Talk:Life on Mars

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Mars had oxygen-rich atmosphere 3.7 billion years ago[edit]

"Volcanism on Mars controlled by early oxidation of the upper mantle" (talk) 10:49, 24 June 2013 (UTC)

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


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.[edit]

Would this information be deemed valid enough to include in the article? [2] (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:[edit]

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

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. (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[edit]

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)

@Jimmarsmars: 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)

There are no full-Mars simulations...[edit]

"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 (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. (talk) 10:38, 22 May 2014 (UTC)