Chemistry and Mineralogy (CheMin)

Chemistry and Mineralogy (CheMin)
Name	Chemistry and Mineralogy (CheMin)
Caption	CheMin X-ray diffraction instrument aboard the Curiosity rover
Operator	National Aeronautics and Space Administration (NASA)
Manufacturer	Los Alamos National Laboratory and Jet Propulsion Laboratory
Launched	Mars Science Laboratory (Curiosity) launch 2011
Mission	Mars Science Laboratory
Type	X-ray diffractometer and X-ray fluorescence instrument

Chemistry and Mineralogy (CheMin) is a compact X-ray diffraction (XRD) and X-ray fluorescence (XRF) instrument flown on the Mars Science Laboratory rover Curiosity (rover). Developed by teams at Los Alamos National Laboratory and the Jet Propulsion Laboratory, CheMin provides in-situ mineralogical and bulk chemical analyses of Martian rocks and soils to support investigations led by institutions including California Institute of Technology, NASA Goddard Space Flight Center, and the Smithsonian Institution. CheMin's results have been integrated into studies alongside work from missions such as Viking program, Mars Exploration Rover, and Perseverance (rover) investigations.

Overview

CheMin combines powder X-ray diffraction techniques rooted in work at University of Oxford, Massachusetts Institute of Technology, and Brookhaven National Laboratory with X-ray fluorescence approaches developed at Los Alamos National Laboratory and Stanford University. The instrument analyzes powdered samples delivered by Curiosity's SAM and APXS contexts, supporting comparative studies with data from Mars Reconnaissance Orbiter, Mars Odyssey, and terrestrial analog programs at Antarctic research stations. CheMin's design reflects heritage from laboratory diffractometers used at Argonne National Laboratory, European Space Agency, and field instruments in projects tied to Smithsonian Institution mineralogy collections.

Instrument Design and Operation

CheMin's hardware integrates a microfocus X-ray source and a transmission-style sample cell inspired by instruments at Los Alamos National Laboratory and the University of California, Berkeley. The detector is a CCD derived from technologies used at Lawrence Berkeley National Laboratory and NASA Jet Propulsion Laboratory, enabling diffraction ring imaging comparable to systems at SLAC National Accelerator Laboratory and Diamond Light Source. CheMin includes a sample wheel and vibratory sample delivery influenced by mechanisms tested at Johnson Space Center and Aerospace Corporation. Operational control software was developed with contributions from researchers at California Institute of Technology and Arizona State University, and interacts with rover systems built by Jet Propulsion Laboratory and flight dynamics teams at Jet Propulsion Laboratory.

Science Objectives and Methods

Primary objectives align with goals set by NASA and the Mars Science Laboratory project office: determine mineralogy to assess past aqueous environments and potential habitability, complementing chemical analyses from Sample Analysis at Mars and contextual imaging from Mast Camera (Mastcam). Methods employ XRD pattern fitting using databases and techniques originating at International Centre for Diffraction Data and algorithms developed at Los Alamos National Laboratory and California Institute of Technology. CheMin analyses are combined with stratigraphic mapping informed by United States Geological Survey Mars geologic studies, crater-count chronologies from Planetary Science Division, and analog research performed at sites such as Rio Tinto and Atacama Desert.

Key Discoveries and Results

CheMin provided the first definitive X-ray diffraction identification of clay minerals and crystalline phases on Mars, corroborating hypotheses from Mars Reconnaissance Orbiter spectral detections and inferences from Spirit (rover) and Opportunity (rover) results. Notable findings include recognition of phyllosilicates analogous to terrestrial smectites studied at Smithsonian Institution and saline minerals comparable to deposits at Great Salt Lake sites. CheMin data supported interpretations of diagenetic processes compared with terrestrial analogs from Yellowstone National Park and Sierra Nevada (U.S.) studies, and informed astrobiology assessments aligned with research at SETI Institute and European Space Agency astrobiology programs. Results were published by teams at California Institute of Technology, University of Tennessee, and University of Arizona.

Calibration, Performance, and Limitations

Calibration strategies used standards from organizations such as the National Institute of Standards and Technology and techniques refined at Los Alamos National Laboratory and Brookhaven National Laboratory. In-flight performance demonstrated reliable phase identification down to weight-percent abundances comparable to laboratory diffractometers at Lawrence Livermore National Laboratory, though limitations include sample preparation constraints and detection thresholds influenced by grain size and preferred orientation issues noted in terrestrial studies at University of Cambridge and Imperial College London. Radiation environment effects studied in coordination with NASA Goddard Space Flight Center and thermal cycling tests at Jet Propulsion Laboratory dictated operational windows and exposure times.

Development, Deployment, and Mission Context

CheMin's development involved collaborations among Los Alamos National Laboratory, NASA Jet Propulsion Laboratory, California Institute of Technology, and academic partners including Arizona State University and University of New Mexico. The instrument was integrated into the Curiosity (rover) payload alongside instruments like Mast Camera (Mastcam), ChemCam, and SAM under oversight from NASA and the Mars Science Laboratory project managed at Jet Propulsion Laboratory. CheMin's flight heritage and scientific legacy influence instrument concepts on subsequent missions including efforts by European Space Agency teams and proposals reviewed by the NASA Decadal Survey.

Category:Instruments aboard Curiosity