PDA

View Full Version : Discussion: What's Making Martian Methane?



Fraser
2005-Jul-27, 05:46 PM
SUMMARY: With the discovery of methane in Mars' atmosphere, scientists are trying to find out what the source is. Since methane is destroyed by sunlight, there has to be an active source constantly producing it. Here on Earth, methane is largely produced by living bacteria, called methanogens, which convert carbon and hydrogen into methane. The problem is that Earth bacteria go into a dormant state when exposed to the low pressure Martian atmosphere. So they're probably deep underground, and the methane they produce slowly moves to the surface.

View full article (http://www.universetoday.com/am/publish/mystery_methane_maker_mars.html)

What do you think about this story? Post your comments below.

antoniseb
2005-Jul-27, 05:57 PM
It is interesting that there doesn't appear to be a Martian Seismology experiment going on any currently planned mission to Mars. We seem very interested in understanding the surface of Mars, and history of the surface, but we haven't yet generated the interest to set up three or more sensative Seismic listening stations to try and get a sense of the interior of Mars.

It is amazing to me that with all the instrumentation that we've sent there that we have no idea how these volcanos could have formed so recently, with no real record of previous volcanism. Are there pools of magma? Does Mars have a molten core? We have no idea, and won't for at least another decade... maybe much longer.

lswinford
2005-Jul-27, 09:22 PM
At least it wasn't from red cows (as methane generators) eating red grass growing in the red sands of the red planet's now dry riverbeds.

The first time I read of anerobic bacteria like these methagins was as a child reading of the deep gold mines in South Africa. That bacteria supposedly produced some of the trace minerals that were indicative of certain other minerals. One of the surprises for me, who had visited several caves but was always impressed with them being cold, down deep in those mines the temperature was quite hot. From that I got to look up and learn about subterranean temperature gradients. In this case, we have to surmise about a subsurface martian temperature gradient. Whether Mars has currently active vulcanism, much of the subterranean heat is from radioactive decay (pressure of surface load and the heat pool of our molten middle contribute too, for us, so factor accordingly). Anyrate, the subsurface environment, even if cold, would doubtfully be fully cold.

Guest_James
2005-Jul-28, 01:38 AM
Methane is a chemical reaction between carbon and hydrogen. -->CH4

1) If mars has plenty of CO2 (Check!) and plenty of H2O (Check!), then it can certainly sustain methane producing life.

2) We've already ruled out the possibility of meteorites bringing to mars the observed amount of methane.

3) IF hydrogen seeps out of the core of mars (how so?) and gets stuck to hot rocks (are these present on mars?), then it could react with the CO2 in the atmosphere to create methane.

From what has already been confirmed by NASA, I'd say the most probable thing is the first possibility... Life is responsible for the methane on mars.

However, it's just bacteria, which, given "millions of years" hasn't evolved into anything other than more bacteria. Why did Earth bacteria, given approximately the same amount of time that Mars bacteria had, evolve into intelligent life, while marshion bacteria didn't even evolve into any plants or animals?

imported_Frank
2005-Jul-28, 05:49 AM
I'd suggest that anyone interested in pursuing the idea of Martian methane being produced by organisms deep under the surface read " Hot, Deep Biosphere" by Thomas Gold. Interesting and informative to read.

Matthew
2005-Jul-28, 07:28 AM
If methane is being produced by life then that life can't be too far beneathg the surface, otherwise the methane would be trapped in the rocks.

Eric Vaxxine
2005-Jul-28, 09:22 AM
http://www.msss.com/moc_gallery/m07_m12/im...9/M0900068.html (http://www.msss.com/moc_gallery/m07_m12/images/M09/M0900068.html)

This looks like a mass of....er....you tell me. This is a mat of something (seemingly) from a Polar region of Mars. If anyone knows what it is, would it generate methane .. or is most methane really bovine generated gas?







Underground Martian cows, hundreds of them !! :D

Eccles
2005-Jul-29, 04:29 AM
In response to Guest_James question as to why there is not much more than possible bacteria on Mars, you must remember that complex life on Earth is a new event if looked at from the time scale of the solar system. In the 4 Billion years of time available complex life has only existed for 900 million (less than a quarter of the time). From where we are standing it appears that the Earth got lucky. But who is to say that in a billion years time there will be much surface evidence left of us (non monerans) anyway.

Nereid
2005-Jul-30, 09:46 PM
Originally posted by Eric Vaxxine@Jul 28 2005, 09:22 AM
http://www.msss.com/moc_gallery/m07_m12/im...9/M0900068.html (http://www.msss.com/moc_gallery/m07_m12/images/M09/M0900068.html)

This looks like a mass of....er....you tell me. This is a mat of something (seemingly) from a Polar region of Mars. If anyone knows what it is, would it generate methane .. or is most methane really bovine generated gas?







Underground Martian cows, hundreds of them !! :D
Unlikely to be generating methane .... if it were, it would be a 'methane hotspot', and (IIRC) no such were detected by either of the two teams which included regional variations in their observations.

That said, it 'looks' rather like sandpaper, doesn't it? Or part of a sandy beach (no, wait, the scale would surely be all wrong)?

Nereid
2005-Jul-30, 09:58 PM
2) We've already ruled out the possibility of meteorites bringing to mars the observed amount of methane.
No, it's not ruled out; it's merely improbable.

One of the difficulties we face, doing analyses, is that we have but a single datapoint (by time) - if there were even a poorly-constrained estimate of the variation in the Martian atmospheric concentration of methane by time, we could (in principle) do much more to constrain 'one-off' events such as meteorites, comets, and volcanic eruptions.
From what has already been confirmed by NASA, I'd say the most probable thing is the first possibility... Life is responsible for the methane on mars.
And if I were a 'betting person', I'd bet that the most probable thing is vulcanism.

Surely the point is that we have, as yet, far too little data to seriously constrain the various possibilities? On top of which, we need to add 'some cause that will be blindly obvious, after the event, that no one has thought of today'; in the history of astronomy/planetary sciences, this is not at all uncommon (e.g. craters on Mars, volcanos on Io).
However, it's just bacteria, which, given "millions of years" hasn't evolved into anything other than more bacteria. Why did Earth bacteria, given approximately the same amount of time that Mars bacteria had, evolve into intelligent life, while marshion bacteria didn't even evolve into any plants or animals?
As Eccles already said (tho' I believe it's now ~1.2 billion years, not ~900 million), we really don't have a good handle on why it took so long for multicellular life to evolve from bacteria, here on Earth (and the details of the evolution from the first eukaryotes to multicellular life, and then from primative plants - yet plants! they appear in the fossil record long before 'animals' - to macroscopic multicellular critters is still very poorly understood). As for 'intelligent life', well, assuming you mean Homo sap., then that seems to have been little more than an accident (or, should we say, a cosmic joke?), that happened so recently that it has no possible relevance to an understanding of evolution of complex life anywhere else in the universe. :P B)

cran
2005-Aug-01, 06:23 AM
Originally posted by antoniseb@Jul 27 2005, 05:57 PM
It is interesting that there doesn't appear to be a Martian Seismology experiment going on any currently planned mission to Mars. We seem very interested in understanding the surface of Mars, and history of the surface, but we haven't yet generated the interest to set up three or more sensative Seismic listening stations to try and get a sense of the interior of Mars.

It is amazing to me that with all the instrumentation that we've sent there that we have no idea how these volcanos could have formed so recently, with no real record of previous volcanism. Are there pools of magma? Does Mars have a molten core? We have no idea, and won't for at least another decade... maybe much longer.
antoniseb, hi,
the answer, I think, goes back to the Viking lander, which did include a seismic probe that detected no activity.

On Earth, at any given time, any seismometer can detect 'background seismicity' (if you like, it's the terrestrial analog to the cosmic background radiation); it is usually filtered out because what most detectors are doing is registering 'first arrivals' of seismic waves due to earthquakes, eruptions, illegal nuclear detonations, etc.

The Viking seismometer was looking for 'background seismicity', evidence of ongoing geologic activity (deep rock movement, magma flow, echoes of geologically recent quakes or eruptions, etc), but detected nothing (except possibly its own landing echoes) - hence the belief that Mars has been geologically inactive for at least one million years.

Given the recent finding/assertion that Mars has been cold for about 4 billion years, some possibilities may be eliminated or seriously modified.

It may be that methane-producing microbes have indeed successfully adapted to the low pressures, and have formed colonies in water and carbon dioxide-rich ice reservoirs at, or beneath, the surface.

It may be that large, deep reservoirs of methane hydrates are trapped within Mars and the surface/atmospheric detections are from seeps resulting from the slow sublimation of said reservoirs.

Or, it may be that Nereid has got it right, and there is another mechanism which we have not considered, possibly not found on Earth because Earth is too hot, too dense, or too rich in free oxygen for such a mechanism.

I think high resolution seismic studies will be carried out in future Mars missions, much like the 'hammer' seismic studies we conduct here, to map the sub-surface layers and improve our understanding of the composition and evolution of Mars.

lswinford
2005-Aug-02, 03:39 PM
With all the impact craters there is some obvious shatter fractures. With the obvious volcanic activity there will also be some shifting and fracturing from the extrusion processes, as well as bubble caves. There are simply oodles of potential places for subsurface gasses to escape. But I'm thinking that if they were bio processes they would have other biochem compounds associating that would not be present in pure geochem processes. We need to see if these sources have some sort of halitosis or more substantial variance to their flatuance. What would be some associated signature compounds? Even in fermentation there are some seven-dozen intermediary chemical steps.

Nereid
2005-Aug-05, 10:42 PM
The Viking seismometer was looking for 'background seismicity', evidence of ongoing geologic activity (deep rock movement, magma flow, echoes of geologically recent quakes or eruptions, etc), but detected nothing (except possibly its own landing echoes) - hence the belief that Mars has been geologically inactive for at least one million years.
Actually, IIRC, the 'problem' was one of design, plus Martian winds.

The device was not sufficiently isolated from 'surface' sources, and while lots of 'activity' was detected, it was all 'wind'.

So, at least in my own (faulty) memory, the question of the level of seismic activity on Mars is still an almost totally open question (we can rule out recent, massive volcanic eruptions of the St Helens kind :P ).

Nereid
2005-Aug-05, 10:49 PM
Originally posted by lswinford@Aug 2 2005, 03:39 PM
With all the impact craters there is some obvious shatter fractures. With the obvious volcanic activity there will also be some shifting and fracturing from the extrusion processes, as well as bubble caves. There are simply oodles of potential places for subsurface gasses to escape. But I'm thinking that if they were bio processes they would have other biochem compounds associating that would not be present in pure geochem processes. We need to see if these sources have some sort of halitosis or more substantial variance to their flatuance. What would be some associated signature compounds? Even in fermentation there are some seven-dozen intermediary chemical steps.
Right on! B) :D

For now - and maybe the next decade or two - we simply have no way to determine the local (Martian) abundance of more complex carbon compounds in the atmosphere - either no one is looking, or the sigs would be too faint (by several OOM) to detect.

If I may make a (very) crude analogy: it's like being near a sewerage outlet, and being limited to detecting merely that there are carbon compounds (details unspecified), while tonnes of odiferous mercaptans waft by ... [yuck!]

cran
2005-Aug-06, 03:15 AM
I think you might be right about Viking, Nereid - it does ring vague bells; my mental library archives are as messy as my computer and hardcopy ones :o
It remains, though, that Viking did include a seismometer, and that the signals did not include anything that could be confidently ascribed to internal seismic activity - that's not to say it wasn't there, it may have been hidden in the 'noise'.
As with seismics, fine-tuning chemical signals (spectra?) is likely to be an ongoing process, but eventually we may be able to differentiate all of the alkanes, -enes, -anols etc...carbon compounds, nitrogen compounds, sulfur compounds, etc - from a limited sampling of atmosphere or soil - or even from light emission/absorption signals...you know, pick a target (set up all of your instruments around the target) and drop a big rock on it from a great height (after carefully analysing the chemistry of the rock) - then sample what gets thrown up (as well as the vibes that get thrown down)...then again, maybe not - I wouldn't want to be the one who has to write the eulogy for the once thriving microbial community that we just wiped out...:(

Just back to Viking for minute, do you recall the 'yes!' :D / 'no!' :( / 'maybe' :blink: results from the soil test for signs of life?

Jakenorrish
2005-Aug-08, 10:35 AM
QUOTE
From what has already been confirmed by NASA, I'd say the most probable thing is the first possibility... Life is responsible for the methane on mars.


And if I were a 'betting person', I'd bet that the most probable thing is vulcanism.



I still don't understand why people are singling out one of the three probabilities as being the cause for the Methane. If I were a betting person, then I would put my money on more than one of the three processes being responsible. After all Methane is produced on Earth by more than one process, so the probability seems that the same thing would happen on Mars, only to a much lesser degree, as its a smaller colder planet.

cran
2005-Aug-08, 10:51 AM
A hit! A very palpable hit!!
Well, done, Sir Jake!
My money&#39;s on that outcome... :D ...at shortish odds <_<