Safety Designfor Space Systems

Edited by

Gary Eugene Musgrave, Ph.D.

Axel (Skip) M. Larsen

Tommaso Sgobba

Sponsored by

The International Association for theAdvancement of Space Safety

AMSTERDAM • BOSTON • HEIDELBERG • LONDONNEW YORK • OXFORD • PARIS • SAN DIEGO

SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYOELSEVIER Butterworth-Heinemann is an imprint of Elsevier

Contents

Preface xxiiiIntroduction xxvAbout the Editors xxviiAbout the Contributors xxxi

CHAPTER 1 Introduction to Space Safety 11.1 NASA and Safety 21.2 Definition of Safety and Risk 31.3 Managing Safety and Risk 31.4 The Book 5References 5

CHAPTER 2 The Space Environment: Natural and Induced 72.1 The Atmosphere 8

2.1.1 Composition 82.1.2 Atomic Oxygen 132.1.3 The Ionosphere 15

2.2 Orbital Debris and Meteoroids 182.2.1 Orbital Debris 182.2.2 Meteoroids 26

2.3 Microgravity 312.3.1 Microgravity Defined 312.3.2 Methods of Attainment 342.3.3 Effects on Biological Processes and Astronaut Health 402.3.4 Unique Aspects of Travel to the Moon and

Planetary Bodies 41Recommended Reading 412.4 Acoustics 43

2.4.1 Acoustics Safety Issues 432.4.2 Acoustic Requirements 432.4.3 Compliance and Verification 502.4.4 Conclusions and Recommendations 51

Recommended Reading 512.5 Radiation 52

2.5.1 Ionizing Radiation 522.5.2 Radio Frequency Radiation 67

Recommended Reading 71

V

vi Contents

2.6 Natural and Induced Thermal Environments 722.6.1 Introduction to the Thermal Environment 722.6.2 Spacecraft Heat Transfer Considerations 722.6.3 The Natural Thermal Environment 732.6.4 The Induced Thermal Environment 802.6.5 Other Lunar and Planetary Environment

Considerations 852.7 Combined Environmental Effects 86

2.7.1 Introduction to Environmental Effects 862.7.2 Combined Environments 872.7.3 Combined Effects 882.7.4 Ground Testing for Space Simulation 92

References 94

CHAPTER 3 Overview of Bioastronautics 1053.1 Space Physiology 106

3.1.1 Muscular System 1063.1.2 Skeletal System 1073.1.3 Cardiovascular and Respiratory Systems 1083.1.4 Neurovestibular System 1103.1.5 Radiation I l l3.1.6 Nutrition 1123-1.7 Immune System 1133.1.8 Extravehicular Activity 114

3.2 Short and Long Duration Mission Effects 1153.2.1 Muscular System 1153-2.2 Skeletal System 1163.2.3 Cardiovascular and Respiratory Systems 1173.2.4 Neurovestibular System 1193.2.5 Radiation 1203.2.6 Nutrition , 1213.2.7 Immune System. 1213.2.8 Extravehicular Activity 122

3.3 Health Maintenance 1233.3.1 Preflight Preparation 1233.3.2 In-Flight Measures 1263.3.3 In-Flight Medical Monitoring 1393.3.4 Post-Flight Recovery 142

3.4 Crew Survival 1433.4.1 Overview of Health Threats in Spaceflight...! 1433.4.2 Early Work 144

Contents vii

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 1503-4.5 Entry, Landing, and Post-Landing 150

3.5 Conclusion 152Acknowledgment 152References 153

CHAPTER 4 Basic Principles of Space Safety 1634.1 The Cause of Accidents 1634.2 Principles and Methods 165

4.2.1 Hazard Elimination and Limitation 1654.2.2 Barriers and Interlocks 1664.2.3 Fail-Safe Design 1674.2.4 Failure and Risk Minimization 1674.2.5 Monitoring, Recovery, and Escape 1694.2.6 Crew Survival Systems 169

4.3 The Safety Review Process 1704.3.1 Safety Requirements 1704.3.2 The Safety Panels 1714.3.3 The Safety Reviews 1714.3.4 Nonconformances 173

References 174

CHAPTER 5 Human Rating Concepts 1755.1 Human Rating Defined 175

5.1.1 Human Rated Systems 1755.1.2 The NASA Human Rating and Process 1765.1.3 The Human Rating Plan 1775.1.4 The NASA Human Rating Certification Process 1785.1.5 Human Rating in Commercial Human Spaceflight 178

5.2 Human Rating Requirements and Approaches 1795.2.1 Key Human Rating Technical Requirements 1795.2.2 Programmatic Requirements 1825.2.3 Test Requirements 1835.2.4 Data Requirements 184

Reference 184

CHAPTER 6 Life Support Systems Safety 1856.1 Atmospheric Conditioning and Control 188

6.1.1 Monitoring Is the Key to Control 188

viii Contents

6.1.2 Atmospheric Conditioning 1906.1.3 Carbon Dioxide Removal 196

6.2 Trace Contaminant Control 1986.2.1 Of Tight Buildings and Spacecraft Cabins 1986.2.2 Trace Contaminant Control Methodology 2016.2.3 Trace Contaminant Control Design Considerations 209

6.3 Assessment of Water Quality in the Spacecraft Environment:Mitigating Health and Safety Concerns 2116.3.1 Scope of Water Resources Relevant to Spaceflight 2116.32 Spacecraft Water Quality and the Risk Assessment

Paradigm 2126.3.3 Water Quality Monitoring 2176.3.4 Conclusion and Future Directions 220

6.4 Waste Management 2206.5 Summary of Life Support Systems 221References 222

CHAPTER 7 Emergency Systems 2257.1 Space Rescue 225

7.1.1 Legal and Diplomatic Basis 2267.1.2 The Need for Rescue Capability 2267.1.3 Rescue Modes and Probabilities 2297.1.4 Hazards in the Different Phases of Flight 2317.1.5 Historic Distribution of Failures 2327.1.6 Historic Rescue Systems 2337.1.7 Space Rescue Is Primarily Self Rescue 2437.1.8 Limitations of Ground Based Rescue 2477.1.9 The Crew Return Vehicle as a Study in

Space Rescue 2497.1.10 Safe Haven 2557.1.11 Conclusions 256

7.2 Personal Protective Equipment 2567.2.1 Purpose of Personal Protective Equipment 2567.2.2 Types of Personal Protective Equipment 257

References 265

CHAPTER 8 Collision Avoidance Systems 2678.1 Docking Systems and Operations 268

8.1.1 Docking Systems as a Means for SpacecraftOrbital Mating..... 268

Contents ix

8.1.2 Design Approaches Ensuring Docking Safetyand Reliability 270

8.1.3 Design Features Ensuring the Safety and Reliability ofRussian Docking Systems 275

8.1.4 Analyses and Tests Performed for Verification of Safety andReliability of Russian Docking Systems 278

Acknowledgment 2808.2 Descent and Landing Systems 280

8.2.1 Parachute Systems 2818.2.2 Known Parachute Anomolies and Lessons Learned 296

Acknowledgment 299References 299

CHAPTER 9 Robotic Systems Safety 3019.1 Generic Robotic Systems 301

9.1.1 Controller and Operator Interface 3029.1.2 Arms and Joints 3029-1-3 Drive System 3039-1-4 Sensors 3039.1.5 End Effector 303

9.2 Space Robotics Overview 3039.3 Identification of Hazards and Their Causes 305

9-3.1 Electrical and Electromechanical Malfunctions 3079.3.2 Mechanical and Structural Failures 3079.3.3 Failure in the Control Path 3079.3-4 Operator Error 3079-3-5 Other Hazards 307

9.4 Hazard Mitigation in Design 3089-4.1 Electrical and Mechanical Design and Redundancy 3089.4.2 Operator Error 3089.4.3 System Health Checks 3089.4.4 Emergency Motion Arrest 3099.4.5 Proximity Operations 3099.4.6 Built in Test 3109.4.7 Safety Algorithms 310

9.5 Hazard Mitigation Through Training 3109.6 Hazard Mitigation for Operations 3129.7 Case Study: Understanding Canadarm2 and Space Safety 313

9.7.1 The Canadarm2 3139.7.2 Cameras 3139.7.3 Force Moment Sensor 314

Contents

9.7.4 Training 3159.7.5 Hazard Concerns and Associated Hazard Mitigation 316

9.8 Summary 317References 318

CHAPTER 10 Meteoroid and Debris Protection 31910.1 Risk Control Measures 319

10.1.1 Maneuvering 31910.1.2 Shielding 324

10.2 Emergency Repair Considerations for Spacecraft PressureWall Damage 33210.2.1 Balanced Mitigation of Program Risks.... 33210.2.2 Leak Location System and Operational Design

Considerations 33710.2.3 Ability to Access the Damaged Area 33710.2.4 Kit Design and Certification Considerations

(1 is too many, 100 are not enough) 33810.2.5 Recertification of the Repaired Pressure Compartment

for Use by the Crew 338References 339

CHAPTER 11 Noise Control Design 34111.1 Introduction 34111.2 Noise Control Plan 341

11.2.1 Noise Control Strategy 34211.2.2 Acoustic Analysis 34411.2.3 Testing and Verification 344

11.3 Noise Control Design Applications 34511.3.1 Noise Control at the Source 34611.3.2 Path Noise Control 34811.3.3 Noise Control in the Receiving Space 35311.3.4 Post-Design Noise Mitigation 355

11.4 Conclusions and Recommendations 355Recommended Reading 356References 356

CHAPTER 12 Materials Safety 35912.1 Toxic Offgassing 360

12.1.1 Materials Offgassing Controls 36112.1.2 Materials Testing 362

Contents xi

12.1.3 Spacecraft Module Testing 36312.2 Stress-Corrosion Cracking 363

12.2.1 What Is Stress-Corrosion Cracking? 36412.2.2 Prevention of Stress-Corrosion Cracking 36412.2.3 Testing Materials for Stress-Corrosion Cracking 36612.2.4 Design for Stress-Corrosion Cracking 36812.2.5 Requirements for Spacecraft Hardware 36912.2.6 Stress-Corrosion Cracking in Propulsion Systems 371

12.3 Conclusions 373References 373

CHAPTER 13 Oxygen Systems Safety 37513.1 Oxygen Pressure System Design 375

13-1.1 Introduction 37513-1.2 Design Approach 37713.1.3 Oxygen Compatibility Assessment Process 386

13.2 Oxygen Generators 39213.2.1 Electrochemical Systems for Oxygen Production 39213-2.2 Solid Fuel Oxygen Generators (Oxygen Candles) 398

References 401

CHAPTER 14 Avionics Safety 40314.1 Introduction to Avionics Safety 40314.2 Electrical Grounding and Electrical Bonding 404

14.2.1 Defining Characteristics of an ElectricalGround Connection 405

14.2.2 Control of Electric Current 40614.2.3 Electrical Grounds Can Be Signal Return Paths 40614.2.4 Where and How Electrical Grounds Should

Be Connected 40614.2.5 Defining Characteristics of an Electrical Bond 40814.2.6 Types of Electrical Bonds 40814.2.7 Electrical Bond Considerations for

Dissimilar Metals 40914.2.8 Electrical Ground and Bond Connections

for Shields 410Recommended Reading 41014.3 Safety Critical Computer Control 411

14.3.1 Partial Computer Control 41214.3.2 Total Computer Control: Fail Safe 413

xii Contents

14.4 Circuit Protection: Fusing 41414.4.1 Circuit Protection Methods 41414.4.2 Circuit Protectors 41614.4.3 Design Guidance 416

14.5 Electrostatic Discharge Control 41714.5.1 Fundamentals 41814.5.2 Various Levels of Electrostatic Discharge Concern 420

Recommended Reading 42614.6 Arc Tracking 428

14.6.1 A New Failure Mode 42814.6.2 Characteristics of Arc Tracking 43114.6.3 Likelihood of an Arc Tracking Event 43214.6.4 Prevention of Arc Tracking 43214.6.5 Verification of Protection and Management

of Hazards 43314.6.6 Summary 433

14.7 Corona Control in High Voltage Systems 43414.7.1 Associated Environments 43414.7.2 Design Criteria 43514.7.3 Verification and Testing 436

Recommended Reading 43714.8 Extravehicular Activity Considerations 437

14.8.1 Displays and Indicators Used in Space 43814.8.2 Mating and Demating of Powered Connectors 43814.8.3 Single Strand Melting Points 43914.8.4 Battery Removal and Installation 44114.8.5 Computer or Operational Control of Inhibits 442

14.9 Spacecraft Electromagnetic Interference andElectromagnetic Compatibility Control 44214.9-1 Electromagnetic Compatibility Needs for

Space Applications 44314.92 Basic Electromagnetic Compatibility Interactions

and a Safety Margin 44414.9.3 Mission Driven Electromagnetic Interference

Design: The Case for Grounding 44514.9-4 Electromagnetic Compatibility Program

for Spacecraft 44614.10 Design and Testing of Safety Critical Circuits 450

14.10.1 Safety Critical Circuits: Conducted Mode 45014.10.2 Safety Critical Circuits: Radiated Mode 456

Contents xiii

14.11 Electrical Hazards 46114.11.1 Introduction 46114.11.2 Electrical Shock 46114.11.3 Physiological Considerations 46214.11.4 Electrical Hazard Classification 46314.11.5 Leakage Current 46414.11.6 Bioinstrumentation 46414.11.7 Electrical Hazard Controls 46514.11.8 Verification of Electrical Hazard Controls 46814.11.9 Electrical Safety Design Considerations 468

14.12 Avionics Lessons Learned 46914.12.1 Electronic Design 46914.12.2 Physical Design..... 47014.12.3 Materials and Sources 47114.12.4 Damage Avoidance 47214.12.5 System Aspects 472

References 473

CHAPTER 15 Software System Safety 47515.1 Introduction 47515.2 The Software Safety Problem 476

15.2.1 System Accidents 47615.2.2 The Power and Limitations of Abstraction from

Physical Design 47715.2.3 Reliability Versus Safety for Software 47915.2.4 Inadequate System Engineering 48215.2.5 Characteristics of Embedded Software 484

15.3 Current Practice 48615.3-1 System Safety 487

15.4 Best Practice 48915-4.1 Management of Software-Intensive, Safety-Critical

Projects 49015.4.2 Basic System Safety Engineering Practices and

Their Implications for Software Intensive Systems 49115.4.3 Specifications 49315.4.4 Requirements Analysis 49415.4.5 Model-Based Software Engineering and

Software Reuse 49415.4.6 Software Architecture 49615.4.7 Software Design 49715.4.8 Design of Human-Computer Interaction 500

xiv Contents

15.4.9 Software Reviews 50115.4.10 Verification and Assurance 50215.4.11 Operations 503

15.5 Summary 503References 503

CHAPTER 16 Battery Safety 50716.1 Introduction 50716.2 General Design and Safety Guidelines 50816.3 Battery Types 50816.4 Battery Models 50916.5 Hazard and Toxicity Categorization 50916.6 Battery Chemistry 509

16.6.1 Alkaline Batteries 50916.6.2 Lithium Batteries 51216.6.3 Silver Zinc Batteries 52316.6.4 Lead Acid Batteries 52516.6.5 Nickel Cadmium Batteries 52716.6.6 Nickel Metal Hydride Batteries 52816.6.7 Nickel Hydrogen Batteries 53316.6.8 Lithium-Ion Batteries 535

16.7 Storage, Transportation, and Handling 544References 545

CHAPTER 17 Mechanical Systems Safety 54917.1 Safety Factors 549

17.1.1 Types of Safety Factors 55017.1.2 Safety Factors Typical of Human Rated

Space Programs 55117.1.3 Things That Influence the Choice of Safety Factors 551

17.2 Spacecraft Structures 55117.2.1 Mechanical Requirements 55217.2.2 Space Mission Environment and Mechanical Loads 55417.2.3 Project Overview: Successive Designs and Iterative

Verification of Structural Requirements 55717.2.4 Analytical Evaluations 55917.2.5 Structural Test Verification 55917.2.6 Spacecraft Structural Model Philosophy 56117.2.7 Materials and Processes 56217.2.8 Manufacturing of Spacecraft Structures 564

Recommended Reading 566

Contents xv

17.3 Fracture Control 56717.31 Basic Requirements 56717.3.2 Implementation 56717.3.3 Summary 568

17.4 Pressure Vessels, Lines, and Fittings 56817.4.1 Pressure Vessels 56817.4.2 Lines and Fittings 57417.4.3 Space Pressure Systems Standards 57517.4.4 Summary 575

17.5 Composite Overwrapped Pressure Vessels 57617.5.1 The Composite Overwrapped Pressure Vessel System 57617.5.2 Monolithic Metallic Pressure Vessel Failure Modes 57717.5.3 Composite Overwrapped Pressure Vessel Failure

Modes 57817.5.4 Composite Overwrapped Pressure Vessel

Impact Sensitivity 57917.5.5 Summary 581

17.6 Structural Design of Glass and Ceramic Components forSpace System Safety 58117.6.1 Strength Characteristics of Glass and Ceramics 58217.6.2 Defining Loads and Environments 58617.6.3 Design Factors 58817.6.4 Meeting Life Requirements with Glass and

Ceramics 58917.7 Safety Critical Mechanisms 591

17.7.1 Designing for Failure Tolerance 59117.7.2 Design and Verification of Safety Critical

Mechanisms 59417.7.3 Reduced Failure Tolerance 60217.7.4 Review of Safety Critical Mechanisms 604

References 605

CHAPTER 18 Containment of Hazardous Materials 60718.1 Toxic Materials 610

18.1.1 Fundamentals of Toxicology 61018.1.2 Toxicological Risks to Air Quality in Spacecraft 61318.1.3 Risk Management Strategies 618

18.2 Biohazardous Materials 62118.2.1 Microbiological Risks Associated with Spaceflight 62118.2.2 Risk Mitigation Approaches 622

xvi Contents

18.2.3 Major Spaceflight Specific Microbiological Risks 62318.3 Shatterable Materials 631

18.3.1 Shatterable Materials in a Habitable Compartment 63118.3.2 Program Implementation 63118.3-3 Containment Concepts for Internal Equipment 63318.3-4 Containment Concepts for Exterior Equipment 63618.3.5 General Comments About Working with

Shatterable Materials 63818.4 Containment Design Approach 639

18.4.1 Fault Tolerance 63918.4.2 Design for Minimum Risk 639

18.5 Containment Design Methods 64018.5.1 Containment Environments 64018.5.2 Design of Containment Systems 640

18.6 Safety Controls 64318.6.1 Proper Design 64318.6.2 Materials Selection 64318.6.3 Materials Compatibility 64318.6.4 Proper Workmanship 64418.6.5 Proper Loading or Filling 64418.6.6 Fracture Control 644

18.7 Safety Verifications 64418.7.1 Strength Analysis 64518.7.2 Qualification Tests 64518.7.3 Acceptance Tests 64618.7.4 Proof Tests. 64718.7.5 Qualification of Procedures 647

18.8 Conclusions 648References 649

CHAPTER 19 Failure Tolerance Design 65319.1 Safe 653

19.1.1 Order of Precedence 65319.2 Hazard 655

19.2.1 Hazard Controls 655192.2 Design to Tolerate Failures 656

19.3 Hazardous Functions 658193-1 Must Not Work Hazardous Function 658193.2 Must Work Hazardous Function 659

19.4 Design for Minimum Risk 659

Contents xvii

19.5 Conclusions 660References 660

CHAPTER 20 Propellant Systems Safety 66120.1 Solid Propellant Propulsion Systems Safety 662

20.1.1 Solid Propellants 66220.1.2 Solid Propellant Systems for Space Applications 66420.1.3 Safety Hazards 66420.1.4 Handling, Transport, and Storage 67020.1.5 Inadvertent Ignition 67120.1.6 Safe Ignition Systems Design 67220.1.7 Conclusions 673

20.2 Liquid Propellant Propulsion Systems Safety 67320.2.1 Planning 67520.2.2 Containment Integrity 67620.2.3 Thermal Control 67720.2.4 Materials Compatibility 67820.2.5 Contamination Control 67820.2.6 Environmental Considerations 67920.2.7 Engine and Thruster Firing Inhibits 67920.2.8 Heightened Risk (Risk Creep) 68020.2.9 Instrumentation and Telemetry Data 68120.2.10 End to End Integrated Instrumentation, Controls,

and Redundancy Verification 68120.2.11 Qualification 68120.2.12 Total Quality Management (ISO 9001 or Equivalent) 68220.2.13 Preservicing Integrity Verification 68220.2.14 Propellants Servicing 68320.2.15 Conclusions 683

20.3 Hypergolic Propellants 68320.3.1 Materials Compatibility 68320.3.2 Material Degradation 68420.3.3 Hypergolic Propellant Degradation 685

20.4 Propellant Fire 68620.4.1 Hydrazine and Monomethylhydrazine Vapor 68720.4.2 Liquid Hydrazine and Monomethylhydrazine 69020.4.3 Hydrazine and Monomethylhydrazine Mists,

Droplets, and Sprays 691References 691

xviii Contents

CHAPTER 21 Pyrotechnic Safety 69521.1 Pyrotechnic Devices 695

21.1.1 Explosives 69621.1.2 Initiators 696

21.2 Electroexplosive Devices 69621.2.1 Safe Handling of Electroexplosive Devices 69721.2.2 Designing for Safe Electroexplosive Device

Operation 70021.2.3 Pyrotechnic Safety of Mechanically Initiated

Explosive Devices 702References 704

CHAPTER 22 Extravehicular Activity Safety 70522.1 Extravehicular Activity Environment 705

22.1.1 Definitions 70622.1.2 Extravehicular Activity Space Suit 70822.1.3 Sensory Degradation 71022.1.4 Maneuvering and Weightlessness 71022.1.5 Glove Restrictions 71122.1.6 Crew Fatigue 71122.1.7 Thermal Environment 71122.1.8 Extravehicular Activity Tools 712

22.2 Suit Hazards 71222.2.1 Inadvertent Contact Hazards 71222.2.2 Area of Effect Hazards 715

22.3 Crew Hazards 71622.3.1 Contamination of the Habitable Environment 71622.3.2 Thermal Extremes 71622.3.3 Lasers 71822.3.4 Electrical Shock and Molten Metal 71822.3.5 Entrapment 71922.3.6 Emergency Ingress 71922.3.7 Collision 72022.3.8 Inadvertent Loss of Crew 721

22.4 Conclusions 722References 722

CHAPTER 23 Emergency, Caution, and Warning System 72523.1 System Overview 72523.2 Historic NASA Emergency, Caution, and Warning Systems : 726

Contents xix

23.3 Emergency, Caution, and Warning System Measures 72723.3.1 Event Classification Measures 72723.3.2 Sensor Measures 72823.3.3 Data System Measures 72923.3.4 Annunciation Measures 730

23.4 Failure Isolation and Recovery 731Reference 732

CHAPTER 24 Laser Safety 73324.1 Background 733

24.1.1 Optical Spectrum 73324.1.2 Biological Effects 734

24.2 Laser Characteristics 73524.2.1 Laser Principles 73524.2.2 Laser Types 737

24.3 Laser Standards 73824.3.1 NASA Johnson Space Center Requirements 73824.3.2 ANSI Standard Z136-1 73924.3.3 Russian Standard 740

24.4 Lasers Used in Space 74024.4.1 Radars 74124.4.2 Illumination 74124.4.3 Sensors 741

24.5 Design Considerations for Laser Safety 74224.5.1 Ground Testing 74224.5.2 Unique Space Environment 742

24.6 Conclusions 744References 744

CHAPTER 25 Crew Training Safety: An Integrated Process 74525.1 Training the Crew for Safety 746

25.1.1 Typical Training Flow 74625.1.2 Principles of Safety Training for the Different

Training Phases 75225.1.3 Specific Safety Training for Different Equipment

Categories 75525.1.4 Safety Training for Different Operations Categories 761

25.2 Safety During Training 77025.2.1 Overview 770

xx Contents

25.2.2 Training, Test, or Baseline Data Collection ModelVersus Flight Model: Type, Fidelity, Source, Origin,and Category 771

25.2.3 Training Environments and Facilities 77525.2.4 Training Models, Test Models, and Safety

Requirements 781252.5 Training Model, Test Model, and Baseline Data

Collection Equipment Utilization Requirements 79525.2.6 Qualification and Certification of Training Personnel 79825.2.7 Training and Test Model Documentation 799

25.3 Training Development and Validation Process 80325.3.1 The Training Development Process 80625.3.2 The Training Review Process 80725.3.3 The Role of Safety in the Training Development and

Validation Processes 80925.3.4 Feedback to the Safety Community from the

Training Development and Validation Processes 81225.4 Conclusions 815References 815

CHAPTER 26 Safety Considerations for the Ground Environment 81726.1 A Word About Ground Support Equipment 81826.2 Documentation and Reviews 81926.3 Roles and Responsibilities 81926.4 Contingency Planning 81926.5 Failure Tolerance 82026.6 Training 82026.7 Hazardous Operations 82126.8 Tools 82226.9 Human Factors 82226.10 Biological Systems and Materials 82326.11 Electrical 82426.12 Radiation 82426.13 Pressure Systems 82526.14 Ordinance 82526.15 Mechanical and Eelectromechanical Devices 82626.16 Propellants 82626.17 Cryogenics 82626.18 Oxygen 82626.19 Ground Handling 827

Contents xxi

26.20 Software Safety 82726.21 Summary 828

CHAPTER 27 Fire Safety 82927.1 Characteristics of Fire in Space 830

27.1.1 Overview of Low Gravity Fire 83027.1.2 Fuel and Oxidizer Supply and Flame Behavior 83127.1.3 Fire Appearance and Signatures 83227.1.4 Flame Ignition and Spread 83627.1.5 Summary of Low Gravity Fire Characteristics 845

27.2 Design for Fire Prevention 84727.2.1 Materials Flammability 84727.2.2 Ignition Sources 852

27.3 Spacecraft Fire Detection 85527.3.1 Prior Spacecraft Systems 85527.3.2 Review of Low Gravity Smoke 85827.3-3 Spacecraft Atmospheric Dust 85927.3-4 Sensors for Fire Detection 860

27.4 Spacecraft Fire Suppression 86427.4.1 Spacecraft Fire Suppression Methods 86427.4.2 Considerations for Spacecraft Fire Suppression 867

References 877

CHAPTER 28 Safe Without Services Design 885

CHAPTER 29 Probabilistic Risk Assessment with Emphasison Design 889

29.1 Basic Elements of Probabilistic Risk Assessment 88929.1.1 Identification of Initiating Events 890291-2 Application of Event Sequence Diagrams and

Event Trees 89129.1.3 Modeling of Pivotal Events 89329.1 4 Linkage and Quantification of Accident Scenarios 894

29.2 Construction of a Probabilistic Risk Assessment forDesign Evaluations 894292.1 Uses of Probabilistic Risk Assessment 89429-2.2 Reference Mission 896

29.3 Relative Risk Evaluations 89829.3.1 Absolute Versus Relative Risk Assessments 899

xxii Contents

293.2 Roles of Relative Risk Assessments in DesignEvaluations 900

293.3 Quantitative Evaluations 90229.4 Evaluations of the Relative Risks of Alternative Designs 904

29.4.1 Overview of Probabilistic Risk AssessmentModels Developed 904

29-4.2 Relative Risk Comparisons of the AlternativeDesigns 905

References 911

Index 913