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Curiosity passes 100,000 shots fired by its laser

Jenny Winder, News Writer
Dec 9, 2013, 8:00 UTC

Sen—Since landing on Mars in August 2012, NASA's Curiosity rover has fired the laser on its Chemistry and Camera (ChemCam) instrument more than 100,000 times.

The laser and telescope on the rover's mast can target rocks and soils up to about 23 feet (7 meters) away. The infrared laser excites material in a pinhead-size spot on the target into a glowing, ionized gas, called plasma. ChemCam observes that spark with the telescope and analyzes the spectrum of light to identify elements in the target.

"Passing 100,000 laser shots is terribly exciting and is providing a remarkable set of chemical data for Mars," said ChemCam co-investigator Horton Newsom of the University of New Mexico, Albuquerque.

Target Rock 'Ithaca' in Gale Crater, Mars. Image credit: NASA/JPL-Caltech/MSSS.

The 100,000th shot was one of a series of 300 to investigate 10 locations on a rock called "Ithaca" in late October, at a distance of 13 feet, 3 inches (4.04 meters). "Ithaca", with a rougher lower texture and smoother texture on top, appears to be a piece of the local sedimentary bedrock protruding from the surrounding soil in Gale Crater.

A vertical line of 10 points examined by ChemCam on Ithaca starts in the pitted lower coarser grained layer and crosses into the finer grained, smoother, upper layer.  Each observation point received 30 laser shots. The chemical composition of the two layers appears to be very similar.

Target for 100,000th Laser Shot by Curiosity on Mars. Image Credit: NASA/JPL-Caltech/LANL/CNES/IRAP/UNM.

By the start of December, ChemCam had fired its laser on Mars more than 102,000 times, at more than 420 rock or soil targets. Virtually every shot yields a spectrum of data returned to Earth. Most targets get zapped at several points with 30 laser pulses at each point. The instrument has also returned more than 1,600 images taken by its remote micro-imager camera.

Each pulse delivers more than a million watts of power for about five one-billionths of a second. The technique used by ChemCam, called laser-induced breakdown spectroscopy, has been used to assess composition of targets  inside nuclear reactors and on the sea floor. Experimental applications have included environmental monitoring and cancer detection. NASA's Mars Science Laboratory Project, using the Curiosity rover, is the first mission to use it on another planet.

An international team of scientists and students is mining information from ChemCam to document the diversity or materials on the surface inside Mars' Gale Crater and the geological processes that formed them. "These materials include dust, wind-blown soil, water-lain sediments derived from the crater rim, veins of sulfates and igneous rocks that may be ejecta from other parts of Mars," Newsom said.