NASA launches controversial Saturn probe

"I find that NASA bureaucrats in some sense are living in fantasyland. Pure guesswork has replaced rigorous physics."
Anti-Cassini physicist Michio Kaku

The nuclear age and space age collided in 1997, as NASA faced off with anti-nuclear activists over a hot issue -- plutonium.

About 72 pounds of the radioactive material -- "the most toxic substance on Earth," some claim -- power the Cassini rocket, launched in October to explore Saturn and its moons.

Opponents of the mission fear that the consequences could be catastrophic if plutonium is accidentally released into the Earth's atmosphere in 1999, when Cassini again swings by the Earth.

NASA argues that the plutonium power cells, used in two dozen spacecraft since 1961, are safe. They are necessary for the mission because the rocket will venture too far from the sun for solar cells to be effective.

Cassini is the last in the old mold of NASA planetary probes -- a massive, do-everything project that cost $3.4 billion. In recent years, NASA has reoriented itself toward "smaller, faster, cheaper" projects like Mars Pathfinder and Mars Global Surveyor.

If all goes according to plan, Cassini will arrive at Saturn in 2004. It is expected to send back data until at least 2008.

During that time, Cassini will orbit Saturn and its moons and dispatch the Huygens probe, which will penetrate the dense atmosphere of Titan, Saturn's largest moon, and send back data as it falls. It may send information for up to 30 minutes on the surface -- if it survives the unknown rigors of Titan's landscape.