The issue concerns the present day habitability of the surface of Mars, subject of a major conference in February of this year.

BatteryIncluded added a statement to the Life on Mars page that the surface is not habitable because of cosmic radiation. This has eventually been expanded into the second paragraph here: Surface brines. He also used the same reasoning as a basis to delete a long section on the topic from Water on Mars.

Most of the recent papers on present day habitability of the Mars surface do not mention cosmic radiation. The one that does, has it as tenth in importance as a habitability limiting factor. UV is high on the list but cosmic radiation is low.

None of the participants in the conference raised cosmic radiation in the questions afterwards. Some of the speakers went so far as to be optimistic about detection of surface life on Mars.

My main contention is with his statement, which currently reads:

"Even at a depth of 2 meters beneath the surface, any microbes would likely be dormant, cryopreserved by the current freezing conditions, and so metabolically inactive and unable to repair cellular degradation as it occurs"

That is OR in my view. The OR part is where he says "any microbes would likely be dormant".

The proposal which the ongoing research is investigating is that microbes can live and reproduce in these habitats. If this turns out to be true, they would not be continuously dormant, but would revive at least occasionally and metabolize or reproduce.

It is of course okay to point out that it is a difficult habitat for life and many problems have been raised for life that might live there. However the consensus seems to be that these issues are just about surmountable for sufficiently hardy life forms (UV, perchlorates, etc all surmountable). If these habitats do exists, the emerging consensus seems to be that there is a chance that some (not all) of them are habitable.

Further more I propose creation of a new article on the habitability of the surface of Mars.

As the subject of a major conference, and dozens of papers every year, it is clearly notable, and there is probably too much material for the Life on Mars or Water on Mars pages. See Recommendation, new article on the Present-Day Habitability of Mars

The deleted section from the Water on Mars page

Possibility_of_Mars_having_enough_water_to_support_life

Brief decription of the surface micro-habitats

They were inspired originally by the surprising observation of what appeared to be small droplets of salty brine on the legs of phoenix in 2008, leading to ideas about ephemeral habitats forming around deliquescing salts.

They are tiny ephemeral habitats of a few millimeters thickness that may form at certain times of day or year, for long enough for life to take advantage of them. The moisture derives from the humidity of the air at times of high humidity. Theoretical modelling and experiments on Earth seem to confirm that such habitats could exist on Mars, depending on the concentrations of various salts and perchlorates.

Background information on cosmic radiation on surface of Mars

This is general knowledge, but can't be included in the article as it is too much synthesis. This is what BatteryIncluded objects to as WP:CHEESE.

The reasons I gave above don't depend on this background information. It is sufficient to just observe, that the experts themselves do not raise it as an issue.

But to understand why they don't, this, I believe, is the reason:

The thing is, though the levels of cosmic radiation on the surface of Mars are far higher than for the surface of the Earth (protected by our thick atmosphere), they are comparable to the interior of the ISS.

Levels of cosmic radiation on the Mars surface

are the same as the levels within the ISS

Many micro-organisms can easily survive that, even if they spend most of their time dormant, so long as they are able to revive and reproduce, or repair damage.

A radioresistant micro-organism like Radiodurans just needs to revive for a few hours to repair DNA damage. Non radioresistant micro-organisms able to revive regularly and reproduce would also have no problem surviving cosmic radiation on the surface of Mars.

These brief revivals are the key. When these micro-organisms are kept dormant continuously, for hundreds of thousands of years, even Radiodurans would be unable to survive the long term accumulated damage to its DNA from cosmic radiation. But Radiodurans and Chroococcidiopsis would just need to revive for a few hours, even as rarely as once every few hundred thousand years, to repair all that accumulated radiation damage.

The difficulty I had to try to find this material in the published literature arises because most of the papers don't mention cosmic radiation at all. The only one that does mentions it only briefly. It says it is not a significant factor as far as limiting habitability, but does not go into detail and explain why.

I have however discussed it with exobiologists to confirm I understand it correctly.

Update - new material which I tried posting to the talk page for Life on Mars - but it gets immediately hidden from the talk page

I've found a lot more material on this, which I have tried posting to the talk page for Life on Mars but it gets hidden immediately as not a forum / soap box / spam. To be clear - these are just suggestions on the talk page that get hidden. I haven't tried editing the article itself for nearly two years now.

Here is some of the hidden material on the talk page:

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. [note, he just hid this post without discussion]

"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.

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

http://www.youtube.com/watch?v=iLWv9UGwjdE#t=135

"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 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?

Encyclopedia Britannica reference

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.

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

Lots more

I wrote a lot more but it just gets moved into the not a soapbox / spam section of the article often without any comment nowadays. Last attempt was 8th September 2014 but I don't see much point in trying any more.

To see my other comments on the talk page there, go to Talk:Life_on_Mars#Warm_seasonal_flows_section_is_inaccurate and then you need to click "Show". Robert Walker (talk) 14:48, 1 January 2015 (UTC)