00-037

Jovian System Data Analysis Program

Cover Page/Proposal Summary

ROSS-99    NRA 99-OSS-01

Date Due: 5/5/99

NASA PROCEDURE FOR HANDLING PROPOSALS

This proposal shall be used and disclosed for evaluation purposes only, and a copy of this Government notice shall be applied to any reproduction or abstract thereof. Any authorized restrictive notices that the submitter places on this proposal shall also be strictly complied with. Disclosure of this proposal for any reason outside the Government evaluation purposes shall be made only to the extent authorized by the Government.

Proposal Type: New Proposal

Proposal Category: Satellites and Rings

Major Equipment Proposal? No

Do you intend to submit an Education/Public Outreach (E/PO) proposal? No

Proposal Title:
Deformation of the Europan Ice Shell by Tidal and Convective Stresses: Constraints from GEM Data

Abbreviated Proposal Title:
Deformation of the Europan Ice Shell from GEM Data

Principal Investigator:
Dr. William McKinnon
Dept. EPSC Campus Box 1169
Washington University
One Brookings Dr.
St. Louis, MO 63130-4899
Phone: 314-935-5604   Fax: 314-935-7361   E-mail: mckinnon@levee.wustl.edu

SignatureDate
_________________________________________________

Co-Investigators and Collaborators:
Type    Name    Affiliation    E-mail
Sci Collab   Dr. Roger Phillips   Washington University   phillips@wustite.wustl.edu
Sci Collab   Dr. Paul Schenk   Lunar and Planetary Institute   schenk@lpi3.jsc.nasa.gov


Proposal Summary:

Europa's icy surface has been deformed by a variety of tectonic processes: ridge formation, plate rotation and pull-apart, apparent diapiric intrusion, and wholesale crustal overturn. Each of these reflects the response of the ice shell to tidal forces and heat flowing from the rocky interior. Understanding the nature of these responses should provide powerful constraints on the thermal and mechanical nature of the ice shell, e.g., its thickness, whether or not an ocean exists (though this point is now less debated), is radar soundable, etc. We will analyze the overall pattern of lineaments and plate rotation on Europa, as revealed by GEM data (in conjunction with primary mission data), and use the derived stress and strain pattern and, to the extent possible, its time history to constrain the stress sources responsible (e.g., tidal flexing and nonsynchronous rotation). The latter will be numerically modeled to better understand the interplay of multiple stress sources, stress relief during shell failure, and shell thickness variations. Specifically, we will 1) stratigraphically analyze the lineament/ridge pattern to determine the pattern and (partial) time history of deformation; 2) relate these to elastoviscoplastic finite element models of tidally flexed and/or nonsynchronously rotating shells; 3) stratigraphically analyze spreading and rotation centers to establish regional strain histories; 4) relate these to the shell deformation models and to possible convective patterns (determined under separate funding); 5) evaluate whether a truly thin shell (<5-10 km thick) is required to explain most of the observed deformation. The significance of the proposed work for OSS interests is that it should allow for a greater understanding of the history of the Europan shell and its interaction with the presumed ocean below, along with direct bearing on the future exploration of Europa, whether by remote sensing (e.g., radar sounding) or in situ investigations.