Understanding laser-induced breakdown spectroscopy (LIBS) on Mars - New approaches for quantitative elemental analysis and mineral classification

Grant #: NNX13AJ18G
Senior Scientist: Pablo Sobron

Laser-induced breakdown spectroscopy (LIBS) is recognized as a powerful tool for detailed geochemical investigations of rocks and regolith and for exploratory survey in landed missions on planetary bodies including Mars, the Moon, and Venus. A stand-off LIBS spectrometer is part of the ChemCam instrument, included in the scientific payload of Curiosity, which landed on Mars in August 2012. The LIBS technique is particularly well suited for Mars exploration, as the reduced pressure in Mars atmosphere facilitates plasma expansion. However, the mineralogical characterization of the geological samples is ambiguous, as natural samples are often composed of mixtures, which add great complexity to the LIBS spectra. Further, the CO2 enrichment of the Martian atmosphere compromises the detection of carbon in geological samples. In our opinion, these difficulties have been overlooked, and more work on the development of routines for spectral data treatment and on the study of the basic properties of plasma-atmosphere-mineral interaction is needed. 

We propose to study advanced spectral processing methodologies for the extraction of mineralogical information from complex geological materials, and to investigate the atmospheric-mineral matrix coupling effects under Martian environmental conditions. For this, we will make use of Washington University in St. Louis unique laboratory facilities which will allow us perform high-resolution multispectral analysis of standard samples and mixtures representative of Martian mineralogy. 

The outcomes of this project will be:

(1) a collection of well-characterized synthetic and natural samples, and mixtures thereof, relevant for Mars exploration,

(2) a database of LIBS spectra of such samples under Martian conditions, and (3) novel routines for the extraction of mineralogical information from Mars-related geological samples.