# Talk:Life on Mars

## Mars had oxygen-rich atmosphere 3.7 billion years ago

"Volcanism on Mars controlled by early oxidation of the upper mantle" http://www.ox.ac.uk/media/news_stories/2013/130620.html 217.89.117.154 (talk) 10:49, 24 June 2013 (UTC)

That is specified to be unrelated to biogenic oxygen. BatteryIncluded (talk) 13:02, 24 June 2013 (UTC)

## Methane

Hi all,

I have some concerns on the methane section here. It's not really giving fair balance to the possibility that there just isn't any methane on Mars. Note both the Mars and Atmosphere of Mars articles reflect this, but this article doesn't. Kevin Zahnle has been arguing (very convincingly too) there isn't any methane for quite some time based on the quality of the remote sensed data - predating the Curiosity measurements, see, e.g., [1] - and those first Curiosity measurements constitute a pretty convincing test of his hypothesis. I don't mind retaining what's here, but there definitely ought to be 1. at least acknowledgement of the hypothesis that there might not be any, and 2. a bit of a fairer rewrite on the Curiosity data: the key point is that it measured zero, and that 5ppb is basically the precision on the instrument. At the very least, there should be context that this value is NOT consistent with a simple interpretation of those remote sensed studies, and is way below what people (...other than KZ) thought there would be on their basis.

I'm happy to do this, but thought I'd check I wouldn't be rubbing anyone up the wrong way too badly before I do it. DanHobley (talk) 02:49, 15 July 2013 (UTC)

Hi Dan. I had not noticed that the criticism/balance was missing in that section. I promise you I won't file an ANI if you fix it without previous RfC.  ;-) Cheers, BatteryIncluded (talk) 03:09, 15 July 2013 (UTC)

## Earth life may have come from Mars.

Would this information be deemed valid enough to include in the article? [2] 149.254.56.250 (talk) 21:31, 29 August 2013 (UTC)

It would be more accurate to say that one scientist speculates that some RNA came from Mars. BatteryIncluded (talk) 14:03, 30 August 2013 (UTC)

## "Mars Sample Return Mission " entry in the "Future Missions" section:

This entry's title links to wikipedia's entry on the US's Mars Sample Return Mission at:

http://en.wikipedia.org/wiki/Mars_Sample_Return_Mission

That entry's text reads as follows:

"The best life detection experiment proposed is the examination on Earth of a soil sample from Mars. However, the difficulty of providing and maintaining life support over the months of transit from Mars to Earth remains to be solved. Providing for still unknown environmental and nutritional requirements is daunting. Should dead organisms be found in a sample, it would be difficult to conclude that those organisms were alive when obtained."

Not only is this is a statement of somebody's OPINION (as distinct from a recitation of verifiable facts), it is an opinion about sample return missions IN GENERAL rather that having anything specifically to do with America's proposed Mars Sample Return Mission. As such it is misleading and irrrelevant and so should be either replaced with more relevant text or removed. 122.150.41.79 (talk) 18:44, 18 November 2013 (UTC)

Hello. I have not seen he source of that statement, but when looking for biosgnatures in a sample, the issue is quite relevant. It may not be an issue to geologists only interested in its mineral content, but the process must facilitate the return of as much information as possible. Cheers, BatteryIncluded (talk) 19:03, 18 November 2013 (UTC)
I haven't seen any mention of this suggestion to try to maintain life support during return in the literature and with no citation given, the source used by its author can't be checked.
In the usual sample return proposals, the sample would contain Mars atmosphere at Mars atmospheric pressures. However no other attempt is made to keep to Mars temperature cycles or replicate the environment exactly. The thing is, that most microbe species on Earth can't be cultivated, typically only 1% of cells in any environment will replicate in culture medium. So the chance that any Mars life form can be cultivated may also be low.
I have seen it stated the other way round however, as a motivation for analysing the sample as quickly as possible. For instance, proposals to return a Mars sample to Mars orbit and analyse it there give as an advantage that it is less of a transition for any life in the sample.
I have an issue with "The best life detection experiment" as this is controversial and should be presented as an opinion attributed to a source rather than an absolute truth.
A group of 8 exobiologists submitted a white paper to the Decadal review saying the opposite. They said that a Mars sample return, while interesting for geologists, is likely to return a sample no more interesting for biology than the Mars meteorites we already have. They advised that we should send biological detectors to Mars instead.
ExoMars will be the first to do this since Viking, first mission since then to send purpose designed biosignature detectors to Mars. But the search for life on Mars, just begun, is likely to be long and difficult. Past life is sterilized by the ionizing radiation over billions of years and broken into fragments, and over hundreds of millions of years amino acids are also broken down, and some oxidizing process also acts to destroy the organics. Present day life would be able to survive only in rare locations on Mars, and also is likely to be in such sparse populations at those locations, in scattered patches, like the populations in the Atacama desert and in the McMurdo dry valleys, that it would be a challenge to find life even when you find a suitable area.
For those reasons, they concluded that a sample returned from Mars is unlikely to contain either past or present life unless you already know that it has life through biosignature detection. Detection of organics is not enough because it can be delivered by meteorites. Certainly a negative result from such a sample proves nothing at all. In the very remote chance of a positive detection of life, it would prove something but they think that the chance that would happen is very low indeed if the sample is not already known to contain life.
See Seeking signs of life on mars: in situ investigations as prerequisites to sample return missionsRobert Walker (talk) 11:57, 25 January 2014 (UTC)

## Warm seasonal flows section is inaccurate

The footnotes refer to papers on Bright Gulley Flows as reasons for supposing these are not flows of water. That is a different phenomenon. The warm seasonal flows are dark, not bright. AFAIK there aren't any other alternative hypotheses for these flows. They don't fit dust flows because they only occur on equatorial facing slopes, are seasonal, and only happen when the temperatures are above OC. Those three things together strongly point towards some form of liquid water as the only viable hypothesis.

This is mainstream, not fringe, it was a subject of a recent article in Nature for instance, Water seems to flow freely on Mars, note that it doesn't give any other hypothesis except for liquid water and I know of no recent paper that suggests any other hypothesis for them.

It is a challenge to get the models to work for liquid water, but on the other hand the warm seasonal flows are rare and probably represent some rare combination of circumstances, such as geothermal heat, or unusual chemistry and geology, and various hypotheses have been suggested that could make them work. Robert Walker (talk) 12:10, 25 January 2014 (UTC)

Hello, I believe you are familiar with this subject. If you have the time, would you please please check the request above and correct the article section as needed? Thank you, --BatteryIncluded (talk) 15:39, 15 August 2014 (UTC)
Just to say - that section is still inaccurate, confusing three or four things that are nowadays understood to have different causes. All the published alternative theories at present for the warm seasonal flows involve liquid water in some form - because of the conditions in which they form, above 0C on sun facing slopes, and correlated with the seasons and not at all correlated with the winds. These differ from the dark gully streaks (thought to be avalanches of dry sand) and the linear gullies. And the newly formed dry gullies are now thought to be formed by dry ice, although some of the older ones were probably formed by flowing water at times in the recent past when climate conditions on Mars were more favourable for flowing water. Robert Walker (talk) 14:21, 27 July 2015 (UTC)

### Present day habitats for life on Mars

First, for UV: as with ordinary light, a shadow is enough to shield from UV, and since they are beneath the surface, UV wouldn't get to most of them at all. For the layers close enough to the surface then the UV is a benefit as it could be used for photosynthetic life, sheltered from the UV by a thin layer of dust, but enough light filters through to use for photosynthesis. Also some forms of life may be able to survive and metabolize using the surface UV, lichens anyway, in partially shaded conditions, and also some cyanobacteria, as in the DLR experiments mentioned on the page.

But most of the layers would be at least a cm or so below the surface, because it is hard to keep the salts liquid for long right at the surface, temperatures are too high and the liquid evaporates again too quickly. The life would use chemical sources of energy e.g. the perchlorates. Typical temperatures would be well below -10C, still tolerable for microbial life.

For ionizing radiation, then yes that's sterilizing over tens of thousands of years but microbes just need to survive one winter, not tens of thousands of years. That's supposing that the habitats have been continually habited. The other possibility is that life in them retreats to caves and underground at times of high axial tilt if these habitats are no longer present.

Yes water activity is an issue, and you need the right balance of salts. The big question for the sub surface brines is exactly this. Yes almost certainly there must be water on Mars sub surface, now that we've discovered suitable salts to deliquesce - but do any have the right mixtures of chlorides and sulfates and perchlorates to get the right water activity levels for life to be able to use it? That's the big question which nobody knows the answer to yet. If it is possible then it is quite possible that it happens only for scattered areas over the surface of Mars, where the concentrations of salts happen to be just right to create suitable habitats for life.

Another thing to mention, it's no longer believed that past water on Mars was too salty or too acid for life to be able to use it. Curiosity has discovered good evidence that conditions were far more habitable than previously thought. For the latest and best evidence it found, see Martian freshwater lake may have supported life - NASA.

Also another significant possible habitat not mentioned on this page is the solid state greenhouse effect. You can get a thin layer of liquid water below a layer of ice in the polar regions. [3]

This is a good recent (2013) overview of the research on possible water habitats on Mars which looks at just about all the possibilities to date, likely or unlikely. Water and Brines on Mars: Current Evidence and Implications for MSL There are other features on Mars that may be caused by liquid water as well but they have alternative explanations such as dry ice effects.

### The three ones most likely to be liquid water are

• warm seasonal flows, which have no other good explanation at present
• deliquescing salts supported mainly by the droplets on Phoenix's legs and the observation of suitable salts to deliquesce on Mars
• subsurface melts caused by the solid state greenhouse effect, which is a possible explanation for some features such as the dune dark spots. Seems that this should happen on theoretical grounds, that the sunlight should create melt water below sheets of transparent ice, but no feature on Mars has been conclusively identified as caused by it as yet.
Please do not feed the trolls. --BatteryIncluded (talk) 14:26, 28 January 2014 (UTC)

Glad to see the subsurface brines from deliquescing salts are mentioned. But ionizing radiation is not an issue for these, nor is UV. Your references are to papers written in 2007 which is before the Phoenix lander in 2008 - which changed ideas about the possibility of life on the surface of Mars. That included:

• droplets on its legs which coalesce, grow, and fall off - with most straightforward interpretation as salty water droplets forming through deliquescence of salts thrown up on its legs from the surface.
• discovery of salts which theory suggests should deliquesce to make droplets like that in the 100% night time humidity on Mars
• Isotope measurements showing that there is something on the surface which has exchanged oxygen with the CO2 in the geologically recent past
• Discovery of warm seasonal flows, which have no alternative explanation at present except flows of some liquid that melts at around 0C, most likely water.

It is easy to find plenty of references like that from 2008 or earlier - but after Phoenix and its results about possibilities for liquid water on the surface of Mars that changed everything. Now, the microbes just need to overwinter for one year not for tens of thousands of years.

Before 2008 what you wrote would be accepted by everyone. Now they would be accepted by almost nobody up to date with the most recent reasearch, as things have changed so rapidly in this field.

(Please don't remove this. I've restored just my own criticism this time, as if you want to delete your replies then fine but please don't delete what I said. I will keep restoring this as I don't think you are justified in deleting it)

Please note - these are not my opinions. It's just a summary of some of the recent results in papers published in the last 5 years, and I can give citations for anything here if you have questions about it.

Robert Walker (talk) 19:29, 27 January 2014 (UTC)

### Lacks plate tectonics or continental drift

Aren't there any scientists trying to find out if plate tectonics and continental drift are actually essential to sustaining life? Isacc Asimov wrote about a theory that a huge planetoid collided with Earth. If that wasn't hostile enough to life on Earth the remnants of this planetoid stayed in orbit to gravitationally tug Earth's oceans back and forth constantly. If even that wasn't hostile enough, that planetoid gravitationally tugged back and forth on the surface until a liquefaction type process ensuring an constant flow of radioactive materials to the surface to bombard life with harmful radiation. The result of all this hostile action was of course Earth moon and the rapid development and adaptation of life. Just saying, the very things that some people are hoping Mars has to preserve evidence that is supported life could be the very same things that ensured it could never have supported life. — Preceding unsigned comment added by 74.197.244.98 (talk) 20:42, 29 April 2014 (UTC)

Well one idea for reason for development of multi-cellular life on Earth is that it happened as a result of the snowball Earth phase - could be coincidence but first good evidence for true multi-cellular life is immediately after a snowball Earth phase. If so, then early Mars, after it cooled down, is thought to have had many snowball Mars phases followed by global melting again, with evidence for this early flooding still preserved in eskers near the poles. Could even have been freezing and melting of the entire ocean at two yearly intervals when it's orbits are more eccentric, and at longer intervals when its orbit was more circular.
The early Mars and Earth were similar, in many ways - even after impact by the Moon. Earth had a dense atmosphere like Venus, and the seas were well above 100C. Both had plenty of nitrates created by the giant impacts.
There are many theories for origins of life, so of course depends what is your preferred theory. If you think huge tides are vital for origins of life, then that's a reason for favouring Earth. Most of those though would work on early Mars also, especially for instance one of the most favoured ones, hydrothermal vents. And in the early solar system then there was constant exchange of material between the planets through the late heavy bombardment. Some think life might have started on Mars, or on one of the asteroids such as Ceres. Wherever it started, it could then spread through the solar system if it evolved far enough to be as space hardy as some modern micro-organisms.
Lack of plate tectonics is a serious problem for later Mars of course, probably main reason why the atmosphere is so thin now. But for early Earth and Mars, most of the CO2 was still in the atmosphere, and the two planets could have been very similar though Earth probably had a lot more water than early Mars. The early Mars seas were shallow but extensive. That could be a benefit in either direction for origin of life, just depends where you think it originated.Robert Walker (talk) 11:03, 14 May 2014 (UTC)

### Life on Mars surface revisited

BatteryIncluded, I know you think I am a troll for saying that there is a possibility of life on the surface of Mars, and have hidden my replies above including references to cited recent papers and conferences on this topic.

But do you think Robert Zubrin is also a troll? Surely not. Yet he also said he thinks there probably is life on Mars, in a recent Space Show talk. See here, where he caused some surprise by saying that he thinks it is quite probable that there is life on present day Mars Guest: Dr. Robert Zubrin - see in the summary where it says " I asked him about life on Mars. Bob thinks there probably is life on Mars, don't miss what he had to say about this" - do have a listen to the show. It might get you to re-evaluate a few ideas? Robert Walker (talk) 20:52, 1 June 2014 (UTC)

If you want to call me a troll for saying this and hide this post, fair enough. But you need to give me some good reasons for it, not just dismiss my posts and hide them, if you want to change my views on the subject, or the views of others like Robert Zubrin as well as the many researchers who have now said this in print. Robert Walker (talk) 20:52, 1 June 2014 (UTC)

His opinion is not data. Neither is yours. BatteryIncluded (talk) 19:04, 2 June 2014 (UTC)
Okay. I thought opinions might be a help as I've already posted plenty of data. But if not, well leave it at that Robert Walker (talk) 22:47, 2 June 2014 (UTC)
Just to say - your opinion is not data either of course, and the whole article is slanted in direction of your opinion on the possibility of life on present day Mars. I mentioned Robert Zubrin as one of the perhaps least likely people, you'd think, to say this - have already linked to scientists who say life on present day Mars is possible who are experts in the field (in now archived sections of this page) - for summary see for instance 'Mars may be habitable today. You are of course entiteld to personal views that you don't think they are correct - but it is undoubtedly a view held by some experts in the field and so should be mentioned in wikipedia.
It should also be made clear - that this is informed expert opinion by some scientists researching into habitability of Mars - that present day life on Mars is possible.
You won't find a single present day informed review of the subject (i.e. by specialists on this topic) in the last few years, since about 2008, that says that life on the surface of Mars is impossible because of cosmic radiation. Your proof in this article that it is impossible based on dormant micro-organisms doesn't work for micro-organisms that are able to reproduce at least once every few thousand years, as would be the case in surface habitats. It is also original (or at least, out of date) research as you won't find a present day article that argues this way.
And it is incorrect to say that there is no liquid on the surface of Mars. The only accepted models for the rare warm seasonal flows involve liquid water. And the Phoenix carbon and oxygen isotope measurements proved conclusively that there is liquid water on the surface of Mars at least sporadically in recent geological time and quite possibly all the time. Indeed that's the reason for the change in scientific opinion since 2008. Before 2008 there were a few scientists who said that life on present day Mars is possible on the surface and in caves - but they were a minority, and most argued exactly as you do in this article. Since 2008 and especially since 2010, then it is a commonly held view amongst experts on habitability of Mars that life on present day Mars is possible.
Trying again as the article is inaccurate and has been so since the paras on possibility of present day habitats for life on Mars that I and others contributed to were deleted over a year ago. I know any attempts I make to edit it will be reverted or I'd edit it myself right away. Robert Walker (talk) 07:47, 18 July 2014 (UTC)

I know you will always be in denial and will keep trolling this article. Continuously denying the papers/references published 2008-2014 that are cited here does not make them go away, and does not make Martian dragons on the surface any more likely. Cheer, BatteryIncluded (talk) 16:13, 18 July 2014 (UTC)

I don't deny that there is cosmic radiation on surface of Mars - or that dormant life would be sterilized within a few thousand years. But that is not enough to prove the thesis you advance in this article. With liquid water and with life able to reproduce, even with individual lifetimes of a thousand years (as happens in the McMurdo dry valleys) - then cosmic radiation is not a problem. If you want to represent the current understanding of the subject accurately - you should make this clear if you want to retain the material - that your conclusions do not apply for life that revives within the 18,000 year time period and reproduces - and also make it clear that present day understanding suggests possibility of habitats that will permit life on Mars to revive and reproduce even every year (in case of the warm seasonal flows). And - the likes of Chroococcidiopsis doesn't even have to reproduce. If it wakes up and metabolizes for a few hours every few years - that would be enough to keep its DNA free of defects, as it has the remarkable ability to repair damage to its DNA as it occurs. Here for instance, 2.5 kGy of damage is repaired within 3 hours in metabolizing Chroococcidiopsis. Curiosity measured 76 mGy per year at the surface - so 2.5 kGy corresponds to 2500/0.076 or over 32,000 years of radiation so if it wakes up for an average of 3 hours every 32 years that would be enough to keep it free of damage from cosmic radiation indefinitely - which shows how resistant some extremophiles can be.
And - the bottom line is - that it is not my opinion, but a considered opinion by many researchers in this field, which is currently not represented in this article. Yes, I think I will keep returning to this from time to time, maybe every year or so, in hope that some time the article will get corrected as a result - that's my reason for posting. Robert Walker (talk) 21:05, 18 July 2014 (UTC)
So, if you could contaminate Mars with Chroococcidiopsis, they suddenly become Martians?!? Then if I throw a pizza on Mars' surface, you will conclude there are Martian pizza makers on Mars? Please...
The flat Earth "opinion" also goes around, but it doesn't mean it deserves mention. Some "scientists" state that the Earth is 6,000 years old, you want to expand on that BS too? When your physicists say there might be thin temporary liquid water films on Mars' surface, the biologists do the reality check: Maybe, but water is not the only requirement (nor protection) for life. Stop making up BS and just read the in situ results obtained by Curiosity rover on organics, surface water and radiation, then do yourself a favor and snap out of it. BatteryIncluded (talk) 23:28, 18 July 2014 (UTC)
I chose Chroococcidiopsis here because the DLR experiments in Germany showed that it can survive and metabolize in simulated Mars environments. We don't know for sure- just a one month experiment - but it may be able to survive on Mars just using the night time humidity. It is one of a few extremophiles on Earth that may be reasonable analogues for Martian lifeforms. It is a primary producer also, and has minimal requirements - mainly - water and CO2. On the Earth it sometimes occurs as a complete single species ecosystem in the Atacama desert - so could do the same on Mars. Another one is halobacteria - similarly a primary producer and able to form a single species ecosystem - which is able to tolerate high levels of salt and also is a polyextremophile with UV and cosmic radiation resistance. This means - that potentially they could contaminate Mars - and also means - that Martian life could potentially be adapted to these conditions. They are resistant to cosmic radiation and high levels of UV probably mainly as a side effect of desiccation resistance (at least that seems to be the prevailing current view) - and moderate UV resistance on the Earth. On Mars similar micro-organisms would have adapted specifically to cosmic radiation and high levels of UV and may be even more resistant to them.
Nitrogen is in short supply on Mars - and may be an issue, is the main requirement for life that I've seen quoted as an issue for life on Mars. But it is also in short supply in the McMurdo dry valleys - and Mars does have some nitrogen - both in its atmosphere - and also delivered by meteorites - and Curiosity has found nitrates on Mars. So that doesn't rule out the possibility of life on Mars though may limit the locations where it can occur.
As for the origin of life - as you say in the article - there are ideas that early Mars oceans may have been permanently ice covered most of the time (just one of several different hypotheses) - only melting occasionally. But go way back - and the oceans were above 100C same as for the early Earth oceans - with a dense Venus like atmosphere - again same as for Earth - and with nitrogen in the atmosphere and nitrates created by impacts. So - life could easily have originated on Mars and some think Earth was originally seeded by Mars life. Again - your article seems to present only one hypothesis here - when in fact - there are many different ideas without enough data yet to decide between them. If life evolved on Mars and got to the stage where it is as robust as Earth life - it could still be there. Survive underground through the very coldest spells - but at present then there may well be habitats on the surface, and if so the life could be there also. If seeded by Earth life - then the exchange of life could have happened billions of years ago in the early solar system - so plenty of time to diverge to create new life forms on Mars in the different conditions there.
This is not a minority view by fringe scientists. But a view held by respected scientists. Not all - you can find respected scientists who think there is no present day life on Mars also. Just saying this is a point of view on the subject that should be represented in Wikipedia and not ignored. There are areas of science where you don't have a consensus but a variety of different views - usually because there is insufficient evidence to decide the matter.
This is one of them. We have insufficient evidence because there have been no exobiological rovers sent to Mars since Viking. ExoMars in 2018 will be first to be able to search for biosignatures in the tiny concentrations expected on Mars - and it is searching for past life. It will be a while after that before we can send similar rovers to search for present day life on Mars because of the sterilization issues - and because the most promising sites are also hard to access (e.g. high lattitudes or on steep slopes etc). In those situations wikipedia should not present a unified point of view as if everyone had the same ideas on the subject - but should present all the accepted scientifically valid points of view on the subject. That's all I'm saying. Whether they are right or not is something that we will find out in the fullness of time. Robert Walker (talk) 01:13, 19 July 2014 (UTC)
And BTW it's not trolling to say something you believe to be the truth, to the very best of your ability as a result of research into the literature on the subject. And with the intention to correct an article you believe needs correction rather than with any wish to start an argument for its own sake. Robert Walker (talk) 01:53, 20 July 2014 (UTC)
It is trolling to use this Wikipedia talk page as your Truth blog #2. You know I simply don't take your bait nor entertain your Martian dragons fantasies. Rest assured I just don't read your long-winded pseudo-scientific monologues because you are using Wikipedia as soapbox exposure of your armageddon hysterics on the imminent Martian invasion. If the administrators allow you to continue, fine, but I will keep deleting your fiction, fringe, junk and hysterics from this article. Cheers, BatteryIncluded (talk) 14:35, 20 July 2014 (UTC)
I haven't added anything to this article, since you deleted that whole section last year (which I only contributed a couple of sentences to in the first place, most of it was written by other wikipedians).
And talk pages are for discussion of the content of the article so everything I said here is to the point - may be too long for you to read, but it is all totally to do with attempt to improve the article to best of my knowledge.
I can't see how I can reply to your insults and accusations in any detail without re-opening the old debate about the "Concerns for a Mars Sample Return" article which was deleted last year - don't want to do that. And - you have just said you won't read what I say anyway. Did write a reply - but have deleted it again - what's the point if you won't read it? Doesn't work anyway - the more I try to answer in a reasonable way then the more you get upset by it and insult me more.
That's not what I'm trying to do here anyway, not trying to reinstate that article.
All I'm trying to do here is simply to get this page updated to include the latest research on the possibilities of past and present life on Mars, and the views of many researchers that it is possible. The views can be attributed - maybe good if they are - say that so and so in such and such a paper says such and such - and make it clear as one should, that there is not enough evidence to decide the question either way at present - and leave reader to draw their own conclusions.
But to simply leave it all out?
How can an article in an encyclopedia say that there is almost no chance of life on Mars - past or present - when past life especially is the main motivation behind the Curiosity and ExoMars missions to Mars - and future missions hope to search for present life also - and many papers get published each year on the best places to go on Mars to look for past or present life, and other papers written on the possible forms that Martian biology could take - and much work done by dozens of scientists whose life work is to make the best possible instruments to search for it? Why do you think they do all that work and design those instruments and spacecraft, and send those missions to Mars, and write all those papers?
What you wrote here (with some corrections) could do service as an opinion piece by someone who is already almost certain that these searches will turn up nothing - there are a few still who think that way. But as an encyclopedic survey of the field... I am not at all trying to annoy you - so this is not trolling. Just stating what I see as the situation and hoping to correct what I see as a bias in the article which you don't seem to see as a bias yourself. I understand of course that you think I am biased for wanting to include this material. Which leaves us at an impasse, and probably not much one can do about it, but I hope you can see my integrity - that I'm writing this in good faith with the aim to improve wikipedia! And the material I wish to include in wikipedia is generally regarded as neither fringe or particularly controversial so that's why I question your editorial decision not to include it. Robert Walker (talk) 09:50, 22 July 2014 (UTC)

My detailed reasons for suggesting these corrections have all been hidden as "soap box".

But thought it might help to list them briefly as suggestions for others to discuss, without giving my own reasons and citations. If interested you can find in the hidden sections above.

• Article confuses warm seasonal flows with other unrelated phenomena. They can't be wind or dust storm features as they do not form during dust storms. They are not correlated with any wind or dust storm pheonomena - and are strongly correlated with temperature, only form above 0C. The long list of citations given in the article about wind formed streaks are about various other unrelated features.
• Article says that cosmic radiation thoroughly sterilizes dormant life in the top few meters. This is true, but beside the point - as life in surface patches of damp regolith would not be dormant, not all the time. The most radioresistant organisms on Earth can repair damage of several millennia worth of Mars radiation. Or if intermittently metabolizing, need just a few hours of metablizing to repair damage caused by decades of cosmic radiation on the Mars surface.
• UV light similarly can be resisted by extremophiles - and is also easily cut out by just a mm or so of covering soil. Cyanobacteria in the DLR experiments can survive weeks of Martian simulated UV - because of protective pigments.
• These are adaptations Earth microbes evolved in order to resist dessication - not to resist cosmic radiation as such. Martian microbes are likely to be more radioresistant than this.

This list of points is not original research in any way. You can find out more about it all in many scientific papers. And was a major conference about these topics last year on The present day habitability of Mars.

Please don't hide this. And please just don't say that what I say has to be incorrect because you happen to know that I am also concerned about the effects of returning samples that may contain viable Mars life to Earth. I am concerned about that because of this research that suggests that there is life on Mars. It's not the other way around. I didn't start off concerned about a Mars sample return - and then try to show that there was life on Mars to justify that concern!

I think this will be the last I will write here for some time. So - if you want to insult me or say all of this is pseudo science or whatever - well I won't reply any more. But others may be interested to discuss it. Robert Walker (talk) 11:41, 23 July 2014 (UTC)

-

### ExoMars objective to look for present day life on Mars

Just spotted today, that one of the stated prime objectives for ExoMars is to clearly stated, to search for past and present day life on Mars. It's stated in its Call for Landing Site Selection from 2012.

"The ExoMars Programme’s scientific objectives are:

• To search for signs of past and present life on Mars;
• To investigate the water/geochemical environment as a function of depth in the shallow subsurface;
• To study martian atmospheric trace gases and their sources;
• To characterise the surface environment.

"

I've given many other citations in the sections above hidden as "soap box" - but surely this is so unambiguous a statement that you can't hide this? Especially as it is the mission objective for the next mission planned for Mars. Also could be worth stating in the article that ExoMars has this as its objective. Please, please don't hide this as soap box. If you disagree - well let others comment if they wish. Robert Walker (talk) 10:06, 29 July 2014 (UTC)

This is another example of your Martian Invasion Cover Up hysteria; you are a liability to Wikipedia. For your information: 1) ExoMars (and the 2020 Mars Rover) will look for microbial biosignatures BELOW the surface. Years ago we documented and sourced in this WP article that the best chance to find biosignatures or current microbial life on Mars is at the subsurface, so there is no cover up. 2) Habitability ≠ inhabited. 3) Martian soil samples will NOT turn humanity into flesh-eating zombies. BatteryIncluded (talk) 15:33, 29 July 2014 (UTC)
Okay, I'm asking something far simpler than what you seem to think I'm asking for here.

All I'm suggesting here is that you put something in the article similar to the corresponding article in Encyclopedia Brittanica - the sentence in bold at the end.

"Despite this setback, the main driver of the Mars exploration program is still the search for life. Because liquid water is so essential for life, the initial focus has been on the search for evidence of warm conditions that would enable the persistence of liquid water. The evidence for such conditions at least on early Mars is now compelling, and there is some evidence that liquid water sometimes flows on the surface in a few places. The exploration thrust will likely shift to search for more-direct evidence such as organic remains and isotopic signatures. 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."

(from The question of life on Mars - Encyclopedia Britannica ).
It's a much shorter article, doesn't go into the details of this one - but at least it does acknowledge that there is some evidence for liquid water occasionally flowing on the surface of Mars, and that some scientists are interested in looking for present day life on Mars in these niche surface habitats.
If you had a sentence somewhere on your page like that, then it would be representative of present day scientific opinion. Not that life is in those habitats, nobody can know that, not even that those habitats definitely exist as they haven't yet been confirmed - but that it could be argued that those habitats are the best place to look for present day life, or at least - to acknowledge that it is a possibility that there is life in them, and that there are scientists who suggest they may be the best place to find present day life on Mars.
Other possible views, as you say are that deep underground habitats are the best places to look, and another possible view is that we will only find past life because it has gone extinct since then. Or that we won't find any life, past or present. There is no way to decide this until we look.
I get what you are saying, though - okay that what I just gave here, the ExoMars mission objective is not convincing to you because you think they are only looking for deep down life
That hadn't occurred to me as a possible interpretation of their mission objective statement - since they are not digging deep enough to reach geological hot spots or the hydrosphere (some kilometers down). I do agree that their main objective is to look for past life - they are not able to target areas likely to have present day life.
Not at all saying that habitable = inhabited - of course not. That's the big question, first - do these possible habitats actually exist (not yet confirmed) - and if so - are any of the possible habitats inhabited - and if so - which ones?
And not saying anything about a conspiracy! I'm not at all inclined to believe in conspiracies, all I see here is one person, who doesn't want to include any mention of scientific research into potential habitats for present day life on Mars in this article. Why, I don't know. And last year there was another wikipedian who felt strongly that there should be no mention of the possible dangers of a Mars sample return and got my article on the subject deleted. Two wikipedians whose views were influential enough to get a lot of material removed from wikipedia - but two people don't make a conspiracy :).
As for hazards of a Mars sample return, that's not material for this article particularly - but - it's been subject of quite a few papers, including one by the notable microbiologist Joshua Ledeberg, and assessments of hazards of Mars sample return in both the US and ESA going into it in some detail. That was the material that I wanted included in wikipedia in the big debate last year. It is not at all as absurd as you seem to think. Just because it occurs in sci fi. stories - doesn't mean it can't happen in real life. With Carl Sagan, Carl Woese, and Joshua Ledeberg all writing about it - how can you call it hysteria?
And certainly not my own views on the subject, such as they are. I have written about my own views in my blog, and may some day write them up as a paper and try to get that published. That is how I would proceed if I wanted it published. Here on Wikipedia my only objective is to get some of the published and accepted research included in the encyclopedia. Robert Walker (talk) 21:45, 29 July 2014 (UTC)
Here's 25 cents. Call somebody who cares about your fringe blog. I do not entertain trolls. BatteryIncluded (talk) 22:44, 29 July 2014 (UTC)
Oh well, maybe one day Wikipedia will catch up on Encyclopedia Brittanica on this topic :). I will keep trying maybe a year from now, or if I come across something that even you can't deny.

### Breaking news (July 2nd) suggesting widespread habitats for present day life on Mars subsurface and surface

At the end of this video the scientist says very clearly

"Based on the results of our experiment, we expect this soft ice that can liquify perhaps a few days per year, perhaps a few hours a day, almost anywhere on Mars. So going from mid lattitudes all the way to the polar regions. This is a small amount of liquid water. But for a bacteria, that would be a huge swimming pool - a little droplet of water is a huge amount of water for a bacteria. So, a small amount of water is enough for you to be able to create conditions for Mars to be habitable today'. And we believe this is possible in the shallow subsurface, and even the surface of the Mars polar region for a few hours per day during the spring." (transcript from 2 minutes into the video onwards)

That's a verbatim word for word transcript. Not at all quote mining, it is exactly what he says - try listening to the video yourself, it won't take more than a few minutes of your time..

That's Nilton Renno, a professor of atmospheric, oceanic and space sciences at Michigan University who lead the research. See also Martian salts must touch ice to make liquid water, study shows

Robert Walker (talk) 13:00, 1 August 2014 (UTC)

Trying once more with breaking news of possible habitats for life widespread on Mars

There are now numerous news stories about it. Not one of them says that the life is impossible because of ionizing radiation.

I've already given the reasons many times, why it is not impossible. That the levels of cosmic radiation on the surface of Mars are similar to those inside the ISS. That is enough to give humans cancer with years of exposure. Even humans are not killed instantly in the ISS and would not be killed instantly by cosmic radiation on the surface of Mars.

Many microbes far more resistant to ionizing radiation than humans. Some can even survive in reactor cooling ponds.

They just need to wake up for a few hours every few decades to survive the levels on Mars. It is sterilizing over billions of years, and even over millions of years, but not over years or centuries.

Please point to a single story or paper or any reliable account of this new discovery that says that the assertion made by the professor must be incorrect because of ionizing radiation!

Some news stories

Why is Wikipedia the only available online source of information about Life on Mars that says that present day life on the planet is impossible because of ionizing radiation?

You can find news stories that say it is impossible prior to 2008, and papers also - but they all are talking about dormant life because back then they thought there were no possible habitats for present day life on the surface of Mars.

Please, please update Wikipedia to mention this possibility. It is crazy to not mention it at all. Robert Walker (talk) 17:57, 4 August 2014 (UTC)

It is unbelievable you are not able to hold your fiction novels to yourself and how your quote-mining supports your own Martian Invasion histeria. We went over this one hundred times! Yet you ignore and reject the references cited as "outdated". The one-year long in-situ radiation measurements by the Curiosity rover indicate that even the most known radioresistant bacterium Radiodurans was to be provided with the environmental conditions for periodic reanimation for self-DNA repair, it would need to reside at a "minimum of 2 meters deep below the Martian surface." ("Mars' surface radiation environment measured with the Mars Science Laboratory Curiosity's rover". Science. November 2013.) I am not willing to teach you, nor am willing debate NASA's result and conclusion published in November 2013. So just stop your trolling and your ignorant amateur assays. I'd love to start proceedings to ban you from Mars-related topics, but you are not worth that effort. Sincerely, BatteryIncluded (talk) 19:41, 4 August 2014 (UTC)
Okay so I can only reply in hidden areas of the page now. Anyway - yes - but periodic reanimation there is every few tens of thousands of years. Present day life on Mars would be reanimated every year!
It would need to be 2 meters deep if it is only reanimated every few million years. Where do you have a link saying radiodurans would be sterilized within a year? It doesn't make sense. You can just look up the Curiosity surface measurements, is easy to find them - and the measurements of the radiation inside the ISS - and they are similar. And add up to see how much radiation Curiosities reading provides and how many centuries it would take for Radiodurans to accumulate a lethal dose if dormant.
And how do you explain that some people are considering sending humans to the surface of Mars - when it is so lethal that it kills radiodurans. A spacesuit is no protection from cosmic radiation. If you were right this should go on the colonization pages as a prime reason why colonization of Mars is totally impossible.
What you say does apply to Jupiter. Could you be mixing up Europa with Mars? A human could only last a few hours on Europa. Radiodurans could survive longer, but not for very long. But that's because Europa is so close to Jupiter and gets far higher levels of ionizing radiation than Mars.
Simply doesn't apply to Mars. Any amount of repeating what you said doesn't make it so, and insulting me and saying that I don't know what I am saying with no reply to these points ever - you only ever replied to this with insults, no explanations.
Why is nobody else saying this if what you say is true? Why is this wikipedia page the lone voice saying this. It's not the place for wikipedia to present private theories - it should present the consensus of present day opinion, and here it is just obvious that it is not.
Once again why is nobody saying this in their newspaper stories, what you say, that what this professor says must be false. That's what you are saying - is it not. Are you saying that what he says in the video is deluded? Or what are you saying? It's not quote mining. It's exactly what he said - and what all the newspaper reports report him as saying. Just try listening to the video and reading the stories - can you understand him any other way? I also did a verbatim transcript also - which is clear and unambiguous - and not edited - word for word what he said.
I can find numerous papers that talk about potential habitability but you don't read the refs when I provide them here, but this is just so clear, I don't see how you continue to deny it!
What would count, for you, as sufficient evidence to accept that there exist experts in this topic area who think that the surface of Mars is habitable? What do they need to write in their papers or say their interviews? Or is there nothing they can say that you would accept as evidence that they believe that Mars is habitable? Robert Walker (talk) 21:36, 4 August 2014 (UTC)
As for banning - if I get banned from posting to Mars talk pages because of posting something obvious like this that everyone in the field accepts except you - and just to a talk page mind you - not even editing the page itself - and just saying something that everyone accepts - including exobiologist friends - my opinion of the way the Wikipedia's Mars section is managed will go right down to rock bottom. It is already very low after the debacle last year, when it became clear to me that nobody here has the time to check citations and give them more than a cursory glance. And that pages can be deleted just because a whole bunch of people who know nothing about the subject and have never edited the Mars section of wikipedia before get convinced by rhetoric on the deletion discussion page - when it is absolutely clear that none of them have read the article or its citations. Robert Walker (talk) 01:23, 5 August 2014 (UTC)

### Proposed Edit and Article

I thought, only fair to say, I've written this up as an article for Hank Cambell's Science_2.0 site, where it is currently featured as the top article for "Physical Sciences" on the home page, where I go through the material I presented to you here in the section hidden as soapbox -and mention the discussion here. See Ionizing Radiation, UV Light, And Perchlorates - Not Deadly For Indigenous Life - On Surface Of Mars

And to be concrete about my proposed edits.

They are

• To add, somewhere in the article that there exist researchers who think that the present surface of Mars is habitable. With links to the professor's video, last year's "Habitability of Present Day Mars" conference, and last year's overview survey of the field of the habitability of present day Mars surface by Martinez and Renno (the same professor who made the remarks in the video).
• To qualify your assertion that the ionizing radiation is lethal - by explaining it is not instantly lethal to microbes, but only lethal to dormant life exposed to it for millions of years without a chance to revive. Martian lifeforms, if as radioresistant as the most radioresistant organism known on Earth, Thermococcus gammatolerans, could revive after dormancy in surface conditions on Mars for up to 400,000 years, so Martian lifeforms could possibly last as long as that or longer. Chroococcidiopsis, one of our best candidates for a microbe able to survive on Mars could revive and repair the effect of 64,000 years of surface ionizing radiation at the levels recorded by Curiosity, in 24 hours.

Those are the two main things. Plus I would recommend that you sort out the confused discussion of Warm Seasonal Flows - where you confuse it with several other Mars phenomena that are caused by dry ice or wind. There are no suggested explanations for the Warm Seasonal Flows known at present involving anything except flows of liquid water, probably salty brine, for the reasons I mention above. Robert Walker (talk) 08:30, 6 August 2014 (UTC)

## Citation for ionizing radiation not a limiting factor for surface habitability of Mars

BatteryIncluded, I know you are probably fed up to the back teeth about me posting about these things. But - at last found a totally unambiguous statement of this, back in 2005. Please take a look at this before hiding my post.

"Finally there are other harmful radiation sources reaching Mars: ionizing and neutron radiation caused by galactic cosmic radiation and solar particle events.

"Due to the lack of a magnetic field and the low shielding of the Martian atmosphere (the Martian overhead airmass is 16 g cm-2 instead of the terrestrial 1000 g cm-2) the doses of ionizing radiation at the surface of Mars reach values about 100 times higher than those on the Earth.

"However, since a great variety of microbes tolerate this type of radiation at similar or even greater doses than those found on Mars, ionizing radiation cannot be considered a limiting factor for microbial life on Mars and thus here we will limit our study to solar UV shielding and VIS radiation pentration."

This is from RADIATIVE HABITABLE ZONES IN MARTIAN POLAR ENVIRONMENTS full text here pdf

Remember it is an old 2005 paper - so - when it goes on to talk about UV and its effect, this was before recent discovery of highly UV tolerant lifeforms.

And the difference between this and the quotes you use is - that this is for life that wakes up often, say once a year. The other papers are for life that is dormant for millions of years and only wakes up when Mars has thicker atmosphere depending on the tilt of the axis - that is the older pre 2008 picture of present day life on the surface - and any life in that picture has to withstand millions of years of dormancy on the surface.

In the new habitats, it only has to survive months of dormancy since the habitats are present every year, not just every few million years.

I found it after posting about this whole thing in the Reddit badscience section, where though 80% upvoted it as bad science, I was surprised to find that some people downvoted it and thought the same way you do. Is this citation good enough for you, seems pretty unambiguous to me? Robert Walker (talk) 15:11, 17 August 2014 (UTC)

## Another couple of citations for surface ionizing radiation on Mars, not limiting for lifeforms that wake from dormancy at least once every few thousand years, very clear

"Although the radiation dose rate on the surface of Mars is 100 times higher than on Earth, it cannot be considered as a limiting factor for microbial life on Mars."

http://www.dlr.de/me/Portaldata/25/Resources/dokumente/strahlenbiologie/astrobook/P3_17.pdf

And here

"If any cycle on Mars allows dormant life forms to awake from their dormant state, repair the accumulated damage, and multiply, then the period of this cycle must be shorter than the time until the viability of spores falls below a certain value. In that case, radiation will not limit the long-term viability of dormant life forms other than setting the upper limit for the time between dormant/active cycles. This period has to be shorter than about 100 to 160 million years for the deeper subsurface and less than about 600,000 years for the uppermost few meters, assuming a D14 until recovery of dormant spores."

## There are no full-Mars simulations...

"There are no full-Mars simulations published yet that include all of the biocidal factors combined."

There are no accurate full-Mars simulations. I can run an inaccurate simulation on my computer right now. — Preceding unsigned comment added by 74.197.244.98 (talk) 20:47, 29 April 2014 (UTC)

I got half-way through a cookie-cutter response concerning basic policy on sourcing and content before I saw what you linked to. Ahh, SimEarth, the one other activity on Earth exactly as fast-paced as Wikipedia editing. ;) Snow (talk) 02:57, 30 April 2014 (UTC)

In the meteorites section, "but the existence of nanobacteria itself is controversial" is written twice so I've removed the second time. 194.138.39.56 (talk) 10:38, 22 May 2014 (UTC)

## WP:WikiProject Life on Mars

As the name of this Wikiproject may provide confusion with this Life on Mars (to which is it unrelated to), I thought you'd like to know about a change to the naming of that project, see WT:WikiProject Life on Mars -- 67.70.32.20 (talk) 05:58, 5 July 2015 (UTC)

## NASA-TV/ustream (9/28/2015@11:30am/et/usa) - Mars Mystery Solved.

NASA-TV/ustream (Monday, September 28, 2015@11:30am/et/usa) - NASA will detail a "Major Science Finding" about the planet Mars[1] - Enjoy! :) Drbogdan (talk) 00:56, 25 September 2015 (UTC)

BRIEF Followup - evidence presented that liquid water may be currently flowing on the planet Mars[2][3][4] (conference videos[5][6] and somewhat related Nature (journal) (1979) reference re lifeforms in the hypersaline (and/or brine) water of Don Juan Pond, Antarctica[7]) - in any case - Enjoy! :) Drbogdan (talk) 18:17, 28 September 2015 (UTC)

References

1. ^ Webster, Guy; Brown, Dwayne; Cantillo, Laurie (September 24, 2015). "NASA to Announce Mars Mystery Solved". NASA. Retrieved September 24, 2015.
2. ^ Chang, Kenneth (28 September 2015). "NASA Says Signs of Liquid Water Flowing on Mars". New York Times. Retrieved 28 September 2015.
3. ^ Webster, Guy; Agle, DC; Brown, Dwayne; Cantillo, Laurie (28 September 2015). "NASA Confirms Evidence That Liquid Water Flows on Today's Mars". Retrieved 28 September 2015.
4. ^ Ojha, Lujendra; Wilhelm, Mary Beth; Murchie, scortt L.; McEwen, Alfred S.; Wray, James J.; Hanley, Jennifer; Massé, Marion; Chojnacki, Matt (28 September 2015). "Spectral evidence for hydrated salts in recurring slope lineae on Mars". Nature Geoscience. doi:10.1038/ngeo2546. Retrieved 28 September 2015.
5. ^ Staff (28 September 2015). "Video Highlight (02:58) - NASA News Conference - Evidence of Liquid Water on Today's Mars". NASA. Retrieved 30 September 2015.
6. ^ Staff (28 September 2015). "Video Complete (58:18) - NASA News Conference - Water Flowing on Present-Day Mars". NASA. Retrieved 30 September 2015.
7. ^ Siegel, B.Z.; McMurty, G.; Siegel, S.M.; Chen, J.; Larock, P. (30 August 1979). "Life in the calcium chloride environment of Don Juan Pond, Antarctica". Nature (journal). doi:10.1038/280828a0. Retrieved 30 September 2015.

## Brines in RSL

The recent detection of hydrated salts on the surface (Recurring slope lineae) does not boost the habitability of the surface; read the last sentence of the report: [4]. BatteryIncluded (talk) 16:38, 28 September 2015 (UTC)

His assessment in the NY Times was deleted in an update there. Hype sells, but no mention of the lethal radiation dose or low water activity. What it boosts is the possibility of deep underground water and life there. Must wait for such assessments to be made public though. BatteryIncluded (talk) 22:14, 28 September 2015 (UTC)
Agreed. Today's stuff not relevant really to habitability one way or another - beyond being able to change "there might be shallow subsurface water on Mars" to "there is almost certainly shallow subsurface brine" somewhere in the text. DanHobley (talk) 22:23, 28 September 2015 (UTC)
The radiation levels only make Mars uninhabitable for dormant life, not to life that is able to reproduce every year. The cosmic radiation levels on Mars were measured by Curiosity to be the same as the interior of the ISS, which of course microbes can easily survive. We have lifeforms that can survive that much in dormancy for 500,000 years. But nothing we know of could survive it for, say, a billion years as a dormant spore without reviving from time to time, which is why if there are no present day surface habitats, most think it is unlikely there is still life there. So, because of that, some people do think that the surface of Mars is uninhabitable, but this is just one of a wide range of views. Others are more optimistic about finding present day habitats - and then that bypasses the cosmic radiation issue, as they don't have to be dormant for millions of years. I summarize some of the published views here: Views on the possibility of present day life on or near the surface Robert Walker (talk) 22:31, 28 September 2015 (UTC)
God's gift to NASA is back in Wikipedia. BatteryIncluded (talk) 23:10, 28 September 2015 (UTC)
The current article presents a single POV when there is a wide spectrum. Nilton Renno, who is in charge of Curiosity's REMS weather station on Mars, is one of those who thinks the Mars surface and near subsurface is very likely to be habitable. He probably knows more than just about anyone about the potential for liquid water and brines on Mars, having also served on the Phoenix team, and written extensively on the topic, and received numerous awards for his achievements.
Other ones with these views include several researchers at DLR in Germany, Jean-Pierre De Vera, Kirk Schulze Makuch[1][2], and even Robert Zubrin, you might think one of the least likely, has said he thinks there may be life on or near the surface of present day Mars. These views surely need to be represented here in some form. Robert Walker (talk) 01:34, 29 September 2015 (UTC)
You are not just a troll, but incompetent (WP:COMPETENCE) at it. The reference you wave above does not state there may be Martian life, but that terrestrial microbes "most likely can adapt." Protection of Mars is their concern. You have been on this campaign for years now, preaching the imminent Martian invasion. May I remind you of the limits imposed by the administrators on your "participation" on Mars-related articles? I am sure that includes the talk pages. -BatteryIncluded (talk) 02:52, 30 September 2015 (UTC)
There have been no administrative decisions against me ever. An inconclusive attempt by me to reverse the deletion of all the material on present day habitability of Mars snd other topics from wikipedia which I was astonished was going against me but ended without conclusion when the opposing editor left wikipedia. I don't want to go into the other arguments here but in short the other editor said many false things about me which were believed by the admins. The deleted article focused mainly on the published design requirements for a Mars receiving facility. Also mentioned views of ICAMSR in one short section but gave equal weight to Zubrin's views. And the decision to delete it certainly gave nobody any authority to delete material on planetary protection and present habitability of Mars by many authors in other articles here.
Have not heard of anyone suggesting the idea of habitats that could be suitable for Earth life that can't be inhabited by native Mars life. You could split it into citations where authors mention habitability by Earth life and ones where they mention habitability by Marrs life if it exists and survives. There are discussions of whether Mars life coul survive in environments uninhabitable by Earth life. But generally assumed that any habitat for Earth life is a potential habitat also for native life if it survived. This material on present day surface habitability you deleted from the article several years ago was written by many editors and I only contributed a couple of sentences or so.Robert Walker (talk) 16:32, 30 September 2015 (UTC)

## Curiosity finding organics

The article stated:

"...until the Curiosity rover, in 2014, found organics.[3][4]"

The first article says nothing about Curiosity finding organics. The second article states that scientists are disappointed by how little Curiosity has been finding versus what would be expected just from simple meteor bombardment alone:

But in its first thorough check of Martian soil, Curiosity's SAM sample-analyzing instrument, designed to sniff out the building blocks of life, did not detect the kind of complex organic molecules many scientists hoped to find.
"So far, we detected some carbon in the rocks and some very simple carbon-containing molecules, but nothing you would call the organics that people were excited to find," Vasavada said. "That's kind of a mystery because we expect there to be carbon or even organics on Mars delivered naturally. We know that, for example, asteroids and comets have organic molecules in them. They form naturally in space and would be delivered to Mars."
Grotzinger and Vasavada have directed their science team to develop a systematic search for organic molecules, driving the rover to locations thought to best sustain carbon. Curiosity is not equipped to find extant life, but there is much to learn about the red planet's ability to preserve organics and how to uncover them.
It won't be easy, Grotzinger said.
"I just think we'd be nuts to go around promising people that we have even a good chance of finding organics," Grotzinger said in April. "On the other hand, I think, as a mission, we have to undertake this search systematically, so that if we don't find anything, we can do a proper post-mortem and say here's what we tried, here's what we discovered, and here's our best attempt to explain why we might have failed."
And if scientists are lucky, the rover could make a discovery, he said.

That's certainly not the impression that this page was giving, so I removed that claim. -- 213.176.153.100 (talk) 13:02, 14 March 2016 (UTC)

This is a better article. Curious about Methane and Organic Molecules on Mars Curiosity has detected long chain organics, but they are the result of pyrolysis so they can't say for sure what the precursors are. As it says they can't tell if it is from life or from meteorites. Curiosity is exploring one of the least likely places to find present day life, though some authors have suggested ways it could survive there on the surface. Also past life on the surface there is also unlikely because to survive billions of years of cosmic radiation - exponential process, halves every few million years - then it has to be buried deep below the surface. So, given the amount of organics they found also, not just trace amounts - and that there is a constant influx of organics from meteorites, the most likely assumption is meteorite organics. Indeed it was a surprise that they didn't find it sooner - there must be some process actively removing it. Robert Walker (talk) 00:42, 5 April 2016 (UTC)

### ALH84001

I noticed today that someone edited this section to remove the details of the evidence for life in ALH84001. I think this article should at least touch on the magnetite, and the carbonate globules, as well as the morphology, as at present it gives the impression that the scientists published these results just based on morphology. In fact they had what seemed excellent evidence for life at the time of publication with multiple lines of evidence in support of it. Historically, at the time, I think NASA can't be faulted for publicizing it as they did.

Also the conclusion "Although the scientific community has largely rejected the claim ALH 84001 contains evidence of ancient Martian life, the controversy associated with it is now seen as a historically significant moment in the development of exobiology." I'm not sure that quite accurately describes what happened. It's more that to prove existence of life on Mars requires a very high level of certainty. What's been proven is that some of the most conclusive evidence McKay's team gave for life, the magnetite grains especially, can be reproduced using unusual inorganic processes that are possible in the conditions on Mars at the time of formation of the globules. However it doesn't prove that the globules were produced by inorganic processes, it just shows that it is possible they were. As a result, the scientific consensus, I agree, except for McKay and a few others, is that this meteorite does not provide conclusive evidence for life on Mars. However the biogenic hypothesis hasn't been disproved strictly. If we found more meteorites from early Mars, which is well possible, or if some rover on Mars found evidence, and if they backed up the original hypothesis with more conclusive data, then these might turn out to be fossils of early life after all. On the other hand further evidence might as easily back up the inorganic hypothesis.

It would be more accurate to say

"Although the scientific community has largely rejected the claim that the evidence from ALH84001 proves existence of ancient Martian life, the controversy associated with it is now seen as a historically significant moment in the development of exobiology."

I.e. they have indeed rejected the claim that it proves existence of ancient martian life, but haven't proved conclusively that it can't be ancient martian life which remains a hypothesis compatible with all the observations.

The deleted material included a few points not included in the ALH84001 article and I've merged it into that article as a new section on List of Hypothetical Biogenic features in ALH84001. Robert Walker (talk) 11:12, 15 September 2016 (UTC)

Note to unsuspecting editors: Robert has been on a years-long campaign to promote his prophecy of a deadly Mars invasion. Do not feed the troll. Cheers, BatteryIncluded (talk) 14:05, 15 September 2016 (UTC)
I see it the other way around. removed the section Possibility of enough liquid water to support life from Water on Mars in spring 2013, and since then, no material ever gets accepted in wikipedia on habitability of present day surface environments such as the RSL. For an idea of how much material there is on this topic, which is all cited and WP:RS and not mentioned in wikipedia at all, see my draft article: Draft:Present day habitability of Mars. The question of whether or not these surface environments exist on Mars, and how habitable they are, and whether they are inhabited by microbes or not, is one of the hottest topics in astrobiology today.
He replaced that section with a "proof" that cosmic radiation on the surface of Mars is deadly to all microbes. But this argument is not valid - the levels of ionizing radiation measured by Curiosity on the surface are similar to those inside the ISS (due to some protection from the Mars atmosphere) and humans can withstand them for some years with an increased risk of cancer. These levels of radiation are not deadly to microbes which can survive even the high levels of radiation of a reactor cooling pond which would kill humans rapidly! Before the observations of the Phoenix lander, it's true, researchers showed that the top few meters of Mars cannot have any viable life, as the article notes. However, they were referring to life dormant for millions of years, not life that grows and reproduces in the present day. That's what makes this article out of date. Many discoveries since 2008 have suggested the presence of flowing thin films of brine in the RSLs and other surprising locations on the surface and near surface and one of the big questions of the day in astrobiology is whether or not these are potentially habitable to present day life. As an example, Curiosity has to avoid the area of the RSLs on Mount Sharp because of the risk of Earth life reproducing in it [5].
There are many papers published every year on this topic of the present day habitability or otherwise of the surface and near surface of Mars, and an entire conference devoted to it in 2013. This entire topic area is just dismissed here with a "proof" that the question is already settled in the negative. For a summary of the conference see Mars may be habitable today, Scientists say article in Space.com and you can watch the video presentations on the conference website here: The Present-Day Habitability of Mars 2013.
Whatever you think of the reasoning he presents in this article for uninhabitability of the RSLs and other suggested surface habitats, it can't be a valid reason for excluding this notable and WP:RS research by authors who talk about the RSLs as potentially habitable. Their publications have already passed peer review and don't need a second process of peer review here. It is up to the original peer reviewers to require authors to include this proof in their papers if they thought it was valid - he should take this up with them, not with us. Most of these recent papers don't even mention ionizing radiation as a limiting factor. I only know of one study which mentions it, and it puts it down near the bottom of the list of habitability factors for present day life on Mars ordered by significance.
For some reason also thinks the article on ALH84001 should not include a mention of the minority view RNA World hypothesis that the small structures in the meteorite could be RNA World cells without DNA or proteins. For the citations see RNA World Cells Hypothesis - summary of the cites - do they pass WP:RS
They justify this by calling me a troll. This is just a way to sidestep discussion of the questions. Please, can we discuss notability and whether they are WP:RS rather digress into a discussion of which of us is a troll! Thanks! Robert Walker (talk) 19:59, 22 September 2016 (UTC)

References

1. ^ de Vera, Jean-Pierre; Schulze-Makuch, Dirk; Khan, Afshin; Lorek, Andreas; Koncz, Alexander; Möhlmann, Diedrich; Spohn, Tilman (2014). "Adaptation of an Antarctic lichen to Martian niche conditions can occur within 34 days". Planetary and Space Science. 98: 182–190. doi:10.1016/j.pss.2013.07.014. ISSN 0032-0633. This work strongly supports the interconnected notions (i) that terrestrial life most likely can adapt physiologically to live on Mars (hence justifying stringent measures to prevent human activities from contaminating / infecting Mars with terrestrial organisms); (ii) that in searching for extant life on Mars we should focus on "protected putative habitats"; and (ii) that early-originating (Noachian period) indigenous Martian life might still survive in such micro-niches despite Mars' cooling and drying during the last 4 billion years
2. ^ Cite error: The named reference `ZakharovaMarzban2014` was invoked but never defined (see the help page).
3. ^ Greenwood, Veronique. "What Life Leaves Behind".
4. ^ "Curiosity tasked with hunting for elusive Mars organics". Astronomy Now. May 22, 2013.

## Speculation versus facts

I find the current article wp:lead heavy on speculation. I'd like to remove this content and focus on facts. Let me know what you think. Daniel.Cardenas (talk) 16:04, 1 October 2016 (UTC)

The lede took time to put together by many editors. I recommend to write a draft and post it here for discussion. Many people think that habitability/habitable implies inhabited; we can do a better job explaining that. Thank you. BatteryIncluded (talk) 16:06, 1 October 2016 (UTC)
I edited the lead. Feel free to edit or revert, although I personally think it is much better without the speculation.   Thanks! Daniel.Cardenas (talk) 17:23, 2 October 2016 (UTC)
It looks good to me. Thx! -BatteryIncluded (talk) 17:32, 2 October 2016 (UTC)

## Present day habitability of surface of Mars again

### Short summary

This is about the section on Surface brines. It says that "The damaging effect of ionizing radiation on cellular structure is one of the prime limiting factors on the survival of life in potential astrobiological habitats.".

Modern researchers do not consider that ionizing radiation is a limiting factor in habitability assessments. Here is a cite to prove it [[6]:

• "Finding 3-8: From MSL RAD measurements, ionizing radiation from GCRs at Mars is so low as to be negligible. Intermittent SPEs can increase the atmospheric ionization down to ground level and increase the total dose, but these events are sporadic and last at most a few (2–5) days. These facts are not used to distinguish Special Regions on Mars."

Here a SPE is a Solar Proton Event (solar storm) and a GCR is a Galactic Cosmic Ray. A "Special Region" is a region where Earth life could potentially survive.

The other statements in this paragraph also need to be updated to take account of the latest research on the topic. The RSL's are treated as "Uncertain Regions, to be treated as Special Regions", not as "Uninhabitable regions". This section should be updated to reflect the latest research. Robert Walker (talk) 22:11, 3 February 2017 (UTC)

### In Detail

I'd like to come back in on this discussion again as I've found a cite that I think surely will settle it once and for all (shown in bold below). The problem before was that few in the literature even discuss ionizing radiation any more as it is only relevant to life dormant for hundreds of thousands of years which is no longer the focus for research. The cited statements date back to before 2008 when ionizing radiation was considered a limiting factor for dormant life, as it still is. It's just that modern researchers are no longer especially interested in long dormant surface life because of the new exciting possibility of life that is actually metabolizing and reproducing right now.

For these newer papers, ionizing radiation is no longer relevant, so most papers don't discuss it at all. This makes it hard to find citations that say that ionizing radiation is not a limiting factor. I did find some but they were disputed. My understanding of the cites was informed by my own personal knowledge. Of course, that this is not admissible as a reason for including content in wikipedia. So the problem was finding a clear enough citation in peer reviewed sources saying that ionizing radiation is no longer a limiting factor. I was labeled a troll for attempting to continue the discussion.

However today, while working on my new kindle book on planetary protection, I've found a clear recent (2014) statement in the literature.

Robert Walker (talk) 22:11, 3 February 2017 (UTC)

It's from A New Analysis of Mars ‘‘Special Regions’’: Findings of the Second MEPAG Special RegionsScience Analysis Group (SR-SAG2). Here "Special Regions" are regions where Earth life might potentially survive in Mars surface conditions. Their findings on ionizing radiation are

• "Finding 3-8: From MSL RAD measurements, ionizing radiation from GCRs at Mars is so low as to be negligible. Intermittent SPEs can increase the atmospheric ionization down to ground level and increase the total dose, but these events are sporadic and last at most a few (2–5) days. These facts are not used to distinguish Special Regions on Mars."

Here a SPE is a Solar Proton Event (solar storm) and a GCR is a Galactic Cosmic Ray. Robert Walker (talk) 22:11, 3 February 2017 (UTC)

The section on surface brines also mentions UV radiation so here is what they say about that:

• "Finding 3-7: The martian UV radiation environment is rapidly lethal to unshielded microbes but can be attenuated by global dust storms and shielded completely by < 1 mm of regolith or by other organisms."

Robert Walker (talk) 22:11, 3 February 2017 (UTC)

The surface brines section cites an early result by Schueger from 2009 soon after the Phoenix discoveries and long before the discoveries of the RSL's in 2011. If you read the article it quotes him as saying "Some salt encrustations might protect with just a few millimeters of salt, while others might need 5 to 10 centimeters." [7]. The use of this as a cite to show that life on Mars below the surface would be subject to UV radiation is cherry picking. UV radiation is easily blocked by a shadow. The iron oxides in the dust are also especially good at attenuating UV light and a thin layer of dust will do the trick as will previous dead microbes. And recent research shows that some very hardy microbes can withstand surface UV for more than 24 hours, and that chroococcidiopsis can survive it indefinitely in partial shade using the light on Mars for photosynthesis. Robert Walker (talk) 12:01, 4 February 2017 (UTC)

### Perchlorates

As for the "superoxides", such as chlorates or perchlorates, the report doesn't cover them but there are plenty of other studies of microbes that actually metabolize perchlorates on Earth. See Perchlorate#Biology. Nowadays perchlorates on Mars are generally thought as boosting habitability. Even when Phoenix discovered perchlorates in 2008, Scientific American published: NASA Says Perchlorate Does Not Rule Out Life on Mars - Unexpected chemical in Martian soil is a food source for some Earthly microbes.

For a modern view on them [8]:

"The salts known as perchlorates that lower the freezing temperature of water at the R.S.L.s, keeping it liquid, can be consumed by some Earth microbes. “The environment on Mars potentially is basically one giant dinner plate for Earth organisms,” Dr. Conley said."

That's by Cassie Conley, the current planetary protection officer for NASA.

The cite given in Surface brines refers to ""superoxides" that break down organic (carbon-based) molecules on which life is based" [9]. Curiosity discovered organics on the Mars surface so we now know from experimental evidence that the surface does have organics. These organics probably came from meteorites, but it also means Mars has organics that life can use. Also primary producers like chroococcidiopsis will be able to create organics from carbon dioxide, water, nitrates, trace elements and sunlight. Indeed for astrobiologists, nitrates are the main limiting factor as Mars has very little nitrogen in its atmosphere, probably too little to fixate. Mars does have biologically nitrates too however, found both in Mars meteorites and found on the surface by Curiosity. (I can provide citations for all this if anyone is interested and provide many more details too if anyone wants them).

Robert Walker (talk) 22:11, 3 February 2017 (UTC)

### RSL's as an example of "Uncertain Regions, to be treated as Special Regions"

On RSLs then the "Special Regions" assessment says:

• "Finding 4-1: Although no single model currently proposed for the origin of RSL adequately explains all observations, they are currently best interpreted as being due to the seepage of water at > 250 K, with ${\displaystyle a_{w}}$ [water activity] unknown and perhaps variable. As such they meet the criteria for Uncertain Regions, to be treated as Special Regions. There are other features on Mars with characteristics similar to RSL, but their relationship to possible liquid water is much less likely"

They were first reported was in the paper by McEwan in Science, August 5, 2011. [10]. Already suspected as involving flowing brines back then. Finally proven pretty much conclusively to involve liquid water in some form, possibly habitable if temperatures and salinity are right - after detection of hydrated salts that change their hydration state rapidly, reported in a paper published on 28th September 2015 along with a press conference [11]. Robert Walker (talk) 12:59, 4 February 2017 (UTC)

Surely these statements are now so clear as to be totally beyond dispute, which is why I thought it was worth trying again.

I strongly recommend that the section on "Surface brines" is edited to present the current scientific consensus that RSLs are potentially habitable and are currently treated as "Uncertain Regions, to be treated as Special Regions" and not as "uninhabitable regions".

What's changed is that before 2008 they were talking about dormant life. Now they are talking about life that can wake up every year. Ionizing radiation is exponential in its effects. So though it has negligible effect on timescales of decades, it is devastating on timescales of hundreds of thousands of years. As an example, suppose that a dormant population is halved in ten thousand years by ionizing radiation (within the range of possibility for hardy ionization resistant life). That would have negligible effect on life able to reproduce every year. Yet if a population of microbes is kept dormant for 500,000 years you would have only 1 in ${\displaystyle 2^{50}}$ or around 1 in ${\displaystyle 10^{15}}$ or one cell remaining out of a quadrillion. After a million years only one viable cell will remain out of a nonillion (${\displaystyle 10^{30}}$). So it is devastating for life that remains dormant for millions of years but has no noticeable effect if it can either replicate or "wake up" for a few hours to repair its own DNA as many ionization resistant microbes can do. It's not limiting at all for life that is able to replicate or metabolize at some point every year. I'm not saying that as OR to be included in the article. It's just to help readers of this talk page to understand the background for the cite, and why it is consistent with the earlier cites that show that dormant life on the surface is impossible. Robert Walker (talk) 14:06, 3 February 2017 (UTC)

If there are no objections, I'll fix this section as well as the Habitability section. I'll leave this for a few days for comments before doing so. Have just added "disputed - discuss" tags to the article linking to this section of the talk page. Robert Walker (talk) 11:48, 4 February 2017 (UTC)

I've now done a new version of the section Life on Mars#Present. For now I have just left out any mention of individual astrobiologist's assessments of habitability from the section, positive or negative, just relying on the assessment for the 2014 Findings of the Second MEPAG Special Regions Science Analysis Group for the RSL's, which can be regarded as a reasonably neutral tertiary source.
I know that the previous version of this section gave a long list of astrobiologists that are of the opinion that the RSL's are probably not habitable. However it was biased as you can come up with an equally long list of astrobiologists who say that they are habitable, and none of those were mentioned. For now I thought it was best to just not try a list like that at all, but simply state the conclusions of the report. That's in the interest of minimizing the potential for controversy. That report has to be one of the least controversial sources in the entire field. Robert Walker (talk) 02:13, 12 February 2017 (UTC)

### Draft article on present day habitability of Mars

I did a draft article on the present day habitability of Mars some years back. It is here: Draft:Present day habitability of Mars. It was almost impossible to get it accepted before, because Life on Mars said that the topic of the new article doesn't exist - that present day Mars is not habitable. As you'll see from my draft article and its very long list of citations, it's a topic of great interest with dozens of papers published on it every year and many articles on it in astronomy news sites, NASA press releases, etc.

Undoubtedly notable and I think myself that it is astonishing that wikipedia has nothing on this entire topic to this day, after eight years of intensive research since the Phoenix lander discoveries in 2008. I've been pressing for inclusion of some material on present day Mars habitability for some time. I recommend a brief section here and in Water on Mars and link to that longer article. Also a habitability section in the article on Seasonal flows on warm Martian slopes. After all that's the main point of interest of those features and again it is extraordinary that the wikipedia article on it doesn't discuss their habitability.

My draft wikipedia article needs some updating but nothing major. It is rather long and I think it would help to separate out the long section on Mars analogue habitats into a separate article.

Hopefully this can change and if my edits of this article are accepted to say that the Mars surface may be potentially habitable, then I'll try resubmitting that article. The reason this may be possible now is because the editor who opposed me for many years on this article, and who hid my comments in the discussion above is no longer contributing to wikipedia. I'm not sure of the reason, or whether this is temporary or permanent. The discussion on his talk page mentions a block for alleged sock puppetry and abusive language, but I'm not sure if he is still blocked or stopped editing voluntarily. Whatever the reason, it gives an opportunity to fix the article at last. Robert Walker (talk) 12:21, 4 February 2017 (UTC)

## New version of the section on Present day life on Mars

I've now done a new version of the section Life on Mars#Present as I proposed above. For now I have just left out any mention of individual astrobiologist's assessments of habitability from the section, positive or negative, just relying on the assessment for the "2014 Findings of the Second MEPAG Special Regions Science Analysis Group" throughout. A "Special Region" on Mars is of course a potentially habitable region for surface life.

Note: the previous version of this section (now reinstated) cited some astrobiologists of the opinion that the RSL's are probably not habitable. However, it made not a single mention of any astrobiologists who think that the RSL's are probably habitable. For now I thought it was best to just not try an independently compiled list, as it can so easily become biased. Instead my edit simply states the conclusions of the "special regions" tertiary level WP:RS about RSL's. That report has to be about the least controversial source you could find in the entire field.

### Edit reverted

My new version has been reverted instantly. Please can you consider it carefully . You can't have had time to read it.

The current version is highly OR stringing together an argument based on mainly out of date sources. Amongst other things, it contradicts the 2014 Special Regions assessment of the habitability effects of ionizing radiation. The current version says that the Mars surface is uninhabitable due to ionizing radiation. That only ever applied to dormant life. The New Scientist article I linked to points out that the Curiosity surface measurements are similar to ionizing radiation levels inside the ISS.

Most of what I wrote is based on the "2014 Findings of the Second MEPAG Special Regions Science Analysis Group"[12] which is a tertiary source that did a survey of the entire field of present day habitability of Mars for the purposes of determining which areas of Mars are to be treated as potentially habitable "Special regions" for the purposes of planetary protection for robotic missions to the planet. You could not find a more reputable, unbiased, and authoritative source in the entire field of the present day habitability of Mars.

(just to say edit was restored, thanks!) Robert Walker (talk) 14:52, 13 February 2017 (UTC)

### Example of the four day Science Conference Session on the Modern Mars Habitability

As an example to show how mainstream this topic is, here is the request for papers for the four day Astrobiology Science Conference Session on the Modern Mars Habitability to be held in April 2017:

"Modern Mars Habitability: Recent discoveries on Mars, including: Recurring Slope Lineae, ground ice, and active gully formation, have been interpreted as indications for the transient presence of water. The potential for liquid water on Mars has profound implications for the habitability of the modern Mars environment. This session solicits papers that examine the evidence for habitable environments on Mars, present results about life in analogs to these environments, discuss hypotheses to explain the active processes, evaluate issues for planetary protection, and explore the implications for future explorations of Mars."

## New article Present day Mars habitability analogue environments on Earth

I've just added this as a new article and linked to it under "See also" Robert Walker (talk) 13:13, 2 March 2017 (UTC)

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## Perchlorate toxicity

I fixed the section on perchlorates as it hinged on a single sensational piece detached from environmental context. I added the latest peer-reviewed research and removed that extreme speculation. Although [very] few known microbes can metabolize perchlorates for energy, NONE ZERO ZILCH can do it under the actual environmental conditions on Mars. In particular, such terran bacteria will not survive the cold, low pressure, absence of nutrients, and sterilizing UV radiation present at the surface of Mars. To that, add the synergistic bactericidal effects of the minnerals now listed. The previous text was alogus to saying that if you throw a ton of spagetti and meatballs on the surface of Mars, any human can thrive there without further life support of any kind. Context is the key. Please refrain from adding sensational claims, even if presented in some seminar, and err in the side of caution. Thank you. 98.100.145.6 (talk) 19:58, 10 September 2017 (UTC)

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## meteorite section

Hi. What about the https://en.wikipedia.org/wiki/Tissint_meteorite ? There were some articles that claimed organic substances have been found inside, that were washed there while being under water, like https://actu.epfl.ch/news/traces-of-possible-martian-biological-activity-ins/ ... 93.198.202.34 (talk) 20:51, 8 January 2018 (UTC)

Hello. First, there is a difference between organic compounds (abiotic carbon- nitrogen-containing chemicals) and organic matter (biological). The meteorites mentioned in this article are thought to host some tiny shapes that could be interpreted by some, as micro-fossils, and although they may contain carbon, nitrogen sulfur, oxygen (organic compounds) none show biological matter (remnant of cells). Many meteorites have been found that contain organic compounds (carbon, nitrogen, oxygen, sulfur) but they are abiotic, meaning naturally occurring chemicals not metabolized by life forms. No single compound will prove life once existed. Rather, it will be distinctive patterns present in any organic compounds showing a process of selection. For example, membrane lipids left behind by degraded cells will be concentrated, have a limited size range, and comprise an even number of carbons. Similarly, life only uses left-handed amino acids. I hope this clears that up. In fact, organic compounds are abundant in cosmic dust, comets, asteroids and meteorites, they are the most abundant atoms in the universe, but none of those objects analysed in situ has shown the peculiarities of being handled (metabolized) by life forms. I hope this helps. Cheers, BatteryIncluded (talk) 22:32, 8 January 2018 (UTC)
I just saw your link to https://actu.epfl.ch/news/traces-of-possible-martian-biological-activity-ins/ It is dated 2014 and it made no waves in the astrobiology journals. I'll take another look at it and research the literature. Cheers, BatteryIncluded (talk) 22:51, 8 January 2018 (UTC)
Yes, it sounded promising by the time, the NHM meteorite curator in Londen called it the most important meteorite of the last 100 years, maybe only because they paid so much money for it. There was talk of organic substances similar to precursors of fossil oil, that had been in the water and washed into the crack, if I remember it correctly. What became of all that? Looking forward to learn it, anyway thanks for the explanations! 93.198.202.34 (talk) 05:00, 9 January 2018 (UTC)