NARRATOR Discoveries here on Earth are revealing that life can withstand an even wider variety of conditions than previously thought. Missions to extreme environments are showing that microbes can live in dry deserts and thrive in lakes full of poisonous arsenic. Bacteria survive in slimy colonies on cave walls, dripping with sulfuric acid, living off noxious hydrogen sulfide gas. And microbes flourish in toxic rivers of corrosive industrial waste.

JIM GREEN (DIRECTOR, PLANETARY SCIENCE DIVISION, NASA) We now know it's possible for microorganisms to exist in these large acidic, and even poisonous, regions.

TIM SHANK (BIOLOGIST, WOODS HOLE OCEANOGRAPHIC INSTITUTION) The more we look at the extreme habitats on Earth, the more we find life there. We're pushing back the limits of where life can live, all the time, through our own discoveries.

NARRATOR From freezing glaciers to super-heated hot springs; from high deserts, blasted by ultraviolet radiation, to deep mines, miles underground and ocean trenches where sunlight never penetrates, scientists are discovering that life finds a way to adapt and thrive.

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