By Kenneth Chang ABCNEWS.com
As planned, NASA’s Cassini spacecraft safely and uneventfully zipped past Earth and is now speeding toward an encounter with Jupiter in December 2000 and its final destination of Saturn in 2004.
 
At 11:28 p.m. ET Tuesday, Cassini made its closest approach to Earth, passing within 728 miles over the eastern South Pacific. The spacecraft passed within three miles of its target and six-tenths of a second late — all within an acceptable margin of error.
 
“It was right by the book,” said Bob Mitchell, Cassini’s program manager at NASA’s Jet Propulsion Laboratory in Pasadena. Anti-nuclear activists have been worried that somehow flight controllers would lose control of Cassini, sending it tumbling into the atmosphere and vaporizing its 72 lbs. of plutonium fuel. NASA officials have said that since Cassini was simply being pulled around by Earth’s gravity, such an accident was almost impossible.
 
In June, demonstrators protested against the flyby, but most activists conceded there was no way to prevent it. Before Cassini’s launch in 1997, protesters filed lawsuits and threatened to chain themselves to the pad.