Ancient Mars May Have Been Habitable for Hundreds of Millions of Years

Steve Williams

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by Mike Wall, Senior Writer |

Mars may have once been capable of supporting microbial life for hundreds of millions of years in the distant past, new findings from a long-lived Red Planet rover suggest.
NASA's Opportunity rover, which celebrates 10 years of Mars exploration on Friday (Jan. 24), has uncovered evidence that benign, nearly neutral-pH water flowed on the Red Planet around 4 billion years ago.

These results, reported today (Jan. 23) in the journal Science, complement the recent work of NASA's bigger, newer Curiosity rover, which discovered a potentially habitable lake and groundwater system in a different Martian locale dating from about 3.7 billion years ago.
"These [benign] water conditions existed over a long period of time," said Ray Arvidson, lead author of the new study and Opportunity deputy principal investigator.
Therefore, primitive organisms may have been able to survive on Mars for long stretches during a period when life was getting a foothold on Earth, said Arvidson, director of the Earth and Planetary Remote Sensing Laboratory at Washington University in St. Louis.
"That wouldn't be a surprise," he told "Maybe not globally; [habitable environments] could have occurred here and there regionally. And it may not have been for the whole time continuously. We don't know."

Studying ancient rocks

The golf-cart-size Opportunity touched down on Jan. 24, 2004, three weeks after its twin, Spirit. Both robots were tasked with 90-day missions to seek out signs of past water activity on Mars. Spirit was declared dead in 2011, but Opportunity is still going strong.

The rover made the new discovery at an outcrop on the rim of Endeavour Crater, a 14-mile-wide (22 kilometers) hole in the ground that Opportunity reached in August 2011.
NASA's Mars Reconnaissance Orbiter spotted evidence of exposed, aluminum-rich clay minerals at a site along the rim called Matijevic Hill. Such clays generally form in the presence of benign, mildly acidic water, so the rover team commanded Opportunity to go check out the rock formation.

When Opportunity got there, the rover encountered the oldest rocks it has ever studied on Mars. Fine-grained, layered rocks in the Matijevic outcrop date from Mars' Noachian period, making them perhaps 4 billion years old, Arvidson said. (It's tough to date Mars rocks and formations definitively, so such numbers have large uncertainties associated with them, he stressed.)

These clay-enriched rocks are studded with BB-size "spherules" and cut by numerous fractures, through which liquid water flowed long ago, Arvidson said.
"The groundwaters that moved through those fractures were only mildly acidic, and mildly oxidizing to reducing," he said. "So, the earlier you go, the more clement the conditions were."

These ancient rocks predate the asteroid or comet impact that created Endeavour Crater, and they're covered in most places by younger material that bears the signature of hypersalty and much more acidic water — the signature, in other words, of a much less hospitable Mars.

Teaming up with Curiosity

Opportunity's new results take on deeper meaning when combined with the observations of the 1-ton Curiosity rover, which touched down on a different part of Mars in August 2012.

Curiosity was designed to extend and advance the discoveries of Spirit and Opportunity. It sports 10 different science instruments — a suite crafted specifically to determine if the Red Planet could ever have supported microbial life.
Last month, the Curiosity team announced that an area near the rover's landing site harbored a large, shallow and potentially habitable lake system during Mars' Hesperian era, which follows the Noachian in Red Planet chronology. This lake and its feeder streams likely existed about 3.7 billion years ago, or perhaps even a bit more recently, mission scientists said.

So researchers are starting to get a better idea of the Martian surface's window of habitability, Arvidson said. It appears that window might have been open — off and on, perhaps, and here and there — for hundreds of millions of years in the distant past.

Liquid water cannot exist for long periods on the surface of present-day Mars, whose atmosphere is just 1 percent as thick as that of Earth. That atmosphere was likely thicker long ago, if lakes and river systems were, indeed, stable for lengthy stretches, Arvidson said.
"One way to do it is to have massive impacts, and to have a [temporarily thicker] atmosphere," he said. "So it could be that you have multiple impacts over that extended period of time, and collectively they made for a sustained presence of water on the surface and in the shallow subsurface. But we don't know, at this point, with just two examples."


WBF Founding Member
Apr 21, 2010
Ann Arbor, Michigan

And here's some older news on Mars.

NASA's New Evidence of Water on Mars Suggests It's Hiding Underground
By Amy Shira Teitel 1 year ago
This discovery supports the theory that simple life forms once thrived in hidden underground Martian waters. And like all things life-related, it’s the comparison with Earth that makes the case so strong.

On Earth, microbes living up to three miles underground account for a significant percentage of the entire planet's living matter. These underground life forms are largely primitive microbes, but life is life. And it’s likely that microbes this far beneath the surface could have survived the Late Heavy Bombardment period, a series of cosmic impacts the inner planets endured between 4.1 billion to 3.8 billion years ago.

So say the same thing happened on Mars around the same time – primitive microbes sprung up in underground lakes and survived the Late Heavy Bombardment. What happened? Well, Mars’ gravity is a little more than a third of what we feel on Earth and its crust is a little less dense. This means that while the planet is dry now, more water could have leaked underground in the past. And if it didn’t all evaporate, it could be that energy sources and chemical reactions similar to those that support deep-dwelling organisms on Earth – like every astrobiologist’s favourite, the deep sea hydrothermal vents – could have done the same thing on Mars. Or might be doing the same thing on Mars right now.................................

NASA’s InSight mission, set to launch in 2016, will drill into the surface. It won’t go too far down, but it will help scientists understand what’s going on inside the planet, and that might shed more light on the subsurface lake theory.

See ya in a couple of years to revisit this topic.

My suspicion is that there still is life in Mars, deep underground.


Bacteria Found Deep Underground
by FRASER CAIN on OCTOBER 25, 2006
Princeton researchers have discovered a colony of bacteria that lives more than 3 km (2 miles) underground. This bacteria lives completely cut off from the biosphere on the surface of the Earth, and derives its energy from the radioactive decay of rocks underground. By finding life in these extreme conditions, scientists are expanding their understanding of what kinds of habits can support life.....................................

“What really gets my juices flowing is the possibility of life below the surface of Mars,” said Tullis Onstott, a Princeton University professor of geosciences and leader of the research team.

Life in the bacterial underground
Tiny life forms in rock may coax minerals to release hydrogen for food
Scientists now estimate that twice as many microbes live underground than live on the surface or close to it.

Deep Carbon Observatory Spotlights 'Zombie' Microbes Far Below Earth's Surface
Reuters | Posted: 03/04/2013 12:46 pm EST
By Environment Correspondent Alister Doyle

OSLO (Reuters) - A dark realm far beneath the Earth's surface is a surprisingly rich home for tiny worms and "zombie microbes" that may hold clues to the origins of life, scientists said on Monday.

"It's an amazing new world," said Robert Hazen, head of the Deep Carbon Observatory, a decade-long $500 million project to study the planet's carbon, an element vital to life and found in everything from oil to diamonds.

"It's very possible that there's a deep microbial biosphere that goes down more than 10 km (6 miles), maybe 20," Hazen told Reuters of the first book by the Observatory, published on Monday and written by more than 50 experts in nine countries.

Microbes had been reported, for instance, in rocks recovered by drilling more than 6 km below the surface in China's Songliao basin, he said. And tiny worms have been found in fractures in rocks 1.3 km deep in a South African mine.

The single-celled microbes found deep underground include bacteria, which need water and nutrients to grow but not necessarily oxygen, and archaea, which can live off compounds such as ammonia or sulphur.

A lack of food in what the 700-page report called the "Stygian realm" - after the River Styx of the underworld in Greek mythology - meant some microbes might be "zombies", or so slow-living as to seem dead.

The book, "Carbon in Earth", said some microbes may live deep below ground and grow and reproduce extremely slowly or perhaps even "live without dividing for millions to tens of millions of years".

86 Percent of Earth's Species Still Unknown?
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WBF Founding Member
Apr 21, 2010
Ann Arbor, Michigan
Life Underground Critical to Earth's Ecosystems
July 29, 2009
"The unseen, and mostly underappreciated, realm beneath us is teeming with life," says Wall. "Earth is really brown and black, not green."...........................

Wall and colleagues found that nematodes were the dominant soil animals, whether under boreal forest (60.9 percent) or tundra (69.8 percent). Rotifers, microscopic wheel-shaped animals, made up 26.1 percent of the soil animals in the Arctic tundra and 18 percent of life beneath the boreal forest.

Arthropods such as spiders comprised some 19.4 percent of the boreal forest underground, and 2.6 percent of that of the tundra. Tiny tardigrades, better known as water-bears, were rarer, at 1.3 percent and 1.5 percent of boreal forest and tundra, respectively.

The surprising discovery of deep subsurface microbial communities in the mid-1980s launched a new and rapidly expanding subdiscipline within biology, known as geomicrobiology. In geomicrobiology, the fields of geology, geophysics, hydrology, geochemistry, biochemistry, and microbiology have merged to study how life on this planet interacts with the earth's geology, how life may have originated and how life evolved over billions of years. Dark life–those organisms that thrive underground in the absence of sunlight–comprises 50 percent of the earth's biomass, is responsible for many geological phenomena, degrades our wastes and produces some of our energy. Yet many questions remain regarding dark life–questions that can only be answered by going underground...........................

They precipitate minerals and produce gases, thereby changing the rock's porosity and permeability, but normally at rates a million times slower than those of surface life. Given enough time, however, microorganisms secreting sulfuric acid can carve enormous chambers in limestone, like those of the Carlsbad Caverns.

Groundwater activity on Mars and implications for a deep biosphere
Received 15 August 2012 Accepted 07 December 2012 Published online 20 January 2013 et al 2012.pdf

Huge 'Ocean' Discovered Inside Earth
Ker Than | February 28, 2007 08:28am ET
Scientists scanning the deep interior of Earth have found evidence of a vast water reservoir beneath eastern Asia that is at least the volume of the Arctic Ocean.

The discovery marks the first time such a large body of water has found in the planet's deep mantle. [The World's Biggest Oceans and Seas]

The finding, made by Michael Wysession, a seismologist at Washington University in St. Louis, and his former graduate student Jesse Lawrence, now at the University of California, San Diego, will be detailed in a forthcoming monograph to be published by the American Geophysical Union.......................................

"That is exactly what we show here," Wysession said. "Water inside the rock goes down with the sinking slab and it's quite cold, but it heats up the deeper it goes, and the rock eventually becomes unstable and loses its water."

The water then rises up into the overlying region, which becomes saturated with water [image]. "It would still look like solid rock to you,” Wysession told LiveScience. "You would have to put it in the lab to find the water in it."

Although they appear solid, the composition of some ocean floor rocks is up to 15 percent water. "The water molecules are actually stuck in the mineral structure of the rock," Wysession explained. "As you heat this up, it eventually dehydrates. It's like taking clay and firing it to get all the water out."

The researchers estimate that up to 0.1 percent of the rock sinking down into the Earth's mantle in that part of the world is water, which works out to about an Arctic Ocean's worth of water.

"That's a real back of the envelope type calculation," Wysession said. "That's the best that we can do at this point."
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