NASA's Unexplained Files

Lost tapes show that Apollo astronauts heard unexplained transmissions.

Apollo 12 astronauts bring back something alive from the moon.

Neil Armstrong goes into an unexplained spin and must determine the cause.

A mysterious material may have sabotaged earlier Apollo missions.

NASA's secret plan B for failure of the first moon landing is revealed.

Three cosmonauts die mysteriously as they re-enter Earth's atmosphere.

Two astronauts trapped in the vacuum of space face an agonizing death.

Astronauts are evacuated when a mystery object hurtles towards the ISS.

A UFO crashes in Pennsylvania. Was it a secret Soviet satellite, or something far more dangerous? On Mercury, NASA finds the impossible: frozen water.

Images of Mercury reveal massive spider-like formations on its surface. Is it an odd geological formation - or something much more ominous?

What are the mysterious trails on the lunar surface near the Apollo landing sites? Does a strange space object spell disaster for the crew of the space shuttle?

An astronaut on a spacewalk begins to drown. How could this alarming event happen? Plus, have NASA discovered an asteroid that's been converted into a spacecraft?

Could NASA really be responsible for a nuclear explosion on Jupiter? Could new evidence finally reveal the truth behind the mystery of the iconic face on Mars?

A Russian probe discovers something has disturbed the lunar soil before the US or the USSR got there. But did the Nazis get there first?

The show returns with more mysterious encounters, unusual discoveries and strange sightings, straight from NASA's best and brightest.

Something in space is attacking the brains of our astronauts. What is it? Should NASA be worried about the sudden appearance of so-called space fireflies?

Astronomers find evidence for alien technology around a distant star.

A mission to Mars captures an image of a strange structure on the planet.

Geysers are discovered on a frozen moon, and NASA detects evidence of life.

Astronomers detect a potentially habitable planet close to Earth.

A strange phenomenon impacts a NASA experiment during a full moon.

Scientists investigate an ancient claim that the earth had two moons.

Astronomers discover evidence of an invisible planet orbiting a star.

The Mars Orbiter captures an image of odd streaks on the Martian surface.

President Kennedy demanded that the CIA share their UFO data with NASA.

The Curiosity Rover finds a strange, and perhaps sinister, object on Mars.

Two suns photographed in the sky may be a sighting of our sun's evil twin.

Scientists examine strange octopus DNA to see if it could be alien.

NASA investigates what could have made a Stonehenge-like structure on Mars.

The CIA plans revenge when the Soviet Union unveils its own space shuttle.

The last humans on the Moon discover something strange on the surface.

A mysterious object orbiting Saturn looks just like the Death Star.

NASA discovers something strange on Saturn's moon that might be aliens.

An Area 51 insider claims the Roswell incident was a Soviet conspiracy.

Astronomers investigate how much danger a rogue black hole poses to Earth.

Experts investigate if a mysterious object is an alien spacecraft.

Experts ask why Neil Armstrong went on a quest to find a legendary library.

Experts ask if an experiment with dolphins is a prelude to alien contact.

Experts investigate if a nearby exoplanet could be inhabited by aliens.

Experts consider if an alien Armageddon transformed Mars into a wasteland.