On September 11,1985, the veteran NASA spacecraft ISEE-3, which has been renamed the International Cometary Explorer. will make the first visit of a spacecraft to a comet This pamphlet is designed as a teachers' guide to the NASA wallsheet on the International Cometary Explorer (ICE) and its mission. The chapters have been extensively edited and the responsibility for any error inadvertently introduced is mine and not the respective authors'.
Teachers and their students should be aware that a large number of new books on comets have been published and that many of these are available in public libraries and bookstores This circumstance, of course, results from the current interest in the return of Halley's Comet This teacher's guide will be equally helpful in understanding scientists' strong interest in sending the ICE spacecraft to investigate the tail of a much less famous object. Comet Giacobini- Zinner.
For vital support of the ICE mission to Comet Giacobini-Zinner, the participating scientists are indebted to many individuals. This includes the staff of the Deep Space Network (DSN). operated by the NASA Jet Propulsion Laboratory in Pasadena. CA The DSN has been augmented to track ICE Two of its large antennas in Madrid. Spain and in California. will be receiving the data as ICE passes through the comet The great 300 meter radio telescope of the Arecibo Observatory in Puerto Rico. operated by Cornell University, has also been especially equipped to receive the comet encounter data The encounter has been timed for 11:00 am EDT on September 11 when the comet and the spacecraft will be nearly overhead at Arecibo
Appreciation is expressed also to the dozens of astronomers of the International Halley Watch Astrometry Net who have been photographing Comet Giacobini-Zinner and sending data on its changing position to Dr Donald Yeomans of the Jet Propulsion Laboratory. From these data. Dr. Yeomans has kept track of changes in the comet's orbit, enabling controllers at the Goddard Space Flight Center. Greenbelt, MD, to plan the necessary mid-course maneuvers to keep the ICE spacecraft on course.
In the first chapter. John C. Brandt and I describe some basic properties of comets and summarize the observational history of Comet Giacobini- Zinner and its associated meteor showers. Next. flight director Robert Farquhar briefly describes the use of lunar gravity to redirect, accelerate, or decelerate a spacecraft. Lunar gravitational assist played a key role in sending ICE (or ISEE-3. the two spacecraft names are used almost interchangeably throughout this publication) on to Comet Giacobini-Zinner. Dr Farquhar then provides a brief description of the original, unique "halo orbit" of ISEE-3 and the concept of libration points.
In the chapter on History and Discoveries of ISEE-3. Tycho von Rosenvinge mentions just a few of the many interesting findings on the space environment and the terrestrial magnetosphere that have resulted from analysis of data gathered by this spacecraft Malcolm Niedner, in "The ICE Mission to Comet Giacobini- Zinner." describes the instruments carried on the ICE spacecraft that are expected to contribute to our understanding of comets Niedner describes some key features, according to present theory and knowledge, of the interaction of a comet with the solar wind.
The teachers' guide concludes with a short contribution by Dr. Farquhar, on the future of the ICE spacecraft after it passes beyond Comet Giacobini- Zinner first will come two opportunities to sample the solar wind upstream of Comet Halley. then in the year 2013. perhaps an opportunity to recover the aging spacecraft when it returns to the vicinity of Earth. This assumes that ICE will survive its likely bombardment by high-speed dust particles in the tail of Comet Giacobini-Zinner, and remain in operable condition.
For help in designing and producing the ICE poster and teachers' guide. special thanks are due to Elva Bailey, Howard Golden, Sam Haltom, Steve Meszaros, Arthur Shilstone. and Janet Wolfe.
Stephen P. Maran July 1985