Cassini To Saturn . ... Credit Copyright: D. Seal , JPL , NASA Explanation: Scheduled for launch in October, the Cassini spacecraft will spend seven years traveling through the Solar System -- its destination, Saturn . ... Operating in this faint sunlight, the Cassini spacecraft can't use solar arrays so, like other missions to the outer Solar System , it will be powered by radioisotope thermoelectric generators (RTGs). ... NASA Web Site Statements, Warnings, and Disclaimers . ...