page_title: CheMin
section_title: Description
hierarchical_section_title: CheMin / Description
caption_attribution_description: English: 10.30.2012 First X-ray View of Martian Soil http://photojournal.jpl.nasa.gov/catalog/PIA16217 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 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
context_page_description: CheMin, short for Chemistry and Mineralogy, is an instrument located in the interior of the Curiosity rover that is exploring the surface of Gale crater on Mars. David Blake, from NASA Ames Research Center, is the Principal Investigator.
  CheMin identifies and quantifies the minerals present in rocks and soil delivered to it by the rover's robotic arm. By determining the mineralogy in rocks and soils, CheMin assesses the involvement of water in their formation, deposition, or alteration. In addition, CheMin data is useful in the search for potential mineral biosignatures, energy sources for life or indicators for past habitable environments.
  CheMin aboard the Curiosity rover on Mars won the 2013 NASA Government Invention of the year award.
context_section_description: CheMin is an X-ray powder diffraction instrument that also has X-ray fluorescence capabilities. CheMin does not require the use of liquid reagents, instead, it utilizes a microfocus cobalt X-ray source, a transmission sample cell and an energy-discriminating X-ray sensitive CCD to produce simultaneous 2-D X-ray diffraction patterns and energy-dispersive histograms from powdered samples. Raw CCD frames are processed into data products on board the rover to reduce the data volume. These data products are transmitted to Earth for further processing analyses.
  In operation, a collimated X-ray source produces and directs a beam through a transmission sample cell containing powdered material. An X-ray sensitive CCD (charge-coupled device) imager is positioned on the opposite side of the sample from the source and directly detects X-rays diffracted or fluoresced by the sample. The CCD can measure the charge generated by each photon, and hence its energy. Diffracted X-rays strike the detector and are identified by their energy, producing a two-dimensional image that constitutes the diffraction pattern of the sample. Both crystalline and amorphous materials can be analyzed in this fashion. 
  A maximum of 65 mm³ of sample material is delivered to a vibrated funnel system that penetrates the rover deck, although only about 10 mm³ of material is required to fill the sample cell which is transparent with a disc-shaped volume, with an 8 mm diameter and 175 µm thickness. The funnel contains a 1 mm mesh screen to limit the particle size. Five permanent cells are loaded with calibration standards; these are single minerals or synthetic ceramic. Each analysis may take up to 10 hours, spread out over two or more Martian nights.
caption: First X-ray diffraction view of the Martian soil - CheMin analysis reveals feldspar, pyroxenes, olivine and more (Curiosity rover, "Rocknest", October 17, 2012).[5]
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