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| Europa's surface in true color (left) and false color (right). Courtesy of NASA/JPL. |
Europa is a moon with a surface predominantly covered by ice
orbiting the gas giant Jupiter.
The Voyager mission imaged a majority of Europa’s surface in the late
1970s. The Galileo mission was
launched in 1989 to orbit the Jovian system. It obtained higher resolution of sections of
Europa’s surface. These missions
revealed an ice-covered surface that resembled a ball of twine, covered with
linear and curvilinear ridges. Data from these missions also revealed that Europa
generates its own magnetic field, which provides evidence that Europa has a
briny ocean beneath the surface.
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| Image of a ridge on Europa courtesy of NASA/JPL. |
Europan ridges are of specific scientific interest because
they not only reveal information about geologic processes but also the
potential for the existence of shallow water. The interaction of water on Europa with the surface could
have implications for the astrobiological potential of the icy satellite. The reactions of water and the
radiation that bombards the surface of Europa could cause chemical reactions
that may be beneficial for the existence of life in the water.
One hypothesis for Europan ridge formation is that shallow
water intrusions within the ice shell could freeze and expand to create the
surface features of the ridges. As
the water freezes and expands it exerts a significant amount of pressure on the
surrounding ice and may create cracks within the ice. These cracks may serve as a
conduit for water to reach the surface of Europa.
 |
| As the water intrusion freezes it exerts pressure in all
directions
and can cause upward flexure (red) and sideways compression
and flexure (blue) to form a ridge.
|
In order to explore the water intrusion hypothesis several
questions must be answered. How
much pressure can the freezing water exert on the surrounding ice? Is this pressure enough to crack
the ice? How deep can the water
intrusion be and still be able to create these ridge features. These questions are being evaluated
currently through the use of numerical models and may provide the answer to
where is the water on Europa.
References and Further Reading:
Cassidy, T., Coll, P., Raulin, F., Carlson, R. W.,
Johnson, R. E., Loeffler, M. J., Hand, K. P., et al. (2010). Radiolysis and
Photolysis of Icy Satellite Surfaces: Experiments and Theory. Space Science Reviews, 153(1-4), 299-315.
doi:10.1007/s11214-009-9625-3
Christopher F. Chyba and Cynthia B. Phillips. (2002). Europa as an Abode of Life. Origins of
Life and Evolution of Biospheres (Vol. 32, pp. 46-47). doi:10.1111/j.1744-618X.2010.01158.x
Han, L., & Showman, A. P. (2008). Implications of
shear heating and fracture zones for ridge formation on Europa. Geophysical Research Letters, 35(3), 6-10. doi:10.1029/2007GL031957
Very clear and concise explanation of your work, with great images and metaphors.
ReplyDeleteThis was very well-written! Like the images, the placement of them, and your thought-provoking end paragraph.
ReplyDeleteI like the title and pics of this blog.
ReplyDeleteThis is really clear and readable. You might want to emphasize the role of water in the search for extraterrestrial life, to catch the readers interest.
ReplyDeleteThis is an easy and interesting read. I like the ball of twine metaphor for Europa and the big higher resolution picture of Europa.
ReplyDeleteThe body of the blog is well written and easy to follow. The images are relevant and interesting, but the title could be more exciting.
ReplyDeleteI really enjoyed your blog I thought it was well written and easy to understand.
ReplyDelete