Philip Grossman finds firefighting gear under a hospital in Chernobyl, sending his Geiger counter climbing. He believes burying the gear was the Soviet’s attempt to hide the scope of the disaster.

Philip Grossman goes inside the plant near the massive radio tower he finds maps of the U.S and pictures of mushroom clouds. Was the Duga for protecting Chernobyl from incoming missiles or part of a nuclear offensive?

Survivors who worked at nearby factory report production areas they weren’t allowed to visit. Philip visits and finds the basement full of lab after lab of gas masks, radioactive testing materials and sand.

Author Nick Sagan hasn't seen his godfather, Frank Drake, in over 30 years. We capture their reunion - and find out how Drake became friends with Nick's famous father, Carl Sagan, in this exclusive clip.

Since the 1960s, NASA has been keeping an eye on man-made objects in space. Here, engineers are replicating the devastating impact of space debris. 'Alien Encounters' airs Tuesdays at 10/9c.

Since launching in 2009, the Kepler program has detected hundreds of previously unknown planets. How many of them are Earth-like, and what does that mean for the probability of intelligent life beyond our solar system?

What would receiving a message from an alien civilization tell us about human evolution, and about surviving the most serious problems facing our planet?

If the chirality of aliens is different than ours, it couldn't interact with us, and therefore would be non threatening.

An alien spacecraft might not rely solely on sunlight to power its trajectory. Find out what other energy technology aliens could use to travel through the universe.

It's possible that life on earth began off-planet and spread here.

Will ETs look like us? Will they resemble giant insects? Scientists debate how various environments could have created life forms beyond our wildest imagination.

It's likely that an advanced civilization would combine the advantages of a machine with the advantages of biological systems.

Ever wonder how ships stay clean? Find out how one of the world's largest shipping ports manages to keep some of the largest tanker ships on the sea.

When staying at a fancy hotel you expect a good hot shower. So how do hotels provide hot showers for the thousands of guests they have each day?

Deep sea diving is more dangerous than the movies make it seem. Find out how professional divers are trained to handle any situation.

Have you ever wondered how sushi is caught? From the sea to your restaurant table, catching sushi has become not only a delicacy but a difficult job.