Safety Design for Space Systems

956 Pages·2009·14.673 MB·English

by  Musgrave, Gary Eugene, Larsen, Axel M., Sgobba, Tomasso(eds.)

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
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Preface
Bryan O’Connor
AssociateAdministrator,SafetyandMissionAssurance,
Headquarters,NationalAeronauticsandSpaceAdministration,
Washington,DC
In his book, To Engineer Is Human, Henry Petrosky said, “No one wants to learn by
mistakes, but we cannot learn enough from successes to go beyond the state of the art.”
In this elegant statement, he poses both the challenge and the opportunity for the space-
flight system safety engineer. Just how does the engineer facilitate the incorporation of
lessons learned from historical failures and close calls into the design of the next space-
flight system?
This book is a compilation of muchof the best thinking of the spaceflight safety commu-
nity.Itincludesdiscussionofphilosophies,techniques,methods,processes,andstandards
that over the first 50 years of spaceflight have proven themselves as the basics of the
profession. The authors are accomplished practitioners,and acknowledged leaders repre-
senting most spacefaring nations of today. They cover a variety of topics relevant to
roboticaswellashumanspaceflightsystems.Theydiscusstheenvironment,bothinEarth
orbit and deep space, as well as operational hazards both on the ground and in flight.
Theydescribethelatestmethodsandtechniquesthesystemsafetymembersofthedesign
team apply to system design, development and testing, as well as integrated hazard and
risk methods that the safety integration team applies to the entire system.
Ifthereisacommonthemeinthiscomprehensivebook,itisveryclosetothenotioncap-
tured in Petrosky’s quote. Many of the safety engineering tools and techniques of today
were spawned as “fixes” to what in retrospect had been inadequate processes leading
up to incidents and mission failures. One of the professional challenges of the system
safetycommunity isthe sure knowledge that the mishap boardinvestigating a failure will
almost always havea chapter in their report dealing with the failure of the safety team to
prevent the mishap. Clearly, preventing mishaps is the job of everyone, but traditionally,
the safety community nearly always finds itself trying to figure out how to do a better
job of anticipating, analyzing, predicting, and thus preventing another failure. This book
is an attempt to capture the most important aspects of that ongoing improvement pro-
cess.Usethisbooktolearnyourtradeandbetterunderstandthethingsyourpredecessors
andpeershavelearnedovertheyears,oftenthehardway.And,ifyouneverexperiencea
majorfailure,youarenotoffthehook.Takeadvantageofyourclosecalls,nearmisses,and
high probability risks to continuously improve your trade and your tools. Your learning
should never stop, and it will be the basis for future revisions to this book.
xxiii
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
vi Contents
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
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......................................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
viii Contents
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
Contents ix
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
x Contents
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
Contents xi
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