Forty-five years after the first Apollo lunar landing, the United States remains divided about the moon's role in future human space exploration.
Ten more U.S. astronauts followed Neil Armstrong and Buzz Aldrin's July 20, 1969, visit to the moon before the Apollo program was canceled in 1972. No one has been back since.
The most recent effort to return astronauts to the moon ended in 2010 when the Obama White House axed an underfunded program of the previous administration called Constellation. Instead, NASA was directed to begin planning for a human expedition to an asteroid.