Season 4

Go beneath the surface to understand forest fires, car exhaust and the space station.

How a spacesuit keeps an astronaut alive, the diesel engines that power the world's biggest ships, and the manufacturing processes behind the famous neon signs which cover Las Vegas

Secrets behind nuclear submarines; crash-test dummies; growing fruits and vegetables.

The world's largest land-mining machine; how airboats are built; warehouse for car parts.

How black boxes survive an airplane crash; transporting giant steam turbines; making fireproof suits for race-car drivers.

The design and manufacturing of large jet engines; non-lethal weapons that stun without killing; the world's largest telescope.