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NASA Jet Propulsion Laboratory

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Last modified: Wednesday, October 31, 2012

NASA roverís first soil studies help fingerprint Martian minerals

Oct. 31, 2012

PASADENA, Calif. -- Initial experiments completed by NASA's Mars rover Curiosity have shown the mineralogy of Martian soil to be similar to that of weathered basaltic soils of volcanic origin in Hawaii. Investigators with Curiosity's Chemistry and Mineralogy (CheMin) experiment, including Indiana University Bloomington geologist David Bish, discussed the results Tuesday.

"Much of Mars is covered with dust, and we had an incomplete understanding of its mineralogy," said Bish, CheMin co-investigator and the Haydn Murray Chair of Applied Clay Mineralogy in the Department of Geological Sciences in the College of Arts and Sciences. "We now know it is mineralogically similar to basaltic material, with significant amounts of feldspar, pyroxene and olivine, which was not unexpected."

Mars x-ray diffraction image


This graphic shows results of the first analysis of Martian soil by the Chemistry and Mineralogy (CheMin) experiment on NASA's Curiosity rover. The image reveals the presence of crystalline feldspar, pyroxenes and olivine mixed with some non-crystalline material.

Print-Quality Photo

The identification of minerals in rocks and soil is crucial for the Curiosity mission's goal to assess past environmental conditions. Each mineral records the conditions under which it formed, while the chemical composition of a rock provides only ambiguous mineralogical information.

CheMin uses X-ray diffraction, which provides more accurate identification of minerals than any method previously used on Mars. X-ray diffraction reads minerals' internal structure by recording how their crystals distinctively interact with X-rays. The CheMin team also includes David Blake of NASA Ames Research Center and David Vaniman of Los Alamos National Laboratory.

The sample for CheMin's first analysis was soil Curiosity scooped up at a patch of dust and sand within Mars' Gale Crater that the team named Rocknest. The sample has at least two components: dust distributed globally in dust storms and fine sand originating more locally. Unlike conglomerate rocks Curiosity investigated a few weeks ago, which are several billion years old and indicative of flowing water, the soil material CheMin has analyzed is more representative of modern processes on Mars.

"So far, the materials Curiosity has analyzed are consistent with our initial ideas of the deposits in Gale Crater recording a transition through time from a wet to dry environment," Bish said. "The ancient rocks, such as the conglomerates, suggest flowing water, while the minerals in the younger soil are consistent with limited interaction with water."

CheMin developed an X-ray diffraction instrument the size of a shoe box, allowing it to be transported with Curiosity. A normal X-ray diffraction instrument is the size of a refrigerator. The advances have resulted in applications on Earth, including portable X-ray diffraction equipment for oil and gas exploration, analysis of archaeological objects and screening of counterfeit pharmaceuticals.

"This is truly an exciting time for planetary science and particularly for me as a mineralogist," Bish said. "It's been an extraordinary experience to participate in the development of CheMin and the first X-ray diffraction analysis of soil on the surface of another planet."

During the two-year prime mission of the Mars Science Laboratory Project, researchers are using Curiosity's 10 instruments to investigate whether areas in Gale Crater ever offered environmental conditions favorable for microbial life. IU Bloomington professor Juergen Schieber, an expert in sedimentary geology, is part of the team analyzing data from the Mars Hand Lens Imager, a focusable color camera that will take close-up photographs of rocks and soil.

NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the project for NASA's Science Mission Directorate, Washington, and built Curiosity and CheMin.

For more information about Curiosity and its mission, visit the NASA or Jet Propulsion Laboratory's websites. You can also follow the mission on Facebook and Twitter.