NASA's Voyager, Cassini, and Juno missions are groundbreaking scientific feats that changed everything we know about our universe, and testimony from the modern-day explorers behind these expeditions reveal the incredible secrets they discovered. This special consists entirely of segments previously aired as part of the Space's Deepest Secrets episodes "Secret History of the Voyager Mission" (Season 1, Episode 5), "Cassini′s Grand Finale" (Season 3, Episode 5) and "Secret History of the Juno Mission" (Season 4, Episode 8).