These two images illustrate the value of being able to identify different compositions at very small scales. At left, a mosaic of images from the remote micro-imager of the Chemistry and Camera (ChemCam) instrument on NASA's Mars rover Curiosity covers a scene about 3.5 inches (about 9 centimeters) across. The image was taken during the 126th Martian day, or sol, of Curiosity's work on Mars (Dec. 14, 2012). ChemCam's ability to zap a target with a laser and analyze the resulting spark identified different compositions in the matrix rock and the lighter-toned veins.
The image at right covers an area about three one-thousandths of one inch (about 75 microns) across in a meteorite from Mars examined on Earth. At this much finer scale, too, the veins have different composition from the matrix around them, as determined using Raman spectroscopy. The color-coding for composition is red for jarosite, green for goethite and blue for clay minerals.
NASA's Mars 2020 rover, as described by the Mars 2020 Science Definition Team, would have capabilities for nested-scale observations and localized composition identification down to microscopic scale. Mars 2020 is a mission concept that NASA announced in late 2012 to re-use the basic engineering of Mars Science Laboratory to send a different rover to Mars, with new objectives and instruments, launching in 2020.
NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages NASA's Mars Exploration Program for the NASA Science Mission Directorate, Washington.