From 1968 to 1972, NASA's Apollo astronauts tested out new spacecraft and journeyed to uncharted destinations. It all started on May 25, 1961, when President John F. Kennedy announced the goal of sending astronauts to the moon before the end of the decade. Coming just three weeks after Mercury astronaut Alan Shepard became the first American in space, Kennedy's bold challenge set the nation on a journey unlike any before in human history. Eight years of hard work by thousands of Americans came to fruition on July 20, 1969, when Apollo 11 commander Neil Armstrong stepped out of the lunar module and took "one small step" in the Sea of Tranquillity, calling it "a giant leap for mankind."