NOVA: The Planets - Season 1

Mars was once a blue water-world with active volcanoes. But when its magnetic field and protective atmosphere faded, it became the frozen desert planet we know today. With so many necessary elements in place, did life ever form on Mars?

Jupiter's gravitational force made it a wrecking ball when it barreled through the early solar system. But it also shaped life on Earth, delivering comets laden with water-and perhaps even the fateful asteroid that wiped out the dinosaurs.

NASA's Cassini explores Saturn for 13 years, looping through its icy rings and its moons. The probe captures stunning ring-moon interactions, but when it finds the ingredients for life on the moon Enceladus, a bittersweet decision is made.