Curiosity’s First Tastes of Martian Soil Offer Insights on Mineral Composition

NASA’s Curiosity rover has taken its first bites out of the Martian surface and used the materials scooped up, sieved and portioned to cleanse the palate of the rover’s sample collection system of any contaminants that may have come from Earth, said David Vaniman, Senior Scientist at the Planetary Science Institute.

A portion of the soil was delivered to the rover’s Chemistry and Mineralogy instrument (CheMin), which uses X-ray diffraction and X-ray fluorescence to identify and measure the abundance of minerals on Mars. This marks the first in-situ use of X-ray diffraction on another planet, said Vaniman, deputy Principal Investigator for CheMin.

“This served two purposes: Purging Curiosity’s sample collection system of any remnant surface contamination on the scoop, sieve and portion hardware, and understanding a scientifically important surface deposit,” Vaniman said.

“The CheMin analysis of this sample is the first complete mineral inventory of a soil on Mars. The analysis provides new information on the sands and eolian deposits of Mars, which are derived from a largely basaltic crust,” Vaniman said. “Analysis of samples from this windblown deposit is continuing and more detailed results will be coming soon.”

“The first results show that the Martian soil consists of local, regional and global components,“ Vaniman said. “Their origin and history is complex and may reveal much about local weathering as well as global processes far removed from the Gale Crater landing site.”

CheMin uses X-ray diffraction to analyze samples that are sieved to less than 150 micrometers in size, similar to silt and fine sand. A beam of X-rays as fine as a human hair is directed through the fine powdered material while it is vibrated to induce grain motion. When the X-ray beam interacts with the sample, some of the X-rays are diffracted by planes of atoms in the sample in a way that allows specific minerals to be identified.