December 6, 2005

NASA Spacecraft Reveals Icy Plumes on Saturn Moon

WASHINGTON -- One of Saturn's moons is spraying icy particles into space from the area around its south pole, a sure sign of geologic activity, NASA reported on Tuesday.

Recent images captured by the Cassini spacecraft reveal what looks at first like the narrow crescent shape of a solar eclipse, with plumes of particles being ejected from the Saturn moon Enceladus.

"For planetary explorers like us, there is little that can compare to the sighting of activity on another solar system body," Carolyn Porco, Cassini imaging team leader at the Space Science Institute in Boulder, Colorado, said in a statement.

"This has been a heart-stopper, and surely one of our most thrilling results."

Images and more information are available online at

The Cassini images show multiple jets emanating from the moon's south polar region. Scientists suspect these jets arise from warm fractures, known as tiger stripes.

A faint extended plume stretches some 300 miles above the surface of Enceladus, which is only 300 miles (483 km) wide.

Andrew Ingersoll, an imaging team member from the California Institute of Technology in Pasadena, said he believes the images show ice particles in jets of water vapor emanating from pressurized vents.

To fling these particles aloft, the vapor must have a certain density, and Ingersoll said this implies "surprisingly warm temperatures for a cold body like Enceladus."

The Cassini-Huygens mission is a project of NASA and the European and Italian space agencies.