http://www.nasa.gov/mission_pages/messe ... flyby.html
On Monday, Jan. 14, a pioneering NASA spacecraft will be the first to visit Mercury in almost 33 years when it soars over the planet to explore and snap close-up images of never-before-seen terrain. These findings could open new theories and answer old questions in the study of the solar system.
The MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft, called MESSENGER, is the first mission sent to orbit the planet closest to our sun. Before that orbit begins in 2011, the probe will make three flights past the small planet, skimming as close as 124 miles above Mercury's cratered, rocky surface. MESSENGER's cameras and other sophisticated, high-technology instruments will collect more than 1,200 images and make other observations during this approach, encounter and departure. It will make the first up-close measurements since Mariner 10 spacecraft's third and final flyby on March 16, 1975. When Mariner 10 flew by Mercury in the mid-1970s, it surveyed only one hemisphere.