Spacecraft-Environment Interactions

Spacecraft interact with the space environment in ways that may affect the operation of the spacecraft as well as any scientific experiments that are carried out from the spacecraft platform. In turn, the study of these interactions provides information on the space environment. Adverse environmental effects, such as the effect of the radiation belts on electronics and spacecraft charging from the magnetospheric plasma, mean that designers need to understand interactive phenomena to be able to effectively design spacecraft. This has led to the new discipline of spacecraft-environment interactions. The emphasis in this book is on the fundamental physics of the interactions. Spacecraft-Environment Interactions is a valuable introduction to the subject for all students and researchers interested in the application of fluid, gas, plasma, and particle dynamics to spacecraft and for spacecraft system engineers.

SPACECRAFT-ENVIRONMENT INTERACTIONS

Cambridge atmospheric and space science series Editors Alexander J. Dessler John T. Houghton Michael J. Rycroft

Titles in print in this series M. H. Rees, Physics and chemistry of the upper atmosphere Roger Daley, Atmospheric data analysis Ya. L. Al'pert, Space plasma, Volumes 1 and 2 J. R. Garratt, The atmospheric boundary layer J. K. Hargreaves, The solar-terrestrial environment Sergei Sazhin, Whistler-mode waves in a hot plasma S. Peter Gary, Theory of space plasma microinstabilities Ian N. James, Introduction to circulating atmospheres Tamas I. Gombosi, Gaskinetic theory Martin Walt, Introduction to geomagnetically trapped radiation B. A. Kagan, Ocean-atmosphere interaction and climate modeling

SPACECRAFT-ENVIRONMENT INTERACTIONS DANIEL HASTINGS

HENRY GARRETT

Massachusetts Institute of Technology

The California Institute of Technology

CAMBRIDGE UNIVERSITY PRESS

PUBLISHED BY THE PRESS SYNDICATE OF THE UNIVERSITY OF CAMBRIDGE The Pitt Building, Trumpington Street, Cambridge, United Kingdom CAMBRIDGE UNIVERSITY PRESS The Edinburgh Building, Cambridge CB2 2RU, UK 40 West 20th Street, New York NY 10011-4211, USA 477 Williamstown Road, Port Melbourne, VIC 3207, Australia Ruiz de Alarcon 13, 28014 Madrid, Spain Dock House, The Waterfront, Cape Town 8001, South Africa http://www.cambridge.org © Cambridge University Press 1996 This book is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 1996 First paperback edition 2004 A catalogue record for this book is available from the British Library Library of Congress Cataloguing-in-Publication

Data

Hastings, Daniel. Spacecraft-environment interactions/Daniel Hastings, Henry Garrett. p. cm. — (Cambridge atmospheric and space science series) Includes bibliographical references and index. ISBN 0 521 47128 1 (hardback) 1. Space environment. 2. Space vehicles — Design and construction. I. Garrett, Henry B. II. Title. III. Series. 95-47376 TL1489. H37 1996 CIP 629.4'16-dc20 ISBN 0 521 47128 1 Hardback ISBN 0 521 60756 6 Paperback

Contents

List of Illustrations List of Tables Preface Acknowledgment

xi xvii xix xxiii

1 Introduction 1.1 Introduction 1.2 Classification of Spacecraft Environments 1.3 Spacecraft Orbits and the Ambient Space Environment 1.4 Spacecraft Systems 1.5 Interactions between the Environment and a Spacecraft 1.6 Historical Review of Spacecraft-Environment Interactions 1.6.1 The Dawn of the Space Age to 1970 1.6.2 The Decade of the Seventies 1.6.3 The Decade of the Eighties 1.6.4 The Nineties 1.7 Purpose of the Book

1 1 2 3 5 6 11 11 12 13 14 14

2 Fundamental Length, Time, and Velocity Scales 2.1 The Concept of a Distribution Function 2.1.1 The Maxwellian Equilibrium Distribution Function 2.1.1.1 Properties of the Maxwellian Distribution Function 2.2 Typical Spacecraft Length and Velocity Scales 2.3 Neutral Gas Scales 2.3.1 Collision Mean Free Path and Knudsen Number 2.3.2 Speed Ratio 2.4 Plasma Scales

16 16 19 20 24 25 25 27 28

vi

Contents 2.4.1 Basic Particle Motion in Constant Electric and Magnetic Fields 2.4.2 Debye Length and Natural Plasma Frequencies 2.4.3 Speed Ratios 2.5 Radiation Invariants 2.5.1 Adiabatic Invariants 2.5.1.1 B-L Coordinates and the Concept of Rigidity 2.5.2 Linear Energy Transfer Distance

28 30 35 35 35 37 40

3 The Ambient Space Environment 3.1 Influence of the Sun 3.1.1 Solar-Cycle Effects 3.1.2 Solar and Geomagnetic Indices 3.1.3 Short-Term Events 3.2 The Neutral Atmosphere 3.3 The Plasma Environment 3.3.1 The Geomagnetic Field 3.3.1.1 The External and Disturbance Fields 3.3.2 Low Earth Orbit 3.3.3 Polar Orbits 3.3.4 The Geosynchronous Plasma Environment 3.4 The Radiation Environment 3.4.1 Energetic Particle Radiation 3.4.1.1 Trapped Radiation 3.4.1.2 Cosmic Rays 3.4.1.3 Solar Proton Events 3.4.2 Electromagnetic Radiation 3.4.2.1 Electromagnetic Radiation at Radio Frequencies 3.4.2.2 Visible and Infrared 3.4.2.3 UV, EUV, and X Rays 3.5 The Macroscopic Particle Environment 3.5.1 The Physics of Macroscopic Particles 3.5.2 Meteoroid Models 3.5.2.1 Cometary Meteoroids 3.5.2.2 Asteroidal Meteors 3.5.3 Space Debris 3.5.4 Gabbard Diagrams for Satellite Fragmentation 3.6 Man-Made Environments 3.6.1 Exoatmospheric Nuclear Detonations 3.6.1.1 Event Morphology

44 44 46 46 48 49 53 53 58 59 62 65 70 71 71 75 77 79 80 80 81 82 83 85 86 89 90 92 95 95 95

Contents 3.6.1.2 The Prompt Environment 3.6.1.3 Debris Environment 3.6.2 Nuclear Power Sources 3.6.2.1 Radioisotope Thermoelectric Generators (RTGs)

vii 95 96 97 97

4 Neutral Gas Interactions 4.1 Neutral Gas Flow Around a Spacecraft 4.2 Atmospheric Drag 4.2.1 Drag and Lift on a Flat Plate at Angle of Attack /} 4.2.2 Drag on a Sphere 4.2.3 Effect of Atmospheric Variability on Drag 4.2.4 Satellite Lifetime and Orbit Determination 4.3 Contamination 4.3.1 Modeling of Contamination 4.3.2 Thruster Contamination 4.3.3 The Shuttle Neutral Environment 4.4 Erosion by Atomic Oxygen 4.5 Glow

100 100 108 111 113 114 116 117 123 128 132 132 137

5 Plasma Interactions 5.1 Spacecraft-Plasma Interactions 5.2 Spacecraft Surface Charging and Current Collection 5.2.1 Current Sources to a Spacecraft 5.2.1.1 Current from the Ambient Plasma 5.2.1.2 Photoelectric Currents 5.2.1.3 Backscattered and Secondary Electrons 5.2.1.4 Effect of Magnetic Fields on Current Collection 5.2.1.5 Artificial Current and Charge Sources 5.2.2 General Probe Theory 5.2.2.1 The Thin-Sheath Limit 5.2.2.2 The Thick-Sheath Limit 5.2.3 Spacecraft Potentials at GEO 5.2.3.1 Barrier Potentials 5.2.4 Potentials, Anomalies, and Arcing on GEO Spacecraft 5.3 Plasma Flow Around a LEO Spacecraft 5.3.1 The Plasma Wake Structure of a LEO Spacecraft 5.3.2 Current Collection in Flowing Magnetoplasmas 5.3.3 Spacecraft Potentials at LEO and Polar Orbits 5.3.4 Particle-Beam Effects on Spacecraft Potentials 5.3.5 Potential Distribution on LEO Solar Arrays

142 142 143 145 145 146 148 152 154 154 158 162 167 175 177 180 181 187 190 191 192

viii

Contents

5.4 Spacecraft Arcing 5.4.1 Arcing on High-Voltage LEO and Polar Spacecraft 5.5 Electrodynamic Tethers 5.6 Plasma Sources on Spacecraft 5.6.1 Plasma Contactors 5.6.2 Electric Propulsion Engines

195 195 199 203 203 206

6 The Space Radiation Environment 6.1 Introduction 6.2 Radiation Interactions with Matter 6.2.1 Single-Particle Interactions 6.2.1.1 Photon Interactions 6.2.1.2 Charged-Particle Interactions 6.2.1.3 Neutron Interactions 6.3 Modeling the Effects of Shielding 6.3.1 Solar-Array Degradation 6.3.2 SEUs Due to Heavy Ions 6.4 Radiation Charging of Dielectric Materials 6.4.1 Physics of Radiation-Induced Charging 6.4.2 Experimental Evidence for Radiation-Induced Bulk Discharges 6.5 Radiation Environment Estimates 6.5.1 Example: The Clementine Program 6.5.1.1 AE8 and AP8 Radiation Dosage Results 6.5.2 Example: Jovian Model Application 6.5.3 Heinrich Flux Estimates 6.5.4 CRRES Results

208 208 208 209 210 211 214 215 223 223 229 230

7 Particulate Interactions 7.1 Particle Impacts on Spacecraft 7.1.1 Hypervelocity Impacts and Shielding Theory 7.1.1.1 A Real Case: Multisurface Shield for Propellant Tanks 7.1.1.2 Meteoroid Failure Probability Calculations 7.1.1.3 Helium Tanks 7.1.1.4 Propellant Tanks 7.1.1.5 The S Correction Factor 7.2 Scattering of EM Radiation from Particles

250 250 251

8 The State of the Art 8.1 Review of the Intellectual State of the Art 8.1.1 Neutrals

271 271 271

232 233 233 234 240 242 244

259 261 263 264 267 269

Contents

8.1.2 Plasmas 8.1.3 Radiation 8.1.4 Particulates 8.2 Review of the State of Current Engineering Practices 8.2.1 Interaction Modeling Codes 8.2.2 Ground-Based Experimental Capabilities 8.3 Future Trends in the Practice of Spacecraft-Environment Interactions 8.3.1 High-Reliability Missions 8.3.2 Class C Programs 8.3.3 Class D Programs 8.3.4 Summary References Index

ix

272 273 273 274 274 275 275 276 277 277 279 281 291

Illustrations

2.1 2.2 2.3 2.4 2.5 2.6 2.7 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16

Reduced Maxwellian Distribution Relative to Velocity. Speed Distribution Function. Intermolecular Force Field Relative to Distance. Cycloidal Trajectories Described by Ions and Electrons in Constant Electric and Magnetic Fields. Debye Shielding in a Plasma. Motion of a Charged Particle in a Dipole Magnetic Field. LET Relative to Energy.

22 22 26

Schematic of Environments for LEO, PEO, MEO, and GEO. Observed and One-Year-Ahead Predicted Sunspot Numbers. Temperature (K) Relative to Altitude (km) for the Neutral Atmosphere. Composition (cm" 3) Relative to Altitude (km) for the Neutral Atmosphere. The Magnetosphere Showing the Plasmasphere, Plasma Sheet, and Polar Plasma Plasmasphere Regions, and the Van Allen Radiation Belts. Geomagnetic-Field Magnetic Elements. Spherical Coordinate System for Geomagnetic and Geographic Coordinates. Total Intensity (F) in Nanoteslas. Altitude (km) Relative to Electron Density (cm" 3) for the Ionosphere. Altitude (km) Relative to Ion Composition (cm" 3) for the Ionosphere. Number Flux (Particles • s"1 • sr"1) Relative to Kp for the Auroras. Electron and Ion Distribution Functions Observed by ATS-5 Along with Single and Two Maxwellian Fits. Van Allen Belt Radiation Flux for Electrons and Ions. Shielded 5-year Radiation Doses in Circular Orbits, with 3 g/cm2 Shielding. Trapped Proton Fluence from AP8-MIN. Trapped Electron Fluence from AE8-MAX.

45 47

XI

30 31 37 42

50 50 54 55 56 57 60 61 64 68 72 73 74 74

xii

Illustrations 3.17 3.18 3.19 3.20 3.21 3.22 3.23 3.24 3.25 4.1

4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20

Cosmic-Ray Differential Energy Spectrum for Iron. GCR Proton Spectrum. Interplanetary Proton Spectrum. Fluence versus Probability Curves for Protons of Energy Greater than 10 MeV for Various Exposure Times. Solar Spectrum. Debris and Meteoroid Flux at 500 km. Gabbard Diagram for Debris from Satellite 1973-86B. Gabbard Diagram for Debris from Satellite 1977-65B. Neutron and Gamma Ray Isodose-Isoflux Contours for Galileo RTGs. Profiles to 700 km of Number Density, Collision Frequency, Mean Free Path, and Particle Speed from the U.S. Standard Atmosphere. Structure of the Gas Flow Around a Model Spherical Satellite in LEO. Curves of Equal Value of Normalized Density Behind a Rapidly Moving Sphere or Ellipsoid Vo/v± = 8. Flat Plate at Angle of Attack in a Molecular Stream. Rebounding Molecules from a Plate Tangential to the Ram. Satellite Lifetimes Relative to F10.7 for Circular Orbits for Various Initial Altitudes. IR Absorption Spectrum of Dioctyl Phthalate. Change in QCM Frequency (Contaminant Deposit Thickness) Relative to Time for the Launch of the LES-8 and LES-9 on a Titan III-C Rocket. On-Orbit Performance of Second-Surface Mirror Radiators. Molecular Irradiance Paths. Returning Flux Relative to Altitude. Number of Surface Collisions Encountered by Particles Prior to Striking the HALOE Aperture. Flow Types in a Plume Expanding into a Vacuum. Angular Far-Field Density Distribution for a Conical Nozzle with an Area Ratio of 25 and Nozzle Exit Angle of 10 deg. Atomic Oxygen Erosion Process for a Graphite Surface. Fluence Profiles for Atomic Oxygen Interactions with Kapton. Failure Mode of Protective Coatings as a Result of Atomic Oxygen Undercutting. Mass Loss of SiO2-Protected Kapton as a Function of Fluence in an RF Plasma Asher. Comparison of the Satellite (AE) and Shuttle Surface Glows as a Function of Altitude. The Appearance of Glow on Different Parts of the Shuttle During the Roll Experiment on STS-5. Arrows Indicate the Velocity Vector.

76 76 78 79 81 88 93 94 99

101 104 107 111 114 115 118 119 121 124 126 128 129 131 133 135 137 138 139 140

Illustrations 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 5.10 5.11 5.12

5.13 5.14 5.15 5.16 5.17 5.18 5.19 5.20 5.21 5.22 5.23 5.24

Composite Plot of the Electron Yield per Photon W(E), the Solar Flux S(E), and Their Product, the Total Photoelectron Yield, as Functions of Energy, £, for Aluminum Oxide. Secondary Electron Yield 1 MeV and E > 10 MeV) Electron Environment. Also Shown for Comparison is the High-Energy Proton Environment (15 MeV < E < 26 MeV). 6.22 Integral LET Spectra Inside a Spacecraft (With 0.064 cm Aluminum Walls) in a 400 km Circular Orbit.The 90 Percent Worst Case Environment is Assumed in the Interplanetary Medium and the AP Trapped Proton Environment at the Earth. The LET Spectra are for the Various Orbital Inclinations Indicated. 6.23 Integral LET Spectra Inside a Spacecraft with 0.064 cm Aluminum Walls that is in a Circular Orbit at a 60° Inclination. As in the Figure 6.22, the 90 Percent Worst Case Environment is Assumed in the Interplanetary Medium and the AP Trapped Proton Environment at the Earth. The LET Spectra are for the Various Altitudes as Shown. 6.24 SEU Locations on the TMS4416 RAMs for UOSAT2. 6.25 SEU Rate from CRRES Relative to L Shell for the Period July 25, 1990, to March 22, 1991. 6.26 SEU Rate from CRRES Relative to the L Shell for the Period March 22, to April 22, 1991. 6.27 SEU Rate and VHLET Count Rate from CRRES Relative to the L Shell. 6.28 Average CRRES Dosimeter Combined HILET and LOLET Data Behind Dome. The GPS Orbit is Shown for Reference in the Upper Quadrant. 6.29 High-Activity CRRES Dosimeter Combined HILET and LOLET Data Behind Dome 4. The GPS Orbit is Shown for Reference in the Upper Quadrant. 6.30 Low-Activity CRRES Dosimeter Combined HILET and LOLET Data Behind Dome 4. The GPS Orbit is Shown for Reference in the Upper Quadrant.

xv

238

239

240

242

243

243 244 246 246 247 247 248 248

xvi

Illustrations 7.1 7.2 7.3

7.4 7.5 7.6 7.7 7.8 7.9

Penetration Depth/Particle Diameter, p/d 1056 , Relative to Impact Velocity for a Range of Particle Diameters. Schematic of Effects of Hypervelocity Impact for ts/d 100 -36,000 Outside magnetosphere