...analysis of the Martian atmosphere that raises the possibility of life or geologic activity...

exoscientist · Jan 25, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>They were aware of it, see my quotes at the top of this page. They did proper background research as would be expected for submission to a peer reviewed journal. Posted by MeteorWayne</DIV>  The points cited above were for photochemical destruction of methane not for its production.     Bob Clark   <div class="Discussion_UserSignature"> </div>

centsworth_II · Jan 26, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'> The points cited above were for photochemical destruction of methane not for its production. Posted by exoscientist</DIV>Quickly looking through the text of the paper linked by jonclarke, I don't see any reference to photochemical production of methane.  Just many references to "plumes" and speculation on  biochemical vs geochemical production.  However, on page S7 of the "Supporting On-line Material" section, there is a much more detailed discussion of possible scenarios for the appearance of methane in the observed areas on Mars.  Here are my (possibly erroneous) interpretations of the points they make in discussing each of four models:Model 1:  A simplistic, unrealistic model which assumes a point source and no atmospheric mixing.  Very slow spread of methane in this scenario is not supported by observations.  Model 2:  Also does not account for atmospheric mixing, but many closely spaced release points allow for quick filling of a large zone with methane.  They parenthetically remark that a "continuous zone of release" could replace the multiple release points.  This would be the model for photochemical production and the data do not discount it. Model 3:  Release of methane from a central point and rapid spreading through atmospheric mixing.  This is the model the authors think best fits their data.Model 4: Seasonal flow of methane from the polar ice cap to lower latitudes.  So far methane has not been detected at higher latitudes along what would be the route of such flows.The authors like model 3, but state that their data do not eliminate from consideration model 2, which would include photochemical production. They do not specifically mention photochemical production of methane however as far as I could see. Below is a copy of their discussion, edited for readability.  I have highlighted in red the part which would pertain to photochemical production of methane:SOM-5:(Model 1) The presence of a well-defined peak in mixing ratio with latitude... coupled with (approximately equal) concentration gradients towards the North and South caused us to consider (first) steady release from a central source with radial expansion driven by the observed concentration gradients. A simple model demonstrated that the time scale for filling the plume by Fick's diffusion is very long (~10,000,000 years); persistence of the plume over this long interval is required but is not supported by our observations. (Model 2) We next considered release from multiple individual release zones distributed over a large region, with Fickian diffusion filling the gaps between local 'hot-spots'. The diffusion radius around a local 'hot-spot' develops... so a source region with 'hot-spots' separated by a modal spacing of 5 cm would fill rapidly after seasonal turn-on and the profile would appear relatively 'smooth' after 3 months. However, such small-scale structure could never be discerned at our spatial resolution. While Model 2 is not eliminated by our data, strong local radients in the density of 'hot spots' (or a continuous zone of release) are needed to produce the observed plume properties.(Model 3) We then considered release from a central source region coupled with eddy diffusion that is often invoked to explain rapid mixing over large spatial scales. Efficient (vertical) eddy diffusion is needed to mix methane rapidly in the first few scale heights above the surface, but (much more efficient) horizontal eddy mixing is needed to effect the large meridional and zonal size of the plume. Estimated values for the vertical eddy coefficient range widely....(Model 4) We also considered release from a polar ice that is seasonally stable (winter) but becomes unstable in early spring, releasing CH4 and H2O . Seasonal streaming of CO2 and eddy diffusion are required to explain rapid transport of water vapor from the seasonal polar cap to mid-latitude regions. Entrainment of CH4 in the  O2-H2O stream could explain a rapid dissemination of released methane and perhaps produce a mixing ratio profile whose peak moves southward as the season advances into mid- and then late summer. The northward gradient that develops by late summer could then reflect decreasing release from the seasonal polar cap. However, the longitudinal gradients seen in our data may require corresponding longitudinal enhancements of methane sourced at high latitudes. <div class="Discussion_UserSignature"> </div>

exoscientist · Jan 27, 2009

Thanks for the response Centsworth. So it's still possible the authors are not aware of photochemical production, though they are aware of photochemical destruction.    Bob Clark <div class="Discussion_UserSignature"> </div>

MeteorWayne · Jan 27, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'> Thanks for the response Centsworth. So it's still possible the authors are not aware of photochemical production, though they are aware of photochemical destruction.    Bob Clark Posted by exoscientist</DIV> Bob, do you have any references describing photochemical production, or have you already posted them and I missed them? <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

centsworth_II · Jan 27, 2009

In a recent unmannedspaceflight.com thread, silylene discusses the photochemical production of methane: http://www.unmannedspaceflight.com/index.php?s=&showtopic=5749&view=findpost&p=134191In that post he also links to an older thread where he gives some references: http://www.unmannedspaceflight.com/index.php?showtopic=1671&hl=methaneI can not find any of the old SDC threads in which this topic was discussed. Just to make my position clear:  I am hopeful that Mars methane is the result of life.  Current life would be preferable over ancient life.  However,  I want the truth, not a fantasy.  I would like to see photochemical production as the source of the methane on Mars looked at seriously, and hopefully discounted on solid scientific grounds.  I do not want to see it ignored because it is not as exciting as the other possibilities.  <div class="Discussion_UserSignature"> </div>

silylene · Jan 27, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>  Silylene, it's possible the authors of the methan paper are unaware of the photochemical explanation. Have you written them about it?    Bob Clark  Posted by exoscientist</DIV> Sorry for not responding sooner.  I don't have much access to this forum anymore.I should write them.  They did not consider photoreductive catalyzed processes to produce methane, perhaps they are unaware.  Instead they only considered photochemical destruction.  They also considered the direct photochemical production of methane via the quite different from that later published by Bar-Nun mechanism (thank you Alex Blackwell for a copy of his paper from Icarus back then)...however the Bar-Nun mechanism is ridiculous, since it requires very high energy photons (ca 172 nm, IIRC), which would be absorbed by the atmospehere before they could do any photochemistry,There are at least a score of papers in the chemical journal literature on the photoreduction of CO2 with hydrogen (from H2O) to form methane over metal oxide or sulfide catalysts.  None of these papers considers the Martian atmosphere, instead they are about the interesting catalytical mechanisms. <div class="Discussion_UserSignature"> petet = silylenePlease, please give me my handle back ! </div>

exoscientist · Jan 28, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>Bob, do you have any references describing photochemical production, or have you already posted them and I missed them? Posted by MeteorWayne</DIV> As Centsworth, noted it was the theory presented by petet = silylene on this thread that I was referring to.    Bob Clark <div class="Discussion_UserSignature"> </div>

MeteorWayne · Jan 28, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'> As Centsworth, noted it was the theory presented by petet = silylene on this thread that I was referring to.    Bob Clark Posted by exoscientist</DIV> I'd appreciate a link directly to it somewhere. I'm currently writing my monthly meteor notes and don't have a lot of spare time to go searching at the moment.... <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

exoscientist · Jan 28, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>I'd appreciate a link directly to it somewhere. I'm currently writing my monthly meteor notes and don't have a lot of spare time to go searching at the moment.... Posted by MeteorWayne</DIV>   petet = silylene , mentioned some references but I don't remember the citation info. You can write him to found out.       Bob Clark <div class="Discussion_UserSignature"> </div>

MeteorWayne · Jan 28, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>   petet = silylene , mentioned some references but I don't remember the citation info. You can write him to found out.       Bob Clark Posted by exoscientist</DIV> OK, I'll do that, Thanx. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

silylene · Jan 28, 2009

Replying to: <DIV CLASS='Discussion_PostQuote'>OK, I'll do that, Thanx. Posted by MeteorWayne</DIV> Wayne, Below are a few of the score(s?) of photochemistry papers on the photoreduction of CO2 with water with shorter wavelength light (250 nm - 450 nm). Light of these ultraviolet wavelengths should reach the martian surface in significant doses. There are at least 20 journal papers on the subject of photoreduction of CO2 to produce methane, of course none of these papers having anything to do with Mars.  They are all lab demonstrations in glassware: +++++++++ Photoreduction of Carbon Dioxide by Aqueous Ferrous Ion. An Alternative to the Strongly Reducing Atmosphere for the Chemical Origin of Life <li class="author">Zofia Borowska and David Mauzerall </li><li class="sourceInfo"><cite>Proceedings of the National Academy of Sciences of the United States of America</cite>, Vol. 85, No. 18 (Sep. 15, 1988), pp. 6577-6580   (article consists of 4 pages) </li><li class="sourceInfo">http://www.jstor.org/pss/32422</li>+++++++++++ Photoreduction of carbon dioxide and water into formaldehyde and methanol on semiconductor materials. Aurian-Blajeni, B.; Halmann, M.; Manassen, J. Weizmann Inst. Sci., Rehovot, Israel. Solar Energy (1980), 25(2), 165-70. CODEN: SRENA4 ISSN: 0038-092X. Journal written in English. CAN 94:124490 AN 1981:124490 CAPLUS Abstract Heterogeneous photoassisted redn. of aq. CO2 to produce MeOH [67-56-1], HCHO [50-00-0], and CH4 [74-82-8] was achieved by using semiconductor powders with either high-pressure Hg lamps or sunlight. The reaction was carried out either as a gas-solid process, by passing CO2 and H2O vapor over illuminated semiconductor surfaces or as a liq.-solid reaction, by illuminating aq. suspensions of semiconductor powders through which CO2 was bubbled. Best results, under illumination by Hg lamps, were obtained with aq. suspensions of SrTiO3, WO3, and TiO2, resulting in absorbed energy conversion efficiencies of 6, 5.9, and 1.2%, resp. +++++++ Titre du document / Document title Photocatalytic production of methane and hydrogen through reduction of carbon dioxide with water using titania pellets Auteur(s) / Author(s) SENG SING TAN (1) ; ZOU Linda (2) ; HU Eric (1) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s) (1) School of Engineering and Technology, Deakin University, AUSTRALIE (2) Institute of Sustainability and Innovation, Victoria University, AUSTRALIE Résumé / Abstract This paper presents an experimental study on employing a pellet form of catalyst in photo-reduction of carbon dioxide with water. Water was first absorbed into titania pellets. Highly purified carbon dioxide gas was then discharged into a reactor containing the wet pellets, which were then illuminated continuously for 65 hours using UVC lamps. Analysing the products accumulated in the reactor confirmed that methane and hydrogen were produced through photo-reduction of carbon dioxide with water. No other hydrocarbons were detected. Increasing the temperature in the reactor has showed little change on the amount of methane produced. ++++++++++++++<div class="disp_elm_title">Title:</div><div class="disp_elm_text">Photochemical method for converting carbon dioxide gas to organic substances </div><div class="disp_doc2"><div class="disp_elm_title">Document Type and Number:</div><div class="disp_elm_text">United States Patent 5482599 </div></div> <div class="disp_doc2"><div class="disp_elm_title">Abstract:</div><div class="disp_elm_text">Fine particles of ZnO are subjected to heat treatment at 400° C. for four hours under vacuum to activate the surfaces thereof, the activated ZnO particles are brought into contact with saturated water vapor, and then subjected to irradiation by visible light under an atmosphere of CO2 gas or CO2 /H2 O mixture gas at 5° C. and 33 atm, that is, under the clathrate hydrate phase forming conditions. </div><div class="disp_elm_text">+++++++++++</div><div class="disp_elm_text">Photoreduction of CO2 Using Metal Complexes</div><div class="disp_elm_text">http://www.osti.gov/bridge/servlets/purl/211478-PvdBPv/webviewable/211478.PDF</div><div class="disp_elm_text">+++++++++</div><div class="disp_elm_text">Photocatalytic reduction of carbon dioxide using sol- -gel derived ...  <a id="XPLSS_564682627" href=""><img src="linkscanner://safe.gif/" border="0" alt="" width="20" height="20" /></a> <div class="s">At the same time, carbon monoxide, methane, formaldehyde and methanol were generated, ... The influence of various catalysts on the photoreduction of CO2. ...</div><div class="s">++++++++++</div><div class="s"><div style="text-align:center"><h1>COMPUTATIONAL AND EXPERIMENTAL STUDIES OF CO2 PHOTOREDUCTION ON TITANIA</h1></div>Find my updated research statement here A recent presentation from Spring 2008 ACS National Meeting: Quantum chemical calculations of the photoreduction of CO2 on defective and stoichiometric TiO2 surfaces My talk from ICCDU-IX is here My research focuses on the conversion of carbon dioxide (CO2) to useful organic compounds like methane using light energy and water. It has become evident in recent times that economic means of CO2 (i.e. carbon) management and alternate energy sources are required by our society in order to maintain a high standard of living without detrimental consequences to the environment. Solar photoconversion of CO2 to produce fuels has the potential to not only be a mechanism to store intermittent solar energy but also recycle CO2 while decreasing the use of fossil fuels.  The science of CO2 activation at metal oxide surfaces also has implications for future human space exploration and the abiotic origins of life. My research comprises of computational and experimental components. The computational studies aim at understanding the intermediates and energetics of various reactions involved in the photoconversion of CO2 in greater detail. Knowledge of these intermediate steps will enable us to design materials that catalyze this photoconversion process. The experimental studies aim at synthesis, characterization and testing of rare earth doped titania catalysts. These catalysts have been shown to perform well in other photoreactions. Our modeling results have shown that carbonate radicals can form at titania TiO2 surfaces during the course of the photoreaction. This is the first computational study that has identified carbonate radicals on irradiated titania surfaces. Our preliminary photoconversion experiments have shown that lanthanum doped TiO2 converts CO2 to methane (CH4) under UV-B radiation.www.personal.psu.edu/vxi103/CO2%20Photoreduction%20Schematic_2_smaller.PNG" alt="Schematic_CO2 Photoreduction" title="Schematic_CO2 Photoreduction" hspace="10" vspace="5" /> The processes involved in CO2 photoreduction are as shown in the figure to the left.:  A semiconductor like TiO2, under band gap irradiation, produces electron hole pairs. A majority of these charge carriers recombine on a very fast time scale. The remainder can be utilized to do useful work, in this case, the conversion of  light energy into chemical energy. The holes can react with water, oxidizing it and producing oxygen. The electrons react with CO2 producing CH4 in a series of reactions. Our computational and experimental studies aim at understanding the various reactions that happen during CO2 photoconversion to CH4.</div></div></div> <div class="Discussion_UserSignature"> petet = silylenePlease, please give me my handle back ! </div>

MeteorWayne · Jan 29, 2009

Thanx, appreciate the reading material!! <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

exoscientist · Jan 29, 2009

Thanks for the those refs. Certainly they should be investigated for the cause of the Martian methane. In that last ref it is very interesting that this is being investigated both as a solution to global warming by eliminating CO2 and as another method for producing fuel,  methane and hydrogen.   Bob Clark <div class="Discussion_UserSignature"> </div>

rlb2 · Feb 6, 2009

I think that several different scenarios besides biological and geological activity such as photochemical can cause the abundance of methane in the Martian atmosphere as mentioned and as far as I can see they haven’t been completely factored out.  I don’t know if this was ever mentioned after the discovery of methane in Mars Atmosphere. Although I personally favor a life connection like so many other people do however my favorite alternative to the other three is the one where a solar storm from a solar flare releases huge amounts of atomic hydrogen striking the Martian CO2 thin atmosphere the resultant collision of the atomic hydrogen with the CO2 splits the carbon atom from the oxygen atom with the free Carbon atom combining with 4 free atomic hydrogen molecules forming CHv4 – methane.  If the Solar Storm hypothesis is going to tread water, my personal concoction, which I haven’t read anything that suggests this was postulated by any other source then it could be traced to solar flare activity and would be less of a Martian seasonal event easily traced to a solar seasonable event, high solar activity, 11 year solar flare cycle.Here is a recent solar event mentioned in Life Science on December 16 2008 of such a flare:A surprising solar flare sent a stream of pure hydrogen at Earth. "We've detected a stream of perfectly intact hydrogen atoms shooting out of an X-class solar flare,""It was a burst of hydrogen atoms," Mewaldt said. "No other elements were present, not even helium (the sun's second-most abundant atomic species). Pure hydrogen streamed past the spacecraft for a full 90 minutes."<span style="color

urple">http://www.livescience.com/space/081216-st-solar-flare-surprise.html Note I mentioned this several years ago but didn’t have the above added source to help explain my madness to support that thought.Another effect of the release of pure hydrogen from solar flare activity on Earth and all other colder worlds could be the deposit of H2O, where the pure hydrogen collision or other smaller particles in the solar flare splits two free Oxygen atoms from O2 gas or CO2 gas and combines to form H2O.Remember there are other ionized or neutral particles that can travel close to relativistic speeds at times projected out from the surface of the sun so the resultant collision has much more energy than is needed to split the gas molecules apart. Its been known for some times that even high energy UV's can split O2 molecules apart producing two single Oxygen atoms which combines with another O2 to form O3 which help form the upper layer of earths ozone O3. However UV's don't have enough energy to split O3 apart thus earth’s shield of O3 protects earth from the most harmful UV's. A solar flare on January 20, 2005 released the highest concentration of protons ever directly measured, taking only 15 minutes after observation to reach Earth, indicating a velocity of approximately one-third light speed.http://en.wikipedia.org/wiki/Solar_flare   <div class="Discussion_UserSignature"> Ron Bennett </div>

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