Cassini Heads for Ring Road

The Cassini spacecraft successfully lifted off this morning from Cape Canaveral, beginning its 3.2-billion-kilometer trek to Saturn. After picking up speed by swinging by several planets, the craft--opposed by antinuclear activists because of its plutonium-based power supply--will reach the ringed planet and its moon Titan on 4 July 2004.

Built by NASA, the European Space Agency (ESA) and the Italian space agency, the $3.4 billion craft will orbit Saturn for 4 years, using a suite of 12 instruments to probe the planet's internal structure, windy atmosphere, rings, and 17 icy satellites. The ESA-built Huygens probe will parachute down to Titan, carrying six instruments to study the atmosphere and surface. Titan has a nitrogen-based atmosphere, like Earth, and what may be lakes of ethane and methane. "There are a lot of neat things we will find out," says Frederick Bruhweiler, an astrophysicist at Catholic University in Washington, D.C.

Cassini's launch comes a decade after the project was first proposed by scientists at the Jet Propulsion Lab in Pasadena, California. "The probe went through a redesign after budget cuts in the early 1990s," says NASA spokesman Douglas Isbell. Then last month, the spacecraft was slightly damaged while being installed atop a Titan IV/Centaur rocket. And antinuclear activists protested the launch, concerned about the 33 kilograms of plutonium 238 that will generate the craft's electricity.