Spongy-Looking Hyperion Tumbles Into View
Two new Cassini views of Saturn's tumbling moon Hyperion offer 
the best looks yet at one of the icy, irregularly-shaped moons 
that orbit the giant, ringed planet.
Two new Cassini views of Saturn's tumbling moon Hyperion offer 
the best looks yet at one of the icy, irregularly-shaped moons 
that orbit the giant, ringed planet.The image products released today include a movie sequence and a 
3D view, and are available athttp://saturn.jpl.nasa.gov,http://www.nasa.gov/cassiniandhttp://ciclops.org.The views were acquired between June 9 and June 11, 2005, during 
Cassini's first brush with Hyperion.Hyperion is decidedly non-spherical and its unusual shape is easy 
to see in the movie, which was acquired over the course of two and 
a half days.  Jagged outlines visible on the moon's surface are indicators 
of large impacts that have chipped away at its shape like a sculptor.Preliminary estimates of its density show that Hyperion is only about 
60 percent as dense as solid water ice, indicating that much of its interior 
(40 percent or more) must be empty space.  This makes the moon more like an 
icy rubble pile than a solid body.In both the movie and the 3D image, craters are visible on the moon’s surface 
down to the limit of resolution, about 1 kilometer (0.6 mile) per pixel. 
The fresh appearance of most of these craters, combined with their high spatial 
density, makes Hyperion look something like a sponge.The moon's spongy-looking exterior is an interesting coincidence, as much of 
Hyperion’s interior appears to consist of voids.   Hyperion is close to the 
size limit where, like a child compacting a snowball, internal pressure due 
to the moon’s own gravity will begin to crush weak materials like ice, closing 
pore spaces and eventually creating a more nearly spherical shape.The images used to create these views were obtained with Cassini's narrow-angle 
camera at distances ranging from approximately 815,000 to 168,000 kilometers 
(506,000 to 104,000 miles) from Hyperion.  Cassini will fly within 510 kilometers 
(317 miles) of Hyperion on Sept. 26, 2005.The Cassini-Huygens mission is a cooperative project of NASA, the European Space 
Agency and the Italian Space Agency.  The Jet Propulsion Laboratory, a division 
of the California Institute of Technology in Pasadena, manages the Cassini-Huygens 
mission for NASA's Science Mission Directorate, Washington, D.C.  The Cassini orbiter 
and its two onboard cameras were designed, developed and assembled at JPL.  
The imaging team is based at the Space Science Institute, Boulder, Colo.