STANFORD UNIVERSITY
EE 350 RADIOSCIENCE SEMINAR
Professor Leonard Tyler
Autumn 2002-2003

Date: Wednesday, December 4, 2002
Time: 4:15-5:30 PM; Refreshments at 4:00 PM
Location: Bldg. TCSeq, Rm. 101

Lunar Interior Modeling from Gravity and Topography Data

Sami Asmar

Dept. of Earth and Space Science, University of California, Los Angeles

Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA

Abstract

One of the primary objectives of the planetary sciences is to investigate the interior structures of the planets and their satellites in order to understand of thermal history and development of the planets. Such studies include estimating the thickness of the planet's crust as well as the rigidity and elastic thickness of the lithosphere in order to understand the depth of compensation, the balancing of topographic loads with sub-surface density variations. For bodies such as Mercury, Venus, Mars, and the Moon, the objective is achievable remotely by using gravity and topography data obtained from spacecraft measurements, along with other available physical, chemical, and geological information. The use of these data is based on the fundamental premise that one can remove the contribution of the planet's topography to the gravity and attribute the remaining signal to variations at depth. The resulting solutions are incorporated into models of constraints on the elastic thickness and dynamic or isostatic compensation mechanisms. Such models require certain assumptions about the density distribution and other considerations. Although methods to investigate the relationship between gravity and topography were introduced at least a century ago in the context of geodetic studies, the last few years witnessed a rapid development of new ones. This was motivated by an explosion of large data sets acquired from spacecraft orbiting Venus, the Moon, Mars, as well as the Earth. Such data have given a boost to comparative planetology and furthered the understanding of the commonalities and differences in large-scale behavior of the terrestrial planets. Some of the methods used in this field will be presented in the context of the lunar interior modeling.