President Barack Obama congratulates MESSENGER Principal Investigator, director of Columbia University's Lamont-Doherty Earth Observatory, Sean Solomon, after awarding him the National Medal of Science, the nation's top scientific honor,Thursday, Nov. 20, 2014 during a ceremony in the East Room of the White House in Washington. MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is a NASA-sponsored scientific investigation of the planet Mercury and the first space mission designed to orbit the planet closest to the Sun. Photo Credit: (NASA/Bill Ingalls)