President George Bush receives a placque commemorating the quincentenary of Columbus' voyage to the new world and exploration from Marshall's sixth Center Director Thomas J. Lee (1989-1994) during an address to Marshall employees. The three replicas of Columbus' ships, the Nina, the Pinta, and the Santa Maria sailed by the launch pad at Kennedy Space Center while STS-52 Columbia awaited launch on the anniversary of Columbus' arrival in the New World.