Alien Files Unsealed

To enter space, humans require a space suit. Are the aliens that are said to have visited earth any different? Or are they more akin to artificial drones? (S4, ep 1)

In Spring 1952, reports of UFO sightings shot through the roof. Can former US Air Officials shed any light on this? (S4, ep 2)

In 1969, the US government officially announced it would stop investigating UFOs, but declassified documents seem to tell another story. (S4, ep 3)

Did the space race stop at just the Moon? Is there any truth to rumours of a secret Space Force developed by America for missions beyond Earth's orbit?

Jets are scrambled to intercept a UFO, but find they are unable to complete their Shoot Down Order. (S4, ep 5)

For decades, governments around the world have investigated UFO sightings. How are these top-secret studies conducted? (S4, ep 6)

Those who claim to have been abducted by extraterrestrials give their accounts of the interior of their spacecrafts. (S4, ep 7)

If aliens have visited Earth, what are their intentions? Do they wish to experiment on the human body, or the human mind as well? (S4, ep 8)

Alien encounters have offered a possible glimpse into the secrets of interstellar navigation. Could this one day ensure mankind's survival? (S4, ep 9)

Advances in technology have given us unprecedented access to distant galaxies that may harbour life. However, alien life may be found closer to home. (S4, ep 10)

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. (S4, ep 11)

For years many have argued that UFOs are as terrestrial as you or I. They may be correct, but not in the way they thought they were. (S4, ep 12)

In 1947, there was an unprecedented wave of UFO sightings that propelled the UFO phenomenon to the world stage. What were the US Air Force's findings? (S4, ep 13)

For many people, the most credible UFO reports are those raised by law enforcement. We investigate the most significant reports from police records. (S4, ep 14)

Between 1981 and 2011, cameras on NASA space shuttles have picked up many images of UFOs that experts still struggle to explain.

While many UFO sightings occur in rural locations with only a single eyewitness, there have been sightings over cities witnessed by hundreds. (S4, ep 16)

With science closer than ever to proving that life once lived on Mars, is there a chance that something still exists there? (S4, ep 17)

With light from distant stars taking millions of years to reach us, how long might it take for alien life to answer any communication sent into space? (S4, ep 18)

Is biological life merely a stepping stone for a universe dominated by alien artificial intelligence? (S4, ep 19)

As humanity continues to search for alien life, experts give their analysis on how close we are to First Contact. (S4, ep 20)