On August 19, 2012, NASA's Curiosity rover used the ChemCam, its
laser-camera combo unit, for the first time on Mars, firing an
energy beam at a small rock called "Coronation." Having excited
the atoms in a target rock into an ionized, glowing plasma with
its million watt laser, ChemCam can then use its telescopic
camera to watch the light emitted and analyze it with three
spectrometers for information about elemental composition. This
first firing of the laser was primarily for target practice and
calibration, but the ChemCam team expects to eventually take
about a dozen compositional measurements of rocks per day. The
spectrometers consist of three separate units covering 240 to
336 nanometer, 380 to 470 nanometer, and 470 to 850 nanometer
spectral ranges, recording intensity at 6,144 different
wavelengths of ultraviolet, visible, and infrared light. "It's
surprising that the data are even better than we ever had during
tests on Earth, in signal-to-noise ratio," said ChemCam Deputy
Project Scientist Sylvest