Some credit Aldrin with the very first words spoken on the lunar surface. His statement, 'Contact light ... okay, engine stop' was beamed into homes all over the world moments before Armstrong's famous declaration, 'The Eagle has landed'.

Aldrin, along with fellow Apollo 11 astronauts Armstrong and Michael Collins, received the Presidential Medal of Freedom from Richard Nixon in 1969.

In his recent autobiography, Aldrin writes that after he retired from active duty in 1972 he struggled with alcoholism and depression for several years, finally checking himself into rehab in 1975.

Aldrin continues to advocate human space exploration and devised a plan for missions to Mars in 1985. He said in a recent interview that NASA explorers could learn more from going to Mars than from going back to the moon. He also owns three patents for rocket and spacecraft designs.

Perhaps more than any other astronaut, Aldrin has become a fixture in popular culture. The popular Disney character Buzz Lightyear was named for Aldrin, and he served as the model for MTV's Moonman mascot and award.