The
geologic processes occurring on icy satellites can differ greatly from those
occurring on terrestrial bodies (such as earth). The main reason for this is behavior of water-ice is fairly
unique in the solar system. Water
is one of the few substances that become less dense when it changes from a
liquid to a solid. Impurities in
water also have a dramatic impact on the rheological characteristics of ice as
well as the freezing behavior of water.
As water freezes it
commonly rejects impurities and can create pockets of brine within an ice mass
or it can cause a weakening of the ice because of rejection “pores”. Most icy satellites are not composed of
pure water and ice, however most models are created assuming pure water and
ice.
Modeling the freezing of an
impurity-rich body of water in an ice shell can provide a better understanding
of the many processes occurring on icy satellites. Multiple models would need
to be created using different impurities in order to systematically explore the
impact of possible impurities in ice. These impurities include clathrates, ammonia and
salts. This could lead to better
constraints on the composition of individual icy satellites. Freezing impure-water containing may
also play an important role in cryovolcanism on icy satellites.
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| Geyser on Enceladus. Courtesy JPL/NASA |
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