This image shows laser plasmas in a test lab at Los Alamos National Laboratory, N.M., under typical atmospheric pressures on Earth and Mars. A plasma is an ionized, glowing gas. The pressure on the Red Planet is only about one percent of that at sea level on Earth, allowing the plasma to expand more and become brighter. The laser beam, which is invisible, crosses the image from the left and strikes a metal target, creating the plasmas. Each image covers about 3 by 3 inches (75 by 75 millimeters).