The 6th ESLAB Symposium, organised by the Space Science Department (formerly ESLAB) of the European Space Research and Technology Center, was held in Noord wijk from 26-29 September 1972. This year the theme was "Photon and Particle Interactions with Surfaces in Space". More than 60 scientists attended mainly from ESRO Member States and from America. The first part of the Symposium was devoted to introductory lectures and to papers on interactions with spacecraft. The second half dealt with the photon and particle interactions with celestial objects, and ended with a general discussion and presenta tions of areas where new developments are required. The purpose of this Symposium was to throw light on the importance of the prob lems which are evoked by E. A. Trendelenburg in his introductory remarks, and to sum up our present understanding of these phenomena. It is hoped that this book will prove useful to physicists and engineers who are actually involved in space ex periments and are concerned with interactions of these types. R. J. L. GRARD OPENING ADDRESS Gentlemen, I should like to welcome you to the 6th ESLAB Symposium. In the past we have always organised this Symposium jointly with our sister in stitute, ESRIN, in Frascati, but unfortunately reductions in the scientific budget have forced ESRO to terminate the activities of that laboratory. Nevertheless, we have decided to carryon the tradition, and we shall continue on our own organising this series of symposia on specialised subjects.

Proceedings of the 6th ESLAU Symposium, held at Noordwijk, The Netherlands, September 26-29, 1972

Inhalt

1. Introductory Lectures.- Fundamental Processes in Particle and Photon Interactions with Surfaces.- The Particle Environment in Space.- 2. Interactions with Spacecraft.- 2.1. Theoretical Sheath Models.- Spherically Symmetric Model of the Photoelectron Sheath for Moderately Large Plasma Debye Lengths.- The Photoelectron Sheath around a Spherical Body (presented by R. J. L. Grard).- Plasma Sheath and Screening of Charged Bodies.- The Distortion of an Electromagnetic Wave Field by a Cavity in a Cold Magneto-Plasma.- 2.2. Numerical Analysis and Simulation.- Structure of the Ionospheric Disturbances about Planetary Entry Probes.- Numerical Calculations of the Perturbation of an Electric Field around a Spacecraft.- 2.3. Influence of Surface Emission on Experimental Measurements.- Possible Effects of Photoelectron Emission on a Low Energy Electron Experiment.- The Effects of Photoelectron Emission on a Multiple-Probe Spacecraft near the Plasmapause.- The Influence of Photoelectron and Secondary Electron Emission on Electric Field Measurements in the Magnetosphere and Solar Wind (presented by K. Knott).- 2.4. Particle Energy Distributions Around Spacecraft.- Charged Particle Distribution in the Nearest Vicinity of Ionospheric Satellites Comparison of the Main Results from the Ariel I, Explorer 31 and Gemini-Agena 10 Spacecraft.- Photoelectrons Emitted from ISIS Spacecraft.- Energy Distribution of Photoelectrons Emitted from a Surface on the OGO-5 Satellite and Measurements of Satellite Potential.- 2.5. Potential of the Spacecraft Surface.- Low-Energy Electron Measurements and Spacecraft Potential: Vela 5 and Vela 6.- Electrostatic Potentials Developed by ATS-5.- Observations of Spacecraft Charging Effects in Energetic Plasma Regions.- A System for Measuring and Controlling the Surface Potential of Rockets Flown in the Ionosphere.- 2.6. Spacecraft Surface Materials.- Work Function Variation Across the Surface of Tungsten and Vitreous Carbon.- Experimental Investigation of Photoemission from Satellite Surface Materials.- Present State of the Art in Conductive Coating Technology.- 3. Interactions with Celestial Objects.- 3.1. Electric Properties of the Moon Surface and Environment.- Plasma and Potential at the Lunar Surface.- The Electric Potential of the Moon in the Solar Wind.- Measurement of the Lunar Photoelectron Layer in the Geomagnetic Tail.- Photoemission and Secondary Electron Emission from Lunar Surface Material.- 3.2. Influence of Surface Emission on the Properties of Other Celestial Objects.- Sheath Acceleration of Photoelectrons by Jupiter's Satellite Io.- Electrostatic Charging and Formation of Composite Interstellar Grains.- 3.3. Solar Wind Interactions with Celestial Objects.- Lunar Ion Flux and Energy.- Photoelectrons and Lunar Limb Shocks.- Kinetic Theory Analysis of Solar Wind Interaction with Planetary Objects.- Magnetic Measurements of the Solar Wind Interaction with the Moon (presented by G. L. Siscoe).- Observation of TM-Mode Induction in a Simulated Solar Wind/ Moon Interaction.- 3.4. Solar X-Ray Interaction with the Lunar Surface.- Lunar Composition from Apollo Orbital Measurements (presented by D. R. Criswell).- 3.5. Erosion Processes on the Lunar Surface.- Sputtering and Darkening of the Grains on the Lunar Surface.- The Lunar Electronosphere and Implications for Erosion on the Moon.- Horizon-Glow and the Motion of Lunar Dust.- Electrostatic Transportation of Dust on the Moon.- 4. Lectures in Conclusion.- Plasma-Vehicle Interactions in Space Some Aspects on Present Knowledge and Future Development.- Particle Interactions with Celestial Objects Concluding Remarks.- Index of Authors.