Gossamer Spacecraft: Membrane and Inflatable Structures Technology for Space Applications

Transcription

1 Gossamer Spacecraft: Membrane and Inflatable Structures Technology for Space Applications Edited by Christopher H. M. Jenkins South Dakota School of Mines Volume 191 PROGRESS IN ASTRONAUTICS AND AERONAUTICS Paul Zarchan, Editor-in-Chief Charles Stark Draper Laboratory, Inc. Cambridge, Massachusetts Published by the American Institute of Aeronautics and Astronautics, Inc Alexander Bell Drive, Reston, Virginia

2 Table of Contents Preface xv Chapter 1. Overview of Gossamer Structures 1 I. Background 1 II. Applications 3 A. Solar Arrays 4 B. Communication Systems 7 C. Human Habitats 8 D. Planetary Surface Exploration 10 E. Radar and Reflect Arrays 12 F. Solar Concentrators 15 G. Solar Shades 17 III. Membranes for Gossamer Structures 19 IV. Rigidization Technology. ' 20 V. Analysis and Modeling of Gossamer Structures 25 VI. Adaptive, Smart, and Multifunctional Gossamer Systems 26 A: Adaptive Compensation of Membrane Reflectors 26 B. Multifunctional Membranes 29 C. Smart Structures : 30 VII. Deployment and Inflation Methods 1 30 Acknowledgments 33 Chapter 2. History of Relevant Inflatable High-Precision Space Structures Technology Developments 35 I. Introduction II. Goodyear's Inflatable Structures 35 A. Inflatable Search Radar Antenna 36 B. Radar Calibration Sphere 36 C. Lenticular Inflatable Parabolic Reflector 37 D. Echo Balloons 37 E. Contraves Inflatable Structures 39 F. Reflector Antenna Concepts for Very Large Baseline Interferometry and Land Mobile Communications 39

3 vi CONTENTS G. Telescope Sunshade Support Structure 40 III. L' Garde Inc.'s Inflatable Space Structures 41 A. L' Garde Inc's Simulated Decoys 42 B. Large Offset Reflector Structure 42 C. Inflatable Antenna Experiment 43 IV. ILC Dover's Inflatable Space Structures 44 A. Large Solar-Array Structure 45 V. Other Organizations with Inflatable Space Structures Technology Capability 45 References 46 Chapter 3. Mechanics of Membrane Structures 49 Nomenclature 49 I. Introduction 52 A. Definition and Unique Behavior of Membranes 52 B. Tensor Analysis 53 C. Coordinate Systems and Configurations 54 II. Kinematics of Deformation 57 A. Motion and Deformation 57 B. Deformation Gradient, Stretch, and Polar Decomposition 57 C. Strain Definitions 58 D. Deformation and Strain Rate 59 III. Stress and Balance Laws 60 A. Concept of Stress 60 B. Stress Definitions 61 C. Mass Balance : 61 ' D. Momentum Balance 61 E. Energy Balance 63 F. Conjugate Stress and Strain 63 IV. Constitutive Equations <; 65 A. Introduction 65 B. Thermomechanics 66 C. Thermomechanic Field Theory 67 D. Constitutive Relations for Elastic Solids and Sheets 70 E. Constitutive Laws for Viscoelastic Materials 85 F. Bodner-Partom-Rubin Model 90 G. Fabrics 92 V. Approximations 94 A. Approximations in the Era of Computational Mechanics 94 B. Nonlinear Nature of Membrane Problems 95 C. Approximations in the Context of the Governing Equations 96 D. Example 99 E. On Accuracy and Modeling 101 VI. Analysis of Wrinkled Membranes 103

4 CONTENTS vii A. Introduction 103 B. Tension-Field Modeling via a Penalty Parameter Modified Constitutive Law 104 VII. Experimental Analysis 105 A. Unique Challenges for Experimental Analysis of Membrane Structures 105 B. Static Deformation Measurement 105 C. Dynamic Displacement Measurement 107 D. Thermal Measurements 107 References 108 Chapter 4. Fundamentals of Membrane Optics Ill Nomenclature Ill Glossary 114 I. Introduction 116 II. Overview 117 III. Mechanical Theory and Modeling of Membrane Optics 118 A. Introduction 118 B. Classical Elasticity 120 C. Recent Extensions 132 IV. Achieving Optical Figure and Enhancing Optical Performance A. Figure Achievement and Maintenance 147 B. Adaptive Optics Correction Techniques 154 V. Experimental Observations and Results 160 A. Metrology 160 B. Experimental Results 166 VI. Summary 196 Acknowledgments 197 References 197 Chapter 5. Modeling the Deployment of Inflatable Space Structures I. Introduction 203 II. Review of Relevant Literature on Flexible Structure Deployment Modeling 204 A. Deployment Modeling and Testing of Conventional Aerospace Structures 204 B. Tethers: Extremely Large, Flexible Space Structures. 207 C. Deployment of Balloons, Parachutes, Airbags, and Other Inflating Structures 210 D. Inflation Gas-Structure Interaction 211 III. Review of Relevant Literature on Inflated Structure Deployment 212 A. Background 212 B. Design for Controllable Deployment 212 C. Ground and Flight Testing of Space Inflatables 213

5 viii CONTENTS IV. Deployment Modeling of Inflated Structures 215 A. Scale Modeling 215 B. Finite Element Modeling: Gas Flow in Flexible Structures 216 C. Modeling the Deployment of Rolled Tubes D. Nonlinear Hinge Models V. Summary 235 Acknowledgments 237 References 237 Chapter 6. Materials for Inflatables in Space 243 I. Introduction 243 II. Commercial Films 245 III. Emerging Materials 249 IV. Summary 254 References 254 Chapter 7. Rigidization Mechanisms and Materials 257 I. Introduction 257 II. Thermally Cured Thermoset Composites 259 III. UV-Cured Thermoset Composites 263 IV. Inflation Gas Reaction Thermoset Composites 265 V. Second-Order Transition Change and Shape Memory Polymer Thermoplastic Composites 266 VI. Plasticizer or Solvent Boil-Off Thermoplastic Composites 269 VII. Foam Rigidization 271 VIII. Aluminum Laminates 273 IX. Summary 275 References 275 Chapter 8. Atomic Oxygen Effects on Space Inflatable Materials 281 I. Introduction 281 II. Space Environment and Atomic Oxygen 281 III. Erosion of Polymers by Atomic Oxygen 286 IV. AO-Resistant Polymers 293 V.AO Test Facilities 298 VI. Conclusions 300 Acknowledgments 300 References 300 Chapter 9. Solar Ultraviolet and Space Radiation Effects on Inflatable Materials. 303 I. Introduction 303 II. Space Environment Considerations for Materials Effects 304

6 CONTENTS ix III. Predictions of Radiation Levels in Thin-Sheet Membranes 306 IV. Thin-Sheet Material Results 312 V. Simulation of Space Environment Effects 315 VI. Summary 319 References "320 Chapter 10. Electromagnetic Properties of Thin Metallized Materials 321 I. Introduction 321 II. Electromagnetic Properties of Thin Metallic Layers 323 A. Basic Properties of Thin Metallic Layers in Terms of Bulk Properties 323 B. Reflective Properties of Thin Metallic Layers in Terms of Basic Properties 325 III. EM Properties of Materials for Remote Sensing Applications A. Overview of Remote Sensing Concepts 326 B. Emissivity Requirements for Radiometers 327 IV. Summary 331 References 331 Chapter 11. Multidisciplinary Testing of Thin-Film Inflatable Structures 333 Nomenclature 333 I. Introduction 333 II. Program Requirements for Inflatable Structures at Marshall Space Flight Center '. 334 III. Unique Test Hardware and Methodologies for Inflatable Spacecraft Structural Testing 334 A. Application of Laser Vibrometers 334 B. Excitation Techniques \ 336 C. Linearity Assessment using Sinusoidal Sweeps 337 D. Boundary Conditions for Modal Tests 338 E. Data Acquisition and Modal Parameter Identification 339 IV. Inflatable Strut Modal and Static Tests 339 A. Modal Tests 339 B. Static Tests V. Inflatable Concentrator Modal Tests 342 A. Preliminary Modal Tests 342 B. Thermal-Vacuum Modal Test 345 C. Off-Axis Inflatable Concentrator Modal Test 348 VI. Inflatable Concentrator Thermal Tests 351 A. Test Configuration and Approach 351 B. Results 354 C. Summary of Thermal Tests 357

7 CONTENTS VII. Observations of Inflatable Structure Behavior from Testing and Modeling 357 A. Structural Behavior of Inflated Cylinders or Struts 357 B. Observations of Structural Behavior of Inflatable Solar Concentrator Assemblies '.." 366 IV. Summary 377 References 378 Chapter 12. Rigidization Materials Testing 381 I. Introduction 381 II. Ground Environment 382 III. Launch and Predeployment Environment 383 IV. Deployment Environment Including Rigidization 385 V. Deployed Condition Environment 387 VI. Summary 390 References 391 Bibliography 391 Chapter 13. Electromagnetic Testing of Thin Metallized Materials 393 I. Introduction 393 II. Vector-Network-Analyzer Measurements of Thin-Film Materials A. Waveguide Measurement Technique 394 B. Free-Space Transmission Measurement Technique 395 C. Metallized Thin-Film Study 396 III. Radiometric Measurement Approach 398 A. Measurement Setup 400 < B. Measurement Results 404 IV. Summary 406 References 406 Chapter 14. Inflation Systems 407 I. Introduction 407 II. Historical Perspective 408 III. Near-Term Inflation Systems 409 A. Tanked-Gas Systems 410 B. Phase-Change Systems 410 C. Chemical Gas-Generation Systems 410 IV. Midterm and Far-Term Inflation Systems 412 A. Midterm Applications 412 B. Midterm Inflation Systems 413 C. Far-Term Applications 413 D. Far-Term Inflation Systems 414 V. Summary: Operational Issues and General Design Considerations References 415

8 CONTENTS xi Chapter 15. Deployment Control Mechanisms and Packaging Methodologies for Inflatable and Membrane Space Structures I. Introduction 417 II. System Requirements for Controlled Deployment Mechanisms III. Deployment Control Devices 420 A. Compartmentalization 420 B. Columnation Device 422 C. Roll-Up Devices 423 D. Velcro Roll-Up Devices 424 E. Constant Force Spring Roll-Up Devices 426 F. Rolling Brake Mechanism 427 G. Packaging Methodology 428 IV. Summary 430 References 431 Chapter 16. Mission Concepts and Systems: Space Inflatable Radiometer System Concept 433 I. Introduction 433 II. Background 434 III. Need for a Space Experiment 440 IV. Inflatable Structures 441 V. Radiometer Mission Concept 441 VI. Radiometer Mission Flight Experiment 441 VII. Radiometer Mission Concept Experiment Subsystems 444 VIII. Supporting Technology Discipline Areas 445 A. Structural Analysis B. Material Technology 446 C. Data Analysis, Experiment Performance: Science 446 IX. Summary 447 References 447 Chapter 17. Radar Applications 449 I. Introduction 449 II. Roll-Up Inflatable SAR Antenna 450 A. L-Band SAR Antenna 450 B. Roll-Up Inflatable SAR Concept 451 C. Proof-of-Concept Models ;. 451 D. Radar Testing and Results 453 III. X-Band 1-m Reflect Array 453 A. Antenna Description 455 B. Antenna Test Results 456 IV. Ka-Band 3-m Reflect Array 457 A. Antenna Description 457 B. Antenna Test Results 458 V. Comparison with Other Types of Deployable Antennas v 459

9 xii CONTENTS VI. Summary 460 A. Membrane Flatness and Separation 460 B. Membrane Mountable T/R Modules 460 References 462 Chapter 18. Inflatable Solar Arrays 463 _ I. Introduction 463 II. Space Solar Array Design Requirements 464 III. Thin-Film Solar-Cell Products 464 A. Energy Density of Crystalline and Thin-Film Solar Arrays 465 B. Thermal Design Considerations for Thin-Film Solar Arrays C. Thin-Film Solar-Cell Interconnects 468 IV. ST4/Gossamer Inflatable Solar Array 469 A. Structural Support Components 470 B. Controlled Deployment System 471 C. Inflation System 471 D.SSP Concept 472 V. Teledesic Inflatable Solar Array 472 VI.ITSAT 472 VII. Mars Rover Inflatable Solar Array 474 VIII. Power Sphere 477 IX. Summary 477 Acknowledgment 478 References 478 Chapter 19. Gossamer Sailcraft Technology 481 Nomenclature 481 I. Introduction 482 A. Primary Aim of This Chapter 482 B. Concepts and Principles of Solar Sailing 482 C. Historical Sketch of Solar-Sailing Ideas \ II. Review of Mission Design Concepts "' 485 A. Inner Solar System Missions 485 B. Outer Solar System Missions 486 C. Interstellar Sailcrafts 486 D. Non-Keplerian Orbits 487 III. Elements of a Sailcraft Structure 488 A. Sail Film \ 488 B. Support Structure 488 C. Packaging and Deployment 490 IV. Key Material Issues 491 A. Environmental Effects on the Sail Material 491 B. Film Coatings 492 C. Handling and Processing 493 V. Solar-Sail Design Considerations 493 A. Design Parameters 493

10 CONTENTS xiii B. Three-Axis Stabilized Square Sail 494 C. Spin-Stabihzed Heliogyro 495 D. Spin-Stabilized Disc Sail 496 VI. Ground and Space Experiments 497 A. Component Characterization B. Space Experiments 498 VII. Summary 499 References 499 Chapter 20. Solar Shades 503 Nomenclature 503 I. Introduction 503 A. Solar-Shade Applications 503 B. Solar-Shade Features 504 C. Use of Inflatable Structures in Solar Shades 506 II. Mission Design Considerations 506 A. Orbits 506 B. Thermal Performance Requirements 508 C. Sky Coverage and Pitch-Angle Range Requirements 508 III. Thermal Performance Considerations 509 A. Number of Layers 513 B. Angled Layers 513 C. Cold-Side Surface Emittance 513 D. Micrometeoroid Damage Effects 513 E. Sensitivity to Inner-Surface Emittance 513 F. Redundant Sun-Side Layer 514 G. Specular vs Diffuse Surfaces 514 IV. Mechanical Design Considerations 515 A. Stowage and Deployment 515 B. Film Tensioning 519 C. Film Flatness 520 D. Thermal Gradients and Loss of Tensile Preload 521 E. Solar Torque \ 522 F. Materials Selection 524 G. Ripstop 525 V. Summary 525 Acknowledgments 525 References 525 Chapter 21. Inflatable Habitats 527 I. Introduction 527 II. TransHab Architecture 528 III. TransHab Structure 533 A. TransHab Structure Overview 533 B. Environments 534 C. Multilayer Shell 534

11 xiv CONTENTS IV.Testing 548 A. Hypervelocity Impact Testing (M/OD Protection) 549 B. Hydrostatic Pressure Testing 549 C. Folding and Vacuum Deployment 550 V. Summary 551 References 552 Chapter 22 Advanced Concepts 553 I. Gossamer Spacecraft 553 II. Solar Sails 555 A. Background 555 B. Sail Applications 557 C. Sail Performance 559 D. Sail Types 560 III. Large Observatories 561 Bibliography 566 Appendix: Selected Properties of Various Membrane Materials 573