Mars Shows Signs of Acid Fog: Study

Mars Shows Signs of Acid Fog: Study

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A planetary scientist has pieced together a compelling story 
about how acidic vapours may have eaten the rocks in a 100
-acre area on Husband Hill in the Columbia Hills of Gusev 
Crater on Mars.
Shoshanna Cole from the Cornell University used data 
gathered by multiple instruments on the 2003 Mars 
Exploration Rover Spirit to tease out information from 
exposures of the ancient bedrock.
The work focused on the 'Watchtower Class' outcrops 
on Cumberland Ridge and the Husband Hill summit.
By combining data from previous studies of the area on Mars,
 Cole saw some intriguing patterns emerge.
Spirit examined "Watchtower Class" rocks at a dozen 
locationsspanning about 200 meters along Cumberland 
Ridge and the Husband Hill summit.
Across Cumberland Ridge the data showed there was a 
surprisingly wide range in the proportion of oxidized iron to 
total iron, as if something had reacted with the iron in these 
rocks to different degrees.
Meanwhile, further data showed that the minerals within the 
rocks changed and lost their structure, becoming less 
crystalline and more amorphous.
These trends match the size of small bumps, which Cole calls agglomerations, seen in Pancam and Microscopic Imager 
pictures of the rocks.
"So we can see the agglomerations progress in size from 
west to east and the iron changes in the same way," Cole 
said. "It was super cool."
But the fact that the rocks were otherwise the same in 
composition indicates that they were originally identical.
"That makes us think that they were made of the same stuff 
when they started out. Then something happened to make 
them different from each other," she noted.
Cole hypothesises that the rocks were exposed to acidic 
water vapour from volcanic eruptions, similar to the corrosive 
volcanic smog that poses health hazards in Hawaii from the 
eruptions of Kilauea.
When the Martian smog landed on the surface of the rocks it
dissolved some minerals, forming a gel.
Then the water evaporated, leaving behind a cementing 
agent that resulted in the agglomerations.
She presented the findings at the annual meeting of the 
Geological Society of America in Baltimore, Maryland, on 
November 2.


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