After several years of intense competition to see who would dominate the heavens, the Soviet Union and the United States entered the 1960s nearly neck-and-neck. But when Soviet cosmonaut Yuri Gagarin became the first human into space on April 12, 1961, the American space program suffered a significant blow. Yet NASA didn't throw in the towel. Less than a month later, astronaut Alan Shepard became the first American to launch into space, and then, on Feb. 20, 1962, John Glenn followed that great achievement by becoming the first American to orbit the Earth. Now, 50 years later, NASA is celebrating Glenn's historic mission, and all Americans have yet another reason to look back at one of the most ambitious periods in our history, and at some of our biggest heroes.