The first Earth‐Moon spacecraft encounter

Abstract

It was with great interest that we read the article by Fraser Fanale in Eos (November 20, 1990) on “Galileo's Earth‐Moon Encounter Set for December 8.” We noted the number of important observations that were planned and carried out to study the Earth‐Moon system. We are also looking forward to the large number of interesting results that will undoubtedly become available after the encounter with the asteroid Gaspra, the second Earth encounter, and, most importantly, during the Jupiter mission.However, we would like to correct an important historical statement made by the author in the introductory section of his article. The Galileo encounter with the Earth‐Moon system was not the first encounter by a spacecraft from deep space with the Earth‐Moon system. On July 2, 1990, the Giotto spacecraft encountered the Earth with closest approach at a radial distance of 3.56 Earth radii at 10:01:18 UTC. During the encounter, observations were made of the magnetic field and the energetic particle environment of the terrestrial magnetosphere.