An astronaut once observed a great white light shining out from the bottom of our world: Antarctica, the ice-covered continent we are only just beginning to understand. NOVA visits this wilderness of ice, larger than the United States and Mexico combined, whose only warm-blooded residents are seals, skuas, penguins and scientists.

Is there a cure for paralyzing spinal injuries? Most neurosurgeons are doubtful, pointing to the central nervous system's most apparent inability to heal itself. But others dispute the point. NOVA explores the debate, the hopes for a cure and recent breakthroughs to help paralyzed patients.