Transcript Europa - Mayfield City Schools

Europa
Information From
http://solarsystem.nasa.gov
Europa Intro
• Jupiter's icy moon Europa is slightly smaller
than the Earth's Moon. Like the Earth, Europa
is thought to have an iron core, a rocky mantle
and a surface ocean of salty water. Unlike on
Earth, however, this ocean is deep enough to
cover the whole surface of Europa, and being
far from the sun, the ocean surface is globally
frozen over.
• Four hundred years ago, the astronomer Galileo's
discovery of Jupiter's four large moons forever
changed humanity's view of the universe, helping
to bring about the understanding that Earth was
not the center of all motion. Today one of these
Galilean moons could again revolutionize science
and our sense of place, for hidden beneath
Europa's icy surface is perhaps the most
promising place to look for present-day
environments that are suitable for life.
• These cracks had separated, and dark, icy material
appeared to have flowed into the opened gaps,
suggesting that the surface had been active at some
time in the past. Voyager images showed only a
handful of impact craters, which are expected to build
up over time as a planetary surface is constantly
bombarded by meteorites over billions of years until
the surface is covered in craters. Thus, a lack of large
impact craters suggested that the moon's surface was
relatively young and implied that something had
erased them - such as icy, volcanic flows, or settling of
the icy crust under its own weight.
• Scientists also found that the patterns of some
of the longest linear features on the surface
did not fit predicted patterns of fractures that
should be created by tides as Europa orbits
Jupiter. They determined that the patterns
would fit very well if Europa's surface could
move independently and was not locked to
the rest of the interior, as would be the case if
a layer of liquid or slightly warmer ice existed
between the crust and deep interior.
• Ridges criss-cross the surface, and are places
where warm ice or water has pushed up the
surface or erupted. Some ridges are cycloidal in
shape, arcing across the surface: these probably
formed along cracks that were influenced by the
rising and falling tides. Bands are places where
the icy surface has pulled apart, with new warm
ice rising up, chilling, and cracking. Some waterfilled cracks, or dikes, could shoot upward from
the base of Europa's ice.
Thrace Macula
• Thrace Macula is the largest dark spot on
Europa and has been recently modified and
resurfaced. The nature of the dark material is
uncertain but may have a higher
concentration of salts or sulfates associated
with the water ocean lying perhaps around as
few as 6 miles (10 kilometers) beneath the
surface. Some of this dark material appears to
have ponded in low areas indicating that some
liquid might be involved.
The Conamara Chaos
• The following image is a view of a small region of the thin,
disrupted ice crust in the Conamara region of Jupiter's
moon Europa showing the interplay of surface colors with
ice structures. The white and blue colors outline areas that
have been blanketed by a fine dust of ice particles ejected
at the time of formation of the large, 26 kilometer (16 mile)
in diameter crater Pwyll some 1000 kilometers (621 miles)
to the south. The unblanketed surface has a reddish brown
color that has been painted by mineral contaminants
carried and spread by water vapor released from below the
crust when it was disrupted. The original color of the icy
surface was probably a deep blue color seen in large areas
elsewhere on the moon. The image covers an area
approximately 70 by 30 kilometers (44 by 19 miles).
• Europa's Churning Ice Shell (Labeled Version)
• Europa's bizarre surface features suggest an actively churning ice shell
above a salty liquid water ocean. This artistic composite illustrates
Europa's many different types of surface features and the interior
processes that might form them.
Heat is created within the floating ice shell by flexing and squeezing due to
rising and falling tides as Europa orbits the giant planet Jupiter. It is this
tidal heat that keeps the ocean liquid at a temperature near 0 degrees
Celsius (32 degrees Fahrenheit), even though the surface is frigidly cold at
a temperature of about -170 degrees Celsius (-275 degrees Fahrenheit).
The cold near-surface ice can crack or crumble, while the tidal heat keeps
the base of the ice shell close to the ice melting temperature, so the ice
there can slowly flow, like a glacier.
• Blobs, or diapirs, of relatively warm ice may slowly rise
from the base of the floating ice shell to the cold nearsurface ice, and they might melt and expel salts in their
path. Diapirs might push the surface upward to create
domes, or crumble the surface and erupt to form spot.
Diapirs might merge and tidal heat can concentrate
within the ice shell, perhaps partially melting it, to
create the jumbled blocks of chaos terrain. Ice diapirs
could be a sign of convection within the ice shell, like
the rise of warm rock within the Earth's mantle.
• Europa's surface shows few large impact craters, indicating
that vigorous geological activity has wiped out the older
ones. A large impact with bull's-eye rings may have once
punched all the way through the ice shell to the watery
ocean, though the icy hole has since healed.
Europa's churning ice shell could allow surface
contaminants to move downward into the ocean. It can
also dredge up deep slushy ice, allowing material from the
ocean -- including life, if it exists there -- to be carried to
the surface.