Work continues on readying Curiosity for surface operations on Mars, with characterisation phase well underway.
The week has seen the rover’s Chemistry and Camera system – ChemCam – undergoing its calibration tests using a target system located towards the back of the rover, while scientists have been looking for candidates for the first full test firing of the system at a suitable surface target.
ChemCam is a complex system split between Curiosity’s mast and body. The mast unit is the large box-like unit at the top of the mast. It contains a laser unit, a remote micro-imager (RMI) and a telescope for focusing both.
The body unit carries three spectrographs for chemical analysis and has its own power supply and an electronic interface to the rover’s central computer system.
ChemCam has two main functions, split between the laser system (the Laser-induced Breakdown Spectroscopy (LIBS), to give it its proper name) and the Remote Micro-Imager (RMI).
LIBS is designed to fire series of laser pulses at a target spot smaller than 1 millimetre on the surface of rocks and soils, vaporizing it. Light from the resultant plasma is captured by the telescope and sent via fibre-optics to the on-board spectrographs for analysis, which should provide information in unprecedented detail about minerals and micro structures in Martian rocks. Additionally, the laser can be used to remove dust from the surfaces of rocks, allowing the drill on Curiosity’s hand to obtain samples of the rock free from surface contaminants.
The RMI provides black-and-white images at 1024×1024 resolution in a 0.02 radian (1.1 degree) field of view – approximately equivalent to a 1500mm lens on a 35mm camera. RMI has two functions. In the first, it will be used in conjunction with LIBS to identify suitable targets and target locations (targets can be selected autonomously or via Earth-based selection and command). Working independently of LIBS, it will be used to obtain close-up images in support of robot arm-mounted experiments or provide images of very distant objects.
This week, ChemCam was calibrated using a target system mounted on the rear section of the rover, mounted below the UHF antenna. As a result of this, ChemCam was confirmed ready for operations, and is expected to make it first test-firing on an actual Martian rock sample on Saturday August 18th. The sample is provisionally designated N165, and sits a short distance from the rover.
ChemCam is a joint US / French experiment, with the US Los Alamos National Laboratory providing the body unit, the French national space agency (CNES) proving the mast unit (RMI, laser, etc.) and JPL the fibre-optic link between the two.
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