United States. National Aeronautics and Space Administration

Astronaut Michael Collins. He controlled the Apollo 11 command module that circled the moon while Neil Armstrong became the first man to walk on its' surface. Collins has written a history of the space program titled Liftoff.

On the eve of the 20th anniversary of man's first walk on the moon, commentator Stewart Brand shares his thoughts on space exploration and how it has changed us. Brand is founder of The Whole Earth Catalog.

The Pulitzer Prize-winning writer joins Fresh Air to talk about the scientific and cultural history of the Red Planet. He advocates for robotic and human exploration of Mars -- an endeavor that would lead to greater technological innovations and international cooperation.

Writer Frank White's book "The SETI Factor," looks at the ongoing search for extraterrestrial intelligence. In 1992, NASA will begin a comprehensive scan of the heavens for radio signals from other solar systems. White says, as a result of that search, it's quite likely that within the next 25 years we'll finally know if we're alone in the universe.

Shepard was America's first man in space in 1961. Ten years later, during the with Apollo 14 mission, he made it to the moon, where he was able to squeeze in a round of golf.

Kraft was NASAs first flight director, from the first forays into space in the 1960s to after Neil Armstrong landed on the moon in 1969. Kraft also created Mission Control. He has written a new book, –Flight: My Life In Mission Control.

On July 20, 1969, an estimated 530 million people watched on live television as Apollo 11 commander Neil Armstrong became the first human to step upon the surface of the moon. Nearly 50 years later, Academy Award-winning director Damien Chazelle revisits Armstrong's "giant leap for mankind" — but with a more intimate lens.

In 1961, when President John F. Kennedy announced a goal of "landing a man on the moon and returning him safely to the earth" before the end of the decade, the mission seemed all but impossible.

The legendary aviator, who died Dec. 7, served as a fighter pilot in World War II. Later, as a test pilot, he was the first person to fly faster than the speed of sound. Originally broadcast in 1988.

Collins, who died April 27, orbited in Apollo 11 while Neil Armstrong and Buzz Aldrin made their historic moon walk. Speaking to Fresh Air in 1988, he described his solo orbit as "completely serene."