Help Shape the Future of Space Exploration

Join The Planetary Society Now  arrow.png

Join our eNewsletter for updates & action alerts

    Please leave this field empty

Headshot of Emily Lakdawalla

Door 29 in the 2010 advent calendar

Posted by Emily Lakdawalla

29-12-2010 12:25 CST


Time to open the twenty-ninth door in the advent calendar. Until the New Year, I'll be opening a door onto a different landscape from somewhere in the solar system. Where in the solar system is this fractured flowing ice?

Door 29

Bob Pappalardo

Door 29
The large blocks in this image are tens of meters across, while the cracks between them are one to a few meters wide.
We're back on Earth again. This is an icy part of Earth, Llewellyn glacier, in British Columbia near the border with Alaska, which has been explored as an analog for the surfaces of icy worlds like Europa and Enceladus. You can tell it's glacial ice from its blue color; it was once compacted under much more ice above, which altered the crystal structure of the water molecules from their original form (loose aggregates of snow) to its present form, large, interlocking grains of ice, making it much like a crystalline rock. The blue color is the hallmark of these large grains.

Llewellyn is a glacier in motion, but its style of motion changes from its bottom (below what we can see) to its top. At the bottom, the ice is under great pressure, which helps it to flow downhill as a fluid, although a slow fluid. But near the top, without all that confining pressure, the motion of the glacier causes it to crack. In geologic terms, the bottom of the glacier is undergoing ductile strain, while the top is undergoing brittle strain. There's a similar transition going on between the brittle surfaces and ductile interiors of ice moons like Europa and Enceladus, and it's helpful to study such environments on Earth, where they're a bit easier to access.

Thanks to Bob Pappalardo for the photo!The Planetary Society Blog 2010 Advent Calendar

See other posts from December 2010


Or read more blog entries about:


Leave a Comment:

You must be logged in to submit a comment. Log in now.
Facebook Twitter Email RSS AddThis

Blog Search


Our Curiosity Knows No Bounds!

Become a member of The Planetary Society and together we will create the future of space exploration.

Join Us

Featured Images

Mariner 7 approaches Mars
Global color view of Titan from the north, June 10, 2014
Panorama across the lit side of Saturn's rings, May 10, 2014
Cassini looks across Titan's north pole, May 19, 2014
More Images

Featured Video

All those Asteroids with Amy Mainzer

Watch Now

Space in Images

Pretty pictures and
awe-inspiring science.

See More

Join the New Millennium Committee

Let’s invent the future together!

Become a Member

Connect With Us

Facebook! Twitter! Google+ and more…
Continue the conversation with our online community!