Quantum Quest: A Cassini Space Odyssey (originally titled as 2004: A Light Knight's Odyssey) is a 2010 animated educational documentary science fiction adventure film, written by Harry "Doc" Kloor and directed by Kloor and Dan St. Pierre, that takes the viewer on an atomic adventure in space.

The voice cast originally included Christian Slater, John Travolta, Samuel L. Jackson, Sarah Michelle Gellar, Michael York, and James Earl Jones, but the cast changed in 2008, reflecting a new script that detailed a host of new discoveries made by the Cassini–Huygens mission to Saturn. Using a cast of major actors to provide their voices to the characters, the film was initiated by JPL/NASA through a grant from Jet Propulsion Lab via the international Cassini-Huygens mission to Saturn.

The story begins with the Cassini Saturn spacecraft releasing the Huygens Titan probe. The scene is then transposed to Earth, where a 12-year-old girl, Jeana (voiced by Abigail Breslin), places a sun filter over a telescope to view sun spots. She asks her mentor, a Professor (voiced by Neil Armstrong) "Why is the Sun so bright?" This leads the professor to launch into a scientific explanation about fusion. The little girl laughs, having played this trick on her mentor many times, she says "No, I meant bright, bright like happy. In most drawings, the sun has a big smile. Is he good, like the man in the moon." Knowing this means she wants a story, the mentor begins to spin a tale, but as a mentor, this one, while entertaining, is also educational.

As he speaks, we transfer to the Sun, and watching a sunspot spin into view, we dive into and pass through the chromosphere, and head toward the center. The mentor lays down the basis of our story as we travel through the Sun. He explains that the "man in the sun is called the Core (voiced by William Shatner)" and spins a story how he is good and that his children "photons" are sent out to chase away the darkness, and bring life, warmth, and knowledge to Earth. He adds that the only being who does not like the Core is a creature called the "Void" (voiced by Mark Hamill) who is an ancient, malevolent, being who existed before the Big Bang, and who sits at the edge of the Solar System, scheming to stop the Core.

The scene fades through a plasma wall, into "The Hall of Destiny" where we are introduced to the main character in the story – David (voiced by Chris Pine), a young Photon who should have begun his travel to the surface a million years ago. The Core, tries to get him moving on his journey, but David is fearful.

We cut to the Kuiper Belt where a large space battle rages between two fleets – one composed of protons, and the opposing fleet of anti-protons. A character we call "The Ranger (voiced by Amanda Peet), who is a neutrino scout, makes it through the battle lines and heads to the Sun.

Back in the Sun, David is kicking solid light sculptures into a plasma fountain. The Ranger crashes through the wall into David, followed by some imaginary creatures called Gell-Mann ghosts. The Ranger is trying to get to Saturn (other side of the Sun), to deliver a message to the Cassini Space Core Commander. The Gell-Mann ghosts (nasty creatures) surround them. The only way to escape is to give the message scroll to David, and ask him to deliver it while the Ranger holds the ghosts at bay. David sails through the Sun and encounters a "surfer dude" Solar Proton, Jammer (voiced by Hayden Christensen), who surfs the solar winds.

David's journey takes him through the Solar System, to an exploration of the moons of Saturn. Eventually he finds Milton (voiced by Robert Picardo), an older photon character who is mining for free quarks. Milton teaches David introductory material about electrons, protons, quarks, etc. The two evade the evil/comical forces of the Void, until they get captured by the "Dark Side of the Moon".