Talk:Life on Mars/Archive 2

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Archive 1

Archive 2

Archive 3

Archive 4

I think there should be something in this article about Abiogenesis. Mars is of especial interest for the study of the origins of life, especially since it had no continental drift, and has been pretty much unchanged since its formation. You often get the impression that a Mars without life is one of no scientific interest for the origins of life. Instead it would be of great interest.

I'd do just a short paragraph that can be expanded later, based on this section in the Manned Mission to Mars page:

.

I'm actually the author of that section and am exploring possibility of merging some of that material with the linked to articles on wikipedia, as it is over long where it is.

This is the section which I propose moving here (edited if necessary to fit this article):

There's also the tantalising possibility of much earlier types of life, or proto-life that might have survived since the early days of Mars in some niche area.

Since over two thirds of the Martian surface is more than 3.5 Gyr old, the possibility exists that Mars may hold the best record of the events that led to the origin of life, even though there may be no life there today.^[1]

The proto-life could include the extremely small

What does anyone think? If there are no comments I will just go ahead and add it after a few days as it seems clear that something needs to be said here about the value of Mars for studies of abiogenesis. Robert Walker (talk) 14:59, 6 May 2013 (UTC)

Hello. I think that the encased sentence if fine, especially if the reference is reliable. After all, that is what the mission is all about. But I would not venture into the living fossils, nanobe, and protobiont speculations. Cheers,

talk

) 14:43, 9 May 2013 (UTC)

Okay I'll add in the bit that you agree is okay. With the protobionts - well it's not really speculation as you get them even in laboratory experiments with a simulated early Earth, so it is just describing what you would probably expect to find, if there is any evidence of abiogensis. But the reader can figure that out for themselves so don't really need to say it explicitly. Perhaps I can find a quote or paper about them at some stage. The living fossils idea is something that has been published though I can't find the paper on it right now. Anyway they are both minor points and no problem at all leaving them out for now :) Robert Walker (talk) 22:27, 9 May 2013 (UTC)

Added the new section now, hope it is okay Robert Walker (talk) 22:33, 9 May 2013 (UTC)

I've moved most of the quotes to a full paragraph, but I also noticed that the statement, "The oldest planetary rock on Earth is one from Mars (ALH 84001, 4.5 Ga)." seems to contradict the Allan Hills 84001 page, which claims it is 4.091 gyr old. It's been flagged it with a contradict tag till someone can resolve this. Reatlas (talk) 02:31, 10 May 2013 (UTC)

Okay that's great, good summary! The reference is from 2006, and the reference for ALH 84001 is this paper: A Younger Age for ALH84001 and Its Geochemical Link to Shergottite Sources in Mars and science news story about it here Rock of ages: Clues about Mars evolution revealed - doesn't seem to be any debate or conflict about the result either that I can see, so I think consensus is that the newer date is best.Robert Walker (talk) 11:01, 10 May 2013 (UTC)

Why no mention in the article about the first IICI to Mars, the Soviet program Mars 1? JukoFF (talk) 10:00, 29 September 2012 (UTC)

Was that flyby attempt an astrobiological mission? Any way, radio contact was lost while enroute to Mars. Cheers,

talk

) 12:55, 29 September 2012 (UTC)

The first spacecraft sent to Mars in 1962 was a Soviet "Mars-1" apparatus analyzed space separating the planet, the data about the intensity of the cosmic radiation of the planet, study the flow of ionized gas coming from the Sun to Mars [2] were obtain information on the nature of the surface species and the surface elevation profile, the soil density, the thermal conductivity, thermal anomalies detected on the surface of Mars, it is established that its northern polar cap has a temperature of minus 110 ° C and that the water vapor content in the atmosphere of Mars in five thousand times less than on Earth. In 1971, the unit "Mars-2" is the first artificial object in the world. [3] Of any signs of life by the installation software was identified. ru-wiki/ JukoFF (talk) 16:28, 29 September 2012 (UTC)

Yes Mars 1 and Mars 2 were designed to study some aspects of Mars, and it is too bad they did none of it as they failed in cruise and launch, respectively. The probes had abolutely no impact in our knowledge of Mars' habitablility.

talk

) 17:56, 29 September 2012 (UTC)

You are wrong, but unfortunately my knowledge of English is not enough to complete this article on the contribution kosmichessskoy Russian mission to the topic of the article. JukoFF (talk) 15:57, 30 September 2012 (UTC)

That will save us the effort to delete your unsupported original research.

talk

) 18:22, 30 September 2012 (UTC)

That is, do you really think that the first sent to Mars spacecraft has received information about the planet did not bring anything to the question of life on Mars? JukoFF (talk) 18:18, 3 October 2012 (UTC)

The Mars 1 probe FAILED shortly after launch (1/3 the distance between Earth and our Moon). It did NOT study Mars - not even from the distance. So NO, it did NOT bring any information to the question of life on Mars.

talk

) 20:00, 3 October 2012 (UTC)

Formatting issue?

In chrome, on my 1920 x 1080 monitor, the text "By the mid-19th century, astronomers" overlays the image "Historical map of Mars from Giovanni Schiaparelli." It seems fine in IE. I haven't checked any other browsers. I don't really know how to edit this and don't have time to check how right now so I hope this is an appropriate place / way to highlight it for someone else to fix if deemed necessary. Thargtm (talk) 06:25, 21 January 2013 (UTC)

I've put this back in as: "For a detailed discussion of possible locations for water on Mars see Possibility of Mars having enough water to support life."

The problem is it is not obvious when reading the current page about life on Mars that there is an entire section specifically on the possibility of liquid water able to sustain life in the Water on Mars page. One possibility is simply to duplicate all of that section here, but that is overly repetitious, but I think it needs a closer link than just a mention of Water on Mars. I have added a new section which covers two of the most significant habitats discussed there and a link to the page for more detail. Any other suggestions welcome. I don't think though that just removing the link to the section (in a very long page so hard to find) is the solution. What does anyone else think?Robert Walker (talk) 10:41, 25 May 2013 (UTC)

Hello. I edited in - good faith - for these objectives:

• I placed your entry on water under the water section.
• Not necessary to write the researcher's hypothesis as a block quote. In science articles we use an inline reference.
• Specified that the research extrapolation is limited to terrestrial extremophiles; Antarctica is presented as an analog to Mars.
• Gave balance to the entry: lethal cosmic radiation makes that "habitat" unfriendly at several meters deep, even if liquid water was present periodically. The environment and life requirements (true habitability) go much further than the sole presence of water.

Cheers,

talk

) 14:19, 25 May 2013 (UTC)

Okay fine, removing the block quote is fine. However that research about cosmic radiation you refer to is only relevant for long time scales. The researchers talk about periods of hundreds of thousands of years. So, if you want to look for millions of years old dormant life on Mars you need to dig several meters below the surface. But for present day life, if reproducing in liquid water near the surface in first cm of soil, other research that shows that dormant states can easily survive for years in those conditions when protected by a few mm of soil (including the Expose E experiments on the ISS and several experiments in laboratories on Earth). Some can even survive for months or years on the surface just in shadow from the sun. Also other research shows that the soil is not especially biotoxic either (as some have claimed). I added one of the links to the research, and put habitable back into the title because the current research suggests it probably is habitable if the habitat exists. Hope that is okay now. I thought it was unbalanced the other way to say that the cosmic rays make it inhospitable without referring to the long timescales involved Robert Walker (talk) 19:32, 25 May 2013 (UTC)

That is OK. I will read the original papers with calm to review the time difference you mention. Looking good! Cheers,

talk

) 15:50, 26 May 2013 (UTC)

Reviewing apparent contradiction:

"only applies for DORMANT forms of life. Other studies show that a covering of a few mm of soil is enough to enable life to survive in DORMANT states for years"

talk

) 16:32, 26 May 2013 (UTC)

Sorry, but the cited references do not support your text as written, specifically microorganisms on water films undergoing a spore state daily, reproducing and surviving under cosmic radiation. Although the quoted researchers make their point on the water physics, your entry looks like

talk

) 17:23, 26 May 2013 (UTC)

I thought this was unambiguous enough: "We establish the physical conditions for the existence of saline aqueous solutions in the pores of the martian near surface substratum. We find that thin films of near subsurface liquid water on Mars at –20°C could provide a viable niche for terrestrial psychrophilic halophiles. Since some martian salts can suppress the freezing point of aqueous solutions with minimal suppression of the water activity, some martian liquid water environments with a water activity above 0.6 may also be able to support terrestrial life at temperatures as low as −30°C, 10°C lower than the limit of terrestrial life." Using the phase diagram of liquid water to search for life. Pretty clear from the abstract that by viable niche means reproducing or they would say "dormant life" though I sadly can't read the article itself because no longer affiliated to a university and it is behind a paywall. BTW terrestrial life has now been found able to survive at even lower temperatures -25C see Bacterium from Canadian High Arctic Offers Clues to Possible Life On Mars. Does this answer your question? I know what you mean about synthesis and I have to be careful about that. Sometimes I have personal conclusions I draw about some of this stuff which can't be included in wikipedia even though they are logical consequences of well established facts, I don't say them unless backed up by citation for that reason. So am careful about that, but it is an easy thing to miss :). Hopefully this is enough to back it up now, but if not do say and I'll research some more for whatever is needed Robert Walker (talk) 00:31, 27 May 2013 (UTC)

BTW didn't say that they form spores daily or anything specific about how they reproduce. Just that they survive somehow in those conditions and reproduce, which is what the paper implies. And reproducing of course means that the cosmic ray damage doesn't accumulate as it does in a dormant spore - that the ones that are damaged by it simply don't reproduce and the rest survive and reproduce to the next generation. It is after all synthesis the other way around to draw from that paper about life that stays in a dormant state for hundreds of thousands of years any conclusion about life reproducing in a habitat on Mars now which is a different situation not covered by the paper. Robert Walker (talk) 00:35, 27 May 2013 (UTC)

This is a more recent paper Present day liquid water on mars: theoretical expectations, obervational evidence and preferred locations. No-one is saying that any of these habitats definitely exist yet, but theoretically they could exist, and if they do exist, then they could allow life to reproduce. And if life reproduces even as rarely as every few years then the conclusion of that paper doesn't apply to it. Does that make sense? I know it is easy to go overboard either way, but there is increasing evidence for possible locations for life on Mars, so we need to reflect that without going so far as to say it is definitely there or even probably there (personally I think it is quite a high probability that there is life still there, because life on Earth is so resilient and Mars was similar to Earth in the early stages and life started off so soon on Earth, and if inhabiting such sparse habitats on the surface then we wouldn't expect the atmosphere to be out of balance, and surprising if there really is no liquid water at all forming even briefly on Mars on its surface when midday temperatures go well above OC in regions where there is ice just below the surface, and with salt for brine also available - that of course is a synthesis and can't go into the article :) ). Robert Walker (talk) 00:59, 27 May 2013 (UTC)

Hello Robert. First of all, I thank you for the objective discussion. Second: welcome to the clash between physicists and biologists (such as myself). When dealing with microbiology it is necessary to be familiar with the terminology. Viable does not mean living: When an organism is said to be 'alive', it means it is metabolizing, growing, adapting, and maybe even reproducing. The word 'viability implies the potential of the spore to germinate and thus, re-initiate life, e.g: metabolism, growth, reproduction, homeostasis, etc. When a bacterium is in the spore state is because its physical/chemical environment is hostile, and it is metabolically inactive or 'dormant'. If its environment was to change to favorable conditions, and IF its coding nucleic acids have not been cleaved by whatever reason (such as radiation), then it is said to be "viable", meaning that the spore has the POTENTIAL to germinate. Spores do NOT reproduce.

Now, here is where your paper may state a fringe extrapolation (the reason of my challenge: WP:Cherrypicking out of context): "Since some martian salts can suppress the freezing point of aqueous solutions with minimal suppression of the water activity, some martian liquid water environments with a water activity above 0.6 may also be able to support terrestrial life at temperatures as low as −30°C, 10°C lower than the limit of terrestrial life."

This quote is one example of [competent] physicists looking at only one parameter of a set of physico-chemical environmental requirements for one type of bacteria: halophile psychrophilic. Using this quote in Wikipedia ("support terrestrial life") is not accurate as they used it in the abstract in a very lose way (limited to only one type of bacteria: terrestrial halophile psychrophilic), and not as their conclusion. Yes, liquid water is a fundamental ingredient for life, but it is one of several required factors to support life. That physicist's team made a an excellent scientific assessment on the potential of liquid water films on the surface, but to say -and quote- that a particular "extraterrestrial environment may support bacterial life" (e.g. metabolizing and thriving), it requires to evaluate all the inert components of an ecosystem necessary for life:

• water  Done
• energy (sunlight or chemical energy)
• temperature (related)
• atmospheric pressure (related)
• gravity
• nutrients
• cosmic and Solar radiation protection

Your quoted papers make use of a model to estimate only the possible existence of surface films of liquid water, albeit transient, and non-stable. Extrapolating their research to hypothesize that they found niches that "support terrestrial life" is a very far stretch. They modeled one factor of many. Please know that I am not splitting hairs here, and I understand where you are coming from and I do not seek an edit war. I wish as much as NASA, ESA, JAXA or Roscosmos to find biosignatures on Mars, if not living microorganisms. But I am also a molecular biologist and a Wiki editor committed to building this and other astrobiology-related articles with the true meaning or main ideas of the quoted papers, and will challenge the use of

to support unjustified extrapolations of planetary habitability. Cheers,

talk

) 03:44, 27 May 2013 (UTC)

Hello, BatteryIncluded, Thanks, those are all good points. We need the article to accurately and objectively assess the situation. It is all qualified though in the quote just saying "could provide a viable niche for terrestrial psychrophilic halophiles" they don't say that the niche does exist on Mars or that terrestrial psychrophilic halophiles would be able to colonize it. Just that, on present knowledge, it is possible that the niche exists and it is possible that they could colonize it.

I agree that none of this has been proved. But the other point of view that life is not possible in these habitats also hasn't been proved, and the article shouldn't suggest that it has been proved to be impossible for the habitats to exist or for life to colonize them.

The best thing would be to find research that simulates these possible sub soil liquid brine environments on Mars, and sees if anything can grow in them on Earth, also long term experiments. Because that is another line of research that is going on at present, increasingly accurate simulation of Mars environment in the laboratory and in space and attempts to grow Earth life in those environments. Of course all that is assuming that Martian life resembles Earth life but is best can be done.

Anyway I'll do some more literature survey to see what I can find by way of more recent research. I have turned up a few more papers just now that might be of interest, I think they should be added as references.

I am not deliberately cherry picking. Where a paper shows two sides of the case then I reflect that in a summary, and when there are opposing points of view in other papers I include those too when I know about them. I have ignored some papers I found from several years ago that say things that are no longer supported by the recent research, especially if they say that life is almost instantly sterilized by the Martian UV which is now known to be untrue, or if they say that perchlorates are toxic for all life, again known to be untrue.

I am focusing on more recent research where possible because it is a field where it seems from the literature that ideas are changing rapidly and papers from just 4 years ago (say) are out of date. So if a paper of more than a few years ago says that life is not possible on the surface of Mars, if based on UV flux, then it can probably be discounted. Especially if it predates the Expose E experiments so a cut off of pre 2010. Also papers that assume that the soil on Mars is biotoxic, if not based on recent research, are out of date.

So, am focusing particularly on a literature search for the last couple of years. First just to confirm those earlier physics papers, Here is a paper from 2012 that surveys the water question again from Space Science, September 2012 Water and Brines on Mars: Current Evidence and Implications for MSL] It is particularly focused on the Curiosity landing site which is an unlikely location for brines because so close to the equator. But they survey other areas concluding polar regions as most likely and say

"There is no question that theoretically liquid brines can form at the surface and in the shallow and deep subsurface of Mars, even in the present climate. Indeed, liquid brines can form by deliquescence at the surface and in the shallow subsurface (≤1 m). At the shallow subsurface it can also form by direct contact of salts with physisorbed water and melt water. In the deep subsurface (≥100 m) it can form by direct contact of salts with aquifers."

Here is a habitability assessment for the Phoenix landing site published February of this year: Assessing Habitability: Lessons from the Phoenix Mission

"During high obliquity periods, temperatures allowing metabolism extend nearly a meter into the subsurface. Phoenix discovered ~1%w/w perchlorate salt in the soil, a chemical energy source utilized by a wide range of microbes. Nutrient sources including C, H, N, O, P and S compounds are supplied by known atmospheric sources or global dust. Environmental conditions are within growth tolerance for terrestrial microbes. Summer daytime temperatures are sufficient for metabolic activity, the pH is 7.8 and is well buffered and the projected water activity of a wet soil will allow growth. In summary, martian permafrost in the north polar region is a viable location for modern life. Stoker et al. presented a formalism for comparing the habitability of various regions visited to date on Mars that involved computing a habitability probability, defined as the product of probabilities for the presence of liquid water (P(wsub l)), energy (P(sub e)), nutrients (P(sub ch)), and a benign environment (P(sub b)). Using this formalism, they argued that the Phoenix site was the most habitable of any site visited to date by landed missions and warranted a follow up mission to search for modern evidence of life."

That seems to answer most of your habitability questions for the brine habitats (if they do exist). BTW there is a bit of confusion sometimes as there is another phenomenon, monolayers of liquid water just one molecule thick that may occur on Mars. Those seem unlikely to be a habitat for life, or at any rate very challenging. But these are not monolayers.

This is another one, this time it's about advancing sand dunes, a new habitat I haven't seen mentioned before: HABITABILITY OF TRANGRESSING MARS DUNES

"Advancing martian dunes mix oxidants, reductants, water, nutrients, and possibly organic

carbon in what could be considered bioreactors. Thus, martian dunes function as small scale analogues of the global geological cycles that are important in maintaining Earth's habitabiliy. On Mars, carbon can be cycled from the surface of the dune to its subsurface where it may come in contact with moisture and oxidants. Compounds oxidized at the surface of dunes by UV radiation and oxygen are buried on the lee side of dunes and mixed with reductants, carbon, and ephemeral brines. In addition, reduced compounds will be exposed at the surface on the windward side of dunes where they can be oxidized and complete the cycle. Other global cycles on Mars are likely to be driven by rising and sinking fluids in the subsurface [11]; however, transgressing dunes are a recyclable potential habitat readily accessible by the Mars Science Laboratory. Additional measurements by MSL such as detecting organic carbon and reduced nitrogen compounds would support the hypothesis that moving dunes are potential microbial habitats. The absence of these compounds would

indicate that the today's dunes are unlikely to be habitable."

The general trend over the last four years is towards more and more papers suggesting potential for habitability on the surface of Mars, and I haven't seen any recent papers, since, say, 2010, after the Expose E experiments, saying that habitability on the surface is impossible. So wikipedia should reflect that, I suggest. Or, can you find any recent papers supporting your view that habitability of the surface is unlikely?

I'll continue to research into the literature, and see if I can find good papers by microbiologists and especially, any that have researched into it using Mars analog soil and Mars simulation chambers etc. It seems an experiment one could surely do, to simulate the formation of these brine layers on Earth, and see if anything can grow in them.

Oh since you gave your background, I'll share mine too. I'm a mathematician by training. Later did research in philosophy and logical foundations of mathematics. Am now a programmer of (mainly) music software. But I have a long term keen interest in this, and also general interest in related areas, and learnt to do literature surveys for my own maths research.

Do please keep me "on track" if I have misunderstood anything. But I have learnt not to accept points of view unless based on recent research, especially in this area, so you need to back up what you say by references to the literature too, many people even very knowledgeable microbiologists, can easily not be aware of all the recent research in such a rapidly changing field and specialists researching into the field have been proven wrong in their views as well. Cheers, Robert Walker (talk) 10:35, 27 May 2013 (UTC)

This is a recent paper that studies brines formed in similar conditions in Antarctica, obviously not exactly the same but relevant: Don Juan Pond, Antarctica: Near-surface CaCl2-brine feeding Earth's most saline lake and implications for Mars]

"Don Juan Pond (DJP), found at the lowest point in the South Fork of Upper Wright Valley, Antarctica (Figure 1a), is the most saline natural body of water in the world1. As a consequence, it rarely freezes, even when the surface temperature descends to −50°C during Austral winter and it is a unique site for the study of habitability in extreme environments on Earth, and potentially for life on Mars

"While the volumes of freshwater available to these hydrologic systems on Mars is unknown, recent work in the Atacama desert has provided in-situ documentation of cyanobacteria that are capable of subsisting entirely on the brines created from deliquescence in halite rocks34, a very localized ecological model that has been proposed for Mars in the past35. Furthermore, work in the MDV has shown that certain organisms are capable of being preserved in a cryptobiotic state for decades, then flourish once exposed to stream waters36. Thus, if RSL and chloride-bearing basin floor units on Mars do represent DJP-like hydrologic systems, they may have significant potential for hosting resilient microbiota, and the most habitable places on Mars may mimic the least habitable places on Earth."

Here are a few more sources. So far I haven't found a single paper in the last two years (am just doing a literature survey for 2012-2013) that takes the point of view that there are probably no habitats suitable for life on the Mars surface. Most suggest the circumpolar regions as most likely to be habitable, especially at low elevations. The Astrobiological Potential of Polar Dunes on Mars

Analysis of seasonally frost-covered Martian dunes and terrestrial extremophiles in cryptobiotic crust revealed that circumpolar dark dunes on Mars form an ideal habitat for hypothetic photosynthesizing organisms on the planet. In springtime, the dark basaltic dunes show ephemeral seepage-like features on their surface, which (based on theoretical calculations) may be the result of interfacial water or bulk brine-related movement. Such a thin water film may also decompose the aggressive oxidants there. Temperature values in spring around noon could be favorable for metabolism of known extremophiles on Earth. During this warming period, the water loss could be reduced by densely packed grain structure of the soil, hygroscopic salts, and the embedding polysaccharide-like materials, as it was observed in the samples of cryptobiotic crust from hot and cold deserts on Earth. The best periods for H2O uptake are the nighttime hours.

Terrestrial cyanobacteria living 2–4 mm below the rock surface in the so-called cryptobiotic crust demonstrate possible analogous strategies for survival in the Martian environment. On Mars, even a thin grain layer coverage decreases water loss rate and screens UV radiation. The organisms we collected in hot and cold deserts on Earth showed examples for survival strategies like seasonal movement, task sharing in UV screening, and a special method called optical fiber strategy (whereby organisms conduct light to the deeper subsurface). The terrestrial observation of recovery of cyanobacteria in minutes after wetting also supports the supposed long dormant-short active life cycle of hypothetical organisms on Mars.

The circumpolar region on Mars has been found to be one of the best possible habitats today, because water ice and springtime-elevated temperature are both present there. These dark dunes are less oxidized than the average Martian surface, and their grain structure enhances the trapping of volatiles, while their dark color helps the fast warming in daytime.

This is also relevant: Hygroscopic Salts and the Potential for Life on Mars]

The deliquescence of sodium chloride results in transient solutions with aw compatible with growth of terrestrial microorganisms down to 252 K, whereas for calcium chloride and magnesium chloride it results in solutions with aw below the known limits for growth at all temperatures. However, taking the limits of aw used to define special regions on Mars, the deliquescence of calcium chloride deposits would allow for the propagation of terrestrial microorganisms at temperatures between 265 and 253 K, and for metabolic activity (no growth) at temperatures between 253 and 233 

Also this 2012 thesis looks at alkalitolerant strains that are found in soda lakes on Earth and are also common in clean rooms. Raises concern that spacecraft to Mars could transfer these to habitable environments on Mars and so contaminate the planet/ An astrobiological study of an alkaline-saline hydrothermal environment, relevant to understanding the habitability of Mars see 8.5. Relevance of alkaline/saline analogue studies to the contamination of Mars abstarct here

The culture based study of the

Phoenix spacecraft clean-room demonstrated that alkalitolerant strains (such as Bacillus pumilus and Oceanobacillus iheyensis) were present and were not a minor part of the cultured community, being frequently detected (Ghosh et al., 2010). This indicates that these alkalitolerant organisms have survived the sterilisation procedure applied, and there is no reason why the strains could not also be present on the space craft itself. If this is the case, and the organisms were shielded during the flight to Mars, then theoretically they could be transferred to the surface/subsurface of the planet. This would have implications for the discovery of life on Mars.

These organisms would not necessarily be strictly defined as extremophiles, but are tolerant of extreme conditions such as pH. Together with the fact that alkalitolerant isolates from Lake Magadi could survive desiccation, oxidative atmosphere and low temperatures, as long as they are provided with some protection from UV-C irradiation (and ionizing radiation), makes the potential contamination of Mars with alkalitolerant organisms a real consideration. The additional tolerance of these organisms to high salinity and temperatures makes them

resistant to a wider range of environmental stresses.

This looks like an interesting recent survey paper (2013), but unfortunately can only find an abstract for it: Metabolic Activity of microorganisms during and after simulated Mars-like conditions – what do we learn about the habitability of the Red Planet?. It is from a conference from February of this year, I wonder if that just means it hasn't been published yet?

What do you make of this research? And do you know of any recent critical or skeptical papers concerning all this recent research on the potential for surface habitability on Mars? If there isn't any then I'm not sure that skepticism is appropriate in the entry here, as being probably out of date, could be done as historically skeptical that "it used to be thought that such environments couldn't exist", for present day summary of views from the papers I've read, "unproven but possible" might be more appropriate. Robert Walker (talk) 12:15, 27 May 2013 (UTC)

Hello again. It seems we are in agreement in that scientists are rapidly producing models and hypothesis on Mars habitability, so we need to keep updating the article with mainstream ideas, as supposed as fringe hypotheses. My point is that as long as we remark in no uncertain terms the observations vs. the hypotheses, we may include them. I take great effort to not mislead the reader in believing that current habitability is proven. My greatest grief in the [wiki] astrobiology-related articles has been correcting (or placing in context) entries that bypass the actual observations & conclusions reported in the literature and unrealistically focusing in the [extreme] hypothetical or possible implications/extrapolations mentioned in the Discussion section of the research papers.

From the perspective of planetary protection, yes, it is important to realize that non-sterile probes can seed terrestrial extremophiles on Mars. That is the value of it, not the wishful thinking (or misrepresentation of the data) of the imminent discovery of Martian microbes at the surface.

Wikipedia aside, as scientists, you and me MUST remain skeptical. Let the observations and knowledge lead, not our wishful thinking, or worse: our beliefs. Since there has not been any organic carbon detected by any probe so far, I don't think is a "pessimist" approach to be conservative in the formulation (or quotation) of hypotheses that rely only on transient liquid salted water to stake a claim of current habitability - especially at the radiated surface! Habitability requires other factors in addition of water, so it is not a slam-dunk if a computer model predicts transient salty films of water. Do we agree?

You know very well that no self-respecting scientist can claim that X is "impossible", so my obvious inability to quote a paper stating the impossibility of current Mars habitability is not a ticket to highlight the "possibility" of native microbes (or invisible PinK unicorns) on Mars. Although some speculation is entertained to give context, astrobiology concerns itself primarily with hypotheses that fit firmly into existing scientific facts and observations. But you have been pretty level-headed in your comments and your stated criteria to select references; and it helps me better assess your intentions and work with you. Have a nice week. Cheers, -

talk

) 16:16, 27 May 2013 (UTC)

As far as personal skepticism that is fine. But for a wikipedia article we need to reflect what the research itself says rather than our own views on the matter.

When I asked for an article that shows skepticism of the findings, I wasn't asking for an article to say it is impossible. Just asking if you know of any article that surveys the recent research and concludes that it is low probability that there are surface habitats for life on Mars. You used to get articles like that, but not any more, not in the last two years.

Then if you look at some of the quotes I gave above, they go into detail of all the requirements in your list:

• water  Done
• energy (sunlight or chemical energy)  Done
• temperature (related)  Done
• atmospheric pressure (related)
• gravity
• nutrients  Done
• cosmic and Solar radiation protection  Done

They don't discuss gravity which I imagine is not much of an issue for micro-organisms. Also don't discuss atmospheric pressure particularly except as far as it is needed for liquid brine to form. For micro-organisms that live in the brine, the atmospheric pressure is not going to make any difference apart from the rate of evaporation. And many micro-organisms are very resistant to low pressure when in dormant states. So I would say that is answered too.

I totally agree that we should take care to not mislead the reader in believing that current habitability is proven. As a mathematician I have a clear distinction in my mind between possible habitats and proven habitats or habitats actually known to have life. We don't have any proof at all of life on Mars of course. This needs to be clear. But we have several suggestions for possible habitats for life on Mars, habitats that if they exist would almost certainly permit survival of Earth micro-organisms at least on the basis of the research so far, which is on-going, using ever better simulations of the Mars surface environment. From what I've read, then for some of the habitats at least, if they do exist, it seems the consensus is for a high probability that Earth life could survive and reproduce in them at least based on the evidence so far. Whether any Mars life would is of course another matter that has to be unknown at this stage. Also whether the habitats exist is unknown, the evidence for them is suggestive but not conclusive, (apart from the dew on the surface and fairly good observational evidence for deliquescing salts from Phoenix)

See particularly the Phoenix paper Assessing Habitability: Lessons from the Phoenix Mission and the sand dunes one, both addressed just about all the requirements you mention and are not just about the presence or not of liquid water Robert Walker (talk) 20:39, 27 May 2013 (UTC)

Let's review it:

• water  Done => transient, unstable, cold and saline microfilms at the surface.... Hardly a homeostatic environment inviting for a thriving and reproducing colony, which NOBODY even hypothesize on. That is your assumption.
• energy (sunlight or chemical energy)  Done => So the hypothetical extremophile in a hypothetical film of saline water has been assigned a hypothetical energy source. In which page they concluded it is Sun light or chemical?
• temperature (related)  Done => No, in progress.
• atmospheric pressure (related) => in progress.
• gravity
• nutrients  Done => So the hypothetical extremophile in a hypothetical film of saline water has been assigned a hypothetical diet. No more research is needed! It has been done! Slam-dunk! The land of milk and honey!
• cosmic and Solar radiation protection  Done => Of course it has been done: There is NONE at the surface!! What part sterility for the first 7.5 meters is hard to understand to a mathematician?

Working hypotheses and computer models are quite useful but only to a degree. I am not satisfied that the models you cite have considered all basic known factors required for microbial life, only salty water films. But I am almost satisfied with the article neutrality as it is now. Your sources are valuable for the physical parameter predictions on water, and I will strive to keep them in that perspective and in relation of the other requirements, the most cumbersome being the lack of cosmic and Solar radiation protection at several meters depth. By the way, for now I am letting slide the [viability] radiation experiment on the exterior of the ISS, which took place within the protection of the magnetosphere, not in the exposed interplanetary space nor on Mars. Expansion for context or deletion may be required. As stimulating the conversation may be, I will debate only future edits as needed. Cheers,

) 00:36, 28 May 2013 (UTC)

I haven't seen any paper criticizing the Expose E experiments on grounds that they were done within the Earth magentosphere. Also I haven't seen any criticism of the recent habitability suggestions on the grounds of the cosmic radiation earlier paper. How can I or any wikipedia editor be expected to find published material to counter criticisms made by a wikipedia editor that have never been published or peer reviewed? Or do you know of a paper that raises either of those points in criticism of the recent suggestions? If you do then do say and I can then look for other papers that cite it to get a balanced point of view on the subject. Or if you are expert on the subject, why not publish a paper yourself with these criticisms? Robert Walker (talk) 01:12, 28 May 2013 (UTC)

Hi, I think the current text still needs to be changed. You say (dormant or living), but it is clear that the paper is only about dormant life. I know the popular article cited is somewhat ambiguous in the phrasing. I can't find the original paper for some reason. But this is another exposition of it in National Geographic Magazine:

Mars Life May Be Too Deep to Find, Experts Conclude

If Earthlike life survived the climate shift, it would most likely be bacteria that live close to the surface.

Such bacteria would spend most of their time dormant, waiting for rare geological events to bring water from deeper in the planet.

Unfortunately, Dartnell said, such a scenario would have left the bacteria vulnerable to years of radiation damage.

In a study published January 30 in the journal Geophysical Research Letters, Dartnell's team found that even the most radiation-tolerant Earthly bacteria would survive only 18,000 years at the surface.

Bacteria living at greater depths could survive longer.

But even at 6.5 feet (2 meters)—the greatest depth at which a Mars probe scheduled for launch in 2013 will be capable of reaching—survival time would be 90,000 to half a million years, depending on the type of rock

It is clear he is talking about dormant forms of life. Which is also the only thing that makes sense logically too, because life that reproduces every year or every few years clearly can't accumulate a multi-millenium dose of cosmic ray damage. And my point remains too, that if this were a serious objection to the modern habitability suggestions, there would be papers making this point, and I haven't found any. It is just you that makes this connection between this older paper and the more recent research, as far as I know. Do correct me if wrong.

So, seems from the quote above that your addition (dormant or not) should be replaced by "dormant for tens of thousands of years". Do you agree? If not, what is your evidence? Robert Walker (talk) 01:36, 28 May 2013 (UTC)

I have just noticed that you found the original paper for the page itself, and the quote you give from it is unambiguous that it is about dormant micro-organisms so have changed it back. It is also clear BTW from example of radiodurans living in reactor cooling ponds that reproducing life can survive in conditions of high levels of radiation, far higher than the surface of Mars. Robert Walker (talk) 09:49, 28 May 2013 (UTC)

Sorry I missed this,

• water  Done => transient, unstable, cold and saline microfilms at the surface.... Hardly a homeostatic environment inviting for a thriving and reproducing colony, which NOBODY even hypothesize on.

I think you are referring here to monolayers which some of the papers discuss. But others discuss a habitat that is suitable for a thriving colony. The antarctic paper I cited shows an example of a colony living in conditions of thin layers of brine at extremely low temperatures. Many extremophiles, including halophiles in films of water in ice and snow, also salts, and also endoliths, survive and reproduce on Earth in conditions of very small amounts of water in microclimates

• energy (sunlight or chemical energy)  Done

Normally chemical. But it can also use light as an energy source in some papers.

• temperature (related)

Temperatures in surface layers go above OC and well above the limits for halophile. The permafrost layer on Mars is some cms below the surface of the soil, which is enough for a thin habitable layer for life.

• atmospheric pressure (related)

There are studies showing that life can survive and reproduce under Mars atmosphere conditions, and also any living organisms that survive in the briny layers don't need to reproduce under Mars atmosphere, just be able to survive it during periods when they are dormant.

• gravity
• nutrients  Done

Just saying it is possible, many micro-organisms from Earth could survive those conditions if they exist - whether Martian life can is of course another matter and depends on what evolved there.

• cosmic and Solar radiation protection  Done

This is a misunderstanding of that paper, it is not instantly or short term lethal, only over tens of thousands of years for dormant or non reproducing life.

Sorry for not answering point by point before, when you said you didn't want any more discussion I didn't think to read back before your last para. I can provide citations for any of these things, but it is work to search it up and paste links in here, so will do it if you are interested and ask for it, as I felt that some of my earlier citations were not read, perhaps I posted too many, so better to post them on demand rather than a lot of them in one go. Indeed most of them I would back up by reposting citations I already made above. Robert Walker (talk) 07:42, 29 May 2013 (UTC)

I see you have reverted it back to "any life". But it is clear the study was only about life dormant for tens of thousands of years. Please explain. I don't want to get into an edit war but it seems to me that you are using this article to put forward a point of view that is not supported by any of the citations, and you haven't got a citation to back up your point of view. I asked for one but you haven't given one. Please give your citation and not just arguments of your own in favour of your belief that the cosmic radiation makes life in the surface layer impossible for all forms of life, dormant or reproducing. If you have no citation, then it should say clearly "life dormant for tens of thousands of years" as that is what the paper is about. I am questioning your reversion under Wikipedia:No_original_research Robert Walker (talk) 10:01, 28 May 2013 (UTC)

It is now back to the way it was when I edited it, so seems it isn't an edit war, that's fine, sorry for assuming it was. Robert Walker (talk) 10:15, 28 May 2013 (UTC)

Not sure what all that was about. I am quoting the papers and am correcting your interpretations of them. You are still arguing something that I, and the paper explained plainly.

1) The Dartnell paper quote:

"Bacteria OR spores held dormant by freezing conditions cannot metabolise and become inactivated by accumulating radiation damage." "Unlike Earth, Mars is no longer protected by a global magnetic field or thick atmosphere. As a result, the planet has been vulnerable to radiation from space for billions of years. Even the hardiest cells we know of could not possibly survive the cosmic radiation near the surface of Mars for that long," said study leader Lewis Dartnell".

2) Bacteria are living, spores are dormant. Both are killed by radiation. There is no

WP:OR

as you charge, it is Biology 101 and clearly stated in that sentence. Please!! Step simply back if you do not understand it (and that that is OK, I can't do differential calculus so won't attempt to argue that subject). Reversion will be contested as I have exhausted my "teaching time."

3) Note the geological CONTEXT! If there was microbial life in the past, when Mars lost its water, atmosphere and magnetosphere, any bacteria would have turned into spores for millions or years, but for them to be still viable (able to germinate) they needed that to happen thousands of years ago. Meaning that now it is too late.

4) Hint: The paper title: '"Study: Surface of Mars Devoid of Life" (Triple hint-hint-hint: not stating devoid of "dormant life", or devoid of "dormant spores", it states "devoid of life":.

5) Most bacteria last minutes or hours, so Dartnell studied "the hardiest cells we know of" (e.g. spores!!!!). If spores cannot survive, neither living metabolizing cells.-

talk

) 14:13, 28 May 2013 (UTC)

Dormant is the operative word here Robert Walker (talk) 07:47, 29 May 2013 (UTC)

Living but not reproducing. Reproducing life can easily survive the cosmic ray conditions. The paper does not study the effect of cosmic rays on reproducing life.Robert Walker (talk) 07:47, 29 May 2013 (UTC)

If there is liquid brine on the surface of Mars, it is not a one off event. The habitats described, especially the sub soil thin (but not monolayer) liquid brine would be present continuously on the surface of Mars for those millions of years. Robert Walker (talk) 07:47, 29 May 2013 (UTC)

Yes but that is a popular account. Also it dates from a time when the surface of Mars was believed to be currently too dry to have any liquid water anywhere. Under those assumptions it is reasonable to say it must be devoid of life. But we now know better, and there is evidence that there may be liquid water right now, present every year when the surface is hot enough at midday. It is not proved, but the whole point of the refs is to say that this is possible. Different conditions, so old paper doesn't apply. Robert Walker (talk) 07:47, 29 May 2013 (UTC)

That is only for cells dormant for tens of thousands of years. Robert Walker (talk) 07:47, 29 May 2013 (UTC)

This must be misreporting by the author of the paper. The quote I give below shows that humans could survive those conditions for years, and most bacteria are far more resistant to radiation than humans. It is true that UV flux on the surface of Mars used to be thought to kill bacteria within minutes, though this is no longer accepted as true due to recent research showing that some species can last for days or months. The UV flux however is completely blocked by a shadow from a rock, or a few mm of soil (which works for micro-organisms that get their energy by chemical means as many do) or for photosynthesizing life, can be attenuated e.g. for life within snow or salt, and can also be tolerated by some plants particularly lichen has been shown to be able to tolerate it and even photosynthesize and metabolize under Mars surface conditions of UV. The cosmic ray flux on Mars is similar to that within the ISS and is not instantly lethal or even lethal over periods of many years. Robert Walker (talk) 07:47, 29 May 2013 (UTC)

Yes agree for metabolizing or dormant cells. For instance there are those examples of cells that may survive for millions of years in salt, but do not reproduce, and if they exist, there is controversy about whether they are simply dormant, or slowly metabolizing. Whichever they are, cells in a dormant or slowly or occasionally metabolizing state would accumulate radiation damage over thousands of years if near the surface on Mars. You could replace "dormant" by "dormant or slowly metabolizing" if you want.

What makes it different is that at the time of the paper no-one thought it was possible for liquid water to exist on the surface of present day Mars. So he only considers the possibility of life that is in a dormant state for millions of years, briefly woken up when conditions are more clement. The more recent research and observations though show that there may well be habitats on present day Mars where life may reproduce. Reproducing life is not subject to the same limitations as cells that are dormant or slowly reproducing. So for instance radiodurans Deinococcus radiodurans#Ionizing radiation resistance can survive and reproduce in conditions much much harsher than present day Mars. Present day Mars has a similar level of cosmic radiation to the interior of the ISS Astronauts Could Survive Mars Radiation for Long Stretches, Rover Study Suggests

A person ambling around the Red Planet would receive an average dose of about 0.7 millisieverts per day, while astronauts aboard the International Space Station experience an average daily dose between 0.4 and 1.0 millisieverts

Similarly if you left micro-organisms in the interior of the ISS for tens of thousands of years, and they were left in a dormant state, or slowly metabolizing but not reproducing, they would not survive due to the cosmic rays. That's not the exterior of the ISS, just the interior to be similar to Mars surface conditions for cosmic rays. But put them into a habitat where they can reproduce, and given nutrients, warmth etc, as in your list of requirements, and they could survive indefinitely. Does that clarify it? Do say if I am missing something. Robert Walker (talk) 16:52, 28 May 2013 (UTC)

You had additional 12 h to ponder on the information I gave you so that you may better understand the terminology and context of the related papers. But instead of a scientific objective reply, I get a non-sequitur equivalent to "Oh yes...and the Russians are communist."

The only thing that you "clarified" is your intention in this encyclopedia and your knowledge level of biology. Thank you, now I will get to work on that section and deal with you in the Wiki style -as required.

talk

) 02:34, 29 May 2013 (UTC)

I don't understand. How do the Dartnell results apply to reproducing cells? I agree that they apply to non reproducing dormant or metabolising cells. The thing is that reproducing cells repair their DNA, which dormant cells have only limited capabilities to do, and cells such as radiodurans are able to reproduce in conditions with much higher levels of radiation that would damage a dormant cell and make it non viable over much shorter periods of time than Mars. What matters is the cummulative dose for a single cell and in a reproducing population no individual cell survives for 100,000 years.

Your reply was to say that I am lacking knowledge of basic biology. Please tell me what it is I don't know. It is not helpful to say in a general way that I am not a professional biologist and so must be wrong for that reason, without saying what it is I got wrong.

Your current version of the paragraph does not summarize what the paper says. They do not say "any life" but dormant life under the assumption that the life remains dormant for tens of thousands of years at a time between revivals. So you do not accurately summarize the paper.

That is why I call it OR. What you say does agree with the title of the paper in the original journal. But headlines of journalistic accounts (even in popular scientific journals) of scientific research are not good citation source. Most of the popular accounts of the research at the time were ambiguous or indeed had misleading titles like this one, because they don't spell out the assumptions in detail, but the national geographical one is clear enough. The comparison with the ISS is also highly relevant, because cosmic ray conditions are close to identical. If the cosmic ray flux on Mars was lethal to reproducing life the same should apply to the ISS. It is true it is shielded by our magnetosphere and the ISS itself, but it is also much closer to the sun and the Mars surface is shielded by its atmosphere so the effects balance out.

Your argument seems to be based on a reading of a popular account of a paper from 2001 that assumes as its basic assumption that liquid water or brine on the surface of Mars is impossible. I have argued that the research was not clearly reported in many of the accounts in the popular media at the time, as it did not make clear what the assumptions were in the original paper, that the life is dormant for tens of thousands of years. Some of them such as the one you give also seem to fail to clearly distinguish effects of UV and cosmic rays. There is no published research that I know of that talks about cosmic ray influx on Mars as lethal to microbes, or indeed humans even, over short time periods. The only research of that nature is on long term effects on health over years, mainly for long lived creatures such as humans who can accumulate a significant amount of cosmic ray radiation damage over a lifetime, which is not lethal but a long term health risk in humans. Or, as in the case of the Dartnell paper, life that is dormant or non reproducing for tens of thousands of years.

If what you say is correct, then there must be more recent research that specifically describes a lethal effect on reproducing life. Please supply a citation to back up your claim that it applies to all life, dormant and reproducing. If you can't do that then I see what you say as original research not backed up by the cited source. In that situation it is up to you to provide citations to back up what you say.

I have gone back and answered your points, point by point, since I have apparently not made clear how what I said related to what you said. It was relevant and not a digression, just that I don't seem to have presented what I said clearly. Hopefully this is clearer now. If not do please say what else needs to be discussed. If I have misunderstood something please say what particular it is that I have misunderstood. The main point seems to be your assumption of lethality of cosmic rays over short time periods. If you can back that up, or explain some way that I have misunderstood all the research papers I have read on that subject, then please explain, give a hint about what it is I have misunderstood. Robert Walker (talk) 07:11, 29 May 2013 (UTC)

I have just found this 2010 paper. As with the earlier paper, it is a study of frozen life, not reproducing life in liquid water or brine. The difference from the earlier study is that it uses actual experiments, combined with modelling, and it uses low temperatures of -76C which improves survival rates. Their result is that the shielding for the top 30 cm of soil on Mars are sufficient to permit frozen micro-organisms to survive 100,000 years before you get a million-fold reduction in the viable population. So the figures of the earlier paper for survival times of dormant or frozen micro-organisms may be too low. I think it deserves a mention for that reason. The paper itself is behind a paywall for me, so I am going by the abstract which however seems clear enough. Low-temperature ionizing radiation resistance of Deinococcus radiodurans and Antarctic Dry Valley bacteria..Robert Walker (talk) 09:28, 29 May 2013 (UTC)

Yes, it is in response to the planetary protection of Mars, and to evaluate the possibilities of forward contamination (the stated goal of the paper). Hopefully you will read it and stop your campaign on the existence of native Martians. Simple: quote the refs in their context.

talk

) 23:30, 1 June 2013 (UTC)

I see you have deleted my sentences:

"Other studies show that a covering of a few mm of soil is enough to enable life to survive in dormant states for years, so permitting replication.^{[1] [2]}"

- NOTE THE PROTECTION MENTIONED HERE IS FROM UV, NOT COSMIC RAYS which makes no significant difference to survival over periods of years on Mars, and a few mm of soil will not significantly add to cosmic ray protection.

and

"However this research only applies to dormant forms of life unable to repair damage to their cells over geological time scales. It's been shown that many Earth micro-organisms are resistant to high levels of radiation over time-scales of months and years. ^[1] and the protection from UV provided by just a few mm. of soil.^[2]"

Is that because they are about UV rather than cosmic radiation? If so then perhaps should have a separate section talking about UV? Because UV is the main hazard for life on Mars in the short term period of years. And these studies show that there is enough protection from it for just a few mm of soil. Robert Walker (talk) 09:09, 29 May 2013 (UTC)

1) It was deleted anyway because the brine section it is not about the generalities of extremophiles. 2) Re: UV light on NEO: review

3) Only applies to dormant life (spoes)?? It was easily deleted because it is unreferenced BS. For the 10th time: study done on spores because they are the most resistant cells known. 4) I deleted your unreferenced POV on "replicating" spores. (read that twice). 5) There is one ref quoted in the right context (halophiles) so it stays in the brine section. Your intended piling up dozens of unrelated references on radiation experiments will not take away the synthesis to give the false impression that the experts concluded that transient brine films are a replicating heaven for bacteria. I will not repeat this cycle indefinitely. Rant all you want, I care for the accuracy of the edits.

) 14:42, 29 May 2013 (UTC)

But you haven't explained your POV. It is no good saying that it's because you are a biologist and I can't understand biology. I have had many conversations with microbiologists and I have no trouble understanding what they say and they have no trouble understanding me and I can engage in an intelligent conversation with them.

You must be able to explain it, in a way I can understand, why you think the cosmic rays are deadly for living and reproducing life and not just spores. Your explanations so far haven't been convincing. For instance, what you said about the ISS being inside the Earth's magnetosphere is true but it only reduces the flux slightly, the main thing that protects us from cosmic rays is the atmosphere. The ISS crew experience 150 mSv per year, which is similar to surface of Mars and only causes damage to the DNA over very long timescales. The Earth surface experiences on average 0.4 mSv per year.

Yes spores are more resistant of course. But it is over hundreds of thousands of years that the spores are killed, not just minutes or days or even years, and the amount of the cosmic rays is the same as for the ISS and life has no problem living in the ISS. You need to explain how you get from lethality of spores over hundreds of thousands of years to lethality for reproducing life.

Also your explanation that if spores are affected then ordinary life must be too doesn't take account of the difference in dose, that the spores have a lifetime dose of hundreds of thousands of years, so of 15,000,000 mSv. While if the cells reproduce say once a month, they have a lifetime dose of 12.5 mSv. Also, the effect of the dose is not cummulative from one generation to another, as living cells can repair their DNA, the radiation resistant ones like radiodurans especially, and they don't all have to succeed, it is only necessary that enough succeed in repair to keep a stable population level.

Also it is a synthesis to say that if spores are affected then ordinary life must be too. It is reasonable to ask how you make that deduction. And if it is OR it doesn't belong here though if it is something that anyone expert in the field can see as an immediate deduction it could have its place here. But in that case you should be able to explain why it is so obvious.

If I have somehow misunderstood something fundamental, you MUST be able to explain it, it's hardly a complex situation, if there is something I don't understand it is surely simple and easy to explain, and if it is basic biology then you should be able to explain it in just a few words. BTW, of course I know that a spore doesn't replicate as a spore and has to reactivate and germinate first :). I think you can assume I understand most of the fundamental concepts... Robert Walker (talk) 19:40, 29 May 2013 (UTC)

Respectfully I'd like to suggest a request for comments from other microbiologists to see if they agree on your interpretation of the papers on cosmic ray radiation on Mars, if you are still of the opinion that they support your POV. Robert Walker (talk) 09:17, 29 May 2013 (UTC)

The question would be, which of these statements correctly reports the findings of the papers on effect of cosmic rays on life on mars?:

1. Cosmic rays are lethal for long term survival of all life near the surface, whether dormant or reproducing, so that it is impossible to have permanently colonized habitats on the surface (your version)
2. Cosmic rays are only lethal for long term survival of micro-organisms that are frozen or dormant for the entire period (my version)

where by long term survival, this means survival over periods of tens of thousands of years (or hundreds of thousands of years if you take the more recent paper)

The question is just about the interpretation of those papers you and I have cited. So a relatively straightforward question suitable for a request for comment.

Do you agree that that correctly sums up our point of difference? Robert Walker (talk) 15:04, 29 May 2013 (UTC)

We could also separately ask for comment about whether the other papers I cited support assertion that the potential habitats do not just have liquid water but are fairly described as habitable for terrestrial life, if they exist. Again asking for a third party opinion on interpretation of the papers I cited above. If the answer is yes then can fairly paraphrase the cited material as saying that they are potentially habitable and not just liquid brine. Again, it should be a relatively straightforward question for a microbiologist, just a question about interpretation of the published papers cited. It is not asking an opinion about whether they are habitable, but just about whether the cited papers say that they are habitable (if they exist). Robert Walker (talk) 15:12, 29 May 2013 (UTC)

Do you have any more thoughts about this? If I read the guidelines correctly: Wikipedia:Requests_for_comment, I think I can just go ahead and do a request for comments anyway, unlike the third opinion where we need to mutually agree, but best if you agree. The other alternative is to ask for help at WikiProject Biology but not sure how you set about that. I also welcome other suggestions for dealing with this issue. Robert Walker (talk) 01:20, 30 May 2013 (UTC)

Here is my draft of the question for the RfC (please note I haven't yet put the RfC template in so it is not yet active)

If there are no comments, I'll take it to RfC anyway. I will also post it to the WikiProject Biology talk page. Other editors can then discuss the issue and then we can see what the options are. If I have somehow made a fundamental misunderstanding of biology hopefully some of them will be able to explain where I went wrong. Robert Walker (talk) 06:38, 30 May 2013 (UTC)

I am unable to paraphrase your objections, at least not without putting my own POV slant on them, as I don't know what they are, and I seem to have answered everything you said. Please summarize them in the section below. For discussion of the RfC or the way it is presented please reply here rather than comment directly on my statements in the RfC. Thanks! Robert Walker (talk) 08:29, 30 May 2013 (UTC)

Batteryincluded, I have just rearranged the section, after reading it afresh, the problem was that for someone new to it, if you are a professional biologist or microbiologist, you don't need to read all my reasoning before you get to the opinion section. But if they are not sure of the nature of the dispute it could be useful if they read on to still retain it. So put it into the threaded discussion seciton as well.

Commented out the rfc. Seems unlikely to help. Robert Walker (talk) 22:38, 3 June 2013 (UTC)

Do the cited papers say that the cosmic radiation influx within the surface layers of Mars is lethal only for long term dormant life? Or do they say that it is lethal for all life dormant or reproducing?

This is for the second paragraph of Life_on_Mars#Possible_surface_brine_habitats. The current version reads:

"However, the damaging effect of ionising radiation on cellular structure is one of the prime limiting factors on the survival of life in potential astrobiological habitats.

cosmic radiation levels at various depths on Mars, researchers have concluded that any life within the first several meters of the planet's surface would be killed by lethal doses of cosmic radiation.^[2][3][4]

"

I want to rephrase it to read:

"After modelling

cosmic radiation levels at various depths on Mars, researchers have concluded that life dormant for tens of thouands of years within the first several meters of the planet's surface would be killed by lethal doses of cosmic radiationCite error: A <ref> tag is missing the closing </ref> (see the help page).^{[1] [2][3][4]}. However this conclusion doesn't apply to life that reproduces over shorter timescales, as there is then not enough time to build up a lethal dose of radiation in the cell's lifetime. Indeed, cosmic radiation on the Mars surface is at a similar level to the interior of the ISS^[5], and the ISS is an environment rich in microbial life^[6]. Much higher levels of cosmic radiation can be tolerated by radiotolerant organisms like radiodurans

, which has the capability to repair any radiation damage during the cell's lifetime within a few hours of its occurrence (when non dormant)

The main limiting factor for life on the surface of Mars in the short term is the level of UV. Most micro-organisms are killed by a few minutes, or in a few cases, a few hours of UV [7]^[8] though some extremophile lichens and algae can tolerate the Martian levels of UV long term on the surface, and some experiments suggest they can photosynthesize and metabolize exposed directly to the Martian sunlight ^[9][10] UV does not penetrate below the surface or into shadows, and so causes no direct problems for a subsurface habitable environment."

Survey

Support

Use of new version of the paragraph, that the cosmic radiation influx is lethal only long term for dormant life Robert Walker (talk) 03:04, 30 May 2013 (UTC)

Oppose

Keep the present version, that the cosmic radiation influx is lethal to all life Robert Walker (talk) 03:04, 30 May 2013 (UTC)

Detailed discussions, especially ones that do not express an opinion either way, may be best in the threaded section below.

Opinions and comments from biologists and microbiologists are especially appreciated. It may also help to say so, if you are one or the other.

Thanks!

Threaded discussion

Request for quantative information about effective repair mechanisms

• Comment I refuse to get into the details of any such a vacuously abusive exchange. The parties referenced might or might not care; I don't. As for the material considerations, OR, NPOV and such should be dealt with in the usual manner, but as for substance, my main reserve is whether there is any quantitative information on how long-lived or short-lived notional organisms would have to be to make any interesting difference, what basis there might be for guessing at effective repair mechanisms, and what other considerations might apply to affect rational estimates of rival probabilities. Work it out. JonRichfield (talk) 11:53, 31 May 2013 (UTC)

Yes Jon, that is a good point, please everyone, no need to comment on what my motivation is or what Batteryincluded's motivation is, that's not what the RfC is about, and I don't think it will be helpful. Just keep to the original question, of accurate interpretation of the cited sources. Robert Walker (talk) 12:17, 31 May 2013 (UTC)

Jon, the radiodurans can survive and reproduce in reactor cooling ponds. The microbes in the ISS survive and reproduce under similar cosmic radiation levels to the surface of Mars. There are studies of microbes in the ISS, but not sure it is necessary to cite those, as micro-organisms can reproduce there fine anyway. They have to be careful about build up of micro-organisms, e.g. to keep the air dry and not too damp to reduce problems with micro-organisms. Were some reported problems with micro-organisms on MIR. Also some research papers on the actual microbial populations of the ISS and MIR which I can look up if needed, report similar levels to a normal human habitat on Earth.

For figures for radiodurans, see Deinococcus_radiodurans#Ionizing_radiation_resistance page, one of the most radioresistant organisms known. It can withstand 5,000 Gy with no noticeable loss of viability. I am not sure how you convert that to Sieverts as the conversion factor is different e.g. for X-rays is the same unit, for alpha particles you multiply by 20, but it would be at least 5,000,000 mSv. assuming that cosmic rays are more damaging than X-rays, at any rate an order of magnitude here or there isn't going to make a difference with figures so high. That compares with 0.7 mSv measured by Curiosity on the surface of Mars. Robert Walker (talk) 12:11, 31 May 2013 (UTC)

Jon, I have removed my response to Batteryincluded's accusations, have left his original comments but moved them down as well, to promote. Also removed my comments I just made about what I think his arguments are, as he wants the citations to speak for themselves without comment so will restrict myself to directly answering questions I believe I can answer. Robert Walker (talk) 13:43, 31 May 2013 (UTC)

Batteryincluded's response to the RfC

Since the current [documented and quoted] scientific research on cosmic radiation on Mars does not conform to your (Walker's) expectations, you now want the physics to conform to your voting poll. (How is it going, by the way? [2])

While ignorance can be corrected with self awareness and sincere curiosity, your deliberate BS mixed with hysteria is -almost- a comic relief, if it wasn't so obstructive to serious editors. While I seriously question your intentions (POV, synthesis, bias and editorializing) in this encyclopedia, I want to renew my heart-felt vow to not discuss science with you, and will do my best effort -BS toxicity permiting- to control the damage of your edits in Wikipedia back to the objective spirit in which the cited scientific articles were written.

Sincerely, -

talk

) 00:01, 31 May 2013 (UTC)

While I have not read any of the apparently contentious argument that lead to this statement, I believe it is clear that User BatteryIncluded has completely lost sight of both

WP:NPA. This is egregious name-calling, thinly disguised as reasonable discussion. Based on this single paragraph, I would consider BatteryIncluded to be tenditious and insulting. Without regards to the merits of any of this, this paragraph has left a very bad impression with this experienced editor. Eaglizard (talk

) 19:53, 2 June 2013 (UTC)

Hope you don't mind, I've moved this down to the bottom of the threaded discussion and done the best at a fair reporting of your reasoning as I understand it instead. Not intended as POV pushing, but in response to Jon's comments, don't want this RfC to be about personal matters between you and myself. You can of course move it back up again if you want to, but would suggest it is best to do it like this. Robert Walker (talk) 12:59, 31 May 2013 (UTC)

My actual response is: read the references, not your blog.

talk

) 13:09, 31 May 2013 (UTC)

Okay have removed the section about my reasoning too, doesn't seem to be fair to just give my POV without yours there.

Also removed all my comments where I talk about what I thought your reasoning might be, as it obviously isn't useful. Robert Walker (talk)

Cosmic radiation for human crew flight to Mars

Batteryincluded, your ref to [[3] is about a human mission to Mars. It shows that there is an increased level of radiation compared to the ISS which leads to an increased risk of cancer long term for human beings compared with the ISS. It is not a massive increase of risk, but enough to go over the NASA guidelines of a maximum of a 3 percent increased risk for astronauts in low-Earth orbit. As I understand it, this level of cosmic radiation would not be a problem at all even for ordinary microbial life, reproducing on normal timescales, never mind something like radiodurans which can repair its DNA continuously as it gets damaged during the lifetime of a single (non dormant) cell. (It is also the level of cosmic radiation recorded in deep space, the cosmic radiation on the surface is about half of this, but the difference between the two isn't that significant for micro-organisms). Do explain if I have misunderstood somehow. Robert Walker (talk) 11:41, 31 May 2013 (UTC)

Call NASA and tell them you disagree.

talk

) 13:34, 31 May 2013 (UTC)

Where do they say that all (or indeed any) of the living (non dormant) micro-organisms on a spaceship will be killed by lethal cosmic radiation in a mission to Mars? Robert Walker (talk) 20:10, 31 May 2013 (UTC)

Where in the article is that reference being used? Did you bother to actually read the current references? Your circus is not about science. Drama queen!

talk

) 21:52, 1 June 2013 (UTC)

Okay, what I said wasn't clear, I didn't mean that it does say that. Was a "rhetorical question".

Try again:

• The article is about the effect of cosmic radiation on the incidence of cancer in humans who travel to Mars
• it is about a small % increase in the lifetime risk of cancer for a human
• what is the connection with the effect of cosmic radiation on the survival of micro-organisms on the surface of Mars? Robert Walker (talk) 00:14, 2 June 2013 (UTC)

• Comment Some of the discussion above look a bit like OR to me. We must be careful to say only what is actually said in the sources. Martin Hogbin (talk) 15:53, 2 June 2013 (UTC)

Hi BatteryIncluded, I have put in a request for assistance as a first step towards finding a way forward/

See Wikipedia:Editor assistance/Requests#Dispute with BatteryIncluded

Robert Walker (talk) 08:34, 1 June 2013 (UTC)

Fantastic idea! To start I highly recommend you try a Rx of Lithium. Then you may understand the scientific method, not editorializing, the concept of

WP:POV

.

The only dispute you have is with the authors' veracity of the cited references.

talk

) 21:56, 1 June 2013 (UTC)

Well basically it is an edit war, or would be, because I want to substitute my version of the para. for yours which I consider to be inaccurate. But am not someone who engages in edit wars. Anyway they are against wikipedia guidelines and policies. So looking for a resolution.

I have had lots of conversations with microbiologists some professors and lecturers in their fields. I have not run into any serious communication difficulties understanding or being understood. I simply don't believe that it is a problem of a basic understanding of biology especially since you can't say what the issue is in a way I understand.

So you haven't convinced me that your version is right.

I believe I am right and want other opinions on the matter to resolve the dispute. Robert Walker (talk) 00:19, 2 June 2013 (UTC)

Are you willing to go through the dispute resolution process?

I realize RfC was not the right solution. It is the first ever time I have been involved in an edit war. For some reason I got into two edit wars in the same week, after eight years of dispute free editing of wikipedia.

Only previous thing anything like a dispute was an article I wrote that was nominated for deletion. After a short debate, the almost unaminous decision was to keep the article. Robert Walker (talk) 00:27, 2 June 2013 (UTC)

Short memory, Walker? Look at your opening edit in the article: [4]

"For instance thin films of salty brine may form near the surface and provide a location for life to briefly waken and reproduce every day."

Note the lack of references, subsequent synthesis and original research. Of course, I deleted that, which caused you to go into a hysterical monologue and quoting multiple unrelated research papers trying to synthetize a justification.

You know very well that no single reference supports your story, so don't give me "I don't know what the problem is." The text, as it is now, are direct quotes from the papers, and presented in the context they were written.

Another sorry state of your poor trolling arguments is that you contest the very well REFERENCED statement that liquid water does not appear at the surface of Mars, but you have been unable to understand that disagreeing with the conclusion of peer-reviewed papers, is not enough to delete it from Wikipedia.

It is very revealing that you contest Dr. Darnell's conclusion: "any life within the first several meters of the planet's surface would be killed by lethal doses of cosmic radiation.[80][81][82] Even at a depth of 2 meters beneath the surface, any microbes would likely be dormant, cryopreserved by the current freezing conditions, and so metabolically inactive and unable to repair cellular degradation as it occurs."

However, you blame me for that mainstream scientific conclusion, of not understanding biology, and you even attempt to dismiss this reference (Dr. Dartnell) with a juvenile:

"This must be misreporting by the author of the paper."

After pages of hysterical noise without substance, the heart of the matter remains that because I deleted your unreferenced and biased living Martian bullshit, now I declared an "edit war" on you.

Finally, instead of finding published research to support your living Martians story, you call for a Wikipedia RFC hoping for someone to throw you a bone. Enter JonRichfield stating:

"[...] my main reserve is whether there is any quantitative information on how long-lived or short-lived notional organisms would have to be to make any interesting difference, what basis there might be for guessing at effective repair mechanisms, and what other considerations might apply to affect rational estimates of rival probabilities. Work it out."

My astute friend JonRichfield made a basic comment, but he (as you) missed the fact that the current text is already supported by such references in which radiation damage and the possibility of DNA repair mechanisms were assessed for various strains; the research conclusion is in the Wikipedia article. His suggestion that "we work it out" is not paramount to craft a democratic alternative to the truth.

"So you haven't convinced me that your version is right." -Walker

What it boils down to, is Mr Walker dismissing the veracity of the quoted research and, evidently, this is not my problem nor Wikipedia's. Cheers,

talk

) 04:29, 2 June 2013 (UTC)

Don't know if it is any help to step in here, but this is what shows its age. When he says "any microbes' would likely be dormant, cryopreserved by the current freezing conditions, and so metabolically inactive and unable to repair cellular degradation as it occurs." that is what everyone thought at the time the paper was written.

The new thing that started this all off was the observation of a drop of salty water on the leg of Phoenix which no-one doubts was liquid. This report is in 2011, so by then already the idea that the droplets on the Phoenix were salty water was the consensus - so I think, post around 2011 is when people started to take these salty brine habitat ideas really seriously:

http://www.astrobio.net/pressrelease/4170/a-drop-of-salt-water-on-mars

Independent physical and thermodynamic evidence as well as follow-up experiments have confirmed that the drops were liquid and not frost or ice. The Phoenix photos are believed to be the first pictures of liquid water outside the Earth

Then, developments in theoretical understanding and studies of extremophiles able to live in very salty water lead to the idea of habitats where the salt deliquesces and the temperatures are high enough for the salty water to be liquid enough for long enough for life to reproduce, if it is there. This was not suspected at the time of Dartnell;s paper. That is why his paper is out of date. He says "any life" but when you look at it he is assuming "any life" because it is dormant and he makes that clear. The science news story took that "any life" but some of the more popular stories at the time, e.g. space.com, left out the nuance "because it must be dormant", also of course it didn't get into the headlines, which just said "any life" without explanation of the assumptions about that life made in the paper.

That's what the difference is. Please see the quotes I added below. These are notable POVs, scientists saying that Mars is habitable. Also in an entire conference this February on the habitability of Mars surface, no-one presented paper on lethality of cosmic radiation for the life there. I haven't yet listened to all the video presentations so don't know if the radiation flux was ever mentioned at all, but for sure it wasn't considered enough of an issue for habitability of Mars surface worth having a separate paper about it in the conference. If the old paper was still valid you would expect something like "limitations for life on Mars surface due to cosmic radiation".

Okay, I am not going to reply to all that at this stage because I just want to know, are you willing to go through the dispute resolution process? During the process we get the opportunity to explain ourselves to the other wikipedians who will help to resolve it.

It is natural that you think that there is no dispute because you think you are right. I similarly think that I am right and that there is no dispute for exactly the same reason as you in reverse.

That is why I am asking for help to resolve this, as we can't resolve it between ourselves. Do you agree to start the standard wikipedia process for the situation of an edit war and two editors that are engaged in a dispute over content? Robert Walker (talk) 06:04, 2 June 2013 (UTC)

I can reply if you prefer, if you think that there is still a chance of resolving this between ourselves, and are interested to hear what my replies are, and want to find out why I am not yet convinced by your arguments. Robert Walker (talk) 07:50, 2 June 2013 (UTC)

You can go request a meeting with Obama or Mickey Mouse for all I care. Your POV, synthesis and editorializing do not support your slanted POV. With time, the MSL rover might provide direct data to further evaluate the proposed hypothesis of surface brine habitability. Even then, I will make sure the published research is presented here in the context it was written.

Why do think the future astrobiological missions will be looking for biosignatures on the sub-surface? Because the PIs in charge do not read your blog, but science. Cheers,

talk

) 18:05, 2 June 2013 (UTC)

Okay I know I can't do a dispute resolution by myself. Both editors have to agree. Not sure what the next step is. Robert Walker (talk) 22:35, 3 June 2013 (UTC)

Batteryincluded, please read this reference:

Also wikipedia is about reflecting the current views, notable views. There is no doubt that many scientists are of the view that surface habitats if they exist are habitable. If you can find some who say it is not habitable, then you can add that in as an alternate view.

I don't think that old paper you cite though will do to back it up as it is too old and doens't take account of modern research in such a rapidly changing field. You need a modern one in the last couple of years say, that says that the surface water habitats in Mars (if existing) are not habitable.

Without that then I think the current version of the article is synthesis. It is unfair really to ask me to prove my own POV because that inevitably means I try to string things together to make another synthesis to counter yours, and then you can complain that it is not right of me to do that because I am not an expert and am not a citable notable source on the matter. Which of course is true. Indeed even if I were I would need to publish it first and then cite my published work. You would need to do the same to cite your views.

Instead we should just cite it as the POV of scientists such as those in this conference, and Zubrin etc. Done that way, their view that current water habitats on Mars are quite probable, and if they exist, would be habitable for Mars life is a notable POV and has to be included.

Mars May Be Habitable Today, Scientists Say (space.com article title)

Evidence is building that liquid water might flow seasonally at some Martian sites, potentially providing a haven for life as we know it "We certainly can't rule out the possibility that it's habitable today," said Alfred McEwen of the University of Arizona, principal investigator for the HiRise camera aboard NASA's Mars Reconnaissance Orbiter spacecraft.

... Martian life may be able to survive even in places where water doesn't seep and flow, some scientists stressed.

... "Perchlorate, it turns out, is a potent chemoautotrophic energy source," said Carol Stoker, also of NASA Ames, noting that the chemical could potentially sustain microbes in the dark Martian subsurface, where photosynthesis is not an option.

And some Earth microbes use perchlorate for food, so that could be happening on Mars as well, scientists have pointed out.

... "The Present-Day Habitability of Mars" took place Feb. 4-5 and was co-hosted by the NASA Astrobiology institute and the UK Centre for Astrobiology.

http://www.space.com/19928-mars-habitable-life-possible.html

The relevance of that editorial piece are summarized in the reporter's statement:

"Astrobiologists are keen to learn more about these brines, for not much is known about them at the moment."

I would be OK to include that in the brine section. Cheers,

talk

) 17:20, 2 June 2013 (UTC)

What about: "We certainly can't rule out the possibility that it's habitable today," which was said by the principal investigator for the HiRise camera aboard NASA's Mars Reconnaissance Orbiter spacecraft.?

Or Robert Zubrin's quote, or any of the others by researchers in the area saying they can't rule out habitability? That's inconsistent with your summary which says we can rule out habitability, which no paper in the last two or three years says that I've read.

The old paper it is too old to be used to contradict the more recent research since it took for granted that all life on Mars surface has to be dormant. So you have nothing to support the existing text written in the last two or three years, and many statements that contradict it. Not talking about me establishing anything, just clear statements by experts in the field, ones that count as notable and citable by the wikipedia criteria. Robert Walker (talk) 21:34, 2 June 2013 (UTC)

You could put the bit about "scientists are keen to find out more about them" in place of the second para, though at 2011 this is rather an old source for a statement like that, they have already found out more from theoretical models, and constraints from satellite imagery of Mars and reassessing old observations, but it is still true of course that they are keen to find out more.

. My objection to the second para. is that it is OR for you to use that old paper against the newer results for a situation it was not written to cover. My objections to you doing that are also OR. So best to remove the whole paragraph.

It was such an important result, that I am sure there must be newer papers to cite if still valid for these new situations. Robert Walker (talk) 05:45, 3 June 2013 (UTC)

The Present-Day Habitability of Mars (conference, Feb 2013)

The article links to video presentations from the conference. You can watch them online here: http://planets.ucla.edu/meetings/mars-habitability-2013/program/

Robert Walker (talk) 08:08, 2 June 2013 (UTC)

Potential Mars Water A Big Deal, Scientists Say (space.com article title) - with Zubrin quote

Another one: http://www.space.com/12575-mars-water-life-discovery-significant.html

"Yeah it's a big deal," said Robert Zubrin, president and founder of the Mars Society. "The idea that there's liquid water on Mars today at the surface means that there could be life on Mars today at the surface."

Robert Walker (talk) 08:13, 2 June 2013 (UTC)

I indulged you, read it and again: you have to consider it in the context it was written. Let's start with the title: "Potential Mars Water A Big Deal, Scientists Say." (2011)

The potential of the existence of "briny water" and its potential habitability are already included and referenced in the Wiki article, but I would be happy to include this additional reference.

The fact remains that this or any other article you bring forward (regardless of the date), do not support your POV/synthesis/editorializing/fantasy and UNREFERENCED entry: "For instance thin films of salty brine may form near the surface and provide a location for life to briefly waken and reproduce every day." Nor it supports your alternative editorializing and synthesis. Cheers,

talk

) 17:38, 2 June 2013 (UTC)

Oh - say it as you like. Just want it to say that there is thought to be some potential for life on Mars, that it hasn't been proved to be impossible. As I read it your article seems to attempt to supply a proof in the final paragraph that life in the top surface layer of Mars is impossible. That's what I'm objecting to.

I have no idea how likely it is. No-one is really sure those habitats even exist though to my mind the February lecture about the Phoenix site was pretty convincing, that it probably has some water, also the idea (new to me) of the thick winter layers of dry ice also creating thin films of water beneath them via a greenhouse effect. Personally I would be surprised if there is absolutely no salty brine on Mars anywhere that is briefly habitable every year. (But you might watch the same lecture and think they are unlikely, that's okay :) ).

But as far as reporting what the scientists say they just say that it is potentially habitable. So long as the article says that too then fine. I would just remove your para about cosmic radiation actually, because with the modern research it is irrelevant. Just have the first paragraph without the dubious second para. and I would be completely satisfied. The first para saying " that may provide a potential location for terrestrial salt and cold-loving microorganisms " is accurately reporting what they say.

The second para. was topical and relevant and reporting the most recent research a few years ago, but is no longer valid IMO and the best solution really is just to omit it. Is that a possible solution for you? Robert Walker (talk) 00:02, 3 June 2013 (UTC)

Also the second para. is still to this day highly relevant when you are talking about the search for ancient preserved DNA e.g. from billions of years ago. Seems pretty clear there wouldn't be that much left of it in the top few meters of soil and you would have to dig down at least several meters below the surface to get undamaged deposits from deposits that have remained frozen all that time. That is still true today. Robert Walker (talk) 00:07, 3 June 2013 (UTC)

Here is my suggested new version, this would be absolutely fine by me.

Possible surface brine habitats

Further information:

Possibility of Mars having enough water to support life

Although liquid water does not appear at the surface of Mars,

psychrophilic).^[4] Also, dust grains embedded in snow may form warm micro-climates when the water around them is briefly melted by the Sun, as has been observed in Antarctica.^[5][6] There is also observational evidence which may suggest liquid water forming on or near the surface of Mars seasonally.^[7]

Astrobiologists are keen to find out more, as not much is known about these brines at the moment. The briny water may or may not be habitable to microbes from Earth or Mars. [8]

Is that okay by you? The only part changed is the second paragraph but I put in the first paragraph as well to help judge how it reads in context. Robert Walker (talk) 09:58, 3 June 2013 (UTC)

First: For the n^th time: No, it is not OK to delete the factual radiation lethality at the surface. Deleting those referenced results from Wikipedia, 1) does not make Mars surface habitable, and 2) is bias (

). As I unsuccessfully reminded you many times: surface habitability is not limited to chemistry. Or to temperature. Or to the atmosphere. Or to water. Or to radiation. But to a combination of all those and other environmental factors. Although not much is known on surface brines, a lot is known on bioradiation, its lethality, and its limiting power on surface habitability. So I suggest:

Although liquid water does not appear at the surface of Mars,

psychrophilic).^[11] Also, dust grains embedded in snow may form warm micro-climates when the water around them is briefly melted by the Sun, as has been observed in Antarctica.^[12][13] There is also observational evidence which may suggest liquid water forming on or near the surface of Mars seasonally.^[14] Astrobiologists are keen to find out more, as not much is known about these brines at the moment. The briny water may or may not be habitable to microbes from Earth or Mars,^[15]

However, the damaging effect of ionising radiation on cellular structure is one of the prime limiting factors on the survival of life in potential astrobiological habitats.

cosmic radiation levels at various depths on Mars, researchers have concluded that any life within the first several meters of the planet's surface would be killed by lethal doses of cosmic radiation.^[18][19][20] Even at a depth of 2 meters beneath the surface, any microbes would likely be dormant, cryopreserved by the current freezing conditions, and so metabolically inactive and unable to repair cellular degradation as it occurs.^[17]

Second: You have exhausted the given assumption of good faith, and personally, I believe you are obsessed beyond reason, terrified and convinced of the existence of killer Martian bugs, as you current work reveals at your blog and at

Concerns for an early Mars sample return

. Let the record show that my future non-participation in your rants, do not imply my consent to transcribe them into the article. I will edit or delete any factual inaccuracies, original research, bias, synthesis, deletion, etc that you may introduce to the article. Cheers,

talk

) 23:25, 4 June 2013 (UTC)

Typically it is the top 2 cms above the permafrost layer. Below that everything is indeed permanently frozen. Interest in the thin area of soil above the permafrost layer dates back to the observation of what appear to be droplets of salty brine on the Phoenix lander and theoretical work showing thin layers of liquid brine can form due to deliquescing salts for substantial periods of time, the salts take up the humidity from the air and then retain it for long periods of time even when the air is quite low humidity.

These habitats would be continuously habitable so avoids the problem of cosmic radiation degradation of dormant life forms. Doesn't contradict the earlier work as the possibility of liquid brine in this top layer wasn't suspected, was thought to be too dry for water to form and the idea of deliquescing salts and the idea that some extremophiles can survive in such a habitat is the main new development.

The surface temperature of Mars can go well above OC over much of the surface of Mars with surface temperatures above 20C recorded by the landers, at midday - though of course extremely cold at night. That's why the top two cms are above the permafrost layer and why the surface life forms if they exist would not be permanently frozen. The brine typically would form around deliquescing salts day, at temperatures well below 0C, and the salts effloresce again at night. An extreme habitat but survivable. Cyanobacteria have been found in a similar habitat on Earth (as endoliths) with no source of water, just the salt taking up the humidity, as on Mars.

Ditto also the lichen habitat - Earth lichen from the arctic can metabolize and photosynthesize using just the humidity in the air which they take up rather similary to the deliquescing salts idea and grow at remarkably low temperatures down to -40C. The droplets of water melting around a dust of grain in snow is a third habitat. I can provide urls for citations for all this if anyone wants to follow it up. Robert Walker (talk) 13:31, 24 June 2013 (UTC)

Here I am simply reporting recent research. The only thing that counts as OR is my observation that since it is continuously habitable then the cosmic radiation problems for dormant lifeforms don't apply. That is never said in the literature on these surface habitats but I think only because it is obvious and so doesn't need to be said explicitly. When considering habitability then the cosmic radiation is listed as 10th in importance of 14 limiting factors relevant to habitability of surface layers. But it is not at all OR to say that they are considered to be habitable by modern life if they exist. Many of the published papers say that. Robert Walker (talk) 13:50, 24 June 2013 (UTC)

Third opinion and attempt at conflict resolution

Having slogged through the majority of the discussion in the above eight topics (all of which basically constitute one ongoing disagreement; gentlemen, in the future, please try keep such content discussions orderly and compact - I've created my own thread only to avoid this not getting swallowed in the pre-existent mess) and having read through most all of the sources cited above which are readily available (and having read the abstracts of the remainder), it is my opinion that the position of BatteryIncluded (and the original wording of the content being debated) are more consistent with verifiability guidelines. Specifically, I agree that Robert's synthesis of disparate sources quite obviously crosses well into the territory of original research and that his original proposed text is not adequately supported by the citations given. However, I would like to further note that this is not a matter of whether his theory is fantastical or completely plausible -- the wording as proposed is simply just not reflective of any statement made in the source material, but rather is born of a series of educated suppositions on his part. Such suppositions could of course be included, were they themselves made within a valid source, but that is not the case here and it is not our role as editors to forge those connections. Rather our job here is to represent the exact statements explicitly made by sources and to do so as accurately as possible, adjusting the language only to make it accessible to a wide audience.

Putting a finer point on all of this, statements about the limiting factor of solar/cosmic radiation representing the commentary of appropriate sources should reflect only the specific statements made by the experts (that viable specimens are unlikely to exist above a depth of 7.5 meters bellow the surface) and not suppositions on how this limitation might not have applied to certain organisms in particular contexts (unless an appropriate source is found proposing such environmental circumstances). However, all of this said, Robert's most recent proposed edit adds only a statement that the brine habitat is a notion of interest to researchers. Provided that this statement is meant only as an addition and not to replace the entirety of the current second paragraph discussing the influence of solar radiation on such a proposed environment, then I see little harm in it, although both sentences in this addition seem to add rather little useful information.

As far as I can tell, this issue seems to be the prime point of contention, though there are places above where I lost the train of discussion some (not from lack of familiarity with the subject matter, but rather because of the way the discussion has been formatted, including some redacted comments that were removed in their entirety rather than struck-through). That being said, there is a side issue that should be addressed here:

WP:Original Research, and quite a few of his comments are inappropriate to any Wikipedia discussion, no matter how important the subject or heated the debate. It's true that Robert may have overstepped content guidelines in his pursuit of forwarding a specific idea, but even that disposition is vastly less of an obstruction to constructive editing than a tendency to denigrate fellow editors and opine on what you think their motives may be, rather than discussing content solely on the basis of its own merits and consistency with policy. And outright refusing to discuss a matter while actively engaged in a content dispute/edit conflict is really not an option here, not if one wants their arguments have any traction in general. On the other hand, given two editors have already broached the subject above and Battery's comments to Robert continue to evidence a huge amount of incivility, it is perhaps for the best that he doesn't interact with editors he doesn't agree with if he can't radically alter his approach in those circumstances, seeing as this type of behaviour is vastly more likely to result in community sanction than a little overzealousness with regard to content. Snow (talk

) 02:06, 5 June 2013 (UTC)

Snow, first, thanks for taking the care to read through it. I agree my reply was OR, now I have the chance to reflect on it. The problem with finding a source to cite to support my OR is that the experiments and theoretical work on habitability of present day Mars that I've read so far never mentions cosmic radiation, only mentions UV radiation. It seems to me that if it was a major issue then the papers that present microclimates of Mars as possible habitats for life, when discussing the various issues that might limit life, such as lack of nutrients, or UV radiation, would surely also mention cosmic radiation, discuss it, and talk about its relevance to habitability. But none of them do

For that reason I propose my second paragraph should replace his second paragraph, as a more accurate summary of the recent research on habitability of present day Mars, exactly as it is presented by the researchers. If the researchers in their papers do not follow these statements on habitability of these micro-climates with a refutation of habitability based on cosmic radiation, it is my opinion that wikipedia shouldn't do that either. So in that sense I see his second paragraph as also OR because it applies an old paper to recent research in a way that is not done in any of the recent research on the topic.

I believe the reason for the difference is because the recent research is research into habitats for living and reproducing life and the old paper is research into dormant life, however to add that as an extra comment without a cited source saying what I just said, I agree is OR. I recommend just replacing his second para with mine, which does not present an opinion either way on the effect of cosmic radiation on habitability of the microclimates for life. Robert Walker (talk) 10:11, 5 June 2013 (UTC)

Dear Snow, yes, after 39 pages long (screens on my computer) of R. Walker's denial of the biophysics at work in this universe, nobody is forced under any Wikipedia guideline to entertain such one-sided and unreferenced POV. His open mission to delete the published scientific research at hand, and obsession to introduce his POV & synthesis, should not be a burden to be imposed onto ANY editor in this encyclopedia. You are right in that the lurking readers deserve an apology from me. And I do apologize to them. I do not apologize to calling Walker's trolling behavior what it is.

The subject at hand is not a subjective issue like what are the most beautiful shoes worn by the British princess where one can debate it unlimitedly for weeks. Science is not a democratic alternative to the facts. As I said before, Walker is not disagreeing with me, but with the published and quoted research, so there is little I can do to alleviate his discomfort.

With regards to your request for me to keep to entertaining his bizarre behavior on a daily basis, respectfully, you are quite incorrect. As an editor and reviewer, I am very well aware of the policies and dynamics in this environment, and nobody is forced to edit or argue endlessly in Wikipedia. I have chosen to not respond to his obtuse POV and limit my interaction to editing the article itself from his POV, O.R. and synthesis -as needed. Feel free, however, to dance with him for another 39 talk pages if you feel you must do it. I'm out. Thank you, -

talk

) 18:36, 5 June 2013 (UTC)

This might help, because it is a video of an expert, a researcher into the habitability of the phoenix landing site and because it is my expertise that is questioned when I try to say that this or that paper is relevant or bring up quotes from the papers that I have read.

At 12.07 into the presentation after surveying habitability of the Phoenix landing site, she says

"Furthermore the site appears to be habitable in modern times. I assert that signatures of modern life are more likely to be found than signatures of life deposited millions of years ago"

https://connect.arc.nasa.gov/p433sesizp5/?launcher=false&fcsContent=true&pbMode=normal

Robert Walker (talk) 19:51, 5 June 2013 (UTC)

And as usual in all the modern paper and disussions, no mention of cosmic radiation, just UV, doesn't consider it while assessing habitability.

• Another third opinion:
  WP:CHEESE is clearly relevant to this situation. Why exactly is it that POV-pushing SPAs like User:Robertinventor suffered to exist on this project? Sławomir Biały (talk
  ) 21:46, 24 June 2013 (UTC)

Analogy: SPA user Robert Walker finds a paper that states that the 3 primary colors are 1-blue, 2-red, and 3-green. He then writes on Wikipedia that physicists have proof that red is the least important primary color, he invites all Wiki editors to see the video showing the numbered list in the reference, and swears by all the goats in Kerry that this very-notable-Nobel-winning-modern-research.

I do not feed that troll any more. -

talk

) 23:27, 24 June 2013 (UTC)

It is BatteryIncluded who is asking me to find a citation to prove that the life on the surface is not destroyed by cosmic radiation, to oppose his theory that it is. His theory is based on old papers that only refer to dormant life plus a quote of a researcher from a Daily Telegraph article which is not a reliable primary source for this as science researchers are sometimes misquoted in popular newspapers. I have read many papers on this subject from the last five or six years I've come across, and many papers say that these brine microhabitats on Mars are habitable, and not a single paper says that these microhabitats are made uninhabitable by cosmic radiation. I am just attempting to get some mention of this modern research by at least three dozen main authors in many different countries including USA, UK, Germany etc who publish papers every year on the subject. They held a major multi-day conference on the present day habitability of Mars in February this year. I write on many topics in wikipedia. BatteryIncluded has deleted all mention of potential habitability of these habitats. The material he deleted was added by other editors, especially in the Water on Mars page, where I only added a couple of sentences to a multi-paragraph section which he then deleted in its entirety and replaced with a section putting forward his OR that these liquid brines on the surface of Mars are uninhabitable. So the POV pushing is the other way around, there is a single editor engaged in a policy of removing mentions of this peer reviewed and notable recent research from Wikipedia based on his ideas that were valid six years ago. Robert Walker (talk) 00:04, 25 June 2013 (UTC)

FWIW this is what Encyclopedia Brittanica says about Life on Mars:

It could be argued that the best strategy is to look for fossil remains from the early period in Mars’s history when conditions were more Earth-like. But the Martian meteorite debate and disagreements about early terrestrial life point to the difficulty of finding compelling evidence of microbial fossil life. Alternatively, it could be argued that the best strategy is to look for present-day life in niches, such as warm volcanic regions or the intermittent flows of what may be briny water, in the hope that life, if it ever started on Mars, would survive where conditions were hospitable.

How, post Phoenix, can the wikipedia page on Life on Mars say that habitability of the present day surface of Mars is impossible. Which none of the present day researchers say in their papers. You can find papers pre 2008 that say this. Oh and BTW, back then, I had similar views to everyone else at the time. I changed my views as a result of this research. Oh and in the 14 point list of habitability factors, the researcher himself says in the video that they he ordered them by their importance for habitability, and cosmic radiataion is 10th. Robert Walker (talk) 03:43, 25 June 2013 (UTC)

Orphaned references in Life on Mars

I check pages listed in Category:Pages with incorrect ref formatting to try to fix reference errors. One of the things I do is look for content for orphaned references in wikilinked articles. I have found content for some of Life on Mars's orphans, the problem is that I found more than one version. I can't determine which (if any) is correct for this article, so I am asking for a sentient editor to look it over and copy the correct ref content into this article.

Reference named "Wall":

• From
  Gliese 581 g: Wall, Mike (2010-10-13). "Astronomer Stands By Discovery of Alien Planet Gliese 581g Amid Doubts". Space.com
  . Retrieved 2010-10-13.
• From Titan (moon): Wall, Mike (December 17, 2010). "Saturn Moon's 'Lake Ontario': Shallow and Virtually Wave-free". Space.Com web site. Retrieved 2010-12-19.

I apologize if any of the above are effectively identical; I am just a simple computer program, so I can't determine whether minor differences are significant or not. AnomieBOT⚡ 07:21, 6 June 2013 (UTC)