The ChemCam Instrument Suite on the Mars Science Laboratory (MSL) Rover: Science Objectives and Mast Unit Description

Abstract

International audienceChemCam is a remote sensing instrument suite on board the "Curiosity" rover (NASA) that uses Laser-Induced Breakdown Spectroscopy (LIBS) to provide the elemental composition of soils and rocks at the surface of Mars from a distance of 1.3 to 7 m, and a telescopic imager to return high resolution context and micro-images at distances greater than 1.16 m. We describe five analytical capabilities: rock classification, quantitative composition, depth profiling, context imaging, and passive spectroscopy. They serve as a toolbox to address most of the science questions at Gale crater. ChemCam consists of a Mast-Unit (laser, telescope, camera, and electronics) and a Body-Unit (spectrometers, digital processing unit, and optical demultiplexer), which are connected by an optical fiber and an electrical interface. We then report on the development, integration, and testing of the Mast-Unit, and summarize some key characteristics of ChemCam. This confirmed that nominal or better than nominal performances were achieved for critical parameters, in particular power density (>1 GW/cm2). The analysis spot diameter varies from 350 μm at 2 m to 550 μm at 7 m distance. For remote imaging, the camera field of view is 20 mrad for 1024×1024 pixels. Field tests demonstrated that the resolution (˜90 μrad) made it possible to identify laser shots on a wide variety of images. This is sufficient for visualizing laser shot pits and textures of rocks and soils. An auto-exposure capability optimizes the dynamical range of the images. Dedicated hardware and software focus the telescope, with precision that is appropriate for the LIBS and imaging depths-of-field. The light emitted by the plasma is collected and sent to the Body-Unit via a 6 m optical fiber. The companion to this paper (Wiens et al. this issue) reports on the development of the Body-Unit, on the analysis of the emitted light, and on the good match between instrument performance and science specifications

Development of a deep-sea laser-induced breakdown spectrometer for in situ multi-element chemical analysis

“…The two methods are essentially complementary, however, while not all materials are Raman active, LIBS can in theory measure the composition of any target since all matter is composed of elements. The advantages of LIBS for in situ analysis has been recognized by several groups and it has found application in the field for environmental soil monitoring (Wainner et al, 2001;Harmon et al, 2005;Yamamoto et al, 1996;Mosier-Boss et al, 2002), survey of nuclear power plants (Whitehouse et al, 2001;Saeki et al, 2014) and recently planetary exploration (Wiens et al, 2002Maurice et al, 2012;Meslin et al, 2013).…”

Gale crater and impact processes – Curiosity’s first 364 Sols on Mars

“…Other images from The Mars Descent Imager (MARDI) and Hazcam were examined but were very limited in areal extent for the first 360 Sols. High resolution images of impactite materials were also obtained with the mast mounted Remote Micro Imager (RMI), which is part of the ChemCam instrument (Maurice et al, 2012;Le Mouélic et al, 2015). The Mars Hand Lens Imager (MAHLI) on the rover arm (Edgett et al, 2012) provides high-resolution ($15-30 lm per pixel) color images of materials close to the rover, and this was used to image candidate impact spherules in the trenches and rover tracks, on rock outcrops and material dumped on the observation plate.…”

Microscopic emission and reflectance thermal infrared spectroscopy: instrumentation for quantitative in situ mineralogy of complex planetary surfaces

“…These instruments include the Mast Camera [16], a laser induced breakdown spectrometer for remote elemental composition (ChemCam, [17,18]), a microscopic imager (MAHLI, [19]), an APXS [16], and chemistry and mineralogy by powder x-ray diffraction and x-ray fluorescence (CheMin, [20]), as well as a quadrupole mass spectrometer, a gas chromatograph, and a tunable laser spectrometer (SAM, [21]). This suite of instruments onboard MSL will characterize the martian surface in unprecedented detail, rivaling what can be done in the laboratory on Earth.…”