Author/Authors :
Melikechi، نويسنده , , N. and Mezzacappa، نويسنده , , A. and Cousin، نويسنده , , A. and Lanza، نويسنده , , N.L. and Lasue، نويسنده , , J. and Clegg، نويسنده , , S.M. and Berger، نويسنده , , G. and Wiens، نويسنده , , R.C. and Maurice، نويسنده , , S. and Tokar، نويسنده , , R.L. and Bender، نويسنده , , S. and Forni، نويسنده , , O. and Breves، نويسنده , , E.A. and Dyar، نويسنده , , M.D. and Frydenvang، نويسنده , , J. and Delapp، نويسنده , , D. and Gasnault، نويسنده , , O. and Newsom، نويسنده , , H. and Ollila، نويسنده , , A.M. and Lewin، نويسنده , , E. and Clark، نويسنده , , B.C. and Ehlmann، نويسنده , , B.L. and Blaney، نويسنده , , D. and Fabre، نويسنده , , C.، نويسنده ,
Abstract :
As part of the Mars Science Laboratory, the ChemCam instrument acquires remote laser induced breakdown spectra at distances that vary between 1.56 m and 7 m. This variation in distance affects the intensities of the measured LIBS emission lines in non-trivial ways. To determine the behavior of a LIBS emission line with distance, it is necessary to separate the effects of many parameters such as laser energy, laser spot size, target homogeneity, and optical collection efficiency. These parameters may be controlled in a laboratory on Earth but for field applications or in space this is a challenge. In this paper, we show that carefully selected ChemCam LIBS emission lines acquired from the Martian dust can be used to build an internal proxy spectroscopic standard. This in turn, allows for a direct measurement of the effects of the distance of various LIBS emission lines and hence can be used to correct ChemCam LIBS spectra for distance variations. When tested on pre-launch LIBS calibration data acquired under Martian-like conditions and with controlled and well-calibrated targets, this approach yields much improved agreement between targets observed at various distances. This work lays the foundation for future implementation of automated routines to correct ChemCam spectra for differences caused by variable distance.
