Shake it up, CheMinThis image shows the cells that hold the soil samples that are vibrated by the Chemistry and Mineralogy (CheMin) instrument on NASA's Curiosity rover. When the rover delivers samples to CheMin, they are funneled into one of the windowed areas in the cell assemblies. (There are 16 pairs of dual-cell assemblies in CheMin.) These cell pairs act like a tuning fork, vibrated at about 2,000 times per second by a piezoelectric device placed between the two arms of the fork. When vibrated, the particles flow like liquid. This movement enables the instrument's X-ray beams to hit all of the grains in random orientations over time. This innovative technology has been spun off for commercial use in miniaturized portable X-ray diffraction instruments. The powder vibration system enables poorly prepared or as-received samples to be analyzed without further sample preparation. This is useful in cases where extensive sample preparation is either not possible (e.g., on Mars) or when delicate materials (such as pharmaceutical products) would be destroyed or altered by extensive grinding. Implementation of the powder vibration system was a crucial step in enabling small portable X-ray diffraction instruments because many of the moving parts in conventional X-ray diffraction instruments could be eliminated.
Image Credit: NASA/Ames/JPL-Caltech