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RE: Mars life
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Life on Mars? Brown-led Research Team Says Elusive Mineral Bolsters Chances
During the last several years, scientists have built a very convincing case that Mars hosted water, at least early in its history. Recent observations from the Mars Phoenix lander and other spacecraft show that the planet still holds vast deposits of water as ice at its poles and in soil-covered glaciers in the mid-latitudes.
What is less known is how much water occupied the red planet and what happened to it during its geological march to the present. Mostly, evidence has pointed to a period when clay-rich minerals were formed by water, followed by a drier time, when salt-rich, acidic water affected much of the planet. Assuming that happened, the thinking goes, it would have been difficult for life, if it did exist, to have survived and for scientists to find traces of it.
Now a research team led by Brown University has found evidence of carbonates, a long-sought mineral that shows Mars was home to a variety of watery environments - some benign, others harsh - and that the acidic bath the planet endured left at least some regional pockets unscathed.

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Rock Varnish
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Rock Varnish: A Promising Habitat for Martian Bacteria
As scientists search for life on Mars, they should take a close look at rock varnish, according to a paper in the current issue of the "Journal of Geophysical Research."
The paper describes how a research team led by Kimberly R. Kuhlman, of the Tucson-based Planetary Science Institute, found bacteria associated with rock varnish in an area where the surrounding soils were essentially devoid of life. The study suggests that rock varnish could provide a niche habitat for microbial life on Mars and in other extraterrestrial environments devoid of liquid water.
Rock varnish is an extremely slow-growing coating that forms on the surfaces of rocks in arid and semiarid climates. In Southwestern deserts, it often appears as a tough, dark stain on light-coloured canyon walls. Ancient petroglyphs are often found etched into rock varnishes.
Kuhlman's team analysed samples of rock varnish collected from the Yungay region of Chile's Atacama Desert, which is the closest analogue to Martian environments found on Earth.


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A leading international space scientist says there is now clear evidence of life on Mars but that American authorities are hesitating from announcing it for political reasons.

"The discovery of liquid water on Mars combined with earlier discoveries of organic substances in a meteorite that came from Mars, and also of methane in the Martian atmosphere all point to the existence of life -- contemporary life -- on the Red Planet" - Chandra Wickramasinghe, a globally renowned astrobiologist.

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Mars was once covered once by lakes, rivers and other bodies of water that could have supported life, according to scientists.
Stunning mages from US and European spacecraft have revealed details of regions thought to contain water-bearing minerals and geological formations formed billions of years ago.
The High-Resolution Stereo Camera onboard the European Space Agency's Mars Express took pictures of Echus Chasma, thought to have been one of the largest sources of water on Mars.

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Mars Methane
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In a quest to understand the source of methane detected in the atmosphere of Mars, NASA scientists are looking at methane bubbling from the ground at an outdoor salt factory on Mexicos Baja Peninsula. By measuring carbon isotopes in the Mexican methane, these scientists hope to help unravel the mystery of the martian methane. In particular, they want to know whether or not the martian methane, like most methane on Earth, is made by microbes.

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-- Edited by Blobrana at 13:50, 2008-06-09

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Interview with Cassie Conley, Part III
NASA plans to send humans back to the moon, and eventually to Mars. But humans and the food they eat are chock full of microbial contaminants. Figuring out how to keep that contamination in check is the job of Dr. Cassie Conley, NASAs acting planetary protection officer. In this, the third and final part of Astrobiology Magazines interview with Conley, she explains that, sometimes, its okay to make a mess.
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Title: The Potential for Lithoautotrophic Life on Mars: Application to Shallow Interfacial Water Environments
Authors: Steven M. Jepsen, John C. Priscu, Robert E. Grimm, Mark A. Bullock

We developed a numerical model to assess the lithoautotrophic habitability of Mars based on metabolic energy, nutrients, water availability, and temperature. Available metabolic energy and nutrient sources were based on a laboratory-produced Mars-analogue inorganic chemistry. For this specific reference chemistry, the most efficient lithoautotrophic microorganisms would use Fe2+ as a primary metabolic electron donor and NO3- or gaseous O2 as a terminal electron acceptor. In a closed model system, biomass production was limited by the electron donor Fe2+ and metabolically required P, and typically amounted to ~800 pg of dry biomass/ml (~8,500 cells/ml). Continued growth requires propagation of microbes to new fecund environments, delivery of fresh pore fluid, or continued reaction with the host material. Within the shallow cryospherewhere oxygen can be accessed by microbes and microbes can be accessed by explorationlithoautotrophs can function within as little as three monolayers of interfacial water formed either by adsorption from the atmosphere or in regions of ice stability where temperatures are within some tens of degrees of the ice melting point. For the selected reference host material (shergottite analogue) and associated inorganic fluid chemistry, complete local reaction of the host material potentially yields a time-integrated biomass of ~0.1 mg of dry biomass/g of host material (~10^9 cells/g). Biomass could also be sustained where solutes can be delivered by advection (cryosuction) or diffusion in interfacial water; however, both of these processes are relatively inefficient. Lithoautotrophs in near-surface thin films of water, therefore, would optimise their metabolism by deriving energy and nutrients locally. Although the selected chemistry and associated model output indicate that lithoautotrophic microbial biomass could accrue within shallow interfacial water on Mars, it is likely that these organisms would spend long periods in maintenance or survival modes, with instantaneous biomass comparable to or less than that observed in extreme environments on Earth.

Source: Mary Ann Liebert Inc.

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Probes seeking life on Mars must dig deeply into young craters, gullies, or recently exposed ice to have a chance of finding any living cells that were not annihilated by radiation, researchers report in a new study. One promising place to look for them is within the ice at Elysium, site of a recently discovered frozen sea, they say.

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Elysium's frozen sea on Mars is one of the most promising places to look for life on the Red Planet, scientists say.
But planned missions designed to search for microbes below the Martian surface will not drill deep enough to find living cells, the UK team has said.
Researchers at University College London say that microbes in the first couple of metres of Martian soil would be killed off by intense radiation.
Life might survive deeper down, where conditions are more benign.

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Life on Earth may have announced its arrival billions of years ago with a whistle and a thump, according to planetary scientists.Experiments by an international team of researchers back a controversial theory that life flourished on Earth after primitive organisms arrived aboard a meteorite, itself gouged from Mars by a giant impact.The theory supposes that life was able to gain a tentative foothold on the red planet as it cooled down and became more hospitable several billion years ago. At the time, the planet's surface was regularly bombarded with rocky detritus from the asteroid belt, knocking clumps of rock and the microbes living on them into space, where the gravity of the sun brought them hurtling towards Earth.

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