May Help Explain Earlier Unusual Readings
Excited scientists analyzing images from the Cassini spacecraft
announced Thursday they may have found evidence of liquid water
reservoirs that erupt in Yellowstone-like geysers on Saturn's moon
Enceladus. The rare occurrence of liquid water so near the surface
raises many new questions about the mysterious moon.
"We realize that this is a radical conclusion -- that we may
have evidence for liquid water within a body so small and so cold,"
said Dr. Carolyn Porco, Cassini imaging team leader at Space
Science Institute, Boulder, CO. "However, if we are right, we have
significantly broadened the diversity of solar system environments
where we might possibly have conditions suitable for living
High-resolution Cassini images show icy jets and towering plumes
ejecting large quantities of particles at high speed. Scientists
examined several models to explain the process. They ruled out the
idea that the particles are produced by or blown off the moon's
surface by vapor created when warm water ice converts to a gas.
Instead, scientists have found evidence for a much more exciting
possibility -- the jets might be erupting from near-surface pockets
of liquid water above 0 degrees Celsius (32 degrees Fahrenheit),
like cold versions of the Old Faithful geyser in Yellowstone.
"We previously knew of at most three places where active
volcanism exists: Jupiter's moon Io, Earth, and possibly Neptune's
moon Triton. Cassini changed all that, making Enceladus the latest
member of this very exclusive club, and one of the most exciting
places in the solar system," said Dr. John Spencer, Cassini
scientist, Southwest Research Institute, Boulder, CO.
"Other moons in the solar system have liquid-water oceans
covered by kilometers of icy crust," said Dr. Andrew Ingersoll,
imaging team member and atmospheric scientist at the California
Institute of Technology, Pasadena, CA. "What's different here is
that pockets of liquid water may be no more than tens of meters
below the surface."
oddities now make sense. "As Cassini approached Saturn, we
discovered that the Saturnian system is filled with oxygen atoms.
At the time we had no idea where the oxygen was coming from," said
Dr. Candy Hansen, Cassini scientist at NASA's Jet Propulsion
Laboratory in Pasadena. "Now we know that Enceladus is spewing out
water molecules, which break down into oxygen and hydrogen."
Scientists are also seeing variability at Enceladus. "Even when
Cassini is not flying close to Enceladus, we can detect that the
plume's activity has been changing through its varying effects on
the soup of electrically-charged particles that flow past the
moon," said Dr. Geraint H. Jones, Cassini scientist, magnetospheric
imaging instrument, Max Planck Institute for Solar System Research,
Scientists still have many questions -- Why is Enceladus
currently so active? Are other sites on Enceladus active? Might
this activity have been continuous enough over the moon's history
for life to have had a chance to take hold in the moon's
"Our search for liquid water has taken a new turn. The type of
evidence for liquid water on Enceladus is very different from what
we've seen at Jupiter's moon Europa. On Europa the evidence from
surface geological features points to an internal ocean. On
Enceladus the evidence is direct observation of water vapor venting
from sources close to the surface," said Dr. Peter Thomas, Cassini
imaging scientist, Cornell University, Ithaca, NY.
In the spring of 2008, scientists will get another chance to
look at Enceladus when Cassini flies within 350 kilometers
(approximately 220 miles), but much work remains after Cassini's
four-year prime mission is over.
"There's no question that, along with the moon Titan, Enceladus
should be a very high priority for us. Saturn has given us two
exciting worlds to explore," said Dr. Jonathan Lunine, Cassini
interdisciplinary scientist, University of Arizona, Tucson, AZ.
The Cassini-Huygens mission is a cooperative project of NASA,
the European Space Agency and the Italian Space Agency. JPL, a
division of the Caltech, manages the mission for NASA's Science
Mission Directorate. The Cassini orbiter was designed, developed
and assembled at JPL.