The NASA spacecraft Messenger passed within 124 miles of Mercury Monday, in the first of three maneuvers, over 7 years, designed to give the spacecraft the proper angle and velocity to get into orbit around our solar system's innermost planet. Messenger will also send pictures back of the opposite side of the planet, which has never been photographed (at least by an earthling).
We physics clutzes should bow in awe of those who are able to calculate all the factors necessary to pull this off. Think about it. Mercury is over 40 million miles away from us, depending on where we are in our orbits. Even the tiniest error would doom the project.