Flyby Image of Saturn's Sponge Moon Hyperion
Why does this moon look like a sponge?
To better investigate,
NASA and
ESA sent the Saturn-orbiting robotic
spacecraft Cassini zooming past
Saturn's moon
Hyperion, once again, earlier this week.
One of the images beamed back to Earth is
featured above, raw and unprocessed.
Visible, as expected, are many
unusually shaped craters with an unusual dark material at the bottom.
Although Hyperion
spans about 250 kilometers, its small gravitational tug on
Cassini indicates that it is mostly empty space and so has very low
surface gravity.
Therefore, the
odd shapes of many of Hyperion's craters are thought to result from impacts that
primarily compress and eject surface material -- instead of the more
typical round craters that appear after a circular shock wave that explosively redistributes surface material.
Cassini is
on track for another flyby of
Saturn's
Dione in about two weeks.