With its hundreds of rings and 18 moons, Saturn may be the most fascinating planet in the solar system. For years scientists have been eager to learn just what those dusty rings are made of. They wanted to take a closer look at a moon called Titan. It may offer clues to what Earth was like millions of years ago.
Soon they will have their chance. On October 13, NASA and foreign space agencies will send the Cassini spacecraft on a six-year voyage to Saturn. Cassini will study the peculiar planet and its rings and moons for four years.
Cassini runs on plutonium (ploo-toe-nee-um), a dangerous substance also found in nuclear bombs. Exposure to plutonium can cause cancer. Other space missions have been powered by smaller amounts of plutonium. But some people are worried that if the mission fails, humans could be exposed to the hazardous material. NASA insists that the space mission is safe.
More than 600,000 signatures on a computer disk, from folks in 81 nations, will travel onboard Cassini. "Some of us dream of venturing into the cosmos," says Charley Kohlhase, who helped design the spacecraft. "Sending our signatures can substitute for making the journey ourselves."