|An image from the Mast Camera on NASA’s Curiosity rover shows the upper portion of a wind-blown deposit dubbed “Rocknest.” The rover team recently commanded Curiosity to take a scoop of soil from a region located out of frame, below this view. The soil was then analyzed with the Chemistry and Mineralogy instrument, or CheMin. Image credit: NASA/JPL-Caltech/MSSS.|
New results from NASA’s Mars rover Curiosity show that the mineralogy of Martian soil is similar to weathered basaltic soils of volcanic origin in Hawaii.
The minerals were identified in the first sample of Martian soil ingested recently by the rover. Curiosity used its Chemistry and Mineralogy (CheMin) instrument to analyze the sample.
“Our team is elated with these first results from our instrument,” said David Blake of NASA Ames Research Center in Moffett Field, Calif., who is the principal investigator for CheMin. “They heighten our anticipation for future CheMin analyses in the months and miles ahead for Curiosity.”
Innovations from Ames led to an X-ray diffraction instrument compact enough to fit inside the rover. Mars exploration wasn’t the only benefit, however.
CheMin uses X-ray diffraction, the standard practice for geologists on Earth using much larger laboratory instruments. This method provides more accurate identifications 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 innovations have also led to applications on Earth such as compact and portable X-ray diffraction equipment for oil and gas exploration, analysis of archaeological objects and screening of counterfeit pharmaceuticals, among other uses.
The identification of minerals in rocks and soil is crucial for Curiosity’s mission to assess past environmental conditions in Gale Crater. Each mineral records the conditions under which it formed.
The specific sample for CheMin’s first analysis was soil Curiosity scooped up at a patch of dust and sand that the team named Rocknest.
The sample was processed through a sieve to exclude particles larger than 0.006 inch, roughly the width of a human hair.
|The first x-ray crystallography view of Martian soil. Obtained by the Chemistry and Mineralogy (CheMin) experiment on NASA’s Curiosity rover, these data reveal crystalline feldspar, pyroxenes and olivine mixed with some amorphous (non-crystalline) material. The soil sample, taken from a wind-blown deposit within Gale Crater, where the rover landed, is similar to volcanic soils in Hawaii. Curiosity scooped the soil on Oct. 15, 2012, the 69th sol, or Martian day, of operations. It was delivered to CheMin for X-ray diffraction analysis on October 17, 2012, the 71st sol. By directing an X-ray beam at a sample and recording how X-rays are scattered by the sample at an atomic level, the instrument can definitively identify and quantify minerals on Mars for the first time. Each mineral has a unique pattern of rings, or "fingerprint," revealing its presence. The colors in the graphic represent the intensity of the X-rays, with red being the most intense. Image credit: NASA/JPL-Caltech/Ames.|
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.
“Much of Mars is covered with dust, and we had an incomplete understanding of its mineralogy,” said David Bish, CheMin co-investigator with Indiana University in Bloomington. “We now know it is mineralogically similar to basaltic material, with significant amounts of feldspar, pyroxene and olivine, which was not unexpected. Roughly half the soil is non-crystalline material, such as volcanic glass or products from weathering of the glass. “
Bish said, “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. The ancient rocks, such as the conglomerates, suggest flowing water, while the minerals in the younger soil are consistent with limited interaction with water.”
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.
Dr. Tony Phillips works for the National Aeronautics and Space Administration.