A plutonium-powered NASA spacecraft is hurtling toward a close encounter with Earth tonight to use the planet's gravity to sling it toward Saturn. The Cassini probe is scheduled to fly within 725 miles of Earth. Anti-nuclear activists fear some kind of error could cause the spacecraft to plunge into the Earth's atmosphere and shower the planet with deadly radioactive debris. But NASA officials said there was only a 1-in-1.2 million chance of accidental re-entry. As a child growing up in Cocoa, Florida, Jesse Lee Kercheval experienced the shock of space experiments gone awry along with the intense national pride associated with the Apollo missions and lunar landing. In her memoir "SPACE", Kercheval recounts a time when all of America was riveted by rockets, astronauts and outer space.