Characterization and Calibration of the CheMin Mineralogical Instrument on Mars Science Laboratory

Creators: Blake, David; Vaniman, David; Achilles, Cherie; Anderson, Robert; Bish, David; Bristow, Tom; Chen, Curtis; Chipera, Steve; Crisp, Joy; Des Marais, David; Downs, Robert T.; Farmer, Jack; Feldman, Sabrina; Fonda, Mark; Gailhanou, Marc; Ma, Hongwei; Ming, Doug W.; Morris, Richard V.; Sarrazin, Philippe; Stolper, Ed; Treiman, Allan; Yen, Albert

Abstract

A principal goal of the Mars Science Laboratory (MSL) rover Curiosity is to identify and characterize past habitable environments on Mars. Determination of the mineralogical and chemical composition of Martian rocks and soils constrains their formation and alteration pathways, providing information on climate and habitability through time. The CheMin X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument on MSL will return accurate mineralogical identifications and quantitative phase abundances for scooped soil samples and drilled rock powders collected at Gale Crater during Curiosity's 1-Marsyear nominal mission. The instrument has a Co X-ray source and a cooled charge-coupled device (CCD) detector arranged in transmission geometry with the sample. CheMin's angular range of 5° to 50° 2θ with < 0.35° 2θ resolution is sufficient to identify and quantify virtually all minerals. CheMin's XRF requirement was descoped for technical and budgetary reasons. However, X-ray energy discrimination is still required to separate Co Kα from Co Kβ and Fe Kα photons. The X-ray energy-dispersive histograms (EDH) returned along with XRD for instrument evaluation should be useful in identifying elements Z >13 that are contained in the sample. The CheMin XRD is equipped with internal chemical and mineralogical standards and 27 reusable sample cells with either Mylar® or Kapton® windows to accommodate acidic-to-basic environmental conditions. The CheMin flight model (FM) instrument will be calibrated utilizing analyses of common samples against a demonstrationmodel (DM) instrument and CheMin-like laboratory instruments. The samples include phyllosilicate and sulfate minerals that are expected at Gale crater on the basis of remote sensing observations.

Additional Information

© 2012 The Author(s). This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. Received 15 November 2011; Accepted: 22 May 2012; Published online: 23 June 2012. The CheMin flight instrument could not have been realized without long-term support from NASA's research and technology programs and institutions, including: Ames Research Center's Director's Discretionary Fund, the Exobiology Instrument Development program, the Planetary Instrument Definition and Development program (PIDDP), the Mars Instrument Definition and Development program (MIDDP), the Astrobiology Science and Technology Instrument Development program (ASTID), the Astrobiology Science and Technology for Exploration of Planets program (ASTEP), NASA's Small Business Innovative Research program (SBIR), and the diligent efforts engineers and scientists of the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. We also thank Thomas Chatham of Chatham Created Gemstones for the donation of synthetic emerald for the beryl:quartz standard materials. This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.

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