulting spectrometer that would provide heritage for a Marvel type mission. If ESA needs something cheap to make up for the fact that exomars will surely slip from 2009, a joint program using that technology on a scout type budget might be appealing -- a way of following up what ESA will be spinning as a european discovery.

[Daniele]

I live in Ischia :) I didnt know about all what you are talking about :) Now i know, thx and cya all

[Ischia]

If you need more information about Ischia please follow the link.

[Mario]

Interesting article.
Regards.
Mario