Electromagnetic explosions... devastating climate change... mysterious diseases... all carving a deadly path across the globe. Could mankind's biggest threat come from a natural disaster--or might the cause be something more sinister--something from out of this world? This special examines our planet's complex infrastructure and life-support systems and shows how humans are vulnerable to attack from a variety of threats--be it man-made or extraterrestrial. Leading scientists, government officials, military personnel and others explore where Earth's abundant resources, telecommunications, food and water supplies, weapons and even the human body could be taken over by a hostile force. Are we susceptible to outside control? Could an enemy use our own planet and its natural resources as a weapon against us? If we discover we're not alone in the universe, would an alien invasion be likely?

There used to be many UFO sightings, but with the end of the Cold War the number dropped to a trickle. Why? This critical look at the UFO craze of the last 50 years attempts to determine whether it was a case of mass hysteria. Michael Dorn narrates.

A fascinating examination of ancient evidence of UFO visits to Earth. Includes a look at monuments of antiquity that point toward stars in the sky, and ancient texts that contain references to flying objects.

Could an alien infection cause an epidemic on earth? Some experts believe that spacecraft returning from Mars could bring back a harmful sample or comet dust falling into our atmosphere could cause pandemics. One astronomer believes that the Influenza of 1918, which killed between 50-100 million people, was one such outbreak and that another "infection" could decimate the world's population. Astrobiologists are now poised to bring Mars samples back to earth to examine them in a Bio 4 level safety lab. In a hypothetical future disaster scenario, track how comet dust would seed the earth with a virulent virus. Quarantine measures don't work and panic ensues.

Bill Kurtis travels to Mexico and Brazil to investigate UFO sightings.

In 1978, commercial pilot Frederick Valentich took off on a solo flight from Melbourne, Australia. Some 40 minutes later, Valentich reported a large aircraft 1,000 feet above him. Air control told him there were no aircraft in the area. But Valentich insisted and said the craft appeared to be made of shiny metallic material and displayed four green lights. For six minutes, he and air traffic control discussed the mysterious object. Then there was silence--Valentich and his plane had vanished!

Foo Fighters maneuvered in and around bomber formations.

Electromagnetic explosions... devastating climate change... mysterious diseases... all carving a deadly path across the globe. Could mankind's biggest threat come from a natural disaster--or might the cause be something more sinister--something from out of this world? This special examines our planet's complex infrastructure and life-support systems and shows how humans are vulnerable to attack from a variety of threats--be it man-made or extraterrestrial. Leading scientists, government officials, military personnel and others explore where Earth's abundant resources, telecommunications, food and water supplies, weapons and even the human body could be taken over by a hostile force. Are we susceptible to outside control? Could an enemy use our own planet and its natural resources as a weapon against us? If we discover we're not alone in the universe, would an alien invasion be likely?

There used to be many UFO sightings, but with the end of the Cold War the number dropped to a trickle. Why? This critical look at the UFO craze of the last 50 years attempts to determine whether it was a case of mass hysteria. Michael Dorn narrates.

A fascinating examination of ancient evidence of UFO visits to Earth. Includes a look at monuments of antiquity that point toward stars in the sky, and ancient texts that contain references to flying objects.

Could an alien infection cause an epidemic on earth? Some experts believe that spacecraft returning from Mars could bring back a harmful sample or comet dust falling into our atmosphere could cause pandemics. One astronomer believes that the Influenza of 1918, which killed between 50-100 million people, was one such outbreak and that another "infection" could decimate the world's population. Astrobiologists are now poised to bring Mars samples back to earth to examine them in a Bio 4 level safety lab. In a hypothetical future disaster scenario, track how comet dust would seed the earth with a virulent virus. Quarantine measures don't work and panic ensues.

Bill Kurtis travels to Mexico and Brazil to investigate UFO sightings.

In 1978, commercial pilot Frederick Valentich took off on a solo flight from Melbourne, Australia. Some 40 minutes later, Valentich reported a large aircraft 1,000 feet above him. Air control told him there were no aircraft in the area. But Valentich insisted and said the craft appeared to be made of shiny metallic material and displayed four green lights. For six minutes, he and air traffic control discussed the mysterious object. Then there was silence--Valentich and his plane had vanished!

Foo Fighters maneuvered in and around bomber formations.

Electromagnetic explosions... devastating climate change... mysterious diseases... all carving a deadly path across the globe. Could mankind's biggest threat come from a natural disaster--or might the cause be something more sinister--something from out of this world? This special examines our planet's complex infrastructure and life-support systems and shows how humans are vulnerable to attack from a variety of threats--be it man-made or extraterrestrial. Leading scientists, government officials, military personnel and others explore where Earth's abundant resources, telecommunications, food and water supplies, weapons and even the human body could be taken over by a hostile force. Are we susceptible to outside control? Could an enemy use our own planet and its natural resources as a weapon against us? If we discover we're not alone in the universe, would an alien invasion be likely?

There used to be many UFO sightings, but with the end of the Cold War the number dropped to a trickle. Why? This critical look at the UFO craze of the last 50 years attempts to determine whether it was a case of mass hysteria. Michael Dorn narrates.

A fascinating examination of ancient evidence of UFO visits to Earth. Includes a look at monuments of antiquity that point toward stars in the sky, and ancient texts that contain references to flying objects.

Could an alien infection cause an epidemic on earth? Some experts believe that spacecraft returning from Mars could bring back a harmful sample or comet dust falling into our atmosphere could cause pandemics. One astronomer believes that the Influenza of 1918, which killed between 50-100 million people, was one such outbreak and that another "infection" could decimate the world's population. Astrobiologists are now poised to bring Mars samples back to earth to examine them in a Bio 4 level safety lab. In a hypothetical future disaster scenario, track how comet dust would seed the earth with a virulent virus. Quarantine measures don't work and panic ensues.

Bill Kurtis travels to Mexico and Brazil to investigate UFO sightings.

In 1978, commercial pilot Frederick Valentich took off on a solo flight from Melbourne, Australia. Some 40 minutes later, Valentich reported a large aircraft 1,000 feet above him. Air control told him there were no aircraft in the area. But Valentich insisted and said the craft appeared to be made of shiny metallic material and displayed four green lights. For six minutes, he and air traffic control discussed the mysterious object. Then there was silence--Valentich and his plane had vanished!

Foo Fighters maneuvered in and around bomber formations.