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New Chemical Source of Possible Life on Mars



A chemical reaction between iron-containing minerals and water may produce enough hydrogen "food" to sustain microbial communities living in pores and cracks within the enormous volume of rock below the ocean floor and parts of the continents, according to a new study led by the University of Colorado Boulder. The findings, published in the journal Nature Geoscience, also hint at the possibility that hydrogen-dependent life could have existed where iron-rich igneous rocks on Mars were once in contact with water.

Not only is there a potentially large volume of rock on Earth that may undergo low temperature reactions, but the same types of rocks also are prevalent on Mars.

Scientists have thoroughly investigated how rock-water reactions can produce hydrogen in places where the temperatures are far too hot for living things to survive, such as in the rocks that underlie hydrothermal vent systems on the floor of the Atlantic Ocean. The hydrogen gases produced in those rocks do eventually feed microbial life, but the communities are located only in small, cooler oases where the vent fluids mix with seawater.

The new study, led by CU-Boulder Research Associate Lisa Mayhew, set out to investigate whether hydrogen-producing reactions also could take place in the much more abundant rocks that are infiltrated with water at temperatures cool enough for life to survive.

"Water-rock reactions that produce hydrogen gas are thought to have been one of the earliest sources of energy for life on Earth," said Mayhew, who worked on the study as a doctoral student in CU-Boulder Associate Professor Alexis Templeton's lab in the Department of Geological Sciences.

"However, we know very little about the possibility that hydrogen will be produced from these reactions when the temperatures are low enough that life can survive. If these reactions could make enough hydrogen at these low temperatures, then microorganisms might be able to live in the rocks where this reaction occurs, which could potentially be a huge subsurface microbial habitat for hydrogen-utilizing life."

When igneous rocks, which form when magma slowly cools deep within the Earth, are infiltrated by ocean water, some of the minerals release unstable atoms of iron into the water. At high temperatures — warmer than 392 degrees Fahrenheit — scientists know that the unstable atoms, known as reduced iron, can rapidly split water molecules and produce hydrogen gas, as well as new minerals containing iron in the more stable, oxidized form.

Mayhew and her co-authors, including Templeton, submerged rocks in water in the absence of oxygen to determine if a similar reaction would take place at much lower temperatures, between 122 and 212 degrees Fahrenheit. The researchers found that the rocks did create hydrogen — potentially enough hydrogen to support life.

To understand in more detail the chemical reactions that produced the hydrogen in the lab experiments, the researchers used "synchrotron radiation" — which is created by electrons orbiting in a manmade storage ring — to determine the type and location of iron in the rocks on a microscale.

The researchers expected to find that the reduced iron in minerals like olivine had converted to the more stable oxidized state, just as occurs at higher temperatures. But when they conducted their analyses at the Stanford Synchrotron Radiation Lightsource at Stanford University, they were surprised to find newly formed oxidized iron on "spinel" minerals found in the rocks. Spinels are minerals with a cubic structure that are highly conductive.

Finding oxidized iron on the spinels led the team to hypothesize that, at low temperatures, the conductive spinels were helping facilitate the exchange of electrons between reduced iron and water, a process that is necessary for the iron to split the water molecules and create the hydrogen gas.

"After observing the formation of oxidized iron on spinels, we realized there was a strong correlation between the amount of hydrogen produced and the volume percent of spinel phases in the reaction materials," Mayhew said. "Generally, the more spinels, the more hydrogen."

Mayhew and Templeton are already building on this study with their co-authors, including Thomas McCollom at CU-Boulder's Laboratory for Atmospheric and Space Physics, to see if the hydrogen-producing reactions can actually sustain microbes in the lab.

The photo at thetop of the page was captured by NASA's Mars Global Surveyor in 2000 offering evidence that the planet may have been a land of lakes in its earliest period, with layers of Earth-like sedimentary rock that could harbor the fossils of any ancient Martian life.



Multicellular organisms most definitely exists within the planet Mars that even contains a subsurface ocean early in development.

I can't help feeling that surface water on mars existed much later than the millions of years being said. Is there a correlation between the great climatic changes of Earth to the ones on Mars? Wouldn't it be cool if we found out that water was flowing on Mars at the same time of the medieval warm period of a thousand years ago. Maybe the Viking were farming on Greenland at the same time water was flowing through these ancient Martian stream beds. We know that Climatic changes on Earth are related to the Suns energy flux cycles so it must also be true for the other planets in the solar system as well. Studying Mars could reveal some surprising information about the close interrelationship between all the planets when it comes to climate change. Do the storms raging on Jupitar and Saturn relate to the weather changes on Earth and Mars to? Are these valid questions or are they just politically incorrect?

Interesting story. I suspect if life did get going on Mars billions of years ago when there was water, then it would have found a way to cling on into the present in certain favourable niches. On the down side; who, in the name of all that's holy, reports science stories using fahrenheit these days? Get with it guys, SI unit of temp is centigrade. Water freezes at 0, boils at 100. Not difficult!

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