NASA's Unexplained Files season 4←NASA's Unexplained Files season 3
NASA's Unexplained Files season 4 episodes list:
Evidence of alien technology around a distant star; speculation about Pluto's surface; Apollo astronauts are at a loss of words to describe an object they encountered while they approached the moon. Science Channel has named this episode the first episode of season 4.
A mars mission captures an image of a strange structure on the planet; an intriguing sight on the dark side of the moon; a planet-eating star gives scientists a peek of Earth's bleak future.
The discovery of geysers on a moon; NASA's mission to detect life; an object is spotted approaching an asteroid.
Astronomers notice a planet in Earth's vicinity capable of supporting life; top secret military program exposed; the moon contains the components to start life.
Cosmonauts are trapped in a capsule in a frozen lake; a NASA scientist investigates the Hindenburg; the full moon affects experiments.
A theory of Earth's abiogenesis may have started in the clouds of Venus; a look into the claim of Earth having two moons; a NASA scientist helps the FBI solve the 1996 Olympic bombing.
A probe malfunctions without cause as it enters deep space; a mission goes astray when an imposter breaches Mission Control; evidence of an invisible planet within the Solar System.
Soviet photos of the moon are intercepted by the CIA; a malfunction aboard the ISS, which imperils the whole crew; NASA probe finds evidence of the possibility of life on Mars.