What caused the vast deforestation of Easter Island?

What makes an energy source renewable and how can we use them to power our societies?

The need for alternative energy sources is more pressing than ever.

A Greek shipwreck holds the remains of an intricate bronze machine that turns out to be the world’s first computer.

Modern wind turbines capture energy from the wind and convert it into electricity.

How can we convert the Sun’s light and heat into energy we can use?

What can be done to make the power grid more reliable and efficient?

What is energy and why are we on a never ending search for new energy sources?

A remote, bleak speck of rock in the middle of the Pacific, Easter Island, or Rapa Nui, has mystified the world ever since the first Europeans arrived in 1722. How and why did the ancient islanders build and move nearly 900 giant statues or moai, weighing up to 86 tons? And how did they transform a presumed paradise into a treeless wasteland, bringing ruin upon their island and themselves?

The Vikings were among the fiercest warriors of all time. Yet only a select few carried the ultimate weapon of their era: the feared Ulfberht sword. Fashioned using a process that would remain unknown to the Vikings' rivals for centuries, the Ulfberht was a revolutionary high-tech tool as well as a work of art. Considered one of the greatest swords ever made, it remains a fearsome weapon.

Airing October 17, 2012 at 9 pm on PBS

Witness the exhilarating moments of Curiosity’s Mars landing — and the spectacular discoveries afterward.

Watch an uncut interview with the late astronaut, conducted at NASA in 1984.

Go behind the scenes at CERN for exclusive interviews with lead scientists on the historic July 4 announcement.

Find out how an airliner with elaborate safety and navigation features and a faultless safety record could simply vanish. 6/13/2012

Take a safe front-row seat to the risky and thrilling art of chasing twisters. 5/9/2012

It contains 99.9 percent of all the matter in our solar system and sheds hot plasma at nearly a million miles an hour. The temperature at its core is a staggering 27 million degrees Fahrenheit. It convulses, it blazes, it sings. You know it as the sun. Scientists know it as one of the most amazing physics laboratories in the universe.

Twenty million passengers embark on cruises each year, vacationing in deluxe "floating cities" that offer everything from swimming pools to shopping malls to ice skating rinks. And the ships just keep getting bigger: The average cruise ship has doubled in size in just the last ten years. Some engineers fear that these towering behemoths are dangerously unstable.

In 2011, the worst tornado season in decades left a trail of destruction across the U.S., killing more than 550 people. Why was there such an extreme outbreak? How do such outbreaks form? With modern warning systems, why did so many die? Is our weather getting more extreme - and if so how bad will it get?

NOVA Labs will launch May, 2012.