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

Date: Wednesday, October 16, 2002
Time: 4:15-5:30 PM; Refreshments at 4:00 PM
Location: Bldg. TCSeq, Rm. 101

Earth-based Radar Mapping of Planets

Leif Harke

STAR Lab, Stanford University

Abstract

Earth-based radar astronomy involves transmitting a signal from a large radio telescope to a distant planet, receiving the echo at the transmitting or other radio telescope sites, and converting the collected data into useful scientific information. Digital signal processing techniques exist for generating a map of the distant planet's surface from the received signal. We present 6 km resolution maps of the northern and southern polar regions of Mercury from the Goldstone Solar System Radar, and 360 km resolution maps of Ganymede and Callisto from the Very Large Array. The availability of cheap computing, specifically workstation clusters, has enabled high resolution mapping through the implementation of signal processing techniques that were previously computationally infeasible, including the long pseudo-noise code synthetic aperture radar method, and the aperture synthesis technique.

The study of planets and their moons has benefited greatly from spacecraft technology developed over the last four decades. The ability to launch a small optical telescope or radar instrument and place it into orbit a few hundred miles above another planet in the solar system returns data of unprecedented quality. However, the price tags of such missions, ranging from a few hundred million to several billion dollars, lead to long delays between successive opportunities and spectacular financial and political disasters in the case of mission failure. Earth-based observations of planets, while often not as revealing as spacecraft-based measurements, offer a cost effective alternative to the big interplanetary missions.