This artist's concept of NASA's Mars Reconnaissance Orbiter at Mars features one of its instruments -- the Mars Climate Sounder -- in action. Using nine channels across the visible and thermal infrared ranges of the spectrum, the Mars Climate Sounder looks first at space through the atmosphere above the horizon of Mars to get a vertical profile with temperature, pressure, dust and water vapor concentration measurements every 5 kilometers (3 miles) vertically from the ground to about 80 kilometers (about 50 miles) high. It also looks down onto the planet to get surface temperature and column abundances of dust and water vapor between the spacecraft and the surface.

These "profiles" and surface measurements are combined into daily, three-dimensional global weather maps for both daytime and nighttime. Observations will be made through the martian year to characterize the large seasonal variations in atmospheric dust loading, humidity and thermal structure, providing scientists with the same type of information meteorologists use to understand and predict weather and climate here on Earth.