Since the dawn of humanity, we have stared up at the lights in the sky and wondered. Now join the heroic men and women who have dared the impossible on some of the greatest adventures ever undertaken -- the quest to reach out beyond Earth and into the great unknown of space! To celebrate 50 years of incredible achievements, the Discovery Channel partners with NASA to reveal the epic struggles, tragedies, and triumphs in a bold chapter of human history. Along with the candid interviews of the people who made it happen, hundreds of hours of never-before-seen film footage from the NASA archives -- including sequences onboard spacecrafts in flight -- have been carefully restored, edited, and compiled for this landmark collection. Space-exploration missions are revealed through exclusive interviews with celebrated astronauts including John Glenn, Buzz Aldrin, and Charlie Duke, as well as newly digitized original mission footage from NASA's film vaults. Extras include four hours of bonus features including digitally restored NASA film highlights, mission clips, and astronaut interviews, and a 14-page collectible booklet featuring a timeline of major landmark NASA events, trivia, and archival photos. Narrated by Gary Sinise, When We Left Earth originally aired in six parts in June 2008 on the Discovery Channel.