National Aeronautics and Space Administration Logo
Follow this link to skip to the main content NASA Banner
Solar System Exploration
News & Events
Researchers Find Evidence of Folds on Europa, Provide Clues About Evolution of Jovian Moon's Surface
Researchers Find Evidence of Folds on Europa, Provide Clues About Evolution of Jovian Moon's Surface
10 Aug 2000
(Source: Johns Hopkins University Applied Physics Laboratory)

http://www.jhuapl.edu/public/pr/000810.htm

JHU Applied Physics Laboratory
Mike Buckley
Laurel, MD 20723
Phone: 240-228-7536
E-mail: michael.buckley@jhuapl.edu

Researchers at the Johns Hopkins University Applied Physics Laboratory (APL) and Brown University may have solved a 20-year-old geological mystery surrounding Jupiter's icy moon Europa.

In the August 11 issue of Science, Louise Prockter of APL and Robert Pappalardo of Brown report evidence of "folds" on the moon's frozen surface. The researchers say the mountain-like features - found in three regions - are the first indication of compression on the fractured Europan crust, and provide unprecedented insight into the history and behavior of the Jovian satellite.

"We learned from Voyager images in the late 1970s that there was a lot of extension on Europa - that the surface was pulling apart and a slushy material was moving up through the gaps - but no one could find out how this new material was being accommodated," Prockter says. "Now, we have finally found folds where the icy surface material compresses, and this will help us start to understand how Europa evolved and how it resurfaces."

Prockter and Pappalardo first noticed the folds in high-resolution images of Europa's Astypalaea Linea fracture region, taken by the Galileo spacecraft. Near the large fracture zone they spotted fine-scale features that typically occur in fold structures (such as the Appalachian Mountains) on Earth: regional patterns of fractures and small ridges which mark adjacent crests and valleys.

The folds' direction and location along Astypalaea Linea coincide with models of tidal stress, the gravitational pull from Jupiter that scientists believe creates the pattern of large, canyon-like cracks on Europa's rotating surface. The size and nature of the folds - crests possibly tens to hundreds of meters high and spaced about 25 kilometers (16 miles) apart - also tell the researchers about the surface itself. They indicate warping of a thin brittle lithosphere covering a thicker region, or asthenosphere, of "warmer" and mobile glacier-like ice.

The researchers spotted similar folds in two other regions, and believe they could exist in other areas. One reason the folds have been hard to find is the planet does a good job of hiding them; over time, the researchers hypothesize, the folds "relax away" and push some material back into Europa's interior for recycling.

"There has been no solid evidence for compression folds or material cycling on any other icy satellite, though many show extensional features," Pappalardo says. "This finding potentially has applications for other icy moons as well."

Science is the weekly journal of the American Association for the Advancement of Science (AAAS) in Washington, D.C. Journalists can contact the AAAS News and Information Office at (202) 326-6440 or scipak@aaas.org for copies of the article.

The Applied Physics Laboratory is a not-for-profit division of The Johns Hopkins University, conducting research and development primarily for national security and for nondefense projects of national and global significance. APL is located midway between Baltimore and Washington, D.C., in Laurel, MD. For more information visit www.jhuapl.edu.

News Archive Search  Go!
Show  results per page
 
 
Awards and Recognition   Solar System Exploration Roadmap   Contact Us   Site Map   Print This Page
NASA Official: Kristen Erickson
Advisory: Dr. James Green, Director of Planetary Science
Outreach Manager: Alice Wessen
Curator/Editor: Phil Davis
Science Writer: Autumn Burdick
Producer: Greg Baerg
Webmaster: David Martin
> NASA Science Mission Directorate
> Budgets, Strategic Plans and Accountability Reports
> Equal Employment Opportunity Data
   Posted Pursuant to the No Fear Act
> Information-Dissemination Policies and Inventories
> Freedom of Information Act
> Privacy Policy & Important Notices
> Inspector General Hotline
> Office of the Inspector General
> NASA Communications Policy
> USA.gov
> ExpectMore.gov
> NASA Advisory Council
> Open Government at NASA
Last Updated: 5 Jun 2001