Skip to main content
U.S. flag

An official website of the United States government

Recalibration of the Mars Science Laboratory ChemCam instrument with an expanded geochemical database

March 1, 2017

The ChemCam Laser-Induced Breakdown Spectroscopy (LIBS) instrument onboard the Mars Science Laboratory (MSL) rover Curiosity has obtained > 300,000 spectra of rock and soil analysis targets since landing at Gale Crater in 2012, and the spectra represent perhaps the largest publicly-available LIBS datasets. The compositions of the major elements, reported as oxides (SiO2, TiO2, Al2O3, FeOT, MgO, CaO, Na2O, K2O), have been re-calibrated using a laboratory LIBS instrument, Mars-like atmospheric conditions, and a much larger set of standards (408) that span a wider compositional range than previously employed. The new calibration uses a combination of partial least squares (PLS1) and Independent Component Analysis (ICA) algorithms, together with a calibration transfer matrix to minimize differences between the conditions under which the standards were analyzed in the laboratory and the conditions on Mars. While the previous model provided good results in the compositional range near the average Mars surface composition, the new model fits the extreme compositions far better. Examples are given for plagioclase feldspars, where silicon was significantly over-estimated by the previous model, and for calcium-sulfate veins, where silicon compositions near zero were inaccurate. The uncertainties of major element abundances are described as a function of the abundances, and are overall significantly lower than the previous model, enabling important new geochemical interpretations of the data.

Citation Information

Publication Year 2017
Title Recalibration of the Mars Science Laboratory ChemCam instrument with an expanded geochemical database
DOI 10.1016/j.sab.2016.12.003
Authors Samuel M. Clegg, Roger C. Wiens, Ryan Anderson, Olivier Forni, Jens Frydenvang, Jeremie Lasue, Agnès Cousin, Valerie Payre, Tommy Boucher, M. Darby Dyar, Scott M. McLennan, Richard V. Morris, Trevor G. Graff, Stanley A Mertzman, Bethany L. Ehlmann, Ines Belgacem, Horton E. Newsom, Ben C. Clark, Noureddine Melikechi, Alissa Mezzacappa, Rhonda E. McInroy, Ronald Martinez, Patrick J. Gasda, Olivier Gasnault, Sylvestre Maurice
Publication Type Article
Publication Subtype Journal Article
Series Title Spectrochimica Acta Part B: Atomic Spectroscopy
Index ID 70194123
Record Source USGS Publications Warehouse
USGS Organization Astrogeology Science Center