Ghosts of Machu Picchu
Tuesday, February 2 at 8:00 p.m. on WPBT2
Perched atop a mountain crest, mysteriously abandoned more than four centuries ago, Machu Picchu is the most famous archeological ruin in the Western hemisphere and an iconic symbol of the power and engineering prowess of the Inca. In the years since Machu Picchu was discovered by Hiram Bingham in 1911, there have been countless theories about this “Lost City of the Incas,” yet it remains an enigma. Why did the Incas build it on such an inaccessible site, clinging to the steep face of a mountain? NOVA joins a new generation of archeologists as they probe areas of Machu Picchu that haven’t been touched since the time of the Incas.

Extreme Cave Diving
Tuesday, February 9 at 8:00 p.m. on WPBT2
This program follows the charismatic Dr. Kenny Broad as he dives into blue holes — underwater caves that formed during the last ice age when sea level was nearly 400 feet below what it is today. They are Earth’s least explored and perhaps most dangerous frontiers. With an interdisciplinary team of climatologists, paleontologists and anthropologists, Broad investigates the hidden history of Earth’s climate as revealed by finds in this spectacularly beautiful “alternate universe.”

Extreme Ice
Tuesday, February 16 at 8:00 p.m. on WPBT2
As the world warms, the threat from rising sea levels poses an alarming potential for disaster. Some models now project a one-meter sea level rise over the next century, which could displace millions of people, from Florida to Bangladesh, and require trillions of dollars’ investment in coastal infrastructure. But these models don’t reflect recent findings that glaciers in Greenland and Antarctica are melting at an ever faster rate. In collaboration with National Geographic, NOVA follows the exploits of acclaimed photojournalist James Balog and a scientific team as they deploy time-lapse cameras in risky, remote locations in the Arctic, Alaska and the Alps.

Megabeasts’ Sudden Death
Tuesday, February 23 at 8:00 p.m. on WPBT2
In May 2008, a scientific team made worldwide headlines by announcing evidence of a previously unsuspected impact from space that had devastated prehistoric North America at the end of the last Ice Age. According to this controversial new claim, the extinction of more than 34 types of large prehistoric animals (or “megafauna”) was caused not by climate change or the arrival of the first human hunters, but by the massive breakup of a comet over the Great Lakes region. NOVA explores this provocative new theory about what killed off America’s mammoths and may have come close to extinguishing early human populations as well.

Visit the website at www.pbs.org/wgbh/nova.