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Only a drop of
water will be collected during the 19,000 mph (30,600 kph)
flyby, which is scheduled to take place about 1 p.m. EDT.
Scientists say that will be enough to answer some key questions
about Enceladus, which has a global ocean sealed beneath its icy
surface.
“This is a very big step in a new era of exploring ocean worlds
in our solar system … bodies with great potential to provide
oases for life,” said Curt Niebur, program scientist for NASA’s
Cassini mission at Saturn.
The spacecraft does not have instruments to directly detect
life, but scientists hope to ferret out details about the
underground ocean that is believed to be the source of
Enceladus’ geyser-like plumes. Scientists suspect tidal forces
are keeping the ocean liquid.
Cassini discovered the plumes, which stretch hundreds of miles
into space, in 2005, a year after reaching Saturn.
During repeat flybys of Enceladus, Saturn's sixth-largest moon
and just 310 miles (500 km) in diameter, scientists confirmed
that the moon holds a slightly salty, liquid ocean beneath its
crust.
Saturn, a gaseous planet and the second-largest in the solar
system, is about nine time the size of Earth and is the sixth
farthest from the sun.
During Wednesday’s flyby of Enceladus, which will take place
just 30 miles (50 km) above the moon’s active southern polar
region, scientists hope to make chemical measurements of the
plume that will allow them to determine if the moon has
hydrothermal vents on its sea floor.
Similar superhot, perpetual-night deep ocean habitats on Earth
support a wide variety of life.
Cassini, which is due to end its mission in 2017, will make a
final flyby of Enceladus in December.
(Reporting by Irene Klotz. Editing by David Adams and Christian
Plumb)
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