Butterworth.Safety.Design.For.Space.Systems.Mar.2009.eBook-ELOHiM

Safety Design

for Space Systems

This page intentionally left blank

Safety Design

for Space Systems

Edited by

Gary Eugene Musgrave, Ph.D.

Axel (Skip) M. Larsen

Tommaso Sgobba

Sponsored by

The International Association for the

Advancement of Space Safety

AMSTERDAM • BOSTON • HEIDELBERG • LONDON

NEW YORK • OXFORD • PARIS • SAN DIEGO

SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO

Butterworth-Heinemann is an imprint of Elsevier

Butterworth Heinemann is an imprint of Elsevier

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Copyright # 2009, Elsevier Ltd. All rights reserved.

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A catalogue record for this book is available from the British Library.

ISBN: 978 0 7506 8580 1

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visit our Web site at: www.elsevierdirect.com

Printed in the United States of America.

09 10 11 12 10 9 8 7 6 5 4 3 2 1

Contents

Preface ...............................................................................................................................xxiii

Introduction........................................................................................................................xxv

About the Editors .............................................................................................................xxvii

About the Contributors.................................................................................................... xxxi

CHAPTER 1 Introduction to Space Safety................................................ 1

1.1 NASA and Safety .......................................................................................... 2

1.2 Definition of Safety and Risk ...................................................................... 3

1.3 Managing Safety and Risk ........................................................................... 3

1.4 The Book ..................................................................................................... 5

References .......................................................................................................... 5

CHAPTER 2 The Space Environment: Natural and Induced ....................... 7

2.1 The Atmosphere.......................................................................................... 8

2.1.1 Composition ...................................................................................... 8

2.1.2 Atomic Oxygen................................................................................ 13

2.1.3 The Ionosphere ............................................................................... 15

2.2 Orbital Debris and Meteoroids ................................................................. 18

2.2.1 Orbital Debris .................................................................................. 18

2.2.2 Meteoroids ....................................................................................... 26

2.3 Microgravity............................................................................................... 31

2.3.1 Microgravity Defined....................................................................... 31

2.3.2 Methods of Attainment ................................................................... 34

2.3.3 Effects on Biological Processes and Astronaut Health................... 40

2.3.4 Unique Aspects of Travel to the Moon and

Planetary Bodies .............................................................................. 41

Recommended Reading ................................................................................... 41

2.4 Acoustics.................................................................................................... 43

2.4.1 Acoustics Safety Issues .................................................................... 43

2.4.2 Acoustic Requirements ................................................................... 43

2.4.3 Compliance and Verification........................................................... 50

2.4.4 Conclusions and Recommendations............................................... 51

Recommended Reading ................................................................................... 51

2.5 Radiation.................................................................................................... 52

2.5.1 Ionizing Radiation............................................................................ 52

2.5.2 Radio Frequency Radiation ............................................................. 67

Recommended Reading ................................................................................... 71

v

2.6 Natural and Induced Thermal Environments........................................... 72

2.6.1 Introduction to the Thermal Environment .................................... 72

2.6.2 Spacecraft Heat Transfer Considerations........................................ 72

2.6.3 The Natural Thermal Environment................................................. 73

2.6.4 The Induced Thermal Environment ............................................... 80

2.6.5 Other Lunar and Planetary Environment

Considerations ................................................................................. 85

2.7 Combined Environmental Effects ............................................................. 86

2.7.1 Introduction to Environmental Effects........................................... 86

2.7.2 Combined Environments................................................................. 87

2.7.3 Combined Effects ............................................................................ 88

2.7.4 Ground Testing for Space Simulation............................................. 92

References ........................................................................................................ 94

CHAPTER 3 Overview of Bioastronautics............................................. 105

3.1 Space Physiology ..................................................................................... 106

3.1.1 Muscular System ............................................................................ 106

3.1.2 Skeletal System .............................................................................. 107

3.1.3 Cardiovascular and Respiratory Systems ...................................... 108

3.1.4 Neurovestibular System................................................................. 110

3.1.5 Radiation ........................................................................................ 111

3.1.6 Nutrition ........................................................................................ 112

3.1.7 Immune System ............................................................................. 113

3.1.8 Extravehicular Activity .................................................................. 114

3.2 Short and Long Duration Mission Effects............................................... 115

3.2.1 Muscular System ............................................................................ 115

3.2.2 Skeletal System .............................................................................. 116

3.2.3 Cardiovascular and Respiratory Systems ...................................... 117

3.2.4 Neurovestibular System................................................................. 119

3.2.5 Radiation ........................................................................................ 120

3.2.6 Nutrition ........................................................................................ 121

3.2.7 Immune System ............................................................................. 121

3.2.8 Extravehicular Activity .................................................................. 122

3.3 Health Maintenance ................................................................................ 123

3.3.1 Preflight Preparation ..................................................................... 123

3.3.2 In-Flight Measures.......................................................................... 126

3.3.3 In-Flight Medical Monitoring......................................................... 139

3.3.4 Post-Flight Recovery ...................................................................... 142

3.4 Crew Survival .......................................................................................... 143

3.4.1 Overview of Health Threats in Spaceflight.................................. 143

3.4.2 Early Work...................................................................................... 144

vi Contents

3.4.3 Crew Survival on the Launch Pad, at Launch,

and During Ascent......................................................................... 145

3.4.4 On-Orbit Safe Haven and Crew Transfer...................................... 150

3.4.5 Entry, Landing, and Post-Landing.................................................. 150

3.5 Conclusion............................................................................................... 152

Acknowledgment ........................................................................................... 152

References ...................................................................................................... 153

CHAPTER 4 Basic Principles of Space Safety ..................................... 163

4.1 The Cause of Accidents .......................................................................... 163

4.2 Principles and Methods .......................................................................... 165

4.2.1 Hazard Elimination and Limitation ............................................... 165

4.2.2 Barriers and Interlocks.................................................................. 166

4.2.3 Fail-Safe Design .............................................................................. 167

4.2.4 Failure and Risk Minimization....................................................... 167

4.2.5 Monitoring, Recovery, and Escape ............................................... 169

4.2.6 Crew Survival Systems .................................................................. 169

4.3 The Safety Review Process ..................................................................... 170

4.3.1 Safety Requirements...................................................................... 170

4.3.2 The Safety Panels........................................................................... 171

4.3.3 The Safety Reviews ....................................................................... 171

4.3.4 Nonconformances ......................................................................... 173

References ...................................................................................................... 174

CHAPTER 5 Human Rating Concepts................................................... 175

5.1 Human Rating Defined............................................................................ 175

5.1.1 Human Rated Systems................................................................... 175

5.1.2 The NASA Human Rating and Process ......................................... 176

5.1.3 The Human Rating Plan ................................................................ 177

5.1.4 The NASA Human Rating Certification Process........................... 178

5.1.5 Human Rating in Commercial Human Spaceflight...................... 178

5.2 Human Rating Requirements and Approaches...................................... 179

5.2.1 Key Human Rating Technical Requirements................................ 179

5.2.2 Programmatic Requirements......................................................... 182

5.2.3 Test Requirements......................................................................... 183

5.2.4 Data Requirements ........................................................................ 184

Reference........................................................................................................ 184

CHAPTER 6 Life Support Systems Safety............................................. 185

6.1 Atmospheric Conditioning and Control................................................. 188

6.1.1 Monitoring Is the Key to Control................................................. 188

Contents vii

6.1.2 Atmospheric Conditioning............................................................ 190

6.1.3 Carbon Dioxide Removal .............................................................. 196

6.2 Trace Contaminant Control .................................................................... 198

6.2.1 Of Tight Buildings and Spacecraft Cabins.................................... 198

6.2.2 Trace Contaminant Control Methodology.................................... 201

6.2.3 Trace Contaminant Control Design Considerations .................... 209

6.3 Assessment of Water Quality in the Spacecraft Environment:

Mitigating Health and Safety Concerns .................................................. 211

6.3.1 Scope of Water Resources Relevant to Spaceflight ..................... 211

6.3.2 Spacecraft Water Quality and the Risk Assessment

Paradigm ........................................................................................ 212

6.3.3 Water Quality Monitoring ............................................................. 217

6.3.4 Conclusion and Future Directions................................................ 220

6.4 Waste Management ................................................................................. 220

6.5 Summary of Life Support Systems.......................................................... 221

References ...................................................................................................... 222

CHAPTER 7 Emergency Systems......................................................... 225

7.1 Space Rescue........................................................................................... 225

7.1.1 Legal and Diplomatic Basis ........................................................... 226

7.1.2 The Need for Rescue Capability................................................... 226

7.1.3 Rescue Modes and Probabilities ................................................... 229

7.1.4 Hazards in the Different Phases of Flight..................................... 231

7.1.5 Historic Distribution of Failures ................................................... 232

7.1.6 Historic Rescue Systems................................................................ 233

7.1.7 Space Rescue Is Primarily Self Rescue ......................................... 243

7.1.8 Limitations of Ground Based Rescue............................................ 247

7.1.9 The Crew Return Vehicle as a Study in

Space Rescue ................................................................................. 249

7.1.10 Safe Haven ................................................................................... 255

7.1.11 Conclusions ................................................................................. 256

7.2 Personal Protective Equipment .............................................................. 256

7.2.1 Purpose of Personal Protective Equipment ................................. 256

7.2.2 Types of Personal Protective Equipment ..................................... 257

References ...................................................................................................... 265

CHAPTER 8 Collision Avoidance Systems............................................ 267

8.1 Docking Systems and Operations........................................................... 268

8.1.1 Docking Systems as a Means for Spacecraft

Orbital Mating................................................................................ 268

viii Contents

8.1.2 Design Approaches Ensuring Docking Safety

and Reliability ................................................................................ 270

8.1.3 Design Features Ensuring the Safety and Reliability of

Russian Docking Systems.............................................................. 275

8.1.4 Analyses and Tests Performed for Verification of Safety and

Reliability of Russian Docking Systems ........................................ 278

Acknowledgment ........................................................................................... 280

8.2 Descent and Landing Systems ................................................................ 280

8.2.1 Parachute Systems ......................................................................... 281

8.2.2 Known Parachute Anomolies and Lessons Learned .................... 296

Acknowledgment ........................................................................................... 299

References ...................................................................................................... 299

CHAPTER 9 Robotic Systems Safety ................................................... 301

9.1 Generic Robotic Systems ........................................................................ 301

9.1.1 Controller and Operator Interface................................................ 302

9.1.2 Arms and Joints ............................................................................. 302

9.1.3 Drive System.................................................................................. 303

9.1.4 Sensors ........................................................................................... 303

9.1.5 End Effector ................................................................................... 303

9.2 Space Robotics Overview ....................................................................... 303

9.3 Identification of Hazards and Their Causes ........................................... 305

9.3.1 Electrical and Electromechanical Malfunctions ........................... 307

9.3.2 Mechanical and Structural Failures............................................... 307

9.3.3 Failure in the Control Path ........................................................... 307

9.3.4 Operator Error ............................................................................... 307

9.3.5 Other Hazards................................................................................ 307

9.4 Hazard Mitigation in Design ................................................................... 308

9.4.1 Electrical and Mechanical Design and Redundancy .................... 308

9.4.2 Operator Error ............................................................................... 308

9.4.3 System Health Checks................................................................... 308

9.4.4 Emergency Motion Arrest ............................................................. 309

9.4.5 Proximity Operations .................................................................... 309

9.4.6 Built in Test.................................................................................... 310

9.4.7 Safety Algorithms........................................................................... 310

9.5 Hazard Mitigation Through Training ...................................................... 310

9.6 Hazard Mitigation for Operations ........................................................... 312

9.7 Case Study: Understanding Canadarm2 and Space Safety..................... 313

9.7.1 The Canadarm2 ............................................................................. 313

9.7.2 Cameras.......................................................................................... 313

9.7.3 Force Moment Sensor ................................................................... 314

Contents ix

9.7.4 Training .......................................................................................... 315

9.7.5 Hazard Concerns and Associated Hazard Mitigation ................... 316

9.8 Summary .................................................................................................. 317

References ...................................................................................................... 318

CHAPTER 10 Meteoroid and Debris Protection .................................... 319

10.1 Risk Control Measures.......................................................................... 319

10.1.1 Maneuvering ..............................................................................319

10.1.2 Shielding ....................................................................................324

10.2 Emergency Repair Considerations for Spacecraft Pressure

Wall Damage ......................................................................................... 332

10.2.1 Balanced Mitigation of Program Risks......................................332

10.2.2 Leak Location System and Operational Design

Considerations ...........................................................................337

10.2.3 Ability to Access the Damaged Area ........................................337

10.2.4 Kit Design and Certification Considerations

(1 is too many, 100 are not enough) .......................................338

10.2.5 Recertification of the Repaired Pressure Compartment

for Use by the Crew..................................................................338

References ...................................................................................................... 339

CHAPTER 11 Noise Control Design ..................................................... 341

11.1 Introduction.......................................................................................... 341

11.2 Noise Control Plan ............................................................................... 341

11.2.1 Noise Control Strategy ..............................................................342

11.2.2 Acoustic Analysis.......................................................................344

11.2.3 Testing and Verification ............................................................344

11.3 Noise Control Design Applications ..................................................... 345

11.3.1 Noise Control at the Source .....................................................346

11.3.2 Path Noise Control ....................................................................348

11.3.3 Noise Control in the Receiving Space......................................353

11.3.4 Post-Design Noise Mitigation ....................................................355

11.4 Conclusions and Recommendations.................................................... 355

Recommended Reading ................................................................................. 356

References ...................................................................................................... 356

CHAPTER 12 Materials Safety............................................................ 359

12.1 Toxic Offgassing ................................................................................... 360

12.1.1 Materials Offgassing Controls ...................................................361

12.1.2 Materials Testing........................................................................362

x Contents

12.1.3 Spacecraft Module Testing ........................................................363

12.2 Stress-Corrosion Cracking .................................................................... 363

12.2.1 What Is Stress-Corrosion Cracking?..........................................364

12.2.2 Prevention of Stress-Corrosion Cracking..................................364

12.2.3 Testing Materials for Stress-Corrosion Cracking.......................366

12.2.4 Design for Stress-Corrosion Cracking.......................................368

12.2.5 Requirements for Spacecraft Hardware....................................369

12.2.6 Stress-Corrosion Cracking in Propulsion Systems....................371

12.3 Conclusions........................................................................................... 373

References ...................................................................................................... 373

CHAPTER 13 Oxygen Systems Safety .................................................. 375

13.1 Oxygen Pressure System Design.......................................................... 375

13.1.1 Introduction...............................................................................375

13.1.2 Design Approach.......................................................................377

13.1.3 Oxygen Compatibility Assessment Process..............................386

13.2 Oxygen Generators............................................................................... 392

13.2.1 Electrochemical Systems for Oxygen Production....................392

13.2.2 Solid Fuel Oxygen Generators (Oxygen Candles) ...................398

References ...................................................................................................... 401

CHAPTER 14 Avionics Safety ............................................................. 403

14.1 Introduction to Avionics Safety ........................................................... 403

14.2 Electrical Grounding and Electrical Bonding ...................................... 404

14.2.1 Defining Characteristics of an Electrical

Ground Connection ..................................................................405

14.2.2 Control of Electric Current.......................................................406

14.2.3 Electrical Grounds Can Be Signal Return Paths.......................406

14.2.4 Where and How Electrical Grounds Should

Be Connected ............................................................................406

14.2.5 Defining Characteristics of an Electrical Bond ........................408

14.2.6 Types of Electrical Bonds..........................................................408

14.2.7 Electrical Bond Considerations for

Dissimilar Metals........................................................................409

14.2.8 Electrical Ground and Bond Connections

for Shields ..................................................................................410

Recommended Reading ................................................................................. 410

14.3 Safety Critical Computer Control ........................................................ 411

14.3.1 Partial Computer Control..........................................................412

14.3.2 Total Computer Control: Fail Safe ............................................413

Contents xi

14.4 Circuit Protection: Fusing .................................................................... 414

14.4.1 Circuit Protection Methods.......................................................414

14.4.2 Circuit Protectors ......................................................................416

14.4.3 Design Guidance .......................................................................416

14.5 Electrostatic Discharge Control ........................................................... 417

14.5.1 Fundamentals.............................................................................418

14.5.2 Various Levels of Electrostatic Discharge Concern..................420

Recommended Reading ................................................................................. 426

14.6 Arc Tracking.......................................................................................... 428

14.6.1 A New Failure Mode .................................................................428

14.6.2 Characteristics of Arc Tracking.................................................431

14.6.3 Likelihood of an Arc Tracking Event........................................432

14.6.4 Prevention of Arc Tracking.......................................................432

14.6.5 Verification of Protection and Management

of Hazards ..................................................................................433

14.6.6 Summary ....................................................................................433

14.7 Corona Control in High Voltage Systems ............................................ 434

14.7.1 Associated Environments ..........................................................434

14.7.2 Design Criteria...........................................................................435

14.7.3 Verification and Testing ............................................................436

Recommended Reading ................................................................................. 437

14.8 Extravehicular Activity Considerations................................................ 437

14.8.1 Displays and Indicators Used in Space.....................................438

14.8.2 Mating and Demating of Powered Connectors........................438

14.8.3 Single Strand Melting Points .....................................................439

14.8.4 Battery Removal and Installation..............................................441

14.8.5 Computer or Operational Control of Inhibits..........................442

14.9 Spacecraft Electromagnetic Interference and

Electromagnetic Compatibility Control ............................................... 442

14.9.1 Electromagnetic Compatibility Needs for

Space Applications ....................................................................443

14.9.2 Basic Electromagnetic Compatibility Interactions

and a Safety Margin ...................................................................444

14.9.3 Mission Driven Electromagnetic Interference

Design: The Case for Grounding ..............................................445

14.9.4 Electromagnetic Compatibility Program

for Spacecraft.............................................................................446

14.10 Design and Testing of Safety Critical Circuits................................... 450

14.10.1 Safety Critical Circuits: Conducted Mode ..............................450

14.10.2 Safety Critical Circuits: Radiated Mode ..................................456

xii Contents

14.11 Electrical Hazards ............................................................................... 461

14.11.1 Introduction.............................................................................461

14.11.2 Electrical Shock .......................................................................461

14.11.3 Physiological Considerations...................................................462

14.11.4 Electrical Hazard Classification...............................................463

14.11.5 Leakage Current ......................................................................464

14.11.6 Bioinstrumentation..................................................................464

14.11.7 Electrical Hazard Controls ......................................................465

14.11.8 Verification of Electrical Hazard Controls ..............................468

14.11.9 Electrical Safety Design Considerations .................................468

14.12 Avionics Lessons Learned................................................................... 469

14.12.1 Electronic Design ....................................................................469

14.12.2 Physical Design........................................................................470

14.12.3 Materials and Sources..............................................................471

14.12.4 Damage Avoidance ..................................................................472

14.12.5 System Aspects ........................................................................472

References ...................................................................................................... 473

CHAPTER 15 Software System Safety ................................................. 475

15.1 Introduction.......................................................................................... 475

15.2 The Software Safety Problem............................................................... 476

15.2.1 System Accidents.......................................................................476

15.2.2 The Power and Limitations of Abstraction from

Physical Design..........................................................................477

15.2.3 Reliability Versus Safety for Software .......................................479

15.2.4 Inadequate System Engineering................................................482

15.2.5 Characteristics of Embedded Software.....................................484

15.3 Current Practice ................................................................................... 486

15.3.1 System Safety .............................................................................487

15.4 Best Practice ......................................................................................... 489

15.4.1 Management of Software-Intensive, Safety-Critical

Projects ......................................................................................490

15.4.2 Basic System Safety Engineering Practices and

Their Implications for Software Intensive Systems .................491

15.4.3 Specifications.............................................................................493

15.4.4 Requirements Analysis ..............................................................494

15.4.5 Model-Based Software Engineering and

Software Reuse ..........................................................................494

15.4.6 Software Architecture ...............................................................496

15.4.7 Software Design.........................................................................497

15.4.8 Design of Human-Computer Interaction..................................500

Contents xiii

15.4.9 Software Reviews ......................................................................501

15.4.10 Verification and Assurance......................................................502

15.4.11 Operations ...............................................................................503

15.5 Summary ............................................................................................... 503

References ...................................................................................................... 503

CHAPTER 16 Battery Safety................................................................ 507

16.1 Introduction.......................................................................................... 507

16.2 General Design and Safety Guidelines................................................. 508

16.3 Battery Types ........................................................................................ 508

16.4 Battery Models ...................................................................................... 509

16.5 Hazard and Toxicity Categorization..................................................... 509

16.6 Battery Chemistry................................................................................. 509

16.6.1 Alkaline Batteries.......................................................................509

16.6.2 Lithium Batteries .......................................................................512

16.6.3 Silver Zinc Batteries...................................................................523

16.6.4 Lead Acid Batteries....................................................................525

16.6.5 Nickel Cadmium Batteries ........................................................527

16.6.6 Nickel Metal Hydride Batteries .................................................528

16.6.7 Nickel Hydrogen Batteries ........................................................533

16.6.8 Lithium-Ion Batteries .................................................................535

16.7 Storage, Transportation, and Handling ................................................ 544

References ...................................................................................................... 545

CHAPTER 17 Mechanical Systems Safety ........................................... 549

17.1 Safety Factors ........................................................................................ 549

17.1.1 Types of Safety Factors .............................................................550

17.1.2 Safety Factors Typical of Human Rated

Space Programs .........................................................................551

17.1.3 Things That Influence the Choice of Safety Factors ...............551

17.2 Spacecraft Structures............................................................................ 551

17.2.1 Mechanical Requirements .........................................................552

17.2.2 Space Mission Environment and Mechanical Loads ................554

17.2.3 Project Overview: Successive Designs and Iterative

Verification of Structural Requirements ...................................557

17.2.4 Analytical Evaluations................................................................559

17.2.5 Structural Test Verification........................................................559

17.2.6 Spacecraft Structural Model Philosophy...................................561

17.2.7 Materials and Processes.............................................................562

17.2.8 Manufacturing of Spacecraft Structures ...................................564

Recommended Reading..................................................................................566

xiv Contents