Unsealed: Alien Files Season 4

Many experts believe aliens have visited the Earth for thousands of years, but if we can't survive space travel without a protective suit, how can they? Are some aliens mere shells or clones with an artificial consciousness?

In the spring of 1952, UFO sightings go off the charts. For years, the U.S. government has told the postwar public that UFOs do not exist, but behind the scenes, U.S. Air Force officials are divided.

In 1969, the U.S. government officially announces it will stop investigating UFOs, but declassified documents reveal that multiple government agencies have been hiding important UFO sightings for decades.

Since the early 1960s, we've experimented with how to travel off planet Earth. Many experts believe America has operated a secret Space Force for decades, with ultra high-tech ships designed for missions beyond Earth's orbit.

Since the Jet Age, fighter pilots have been scrambled to intercept UFOs in our skies, but what happens when pilots are sent a Shoot Down Order and can't complete their mission?

For decades, governments around the world have investigated UFO sightings, often times under an umbrella of secrecy. How are these top-secret studies conducted? Who is called upon to analyze the evidence?

Alien abductions are the only types of encounters in which eyewitness testimony can reveal details about the inside of UFOs. Details that can help us understand how aliens live and what they want from the human race.

If aliens have visited Earth, why are they here and what are they truly after? Investigations have revealed the possibility that aliens are interested in experimenting on not only the human body, but the human mind as well.

In order to survive mankind must find a way to navigate the galaxy. Alien encounters have offered a possible glimpse into the secrets of interstellar flight, but how would extraterrestrials know how to navigate the vast regions of space?

Rapid advancements in science and technology have given mankind unprecedented access to distant galaxies that could harbor life. And some scientists believe that to find alien life we need look no further than our own backyard.

Photographic evidence of Unidentified Flying Objects helped usher in the modern UFO phenomenon. As the world continues to evolve into the digital age, more and more people are capturing images in the sky that they are unable to explain.

Where do UFOs come from? Some people believe they're from distant galaxies, wormholes, or other planets within the Milky Way. Join us as we investigate the existence of UFOs and determine the possibility that they may be from Earth.

In 1947, a series of UFO sightings triggers an unprecedented analysis that propels the UFO phenomenon on to the world stage. We investigate how the U.S. Air Force comes to the stunning conclusion that UFOs may not be from Earth.

UFO sightings happen almost every day. But in the court of public opinion the most credible witnesses come from law enforcement. Join us as we investigate the most important police sightings of UFOs.

Between 1981 and 2011, NASA's Space Shuttles flew 135 missions. The Space Shuttle cameras, manned and unmanned, have recorded astounding footage of UFOs that many experts find almost impossible to explain.

Many famous UFO sightings occur in remote locations with just a single eyewitness. But some sightings have taken place over large cities with hundreds of witnesses.

Scientists have never been closer to proving that life once lived on Mars. But is it still there? And if so, how has it evolved? Join us as we investigate the red planet and the possibility that alien life may live within our own galaxy.

Scientists and Ufologists are scouring the vast regions of space for signs of extraterrestrial life. But if it takes millions of years for light from distant stars to reach Earth, how long could it take for aliens to answer our call?

Some scientists believe the survival of mankind hinges upon the revolutionary science of Artificial Intelligence. Biological life may just be an evolutionary stepping-stone in a universe dominated by Artificial Alien Intelligence.

For decades, scientists have been searching for proof that extraterrestrials exist. But just where does alien life exist? And what does it look like? Join us as we investigate just how close we are to First Contact.