Cassini Finds Enceladus Tiger Stripes Are Really Cubs
The Cassini spacecraft has discovered the long, cracked features
dubbed "tiger stripes" on Saturn's icy moon Enceladus are very
young -- between 10 and 1,000 years young.
Image right: This visual and infrared mapping spectrometer image of Saturn's moon Enceladus shows the dark cracks at the south pole dubbed tiger stripes. Image credit: NASA/JPL/University of Arizona
+ Full image and caption + Browse version of image
These findings support previous results showing the moon's southern
pole is active. The pole had episodes of geologic activity as recently
as 10 years ago. These cracked features are approximately 130 kilometers
long (80 miles), spaced about 40 kilometers (25 miles) apart and run
roughly parallel to one another.
The cracks act like vents. They spew vapor and fine ice water particles
that have become ice crystals. This crystallization process can be dated,
which helped scientists pin down the age of the features.
"There appears to be a continual supply of fresh, crystalline ice at the
tiger stripes, which could have been very recently resurfaced," said Dr.
Bonnie Buratti. She is a team member of the Cassini visual and infrared
mapping spectrometer at NASA's Jet Propulsion Laboratory, Pasadena, Calif.
"Enceladus is constantly evolving and getting a makeover."
Image left: Saturn's moon Enceladus is only 505 kilometers (314 miles) across, small enough to fit within the length of the United Kingdom, as illustrated here. Image credit: NASA/JPL/Space Science Institute + Browse version of image
This finding is especially exciting because ground-based observers have seen
tiny Enceladus brighten as its south pole was visible from Earth. Cassini
allows scientists to see close up that the brightening is caused by geologic
activity. When NASA's Voyager 2 spacecraft flew over the moon's north pole
in 1981, it did not observe the tiger stripes.
Cassini's visual and infrared mapping spectrometer shows water ice exists in
two forms on Enceladus: in pristine, crystalline ice and radiation-damaged
When ice comes out of the "hot" cracks, or "tiger stripes," at the south pole,
it forms as fresh, crystalline ice. As the ice near the poles remains cold and
undisturbed, it ages and converts to amorphous ice. Since this process is believed
to take place over decades or less, the tiger stripes must be very young.
"One of the most fascinating aspects of Enceladus is that it is so very small as
icy moons go, but so very geophysically active. It's hard for a body as small as
Enceladus to hold onto the heat necessary to drive such large-scale geophysical
phenomena, but it has done just that," said Dr. Bob Brown. Brown is a team leader
for the visual and infrared mapping spectrometer at the University of Arizona, Tucson.
"Enceladus and its incredible geology is a marvelous puzzle for us to figure out."
Adding to the already mounting evidence for an active body is the correlation of
results from multiple instruments. Cassini's cameras provided detailed images of the
south polar cap, in which the tiger stripe fractures were found to be among the
The timing of the craft's ion and neutral mass spectrometer and the cosmic dust
analyzer observations seems to indicate the vapor and fine material are originating
from the "hot" polar cap region. These data also indicate the production of water vapor
and ejection of fine material are connected, as they are in a comet. This suggests
that vapor and dust-sized icy material are coming from the tiger stripes.
Enceladus is on a short list of bodies in our solar system where scientists have found
internal activity. The others are the volcanoes on Jupiter's moon Io and geysers on
Neptune's moon Triton.
Data for these measurements were taken during Cassini's closest flyby on July 14, 2005.
The spacecraft came within 175 kilometers (109 miles) of the surface of Enceladus.
Enceladus is 500 kilometers (314 miles) across and has the most reflective surface
in the solar system.
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 mission for NASA's Science Mission
For information about the Cassini-Huygens mission on the Web, visit
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Carolina Martinez (818) 354-9382
Jet Propulsion Laboratory, Pasadena, Calif.
Erica Hupp/Dolores Beasley (202/358-1237/1753)
NASA Headquarters, Washington