NOVA observes worldwide preparations as amateur comet hunters, astronomers and scientists armed with specialized cameras, high powered telescopes and spacecraft look to the heavens in search of the expected arrival in 1986 of Halley's Comet.

Gaia, the Greek word for Earth goddess, also is the name of the controversial hypothesis that life on Earth controls the environment. NOVA explores this provocative theory that challenges conventional ways of thinking about the Earth.

For centuries, the Chinese Kazakh horseman preserved their ancient traditions, refusing to be dominated by either the Chinese or nearby Russian cultures. Today, however, this nomadic tribe has integrated communism into its way of life. NOVA traces the ancient Kazahk lifestyle and looks at how the Chinese cultural Revolution has modernized Kazakh customs.

NOVA explores the incredibly complex emotional development of infants and examines the current theory that early childhood psychological intervention can head off emotional problems later in life.

In July 1982, a 42-year-old addict in a San Jose, California jail became paralyzed—unable to move or talk. His symptoms, caused by a bad batch of synthetic heroin, were indistinguishable from those associated with Parkinson's disease, a degenerative nerve disorder that strikes the elderly. NOVA traces the story of a "designer" drug which could lead to a major medical breakthrough.

When a high number of cancer cases struck the suburban community of Woburn, Massachusetts, the town mobilized to investigate why. The result was a landmark study of the effects of hazardous wastes. NOVA explores the legal and scientific implications of the link between environmental pollution and illness.

NOVA journeys to a remote region of southern Venezuela where the land is alive with spectacular waterfalls, colored by exotic flowers and inhabited by rare species of birds and animals.

NOVA follows a conservation success story as environmentalists, scientists and bird-lovers fight to save the majestic Osprey from extinction.

When Alexander Fleming discovered the penicillin mold in 1928, he never considered its possible therapeutic value. NOVA explores the "Fleming myth" and reveals the true story of the scientists who worked behind the scenes to develop the wonder drug of the century.

NOVA examines the medical community's alarm as the spread of antibiotic-resistant infection increases, and studies how one hospital fights its own dramatic epidemic.

NOVA and Frontline combine resources to explore the Strategic Defense Initiative. The two-hour documentary contains the most comprehensive information on "Star Wars" ever produced. Bill Kurtis of WBBM-TV/Chicago hosts.

The adventures of the Voyager 2 spacecraft continue as it passes the rings of Uranus. Scientists suspect that violent events in the early history of the planet may have shaped Uranus and its strange collection of moons.

Scientific breakthroughs now make it possible to reproduce ourselves in ways never before imagined. NOVA looks at the medical, legal and moral questions raised by this brave new technology.

What are the prospects for halting or curing the deadliest epidemic ever to challenge modern medicine? NOVA finds cause for both hope and alarm in the battle against AIDS.

Could there be life beyond Earth? Only recently has it become possible to scan the skies in a systematic attempt to find out. NOVA joins the search with guest host Lily Tomlin.

Birds do it; bees do it, butterflies, bats and eels do it—all leave one habitat to migrate to another, often thousands of miles away. NOVA penetrates the mystery of where animals migrate, why and how they get there.

NOVA dips into the sad plight of our coastal waters, where toxic chemicals, raw sewage and disease-carrying microbes are routinely dumped.

Yankee ingenuity has designs on the America's Cup. NOVA goes behind-the-scenes to look at the engineering effort to design a technically advanced sailboat.

Leprosy, a misunderstood disease that has been curable for 40 years, still afflicts some 12 million people. NOVA looks at the tragedy of the disease that need not be.

NOVA explores the ground-breaking experiments that led to the discovery of a tiny sequence of molecules—and more clues to the mystery of how a complete baby develops from a single cell.