title: The first X-ray diffraction measurements on Mars.
abstract: The Mars Science Laboratory landed in Gale crater on Mars in August 2012, and the Curiosity rover then began field studies on its drive toward Mount Sharp, a central peak made of ancient sediments. CheMin is one of ten instruments on or inside the rover, all designed to provide detailed information on the rocks, soils and atmosphere in this region. CheMin is a miniaturized X-ray diffraction/X-ray fluorescence (XRD/XRF) instrument that uses transmission geometry with an energy-discriminating CCD detector. CheMin uses onboard standards for XRD and XRF calibration, and beryl:quartz mixtures constitute the primary XRD standards. Four samples have been analysed by CheMin, namely a soil sample, two samples drilled from mudstones and a sample drilled from a sandstone. Rietveld and full-pattern analysis of the XRD data reveal a complex mineralogy, with contributions from parent igneous rocks, amorphous components and several minerals relating to aqueous alteration. In particular, the mudstone samples all contain one or more phyllosilicates consistent with alteration in liquid water. In addition to quantitative mineralogy, Rietveld refinements also provide unit-cell parameters for the major phases, which can be used to infer the chemical compositions of individual minerals and, by difference, the composition of the amorphous component.
authors.affiliation: Geological Sciences, Indiana University, 1001 E. 10th Street, Bloomington, IN 47405, USA.
authors.forename: David
authors.initials: D
authors.lastname: Bish
authors.affiliation: NASA Ames Research Center, USA.
authors.forename: David
authors.initials: D
authors.lastname: Blake
authors.affiliation: Planetary Science Institute, USA.
authors.forename: David
authors.initials: D
authors.lastname: Vaniman
authors.affiliation: inXitu, USA.
authors.forename: Philippe
authors.initials: P
authors.lastname: Sarrazin
authors.affiliation: NASA Ames Research Center, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Bristow
authors.affiliation: Geological Sciences, Indiana University, 1001 E. 10th Street, Bloomington, IN 47405, USA.
authors.forename: Cherie
authors.initials: C
authors.lastname: Achilles
authors.affiliation: University of Hawaii at Manoa, USA.
authors.forename: Przemyslaw
authors.initials: P
authors.lastname: Dera
authors.affiliation: Chesapeake Energy, USA.
authors.forename: Steve
authors.initials: S
authors.lastname: Chipera
authors.affiliation: NASA Jet Propulsion Laboratory, USA.
authors.forename: Joy
authors.initials: J
authors.lastname: Crisp
authors.affiliation: University of Arizona, USA.
authors.forename: R T
authors.initials: RT
authors.lastname: Downs
authors.affiliation: Arizona State University, USA.
authors.forename: Jack
authors.initials: J
authors.lastname: Farmer
authors.affiliation: CNRS, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Gailhanou
authors.affiliation: NASA Johnson Space Center, USA.
authors.forename: Doug
authors.initials: D
authors.lastname: Ming
authors.affiliation: NASA Jet Propulsion Laboratory, USA.
authors.forename: John Michael
authors.initials: JM
authors.lastname: Morookian
authors.affiliation: NASA Johnson Space Center, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Morris
authors.affiliation: University of Arizona, USA.
authors.forename: Shaunna
authors.initials: S
authors.lastname: Morrison
authors.affiliation: NASA Johnson Space Center, USA.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Rampe
authors.affiliation: Lunar and Planetary Institute, USA.
authors.forename: Allan
authors.initials: A
authors.lastname: Treiman
authors.affiliation: NASA Jet Propulsion Laboratory, USA.
authors.forename: Albert
authors.initials: A
authors.lastname: Yen
keywords: Curiosity rover; Mars; X-ray diffraction; extraterrestrial mineralogy