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Was there water on Mars long enough for life?
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Based on the lovely green rock, olivine, also known as the gemstone, peridot, a Virginia Tech graduate student has created a mineral lifetime diagram that provides the a clue to when and for how long there might have been water on Mars.
Amanda Albright Olsen of Altoona, Pa., a doctoral student in geosciences at Virginia Tech, will present the research at the Geological Society of America national meeting in Philadelphia on Oct. 22-25. Virginia Tech Geosciences Professor Donald Rimstidt of Christiansburg, Va., is co-author.
Olivine, a silicate mineral rich in magnesium and iron, is found on earth in volcanic rock (basalts). It has also been spotted on Mars – most recently and in significant amounts by NASA's Mars Odyssey spacecraft (Geology, June 2005). Because life requires liquid water and because olivine dissolves in water, Olsen set out to establish how long it takes olivine to dissolve. The answer could help scientists determine if there was liquid water on Mars long enough for life to develop.

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Mars May Be Cosy Place for Hardy Microbes
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A class of especially hardy microbes that live in some of the harshest Earthly environments could flourish on cold Mars and other chilly planets, according to a research team of astronomers and microbiologists. In a two-year laboratory study, the researchers discovered that some cold-adapted microorganisms not only survived but reproduced at 30 degrees Fahrenheit, just below the freezing point of water. The microbes also developed a defence mechanism that protected them from cold temperatures. These close-up images, taken by an electron microscope, reveal the tiny one-cell organisms, called halophiles and methanogens, that were used in the study.

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Arctic life
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Even when it's cold enough to freeze the mercury in your thermometer, life goes on - the frigid wastes of the solar system never looked so habitable

In the icy expanse of the Arctic Ocean, a strange beast glides through the endless tunnels that honeycomb the floating sea ice. Propelled by a whip-like tail, it thrives at temperatures that would kill a human in minutes.
As winter approaches, the mercury drops and the sea ice hardens. Those tunnels of water close up and almost disappear. Temperatures plummet below -20 °C. But the whip-tailed beast, a bacterium called Colwellia 34H, remains alive and well, sealed in the ice in bubbles of briny liquid not much larger than its own single-celled body.
Colwellia used to be seen as a freak of nature, the hardiest of all cold-loving bugs. But biologists are starting to realise that it is not at all unusual. Wherever they look - in permafrost, icebergs, glaciers or ice caps - they find die-hard life forms whose appetite for enduring the cold simply astonishes.

Source


Title: Motility of Colwellia psychrerythraea Strain 34H at Subzero Temperatures
Authors: Karen Junge, Hajo Eicken, Jody W. Deming

We examined the Arctic bacterium Colwellia psychrerythraea strain 34H for motility at temperatures from 1 to 15°C by using transmitted-light microscopy in a temperature-controlled laboratory. The results, showing motility to 10°C, indicate much lower temperatures to be permissive of motility than previously reported (5°C), with implications for microbial activity in frozen environments.

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RE: Mars life
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New research suggests that dust devils and storms on Mars produce oxidants that would render the planet's surface uninhabitable for life as we know it.

"As a consequence, any nascent life (microorganisms, for example) or even prebiotic molecules would find it hard to get a foothold on the surface of Mars, as the organic material would be scavenged efficiently by the surface oxidants" - Sushil Atreya, University of Michigan professor in the Department of Atmospheric Oceanic and Space Sciences.

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Desert Varnish
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Desert varnish is a dark coating on rocks found in arid regions. The coating is composed dominantly of fine-grained clay minerals. Within the clays are black manganese oxide and red iron oxide. A more general term is rock varnish which applies to dark coatings on rocks in general.

Varnish can be a prominent feature in many landscapes. It often coats canyon walls, particularly in the areas where water flows down the the sides of canyons.

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Mysterious Shiny Coating
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A mysterious shiny coating found on rocks in many of Earth's arid environments could reveal whether there was once life on Mars, according to new research.

The research, published in the July edition of the journal Geology, reveals that the dark coating known as desert varnish creates a record of life around it, by binding traces of DNA, amino acids and other organic compounds to desert rocks. Samples of Martian desert varnish could therefore show whether there has been life on Mars at any stage over the last 4.5 billion years.
The researchers hope that these results will encourage any future Mars Sample Return mission to add desert varnish to its Martian shopping list.

The source of the varnish, which looks like it has been painted onto the rocks, has intrigued scientists since the mid nineteenth century, including Darwin, who was so fascinated that he asked the geochemist Berzelius to investigate it. It was previously suggested that its dark colour was the result of the presence of the mineral manganese oxide, and that any traces of life found within the varnish came from biological processes caused by microbes in this mineral.
However, the new research used a battery of techniques, including high resolution electron microscopy, to show that any traces of life in the varnish do not come from microbes in manganese oxide. The research reveals that the most important mineral in the varnish is silica, which means that biological processes are not significant in the varnish's formation. On desert rock surfaces, silica is dissolved from other minerals and then gels together to form a glaze, trapping organic traces from its surroundings.

Dr Randall Perry, lead author of the research from the Department of Earth Science and Engineering at Imperial College London, explained that as life is not involved in desert varnish formation, the varnish can act as an indicator of whether life was present or absent in the local environment.

"If silica exists in varnish-like coatings in Martian deserts or caves, then it may entomb ancient microbes or chemical signatures of previous life there, too. Desert varnish forms over tens of thousands of years and the deepest, oldest layers in the varnish may have formed in very different conditions to the shallowest, youngest layer. These lustrous chroniclers of the local surroundings can provide a window back in time. Martian desert varnish would contain a fascinating chronology of the Martian setting" - Dr Randall Perry.

The research was carried out by researchers at Imperial College and the Universities of Auckland (NZ); Wisconsin-Parkside and Washington (US); and Nottingham Trent (UK).

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See also
Title: `Baking black opal in the desert sun: The importance of silica in desert varnish`
Authors: Perry, Randall S., Lynne, Bridget Y., Sephton, Mark A., Kolb, Vera M., Perry, Carole C., Staley, James T.
Journal: Geology


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Mars Calcite
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Research by Fabien Stalport of the University of Paris in France on the mineral calcite, which is the crystallised form of calcium carbonate say inorganic compounds, shows that it may act as "tracers of biological activity”.
The calcite tends to survive longer than their organic counterparts.
On Earth, calcite is formed in three ways. Living organisms create biotic calcite – limestone. Alternatively, geologic processes such as magmatism can form abiotic calcite. And a combination of processes, which might include biological ones, can act on existing rocks to produce diagenetic calcite.

The researchers used X-ray diffraction and electron scanning microscopy to identify the samples' mineralogical and chemical composition, they found that they could separate the abiotic samples (that were pure) from the biotic samples that contained impurities.




Search for past life on Mars: Physical and chemical characterization of minerals of biotic and abiotic origin: part 1 - Calcite

Fabien Stalport, Patrice Coll, Michel Cabane, Alain Person, Rafael Navarro González, Francois Raulin, Marie Jo Vaulay, Patrick Ausset, Chris P. McKay, Cyril Szopa, John Zarnecki

Abstract
Several lines of evidence suggest that early Mars once had liquid water on its surface, a denser atmosphere and a mild climate. Similar environmental conditions led to the origin of life on the Earth more than 3.5 billion years ago; consequently, life might also have originated on Mars. The Viking landers searched for evidence of organic molecules on the surface of Mars, and found that the Martian soil is depleted in organics at ppb levels at the landing sites.
We contend that inorganic compounds could give us interesting clues as to the existence of possible biological activity in future astrobiological missions to Mars. Consequently, we have investigated the physical and chemical properties of calcite, which could be expected on Mars because liquid water was certainly present on the surface of early Mars and carbon dioxide was abundant in its atmosphere. Calcite is interesting because on Earth this mineral is produced by abiotic processes as well as by biological activity. One may suppose that crystalline defects and trace element in the crystal lattice and the growth speed of biotic calcites must indicate a difference between them and pure abiotic calcites. We investigated twelve different terrestrial calcite samples from various origins: biotic, diagenetic and abiotic.
The minerals were studied by X-ray diffraction and electron scanning microscopy to determine their mineralogical and chemical composition, and differential thermal analysis coupled to thermogravimetric analysis (DTA-TG) to determine their thermal behaviour. Our results show that the thermal degradation of abiotic calcite starts at a temperature at least 40°C higher than the degradation temperature of any biotic calcite investigated. Consequently, in the case of a Martian in-situ study or in a sample return mission, the analysis of Martian minerals by DTA-TG represents a promising approach to detect evidence of past biological activity on Mars.


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Mars Methane
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A University of California, Berkeley, study of methane-producing bacteria frozen at the bottom of Greenland's two-mile thick ice sheet could help guide scientists searching for similar bacterial life on Mars.

Methane is a greenhouse gas present in the atmospheres of both Earth and Mars. If a class of ancient microbes called Archaea are the source of Mars' methane, as some scientists have proposed, then unmanned probes to the Martian surface should look for them at depths where the temperature is about 10 degrees Celsius warmer than that found at the base of the Greenland ice sheet, according to University of California, Berkeley lead researcher P. Buford Price, a professor of physics.
This would be several hundred meters underground, where the temperature is slightly warmer than freezing and such microbes should average about one every cubic centimetre.
While Price is not expecting any time soon a mission to Mars to drill several hundred meters beneath the surface, methanogens (methane-generating Archaea) could just as easily be detected around meteor craters where rock has been thrown up from deep underground.

"Detecting this concentration of microbes is within the ability of state-of-the-art instruments, if they could be flown to Mars and if the lander could drop down at a place where Mars orbiters have found the methane concentration highest. There are oodles of craters on Mars from meteorites and small asteroids colliding with Mars and churning up material from a suitable depth, so if you looked around the rim of a crater and scooped up some dirt, you might find them if you land where the methane oozing out of the interior is highest." - P. Buford Price.

Price and his colleagues published their findings last week in the Early Online edition of the journal Proceedings of the National Academy of Sciences, and presented their results at last week's meeting of the American Geophysical Union in San Francisco.
Variations in methane concentration in ice cores, such as the 3,053-meter-long core obtained by the Greenland Ice Sheet Project 2, have been used to gauge past climate. In that core, however, some segments within about 100 meters of the bottom registered levels of methane as much as 10 times higher than would be expected from trends over the past 110,000 years.
Price and his colleagues showed in their paper that these anomalous peaks can be explained by the presence in the ice of methanogens. Methanogens are common on Earth in places devoid of oxygen, such as in the rumens of cows, and could easily have been scraped up by ice flowing over the swampy subglacial soil and incorporated into some of the bottom layers of ice.
Price and his colleagues found these methanogens in the same foot-thick segments of the core where the excess methane was measured in otherwise clear ice at depths 17, 35 and 100 meters above bedrock.
They calculated that the measured amount of Archaea, frozen and barely active, could have produced the observed amount of excess methane in the ice.

"We found methanogens at precisely those depths where excess methane had been found, and nowhere else. I think everyone would agree that this is a smoking gun"- P. Buford Price

Biologists at Pennsylvania State University had earlier analysed ice several meters above bedrock that was dark gray in appearance because of its high silt content, and identified dozens of types of both aerobic (oxygen-loving) and anaerobic (oxygen-phobic) microbes. They estimated that 80 percent of the microbes were still alive.
Though methane has been detected in Mars' atmosphere, ultraviolet light from the sun would have broken down the amount observed in about 300 years if some process was not replenishing the methane. While interaction of carbon-bearing fluid with basaltic rock might be responsible, methanogens might instead take in subsurface hydrogen and carbon dioxide to make the methane.
If methanogens are responsible, Price calculated that they would occur in a concentration of about one microbe per cubic centimetre at a depth of several hundred meters, where the temperature - about zero degrees Celsius or a bit warmer - would allow just enough metabolism for them to keep alive, just as the microbes in the Greenland ice sheet are doing.

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RE: Mars life
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A French scientist, Jean-Pierre Bibring, believes Europe's next mission to Mars should target some of the oldest rocks on the planet if it wants to find evidence of past life.

He has identified areas that were in contact with water just after the planet's formation.
In one such region, known as Marwth Vallis, conditions could have been stable long enough for life to start.
Prof Bibring is pushing for Europe's ExoMars rover, a 580m-euro robotic vehicle, to be sent there in 2011.

"Marwth Vallis is a good site, too, because the altitude is close to zero. You have to have a site very low on Mars for the parachutes to work" - Jean-Pierre Bibring.

The scientist from the Institute of Space Astrophysics, Orsay, was speaking here at the Fall Meeting of the American Geophysical Union. He made his remarks as Europe's space ministers gathered in Germany to approve the ExoMars rover. An official announcement signing off the project will be made on Tuesday.
ExoMars will carry a drill and a suite of instruments to study surface materials for evidence of past or present biology.
And when mission managers come to decide where to send the rover, they will be listening closely to Prof Bibring's views.
He is the principal investigator on Omega, an instrument on the Mars Express orbiter that is mapping the minerals in the Red Planet's surface rocks. It can see materials that were formed over long time periods in the presence of large amounts of liquid water.
What is fascinating is that these hydrated minerals - so called because they contain water in their crystalline structure - were produced in the first few hundred million years after the planet was created. In other words, the rocks they make up are more than four billion years old.
Crucially, these are not the sulphate minerals seen by the US Mars rovers but a different class of hydrated minerals, known as phyllosilicates - more familiarly called clay minerals.

In Bibring's opinion, it is far more likely that ExoMars will find evidence of life laid down in these rocks than if it were to look at the sulphates documented by the US vehicles.

"Phyllosilicates trace the moment when liquid water was perennial and persistent - something not necessary to make sulphates. To make clay minerals requires long-standing bodies of water and [for life to form] you need that - at least with the experience we have from Earth" - Jean-Pierre Bibring.


Nili Fossae

This puts Marwth Vallis and other clay locations - such as Arabia Terra, Terra Meridiani, Syrtis Major, and Nili Fossae - high on the list of possible ExoMars targets.
And it pushes down the list the sulphate locations such Meridiani Planum and Gusev Crater currently being inspected by the US Mars rovers. Their sulphates were formed in acidic conditions - a challenging environment for any lifeform to evolve.
It is a point echoed last week by US rover scientist Dr Andrew Knoll of Harvard University.

"Life that had evolved in other places or earlier times on Mars, if any did, might adapt to Meridiani conditions, but the kind of chemical reactions we think were important to giving rise to life on Earth simply could not have happened at Meridiani" - Dr Andrew Knoll.

Jean-Pierre Bibring says the instruments on ExoMars should be equipped to look for large carbon molecules in amongst the clays of Marwth Vallis as a possible signature of past life.

From BBC Article

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Posts: 131433
Date:
Methanogens
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A University of Arkansas researcher has found methane-producing microorganisms in an unexpected place - arid desert soils. This finding strengthens the possibility that such microorganisms can exist under the conditions found on Mars and points the way to possible future experiments for detection of life on a distant planet.

Tim Kral, professor of biological sciences in the J. William Fulbright College of Arts and Sciences, along with researchers from the University of Southern California reported their findings online in the journal Icarus.


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"You don't commonly find organisms such as methanogens in dry areas. But finding them in a dry area on Earth is especially significant because the surface of Mars is dry" - Tim Kral.

Researchers collected five vapour samples each from the Mars Desert Research Station in Utah and from the Idaho High Desert, as well as 40 soil samples from the Utah site, one from Death Valley, California, 19 from the Arctic Circle and one from the Atacama Desert in Chile. The samples were sent to Kral for analysis in his laboratory, where he has previously grown and monitored methanogens.

Examination of the vapour samples from the sites found that three of the five gas samples contained methane, indicating the possible presence of methanogens in the soil. In addition, five of the 40 soil samples from Utah produced methane when they were treated with a growth medium, again indicating the presence of methanogens.

Methanogens are found in anaerobic environments on Earth, from hot springs to the deep ocean to the intestinal tracts of humans and animals. Methanogens do not require oxygen to survive; instead, these tiny creatures breathe carbon dioxide and hydrogen gas, producing methane as a waste product. This unique form of respiration makes methanogens potentially viable residents of Mars, whose atmosphere is predominantly composed of carbon dioxide with practically no oxygen.

Methane, a gaseous compound of carbon and hydrogen, recently has been found in the atmosphere of Mars. Methane is unstable in the presence of ultraviolet sunlight and can be completely destroyed in the atmosphere in only a few hundred years. Its presence in the Martian atmosphere can only be explained if there is some process on Mars that is continually creating it.

Two potential scenarios could explain the presence of the gas. Either the methane is being produced by living organisms, which would mean that some type of methanogens already inhabit the planet, or the methane is being made below the planet's surface by subsurface volcanic activity. The presence of such volcanic activity would mean that there is a source of energy and warmth below the surface -- two factors that are indicators that liquid water may also exist below the surface.

Finding methanogens in dry, arid climates shows that they may be able to exist in the limited water conditions found on Mars. The researchers suggest that collection methods used in the desert study could be modified for use in future biodetection experiments on Mars.

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