Rovers on Mars

Along those some lines, long-term effects here on earth of lengthy regular jet flights (trans-oceanic) exposes a crew over their career with a shocking amounts of radiation. I believe that I'm correct in saying that this has resulted in a higher incidence of cancers to flight attendant and pilots.

The only cancer in which there was a slight measurable increase (for pilots involved in transoceanic or continental flights) was brain cancer which, as many studies have shown that irregular sleep patterns, associated diets, and life styles were THE major risk factor).

Maybe now, the risk factor presented by microwave and EM from telephones will be a similar factor

This was from a few months ago.
http://www.astrobio.net/news-exclusive/potential-signs-ancient-life-mars-rover-photos
I don't see enough evidence in those photo's to conclude anything. People who look for microbial mats can see what they want to see just like Gunga sees Pyramids and Propellers. But microbial mats are tantalizingly possible, and maybe even probable.

As Roswell and i have already said, it is most likely that any life on Mars will be underground. I can't consider the idea of bacterial mats plausible. The discoveries of Curiosity of an active hydrological cycle as well as of ancient lakes and rivers gives a good deal of hope for finding life there, though.

The timeframe for these formations on Mars would be around 3.8Bya at a time when Mars shows evidence of being quite wet with full blown oceans, so the possibility of bacterial mats seems very plausible to me. The atmosphere was much thicker at that time as well. So I'm not quite sure why you can't consider the bacterial mats plausible?

Is it the "Wet Mars" hypothesis at the 3.8Bya timeframe that you are in disagreement with?

It's the notion that such bacterial mats survive to this day which i find implausible. Bacterial mats survive on earth because the planet has had an active hydrology cycle and a dense atmosphere since bacterial mats first arose. That is not true of Mars.

a "hydrological cycle" is what it is. It has no defined limits of presence. Mars hydro cycle is kind of interesting since theyve found these intermittent streams . Now they theorize that when the saline water flows , it infiltrates and gets incorporated into some sort of "water table" or vadose zone.

On earth we find several types of very simple (DNA based) extremophiles at great depths in salt mines and metal mines where the ores are based on a sulfur rock (like "fools gold"). I see no reason why NOT a life cycle exists for similar organisms on Mars.
The long time only recognizes that the Earth was impqcted in a huge collision with a "Dark plantetessimal" back in the Hadean time. It took 100's of millions of years for the earth to "come down" to temperature and then accumulate sufficient water.

USGS has a really good collection of photo evidence about water and ice on Mars. Water forms layers of sediment that is often truncated by later "tises". Streams form "V" bottoms and high energy meanders showing young water courses (as well as mature streams with Mississippi delta style meanders). Ice, forms "U" bottomed deposits. And then on top of it all are these ubiquitous bolide holes and tracks of gas and possible vents of some kinds of vulcanism.
These picture collections are based entirely on "Models of similitude" from comparing them to what we see on earth.

MISS and "stromatolite-like" deposits on Mars are pretty convincingly presented by most of the teams that are studying these things,(And writing about em in the Geological Society Journals and USGS pro-papers)

Here's an article from the Scientific American about a hypothetical collision of Mars and a rather large planetesimal (slightly larger than our moon).

Giant Asteroid Collision May Have Radically Transformed Mars

Back in the 1980s, a scientist at Cornell and a scientist working for JPL independently came up with an hypothesis which was quickly dubbed the "Big Hit" hypothesis. They were attempting to account for Mars' low volatiles inventory and the huge discrepancy in elevation between the northern and southern hemispheres--a discrepancy of about 15000 to 20000 feet in elevation. I have been unable to find anything in a web search, which is frustrating because i did find it a couple of years ago, a reference which gave the names of the gentleman from Cornell and the gentleman from JPL. Both of them concluded that the asteroid belt is comprised of the remnants of the impactor and of Martian ejecta. One of them also suggested that the rings of Saturn are formed from the volatiles blasted into space by the impact. The hypothesis was largely ignored until quite recently when these questions about the fate of the hypothesized Oceanus Borealis of Mars and the huge discrepancy in elevation of the two hemispheres seems to have come to the attention of other scientists.

Here are some cached pages from Science on the same topic (in PDF format):

An Early Big Hit to Mars May Have Scarred the Planet for Life

It is with this in mind that i am skeptical of the idea of bacterial mats surviving from the early history of Mars.

Ah, yes, of course. I certainly never meant to imply that mats of that type exist on the surface of Mars today. Nor do I think that was implied in the article, and if it was I missed it.

There are reports of stromatolite-like fossil formations on Mars? I wasn't aware of that.

I find the evidence of the MISS to be pretty tenuous at the moment. I can see how a scientist in that field might recognize familiar structures in a photo from Mars, but people are highly prone to seeing what they want to see anyway, so we're going to need much better pictures or samples in-hand before I would think the MISS evidence was good enough. Even the lady who wrote that article (Nora?) seems to agree with that.

What about the possibility of microbial mats living in underground aquifers on Mars (assuming underground aquifers even exist on Mars)?

If microbial life ever existed on Mars then I would expect that it has survived until present day, just adapted to fill the habitable niches and avoided the surface. I always assumed that if it existed we would find it soaked into the sub-surface dirt/slush.

But if there are underground aquifers on Mars I wonder if life could get the energy to survive in them. Below the surface there's no light for an energy source, and I don't know if Mars has any geothermal heat as an energy source. On Earth, Bacterial mats which exist in the abyssal plane of the oceans gain much of their sustenance from organic debris which drifts down from the surface where there is lots of solar energy to power the biosphere, a situation which wouldn't exist in underground aquifers on Mars.

photo id is a pretty mature craft. We can insert reticles and other measurement and "Pattern recognition " tools to investigate the features.
Im sure that there are aquifers or at least vadose zones on Mars(areas of subsurface water in unsaturated conditions). The water has to go somewhere and we know from desert deposits of vadose water that its possible for the fluids to "wick" from one area to another, all they need is gravity or some sort of chemical gradient.

Mars geologic history was a lot "quieter" than earth's, so its highly possible that life began early on Mars and then, by ejecta that contained encapsulated entire microbiomes, came to earth riding on "strewn field" meteorites (margulis had a lot to say about these mechanisms of transferring genomes by ejecta and a team from Stanford had (incorrectly) identified such an ejecta based biome back in the late 90's--However, it turned out that, instead of microorganisms, the "gnarly" features were a type pf calcium carbonte rock found near volcanic vents).

No matter, Itd be something of we find that all life on earth , in reality, are "Martians by birth". We have a lot of very simple microorganisms with simple DNA configurations (clusters rather than strings) and these organisms could be compared to whatever we find on Mars (if we get lucky)

hmm, reading that Sci Am piece, especially since the Tharsis crater was smooshed a bit. perhaps the Martian "youth" may not have been as quiet as Ive beenpresented in recent past .
Its a pretty good argument when we have tectonic features of vulcanism imprinted by similar features of impact (or at least potential impact).

I wonder if it left an "Impact hiatus" where possible earely life would be obliterated?

Most of the following is speculation, and by scientists, not just by me. It is thought that there is a great deal of water in or under the regolith beneath the surface. It is believed (and not yet probed) that many of the channels that Schiaparelli first mapped may have been glacial in origin. It is believed that large aquifers may exist in many places on Mars (this latter is a part of the effort to explain where the Oceanus Borealis went).

Now, for my own part: Might not there be a dynamic cycle in which different forms of bacteria, or some kinds of symbiotes are active on the surface in austral summer? On both Earth and Mars, the southern hemispheres are the homes of extremes. When it is winter in the southern hemispheres, the planets are at aphelion (farthest from the sun) and therefore far colder than winters in the northern hemispheres. When it is summer in the southern hemispheres, the planets are at perihelion (nearest the sun) and far warmer than summers in the northern hemispheres. This could be crucial on Mars. The mean temperature seems to be about 230 K. (On Earth, that would be about minus 45 centigrade, but with Mars' near lack of an atmosphere, it's about -80 or -90 centigrade) However, in summer on Mars temperatures might reach 20 centigrade (about 70 F). The Martian year is about 22 terrestrial months, so summer lasts longer there than it does here. Right now, it's early spring on Mars. Curiosity may soon be able to tell us what kind of temperatures we will see in Gale Crater in summer time.

So-o . . . perhaps there might be a complex life cycle which takes advantage of a long "hot" summer (by Martian standards) and which lies dormant during the long, severe winter.

That's my story and i'm sticking to it.

Hmmm, well, in that case just how convincing do you find the argument that those photos from Mars do actually show fossilized microbial mats?

Do you think Nora Noffke's interpretation of the photo's is correct?

Now i'm confused . . . according to this (unofficial) blog, they are drilling in Gale Crater--so they must not be too worried about contaminating the site.

Curiosity at "Big Sky"

JPL's blurb on Curiosity is about the same (and doesn't answer the question about site contamination). But i found this, which people might find interesting:

Mars Science Laboratory, Curiosity Rover

From the MSL Curiosity site i just linked:

The Mars Science Laboratory mission and its Curiosity rover mark a transition between the themes of "Follow the Water" and "Seek Signs of Life." In addition to landing in a place with past evidence of water, Curiosity is seeking evidence of organics, the chemical building blocks of life. Places with water and the chemistry needed for life potentially provide habitable conditions. This mission is part of a series of expeditions to the red planet that help meet the four main science goals of the Mars Exploration Program:

Determine whether life ever arose on Mars

Characterize the climate of Mars

Characterize the geology of Mars

Prepare for human exploration

Yeh, as a pretty good hypothesis, I think we should continue down that track unless something rares up to refute it. JPL scientists are carefully cmparing strat features we have on earth with those seen on mars and each of these features (as seen from remote sensing) have a batch of other subfeatures that must be looked for. Then, Im sure, in future missions someone will propose that we look more closely .