RULE-BASED GRAPH THEORY TO ENABLE EXPLORATION OF THE SPACE SYSTEM ARCHITECTURE DESIGN SPACE A Dissertation Presented to The Academic Faculty By Dale Curtis Arney In Partial Fulfillment Of the Requirements for the Degree Doctor of Philosophy in Aerospace Engineering Georgia Institute of Technology August 2012 Copyright © 2012 by Dale Arney RULE-BASED GRAPH THEORY TO ENABLE EXPLORATION OF THE SPACE SYSTEM ARCHITECTURE DESIGN SPACE Approved by: Dr. Alan W. Wilhite, Chairman Dr. Ryan P. Russell School of Aerospace Engineering School of Aerospace Engineering Georgia Institute of Technology Georgia Institute of Technology Dr. Trina M. Chytka Dr. Vitali V. Volovoi Space Mission Analysis Branch School of Aerospace Engineering NASA Langley Research Center Georgia Institute of Technology Dr. Daniel P. Schrage School of Aerospace Engineering Georgia Institute of Technology Date Approved: June 27, 2012 To my wife Jennifer Two roads diverged in a wood, And apparently, we took the longer one. TABLE OF CONTENTS LIST OF FIGURES ......................................................................................................... vi LIST OF TABLES ......................................................................................................... xiii NOMENCLATURE ........................................................................................................ xv SUMMARY .................................................................................................................... xix CHAPTER 1 INTRODUCTION ..................................................................................... 1 1.1. Motivation ................................................................................................................ 1 1.2. Research Goals and Objectives ................................................................................ 9 1.3. Problem Statement ................................................................................................. 11 1.4. Dissertation Overview ........................................................................................... 18 CHAPTER 2 BACKGROUND ...................................................................................... 20 2.1 Space System Architecture Modeling ..................................................................... 20 2.1.1. EXAMINE .................................................................................................. 20 2.1.2. Object Process Network (OPN) .................................................................. 23 2.1.3. Logistics Network ....................................................................................... 26 2.1.4. Overview ..................................................................................................... 27 2.2. Graph Theory ......................................................................................................... 27 2.3. Performance Modeling........................................................................................... 32 2.4. Cost Estimation ...................................................................................................... 36 2.5. Architecture Optimization Methods ...................................................................... 39 2.6. System Architecture Evaluation Criteria ............................................................... 44 CHAPTER 3 METHODOLOGY .................................................................................. 51 3.1. Applying Graph Theory to a Space System Architecture ...................................... 51 3.2. Graph Generation Model ....................................................................................... 53 3.3. Design Space Exploration ...................................................................................... 59 3.3.1. System Map Overview ................................................................................ 59 3.3.2. Rule-Based Graph Traversal ....................................................................... 62 3.3.3. System Hierarchy ........................................................................................ 66 3.4.2. System Modeling ........................................................................................ 70 iii 3.5. Exploration of the Space System Architecture Design Space ............................... 74 3.5.1. Optimization Method .................................................................................. 75 3.5.2. Selection Criterion ...................................................................................... 78 CHAPTER 4 VALIDATION ......................................................................................... 80 4.1. Lunar Mission Design Space ................................................................................. 80 4.2. Architecture Definition .......................................................................................... 81 4.3. Analysis Results and Validation ............................................................................ 88 4.3.1. Analysis Results .......................................................................................... 89 4.3.2. Validation .................................................................................................... 98 CHAPTER 5 FLEXIBLE PATH DESIGN SPACE EXPLORATION ................... 101 5.1. Flexible Path Design Space ................................................................................. 101 5.1.1. System Architecture Design Space Representation .................................. 102 5.1.2. Baseline System Architectures ................................................................. 106 5.2. Design Space Exploration Results ....................................................................... 110 5.2.1. GEO System Architecture Results ............................................................ 111 5.2.2. Lunar System Architecture Results .......................................................... 116 5.2.3. NEO System Architecture Results ............................................................ 121 5.2.4. Evolutionary Exploration Program ........................................................... 125 5.3. Design Space Implications ................................................................................... 128 5.3.1. Launch Vehicle Selection ......................................................................... 128 5.3.2. Propellant Depots and On-Orbit Refueling ............................................... 137 5.3.3. Aggregation Strategy ................................................................................ 144 5.3.4. Comparison between IMLEO and RNPV................................................. 150 5.3.5. Summary ................................................................................................... 153 CHAPTER 6 CONCLUSIONS AND FUTURE WORK .......................................... 155 6.1. Conclusions .......................................................................................................... 155 6.2. Future Work ......................................................................................................... 158 APPENDIX A ................................................................................................................ 162 APPENDIX B ................................................................................................................ 168 APPENDIX C ................................................................................................................ 175 C.1. Launch Vehicles .................................................................................................. 175 iv C.2. Propellant Depot .................................................................................................. 187 C.3. Aggregation Strategy........................................................................................... 191 APPENDIX D ................................................................................................................ 200 D.1. Crew .................................................................................................................... 200 D.2. Crew Capsule ...................................................................................................... 200 D.3. Lunar Descent Stage ........................................................................................... 203 D.4. Lunar Ascent Stage ............................................................................................. 205 D.5. Launch Vehicle ................................................................................................... 207 D.6. Propulsive Stage .................................................................................................. 208 D.7. Propellant Depot ................................................................................................. 211 D.8. Surface Habitat .................................................................................................... 212 D.9. In-Space Habitat .................................................................................................. 213 REFERENCES .............................................................................................................. 215 v LIST OF FIGURES Figure 1: Notional Cost, Freedom, and Knowledge in the Design Process [17],[18],[19] . 4 Figure 2: Design Reference Architecture 5.0 Trade Tree [16] ..........................................