Pre-Launch Calibration Target for ChemCam
<p>This image shows the calibration target for the Chemistry and Camera instrument on NASA's Curiosity rover before it was installed on the rover and readied for launch. 
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The target includes nine circles of materials scientists expect to see on Mars and one titanium square with a painted edge. According to the numbering in this image, the circles in the top row show four glass samples likely to represent Mars igneous rock compositions, plus a graphite rod on the right side. The bottom row shows four ceramic samples representing Mars sedimentary rock compositions and a titanium plate for wavelength calibration and laser diagnostic tests.
NASA/JPL-Caltech/LANL
2012
<a rel="nofollow" class="external text" href="https://www.nasa.gov/mission_pages/msl/multimedia/pia16070.html">Pre-Launch Calibration Target for ChemCam</a>, NASA