NASA's Unexplained Files

A UFO crashes in Pennsylvania. Was it a secret Soviet satellite -- or something far more dangerous? On Mercury, NASA finds the impossible: frozen water. A strange object causes a skyscraper-sized shadow on the surface of Mars's largest moon. What is it?

Was the moon landing faked? Images of Mercury reveal massive spider-like formations on its surface.

Are burning lights in the skies above Nevada and Utah signs of a secret space weapons project?

An astronaut on a spacewalk begins to drown. How could this terrifying event happen?

Could NASA be responsible for a nuclear explosion on Jupiter?

A Russian probe discovers that the Nazis may have landed on the moon before the US or the USSR.

How did pictures from the Hubble telescope make a comet look like an alien spacecraft?

Should NASA be worried about the sudden appearance of so-called space fireflies?