December 16, 2008

Enceladus shows more signs of activity

The U.S. space agency says its Cassini spacecraft has detected Saturn's small moon Enceladus is showing signs of ongoing changes at its south polar surface.

The National Aeronautics and Space Administration said close views of the southern polar region -- where jets of water vapor and icy particles spew from vents within the moon's distinctive tiger stripe fractures -- provide surprising evidence of Earth-like tectonics.

They yield new insight into what may be happening within the fractures, NASA said, noting the latest data on the plume -- the huge cloud of vapor and particles fed by the jets that extend into space -- show it varies over time and has a far-reaching effect on Saturn's magnetosphere.

Enceladus has Earth-like spreading of the icy crust, but with an exotic difference -- the spreading is almost all in one direction, like a conveyor belt, said Paul Helfenstein, Cassini imaging associate at Cornell University. We are not certain about the geological mechanisms that control the spreading, but we see patterns of divergence and mountain-building similar to what we see on Earth, which suggests that subsurface heat and convection are involved.

The new findings were presented Monday during the American Geophysical Union's Fall Meeting in San Francisco.