Sezon 18
Bölümler
1 Return to Mt. St. Helens 8 Oca 1991 2 ConFusion in a Jar 30 Nis 1991 3 The Hunt for China's Dinosaurs (1) 5 Şub 1991 4 Case of the Flying Dinosaur 12 Şub 1991 5 T. rex Exposed 19 Şub 1991 6 The Russian Right Stuff: The Invisible Spaceman 26 Şub 1991 7 The Russian Right Stuff: The Dark Side of the Moon 27 Şub 1991 8 The Russian Right Stuff: The Mission 28 Şub 1991 9 Swimming With Whales 5 Mar 1991 10 The Chip vs. the Chess Master 26 Mar 1991 11 Sex, Lies and Toupee Tape 1 Eki 1991 12 So You Want to Be a Doctor? 9 Eki 1991 13 Secrets of the Dead Sea Scrolls 15 Eki 1991 
14 Suicide Mission to Chernobyl 22 Eki 1991 15 Taller Than Everest? 5 Kas 1991 16 Fastest Planes in the Sky 12 Kas 1991 17 Avoiding the Surgeon's Knife 3 Ara 1991 18 Skyscraper! A NOVA Special 10 Ara 1991 19 The Fine Art of Faking It 17 Ara 1991
14 Suicide Mission to Chernobyl 22 Eki 1991 15 Taller Than Everest? 5 Kas 1991 16 Fastest Planes in the Sky 12 Kas 1991 17 Avoiding the Surgeon's Knife 3 Ara 1991 18 Skyscraper! A NOVA Special 10 Ara 1991 19 The Fine Art of Faking It 17 Ara 1991