Number 21: 05/08/2003
A scientific publication by SGF and NEODyS

NEOs' spacemissions: mission Galileo

Galileo's fast facts

It all started on October 18, 1989, at Cape Canveral: Galielo spaceraft was launched in a Space Shuttle Atlantis, ready to begin a very long journey that would last 6 years, toward Jupiter, the outer planets and to the external frontier of our solar system... (read the introduction)

The Galileo Spacecraft's studies of asteroids and comets
by Clark R. Chapman - Southwest Research Institute (Boulder CO USA)

The spacecraft Galileo took a long, circuitous tour of the solar system before finally arriving at Jupiter in late1995, where it has been performing its prime and extended missions eversince.
Of course, the asteroid belt is between Earth and Jupiter, so it was inevitable that the spacecraft would pass through the belt... (click for the full article)

To know more about Jupiter and its moons, click on the icons on the left. You will find some 3d, interactive models of the planets...

coming soon: the history of the dicovery of Dactyl, Ida's moon!!

The history of NEOs' science

Preface: What has Copernicus to do with NEOs?

It may seem rather strange that a magazine such as Tumbling Stone, which is mainly devoted to NEO research and related topics, should publish a series on the history of science. In fact the readers should not be surprised, because the scientific study of NEOs (and also, of course, of the threat that they may pose to us) involves the use of two fundamental tools: astronomical observations, and orbit computations... read the preface

Astronomy at the time of Copernicus
by Andrea Carusi - President SGF

When Copernicus wrote his important book, De Revolutionibus Orbium Coelestium (1543), the status of planetary astronomy in Europe did not differ too much from that in Ptolemy's time, more than a thousand years for the full article

Other resources and articles:

Discovery of the first Asteroid with an Interior Earth Orbit: 2003CP20
by Jenifer Evans and Grant Stokes - MIT Lincoln Laboratory

Historically, NEAs have been categorized by their orbital characteristics and divided into 3 families - Apollos, Amors and Atens -. Until recently, there have been no asteroids known that have their entire orbit contained inside the Earth's orbit. That changed on the evening of February 10, 2003, with the discovery of 2003 CP20... click here for the article

A movie about keyholes

In the last issue, we published an article by G.B.Valsecchi about keyholes (click here for the article of issue number 20). In this issue, we want to present a movie explaining the meaning of this technical term...

Download the avi movie (click on, 14 MB).


Editor: Nanni Riccobono
Assistant Editor, web master and graphics: Livia Giacomini (

Spaceguard Foundation (SGF) is a private, non profit scientific organization aimed at supporting and co-ordinating NEO researches in the world.
NEO Dynamic Site (NEODyS) is a service offered by the University of Pisa (Italy). It provides catalogues, computation of orbits, and projection of the behavior of NEOs in the future, in order to identify possible impacts in advance.
Our sponsors:
The Astronomic Observatory of Mallorca (OAM)

Images of the heading: courtesy of NASA