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

Topics: pretty pictures, Earth

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: pretty pictures, Earth


Leave a Comment:

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

Blog Search

Essential Advocacy

Our Advocacy Program 
provides each Society member 
a voice in the process.

Funding is critical. The more 
we have, the more effective 
we can be, translating into more 
missions, more science, 
and more exploration.


Featured Images

THAICOM 8 drone ship landing
BEAM on Canadarm
Mars near opposition from Pic du midi Observatory, 2016
Jupiter on May 20, 2016, from Pic du Midi Observatory
More Images

Featured Video

The Planetary Post - A Visit To JPL

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, YouTube and more…
Continue the conversation with our online community!