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.