Methane (and thus life?) on Mars

Update: this was my first post about methane: for a fuller version of the story you might want to try this post written a week later

Dick Kerr of Science magazine, who's been writing planetary science a good bit longer than most of us in this game, has a remarkable story up on the Science Now site -- something potentially far more striking than the crossbedding announcement. The team on the Mars Express Planetary Fourier Spectrometer (PFS) has announced the discovery of what look like methane absorption lines in the Martian atmosphere at 3.3 microns. Kerr quotes the PFS principal investigator, Vittorio Formisano saying it's "A very little amount," -- 10.5 parts per billion -- "but the result is clear." If this is indeed methane, then it's evidence that something is going on: either volcanic activity or life.

Methane is not a stable molecule in the Martian atmosphere. Left in the sun it will fairly quickly react with hydroxyl ions in the atmosphere; estimates suggest that it has an atmospheric lifetime of a few hundred years. And while some chemicals can be made in one part of the atmosphere and used up in other parts, methane isn't one of them, at least not to any appreciable degree. So if there is an even moderately substantial level of methane in the Martian atmosphere, then something on or below the surface is putting it there. Kerr mentions two possibilities; volcanic activity or bacteria. Methane in the atmosphere suggests that one or other of these processes is going on now. (A third possibility comes from above, not below: the recent impact of a comet, since comets contain methane. But there doesn't seem to be any sign of the very fesh looking crater that would be associated with such an event in any of the datasets, and it seems unlikely that a comet small enough to be destroyed by Mars's thin atmosphere, and thus not leave a crater, would be big enough to leave a global methane signature for any length of time.)

On the earth, methane from rocks is for the most part methane that derives ultimately from life -- natural gas, and the like, formed from the bacterial decay of organic matter. There is apparently also, though, a very low level of methane from non-biological stuff, which I believe is thought to be methane left over from the planet's formation. (Some people think there are vast amounts of this primoridal methane, and there would be on Mars, too. But most don't, and I'm not going to get into that here.) The average outgassing flow of methane from the martian depths expected by most people would be a lot less than the flow from the deep earth, and it would not be able to put substantial amounts of methane into the atmosphere. But during active volcanism, or other geothermal activity, the flow would be higher. So that's a possible source.

If it's volcanoes or similar sources, though, we have to wonder where they actually are. Nothing that looks like an active volcano has been seen. And even if the activity were more subtle and less splashy -- the injection of lava below the surface somewhere, say -- it's hard to see how it would avoid giving off heat that TES on Mars Global Surveyor or Themis on Mars Odyssey would have picked up. A small and not very warm spot of geothermal energy might escape TES, which divides the surface up into fairly big parcels. But with a resolution of 100 metres in the infrared Themis should be able to pick up such things, and so far it hasn't, even though it's taken infrared data on large parts of the planet.

The other obvious possibility is life. On earth, almost all the methane in the atmosphere is produced by bacteria, specifically methanogenic archae. These are anaerobic organisms, which would suit them to Mars. Their metabolisms depend on making methane from carbon dioxide and hydrogen (the hydrogen itself sometimes a product of other bacterial life). These have long been seen as the most likely forms of life to be found on Mars.

It would be a jump to go from a single announcement of a single piece of evidence from a single instrument to assuming life on Mars. But there is not just one piece of evidence. As Bruce Moomaw pointed out in the comments to this post (which made some remarks about the role of methane and life early on in martian history), Michael Mumma of NASA's Goddard Space Flight Center presented a poster on methane on Mars at the American Astronomical Society's Division of Planetary Sciences (DPS) meeting last fall. The poster (abstract here) presented results from observations of the Martian atmosphere using two different telescopes, NASA's Infrared Telescope Facility in Hawaii and the international Gemini South observatory in Chile. These showed some evidence for methane absorbing infrared light in the 3.3 micron wavelength, which is what the PFS observations show, too. Mumma and his colleagues have since refined their analysis of the data from Gemini, and taken more data from IRTF. They have also taken data using the NIRSPEC spectrometer on on of the vast Keck telescopes, but not yet reported results from those observations, as far as I know.

In the DPS poster, Mumma and his colleagues note that in one set of observations the strongest methane signal seems to come from the equatorial regions of Mars where the GRS has shown surprising amounts of hydrogen, and thus possibly water, in the surface. That fits the possibility of life quite nicely.

In his piece on Science Now, Dick Kerr quotes Mumma as saying that the PFS result "bears additional confirmation" -- which I assume the work he currently has in hand might provide. (That's if the PFS data don't come to be seen as confirming the initial observations he and his colleagues have already reported). In an email to me earlier this month, Mumma pointed out some of the difficulties of observing at these wavelengths when, as is the case for PFS, you have a relatively poor ability to make fine distinctions between wavelengths; ozone, water vapour and carbon dioxide can all complicate your results. The big spectrometers on earthly telescopes make such fine distinctions rather better. But he also said the PFS team was expert in dealing with these issues, and that he was "guardedly optimistic" they'd be able to measure methane were it there.

As Dick also mentions, there is another set of observations. Vladimir Krasnopolsky and his colleagues have been using the Fourier Transform Spectrometer at the Canada-France-Hawaii Telescope, and they too have detected evidence of methane on Mars. They'll be presenting it at the European Geophysical Union's meeting in Nice next month. Their results are right in line with the PFS measurement -- 11 parts per billion. In their abstract (pdf here) they argue that the best explanation for this is very sparse bacterial life on, or rather in, Mars. With three independent sets of observations, and with no evidence of current geothermal activity, that looks like the best explanation to me as well.

Nor need the life necessarily be quite that sparse. While some bacteria produce methane, others eat it up. If I were a martian ecosystem living in the shallow or deep subsurface, I would want to lose as little methane as I could, and so I would have layers of methane eaters above the methane producers, keeping the net flow to the atmosphere as low as possible. (Yes, that's an absurdly anthropomorphic way of putting it. So sue.) Earthly bacteria are very good at organising themselves this way.

Another possibility is that the methane output might be sporadic; the amount given off might change, for example, with the cycle of the Martian ice ages, or some other ongoing climate change. We might be seeing fallow-period methane levels. It's also possible that we are seeing methane that has been in storage for some time. This could conceivably be the methane from the martian equivalent of natural gas, laid down as biomass and stored in a deep geological formation for hundreds of millions of years ago. That seems unlikely, though -- you need a really productive biosystem to lay down vast fossil fuel reserves (probably one that photosythesises, too) and there's no evidence that anything like that could have been going on on Mars in the recent past. It would basically mean that there would have to have been an earthlike biosphere on Mars in the past 500 million years, and that just didn't happen.

A more plausible reservoir that might have stored up methane in the past would be the ice. Methane can be stored in water ice in the form of something called a clathrate. This is what happens to quite a lot of the methane produced by earthly bacteria -- there are methane-storing clathrates scattered all over the sea floors of the earth. These clathrates may be a potential source of trouble in a greenhouse world; they may also be a potential energy source. Martian ice might be a methane reservoir, storing it up under some circumstances, releasing it under others. So if methane production on Mars was spasmodic, methane stored in clathrates at the time when it's being made might be released from them more slowly later on.

That's probably enough speculaton for this first post. Except to note that even if the methane is coming from a gethermal source and not from bacteria, that itself would be big news. And it would have implications, too. If there's geothermal energy being pumped into a Martian crust which we now know to contain a lot of water ice, then that means there is almost certainly some liquid water down below. So even if the methane is not evidence of bacteria, it sort of has to be evidence of a wet and therefore habitable niche on Mars right now.

Comments

[Rupert Goodwins]

This is very exciting news, and if it truly turns out that the first positive sign of life on Mars is bug farts I shall be even happier.

However:

(A third possibility comes from above, not below: the recent impact of a comet, since comets contain methane. But there doesn't seem to be any sign of the very fesh looking crater that would be associated with such an event in any of the datasets, and it seems unlikely that a comet small enough to be destroyed by Mars's thin atmosphere, and thus not leave a crater, would be big enough to leave a global methane signature for any length of time.)

Don't we know that comets fall apart all the time, and that a considerable amount of the detritus is supposed to constantly impinge on Earth? I'm not sure what the status of Louis Frank's microcomet theory is these days, but it's at least plausible that a constant gentle rain of damp, methane-bearing chunks of recently deceased comet may be arriving in the Martian atmosphere at a rate capable of maintaining the levels these experiments seem to be reporting. That's if it is being maintained - I guess that the next priority is to find a way of monitoring it over time.

R

[Oliver Morton]

I'm faily sure that the Frank idea is a pretty busted flush these days. My impression is that we would see the rain of little comets if there were really that many. See the Crittenden article from the Boston Herald here http://abob.libs.uga.edu/bobk/ccc/cc052898.html. (From watching him for a decade or so now, my impression is that when Al Harris says you're wrong there's a very good chance that he's right)

[Michael Ray Taylor]

One of the things I find frustrating about Opportunity is that, so far, NASA has released only limited spectra--and that has been just to illustrate points of previous announcements. For all we know, MS and Mini-TES readings have also shown methane signatures (or other potential bio signatures) and the science team has been sitting on them while they argue possible scenarios.

[Bruce Moomaw]

(1) Frank is virtually universally regarded now as a crank -- there are multiple strong lines of evidence against him, and an alternative interpretation to his only actual piece of evidence.

(2) None of the MER spectrometers can provide us with any information on biosignatures. Mini-TES doesn't work in the spectral range of methane or other organic compounds (unless they exist in large amounts rather than traces); APXS can only measure element percentages (which tell us nothing); and Mossbauer can only analyze iron compounds (although it DOES have some possible ability to identify biologically formed magnetite if it exists in fair-sized quantities). This mission was specifically designed just to look for evidence of ancient aqueous environments capable of supporting life, NOT to look for actual evidence of life. And the rovers are doing that assigned task pretty well.

[Michael Ferguson]

"This mission was specifically designed just to look for evidence of ancient aqueous environments capable of supporting life, NOT to look for actual evidence of life." quote.

Wouldnt it be more timely and appropriate,given the evidence and the actual technological capabilaties of the current rovers and surveyers,to look for ACTUAL life on the surface of Mars? (microscopic imager anyone? )as well as ancient evidence despite the prelaunch "mission objective" of THIS mission! Or do we,as always,have to wait till the "next" mission to further our understanding of,to me at the very least,a planet that has teamed and may still team with LIFE!

[Luciano S. Mendez]

Methane on Mars is a good evidence that suggest the presence of life, but ¿have anyone noted the promising traces of oxygen? Oxigen is also mainly produced by living organisms, and Mars atmosphere contains from 0,13 to 0,25 % of free oxygen, a thousand times more than Venus and Jupiter (less than 0,0001% of O2) and only ten to thirty times less than the ancient living Earth (3 % of free oxygen, according to James Lovelock and others). Mars oxygen may come other from non biotic processes or from rudimentary life forms, or maybe from a combination of both.

So it will be very important to determine is if those non-biological processes can be responsible for the totality of such amount of free oxygen, which places Mars nearer a living planet than a dead one. Nobody seems to care about it! If you have something on this issue or any other comment please feel free to send me an e-mail.
Luciano S. Mendez - Argentina

[James Payne]

Seems to me the only way to get the answers to the question of life on Mars is to go find out. In person.
With rovers and landers, any results pointing to life will always be found to have other
explanations. Remember the Viking experiments.
So, the ONLY question that is left to be asked is, How bad do we want to know?

[MARTIGNONI MARITZA]

I M A VERY OPTIMISTIC GIRL.
NOW,THERE ARE REALLY MANY SIGNS OF LIFE ON MARS!
SCIENTISTS HAVE ALREADY DETECTED CHLOROPHYLL...
AND NOW METHANE!!!
I THINK THAT IT` S TIME TO ANNONCE TO THE WORLD
THAT MARS IS A LIVING PLANET!!!

[Tate McCall]

It sure is weird that NASA couldn't "detect" this methane Years ago using telescopes and such?? Hmmm....they already knew.
What's next....NASA: "Oops. We now have detected an abundance of breathable oxygen at lower atmospheric levels near the surface and poles of mars" NASA...And structures that aren't natural, but artificial.
NASA will milk this to their Death. I can promis you all this!!

[gary tippett]

why do we have to put up with nasa only telling us what we knew from viking,why cant they tell us the truth now,what have they really found this time.
we probably be told in 20 years time

[trippleblacktheysoldusthewholebloodydealdidnttheythewholebitinanumbrella]

Probly, NASA has knowledge about this matter since 1969.

http://elvis.rowan.edu/~klassen/papers/dissertation/chapter1.htm

Another interesting link concerning NASA "Foreknowledge"

http://www.mars-news.de/life/2001.html.en

NB:
Both links where found at http://www.mars-news.de

[Paul Robinette]

Why isn't this information on the nitely news? It seems to me that this is much more important than the price of gasoline, or if the Heintz corporation is funding Kerry's election campaign.

[Sam Patle]

I think the confirmation of Methane on Mars very exciting. However, any notion that this is something NASA should have known about years ago and has been covering it us is nonsense. For one thing, NASA (as well as many independent observers) have predicted based on Earth-based telescopic observations that Mars does indeed have Methane in the atmosphere (Michael Mumma, Vladimir Krasnopolosky. They even came up with the same number, 10.5 PPB, within error. These character attacks on NASA serve no purpose -- at heart, they really are just scientists (like me) doing what they love, and what they especially love is talking about their findings with other. There is a vast amount of data available publically, both on NASA's web pages, as well as many other space enthusiasts'.

As far as actually looking for life on Mars, well, that's what been happening all along. The idea that we always have to wait until "the next one" to learn more is always going to be the case. I would be very dissapointed if it wasn't. We learned a LOT through Viking. We are currently learning a LOT through Opportunity and Spirit. We will undoubtedly learn a lot through next mission. Some people will continue to keep feeling dissapointed because they firmly KNOW there is/was life on Mars and don't care about negative results. I can't help you there -- have you considered the possiblity that there is no smoking gun? Evidence for or against some hypothesis is a tricky thing. Methane is consistent with microbial life, but it is NOT evidence for it. Methane is also consistent with geothermal activity (note, you don't actually need live exploding volanoes to get methane, just an active core, like the Earth). Taking all the evidence into account, it seems that whether or not there was life once on Mars, it is highly unlikely that it continues to exist and produce Methane CURRENTLY.

[Rafael]

I think that if we all had better things to do we would have more money. Cmon people why are we lookin in mars when we dont have most of the answers regarding our own planet. It would be more exciting to look for life in Europa one of jupiters moons, mars is boring. Viva la raza

[RF]

Bushes on mars? Can't find many pictures left but there were alot more! "They look like bushes". Could they be part of the story?
http://photojournal.jpl.nasa.gov/catalog/PIA02300

[AMANDA]

UMMMM........U NEED PICTURES......OF ALIENS

[David Koch]

Regarding the comment about Orgainc Origins Observatory following up on Kepler detections and looking at the planetary atmosphere: I think if you put the numbers in you will find that the aperture required to get adequate SNR for spectroscopy of a terrestrial planet during transit is on the order of square kilometers, not something that can be done with something like OOO.

[Oliver Morton]

Hi David. It's your mission and I'll take your word on it; but I think Mumma's talking about surveying the atmospheres of hot jupiters, not terrestrials. And don't you get some S/N advantage from a) using occultation and b) knowing exactly when the signal will start and stop?

[maddiline]

this is really interesting and i tottaly agree on every thing that it is talking about!

[Erwann Quelvennec]

Thank you for your blog. A short comment about MerB pictures and Martian underground.
Opportunity is traveling, this sol,
along a crack or trough
in Meridiani planum, remembering me
I was amazed with MerB
sol 3 (1P128456784EFF0200P2216R2M1.JPG)
and sol 17 (1P128456784EFF0200P2216R2M1.JPG),
pictures, who seems to evidenced ground
lowering, features often associated
with karstic milieu on earth. I know there are
no evidence for limestone on mars, but are
karstic landforms an eventuality? Such a
question may be linked with life in the underground, isn't?

Best regards, Erwann Quelvennec

[Bruce Moomaw]

In direct connection with Erwann's note, there was an absolutely fascinating -- and still, to me, mysterious -- statment from Ray Arvidson at yesterday's press conference (which, alas, no one asked him to elaborate on). He said, with absoltue unqualified certainty, that the Anatolia trough definitely overlies a "fracture" in the underlying light-colored rock layer, and that something is definitely widening the trough RIGHT NOW at a rate faster than the rate at which wind-blown sand and sediment can fill it in -- so that sand and sediment are sliding down its slopes into its bottom as gravity-driven mass wasting, rather than just being blown in by the wind.

Now, what the hell could be "widening" the underlying fracture in the light-colored "etched" rock layer at this stage? Surely not seismic disturbances. Continuing underground erosion by a liquid, perhaps? Are we looking at a liquid-eroded cave roof falling in -- precisely as Erwann suggests?

[Erwann Quelvennec]

to specify my comment and add argument to Bruce response, I linked
some MER B pancam images who seems to show at least a lack of
underground cohesiveness, or maybe lead to speculate on void, or holes,
below the surface of Meridiani planum. I ask me if these pictures, taken before
the exit from Eagle crater, may be related to Anatolia
trough and dimples seen these last days by Opportunity.

Some images show, on the inner or outer side of te eagle crater outcrop,
some smooth dimples on the soil who seems to be imprints of light rocks,
coming down just a little below the surface, or alternatively,
flux of sand or dust below, around the edges of underlying rocks:
http://marsrovers.jpl.nasa.gov/gallery/all/1/p/003/1P128456784EFF0200P2216R2M1.JPG
http://marsrovers.jpl.nasa.gov/gallery/all/1/p/003/1P128457294EFF0200P2216R2M1.JPG
http://marsrovers.jpl.nasa.gov/gallery/all/1/p/003/1P128457914EFF0200P2216R2M1.JPG
http://marsrovers.jpl.nasa.gov/gallery/all/1/p/017/1P129702790EFF0338P2262R1M1.JPG
http://marsrovers.jpl.nasa.gov/gallery/all/1/p/020/1P129962030EFF0352P2267R1M1.JPG

Near Shoemaker patio, some outcrop rocks seems to rest a little under the soil level,
with sharp (recent?) edges between rock and soil:
http://marsrovers.jpl.nasa.gov/gallery/all/1/p/050/1P132627480EFF0602P2581R1M1.JPG
http://marsrovers.jpl.nasa.gov/gallery/all/1/p/050/1P132623031EFF0602P2575R1M1.JPG

Finally, on the northern end of the outcrop, some rocks appears stacked, and/or overhanging;
does it imply a lack of underlying material?:
http://marsrovers.jpl.nasa.gov/gallery/all/1/p/013/1P129340376EFF0300P2376R1M1.JPG
http://marsrovers.jpl.nasa.gov/gallery/all/1/p/013/1P129341714EFF0300P2376R1M1.JPG

[Ryven]

Have we forgotten about official NASA policy? Anything concerning extra-terrestrial findings that poses a possible risk to order among us Earth-bound peoples, must be kept from the public eye until security measures have been established, and it is of no risk. It's in writing, however in different words.

Mars has methane; we know that. Mars has H2O; we know that one too. Mars has O2; one more thing we know. Using our somewhat lacking amout of common sense, we can decipher that this evidence suggests the red planet used to have the same things. All of these things point to life, and all point to there having previously been life.

Now that we've established the high probability of past, and the slightly less high possibility of current life on Mars, we must ask ourselves why we recently sent twin probes to the area. We aren't looking for things we've already found, so what are we looking for?

Let's look over the equipment of the rovers. This is just from memory, so excuse me if I'm lying to you a some parts. Aside from all the high-tech cameras that can see super far, super well, and with depth perception, they are equipped with infrared and like scanners, drills (for digging and excavation; almost like archaeology, no?) and many tools for telling what something is made of. That's the basics.

This tells me that instead of looking for life on Mars, our government has decided to take a strategical take on possible atrifacts. What if Hannibal found a stockhold of RCP 90's? He may have won that war.

Things that are good in the long run are not always the best business ideas. For example, in the long run, smoking will be very detrimental. It makes a lot of money though. Fossil Fuel is bad for the atmosphere, but it is a very good money-maker. Good marketing decisions are decisions that cause people to keep coming back to you. If we found something on Mars that could put some business here out on their butts, I don't think those businesses would be too happy.

You have to remember, that people aren't always rational, and that only a fool looks for logic in the chambers of the human heart. Economy is the ruler of all.

[James Payne]

To all who believe NASA is made up of just a good bunch of truthful boys and hard working scientists who announce everything discovered on Mars right away, just a point or two:
First, since NASA uses American tax dollars to make its discoveries, WHY isn't a representative of the public allowed in the control room as the pictures from Mars come in. It use to be that way-----NOT anymore.

Lastly, if you look at the pictures taking by the current spacecraft orbiting Mars, most of them are crisp and sharp. Remember the picture of the "face"? When I looked at that picture in the local paper, I asked , Is this the best they could do? Then I realized it wasn"t the best they could do, but it was the best the public was going to get.

In conclusion, it is my belief NASA invites cover up theories and anyone that starts zeroing in on the truth is labeled a crackpot. The Brookings Report study on the result of disclosure of evidence of Alien life found in the Solar System is probably required reading for top NASA employees.
And the truthful scientists at NASA working on the Rover data, don't forget where their salary is coming from. Money dictates TRUTH.

[Bruce Moomaw]

James, are you talking about the original Viking Orbiter photo of the "face"? I saw that thing when it first came out in 1977, and I remember thinking, "Gee, that looks sort of vaguely like a face". I also remember thinking that (A) there was absolutely nothing surprising about this, because that hummock was one of literally hundreds nearby with eroded pits and grooves in every conceivable configuration; and (B) it looked a lot more like a face because, and only because, there were hundreds of dark specks on the overall picture thanks to dust specks on the camera's vidicon tube -- and one of them, by chance, was in exactly the right place to look like a nostril. Just blot that out, and it instantly looks far less like a face. (Take a look at the entire Viking picture some time, in which the face is only one of a whole swarm of surrounding hillocks.)

It's the new far clearer photos of that hill by MGS and Odyssey that make it abundantly clear that it is NOT a face. As for the Conspiracists' theory that NASA is deliberately covering up evidence of intelligent life on Mars: give me a break. Such a discovery would be the best news conceivable for NASA -- their funding problems would completely disappear for the next century.

And, of course, any large world is absolutely bound to have a few random combinations of totally natural features which -- by pure chance -- look to our feature-recognizing eyes like something unusual. It would be incredibly unlikely for Mars NOT to have a few such chance features. Besides the Face, we do have the 100-mile-wide "Happy Face" crater (alias Galle), not one but two small pairs of blended craters that look EXACTLY like Valentine hearts (there's another one on Eros!), one mesa that looks eerily like a bas-relief of Sen. Edward Kennedy (Teddy himself has commented on this), and a 100-mile-wide combined outflow channel and set of mesas that looks exactly like Kermit the Frog sitting on a branch and singing. For some strange reason, Richard Hoagland and company have never seized on any of these as additional evidence of intelligent Martians, although obviously that last one provides solid evidence not only that they existed but that they worshipped Muppets.