December 21, 2012
Clay Is More Plentiful On Mars Than Was Previously Believed
redOrbit Staff & Wire Reports - Your Universe Online
A larger portion of the Mars surface is covered by clay minerals - a type of rock that typically forms in places where water is present over an extended period of time - than was previously believed, claims a new study published in the current online edition of the journal Geophysical Research Letters.
Eldar Noe Dobrea of the Planetary Science Institute (PSI) and colleagues identified the clay minerals using a spectroscopic analysis from the Mars Reconnaissance Orbiter (MRO). They even discovered that some of the rocks studied by Opportunity at Eagle Crater in 2004, as well as the Meridiani plains that the rover passed over en route to its current location, were comprised of clay.
"It´s not a surprise that Opportunity didn´t find clays while exploring. We didn´t know they existed on Mars until after the rover arrived," James Wray, a professor at the Georgia Institute of Technology School of Earth and Atmospheric Sciences, said in a statement Thursday. "Opportunity doesn´t have the same tools that have proven so effective for detecting clays from orbit."
Eagle Crater's clay signatures are extremely weak, especially in comparison to those located along the rim and on the inside of Endeavor Crater, the university said. Wray said that he believes that there may have been more of these types of rocks in the past, and that the clays were eliminated by volcanic and acidic activity in the planet's past.
"Current theories of Martian geological history suggest that clays, a product of aqueous alteration, actually formed early on when the planet's waters were more alkaline," Georgia Tech officials explained. "As the water acidified due to volcanism, the dominant alteration mineralogy became sulfates."
"This forces us to rethink our current hypotheses of the history of water on Mars," added Dobrea.
Even though Opportunity has discovered an area likely to be rich in clay deposits, analysis of the rocks faces several obstacles. The rover itself was expected to survive for a period of just three months, but that was more than eight years ago. Neither of its two mineralogical instruments are operational either, forcing Opportunity to take images of the surface with its panoramic camera and attempt to analyze their composition with a spectrometer.
"So far, we´ve only been able to identify areas of clay deposits from orbit," Wray explained. "If Opportunity can find a sample and give us a closer look, we should be able to determine how the rock was formed, such as in a deep lake, shallow pond or volcanic system."