Alpha Centauri 2

Community => Recreation Commons => Destination: Alpha Centauri => Topic started by: Buster's Uncle on January 23, 2014, 09:35:50 pm

Title: Ancient Mars May Have Been Habitable for Hundreds of Millions of Years
Post by: Buster's Uncle on January 23, 2014, 09:35:50 pm

Ancient Mars May Have Been Habitable for Hundreds of Millions of Years
SPACE.com
by Mike Wall, Senior Writer  2 hours ago


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Pancam false-color view acquired on sol 3066 of fine-scale layering in the Whitewater Lake locality. Veneers have been resistant to wind erosion and enhanced the layered appearance of the outcrop. Layers are typically several millimeters thick.



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 SPACE.com. "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."


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Pancam false-color image acquired on sol 3208 of Matijevic formation rocks at the Whitewater Lake locality, showing embedded spherules. Approximate scale across image is 40 cm.


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.


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MI mosaic acquired on sol 3064 showing a dense concentration of spherules at the Kirkwood target and locality. Approximate scale across the scene is 5 cm, and illumination is from the top.


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."


http://news.yahoo.com/ancient-mars-may-habitable-hundreds-millions-years-192336149.html (http://news.yahoo.com/ancient-mars-may-habitable-hundreds-millions-years-192336149.html)

Title: NASA rover Opportunity finds signs Mars once had fresh water
Post by: Buster's Uncle on January 24, 2014, 12:34:13 am

NASA rover Opportunity finds signs Mars once had fresh water
Reuters
By Irene Klotz  43 minutes ago


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A 360-degree digitally-compressed panorama image of Mars is seen in this composite of 800 images sent from the NASA Opportunity rover on Mars released on July 9, 2012. REUTERS/NASA/JPL-Caltech/Cornell/Arizona State University/Handout



(Reuters) - NASA's decade-old Mars rover, Opportunity, has found evidence that life-friendly fresh water once pooled on the red planet's surface, reinforcing similar discoveries made by newcomer Curiosity on the other side of the planet, scientists said on Thursday.

Opportunity, along with its now-defunct twin, Spirit, landed 10 years ago for concurrent 90-day missions to look for clues of the past existence of water.

Both rovers did so, confirming evidence collected by orbiting spacecraft that Mars, the planet believed to be most like Earth in the solar system, was not always the cold, dry desert that appears today.

In August 2012, Curiosity, equipped with an onboard chemistry lab, arrived for follow-up investigations to determine if Mars had other ingredients essential for supporting life.

The answer, returned very early in the ongoing mission, was a definite 'yes'.

On the other side of the planet, meanwhile, Opportunity has been analyzing water-bearing rocks at the rim of an ancient impact crater called Endeavour.

Rather than the chemical fingerprints of acidic, salty water found at previous sites, Opportunity discovered telltale clays called smectites that form in Ph-neutral water.

"It's like drinking water," planetary scientist Ray Arvidson, with Washington University in St. Louis, said in an interview.

"This would have been a niche for whatever life at the time existed," he said.

The finding adds to an emerging picture of a planet that spent its first billion years or so warmer than it is today, with pools of fresh water on its surface, scientists say.

Gradually, water activity declined and what did exist became acidic, scientific findings reveal, and then, beginning about 3 billion years ago, Mars dried up.

"Most of the activity on Mars in terms of habitability and water activity was concentrated in the first billion or so years," said Opportunity lead scientist Steve Squyres, with Cornell University in New York.

Opportunity is expected eventually to head south toward a ridge on the rim of Endeavour Crater that appears to contain a much richer cache of clay-bearing rocks.

Curiosity, which is exploring an area known as Gale Crater, is driving toward a three-mile high mountain of layered deposits.

By studying rocks at various levels, scientists expect to not only get a better idea of how long the planet was able to sustain life, but where conditions might be favorable to perverse key evidence, such as organic carbon.

The research appears this week in the journal Science.


http://news.yahoo.com/nasa-rover-opportunity-finds-signs-mars-once-had-234136353--sector.html (http://news.yahoo.com/nasa-rover-opportunity-finds-signs-mars-once-had-234136353--sector.html)