Death of a Spacecraft: The Unknown Fate of Cassini

The Cassini spacecraft is roughly halfway through its looping voyage of the Saturn system and is continuing to return a bounty of data on the ringed planet and its moons. Yet all journeys must have an end and Cassini's eventual fate is now being discussed.

"Current planning is for a two year mission extension that ends on July 1, 2010," said Robert Mitchell, NASA's Cassini mission program manager. "However, presuming that the spacecraft continues to function well, it's reasonable to expect that one or more further extensions will be supported."
Sometime around 2012, Cassini, like the ocean-going ships of old, will need to be decommissioned. However, the spacecraft cannot be towed to some nearby shore to be dismantled; she must either drop anchor, be scuttled, or cast off her gravitational moorings altogether.
"Perhaps the most likely option is to leave Cassini in a long-lived orbit that would have little to no risk of ever hitting anything," Mitchell said. "Another is to impact Saturn like Galileo did at Jupiter, although there are some complications with this one."
The complications arise from the beautiful wafer-thin rings that girdle the planet and the fact that in order to dive into Saturn, Cassini would have to pass through them—a risky maneuver that could render the spacecraft uncontrollable.