A Systems Design for a Prototype Space Colony

A SYSTEMS DESIGN FOR A SPACE PROTOTYPE COLONY A Student Project in Systems Engineering Massachusetts Institute of Technology Spring 1976 with the Support of the William F. Marlar Memorial Foundation, Inc.

A SYSTEMS DESIGN FOR A PROTOTYPE SPACE COLONY A Student Project in Systems Engineering conducted by the Department of Aeronautics and Astronautics of the Massachusetts Institute of Technology during the Spring Term of 1976 with the Support of the William F. Marlar Memorial Foundation, Inc. Cecil W. Acree, Jr. David L. Akin Dominick Bruno Edward F. Crawley K. Eric Drexler Jor,ah L. Garbus James J. Gorman John F. McCarthy, Jr. Professor in Charge Oscar Orringer Lecturer with Mitchell L. Green Francis M. Hriadil Alexander-Thomas A. Siapkaras David B. S. Smith B. Ray Sperber Thomas R. Stagliano Marian S. Tomusiak David B. S. Smith, Editor

A specific design for a space colony is investigated, with emphasis on the engineering aspects of structural and systems design. The problem is first limited by the two assumptions of the colony location at the trailing Lagrangian point LS and the lunar Transport Linear Accelerator. Design criteria are developed to set the operational goals of the colony. A specific 1000-person prototype space colony design is proposed. Systems issues of hull shape and size, agricultural sunlight, radiation shielding, colony attitude control, atmospheric composition and pressure, temperature and humidity control, food production, and living space design are discussed. Structural issues of operational requirements, normal and abnormal loads, materials, fabrication techniques, hull design, stress analysis and sizing, fatigue, operational safety limits, and damage tolerance are investigated. The proposed colony configuration is modified as a result of preliminary technical analyses, leading to the final design of the MIT Prototype Space Colony. A construction scenario is proposed, including design of the construction site. Refining, manufacture, fabrication, and assembly are discussed, including mass, power, and manpower sizing of the machines required. Inspection and repair methods are presented. Transportation systems and vehicles are sized and designed, and program schedules are presented. Based on a yearly costing of 28 line items, total program costs are projected, both direct and discounted. Conclusions and recommendations for further research are presented. iii

ACKNOWLEDGEMENTS The study gr>oup wishes to expr>ess its appreciation to Dr. Gerard K. O'Neill, Professor of Physics at Princeton University, Professor Koichi Masubuchi of the MIT Department of Ocean Engineering and Naval Architecture, and Professors Eugene E. Covert and Rene H. Miller (Chairman) of the MIT Department of Aeronautics and Astronautics, who contributed their time and expertise to our project. We also thank the MIT Space Habitat Study Group for the use of their files on space colonization. For their uJOrk in editing and typing this report, the study group gratefully acknowledges Miss Terri Gigliotti, Mrs . Anne Brocklebank, Ms . Pam Paine, Mrs. Gerti Gillen, and most of all Miss Joan Gillen. Above all, we thank the vlilliam F. Marlar Memorial Foundation, Incorporated, whose financial support made this entire project possible. iv

TABLE OF CONTENTS CHAPTER I - INTRODUCTION I.l The Concept of Space Colonies .. I.2 Projected Uses of Space Colonies I.2.1 General Remarks .... I. 2. 2 Manufacture . . . . . . I.2.3 Large Space Structures I.2.4 Long-Term Uses I.3 History . .... II. l II. 2 II. 3 CHAPTER II - SUMMARY OF RESULTS Introduction Overall Concept. Colony Configuration and Systems II.3.1 Major Components II.3.2 The Colony ..... . II.4 II. 4 .1 II.4. 2 II. 5 II.5.1 II. 5. 2 II.5.3 Structural Design .... Hulls and Compartments Damage Tolerance Colony Construction ... Materials and Refining Manufacture and Fabrication Assembly and Testing II.6 Scheduling and Costs II.6.1 Schedule II.6.2 Costs . III.l III.1.1 III. l. 2 III. l. 3 III. 2 IV.l IV. 2 CHAPTER III - THIS STUDY The Course Course Announcement ..... . Course Personnel and Organization Direction of Investigation The Report CHAPTER IV - ASSUMPTIONS Location Materials and Transportation V 1.1 1. 2 1. 2 1. 2 1.3 1. 3 1. 4 2.1 2.1 2.1 2.1 2.3 2.6 2.6 2.7 2.9 2.9 2.9 2.11 2.13 2 .13 2 .13 3.1 3.1 3.2 3.2 3.2 4.1 4.1

V.l V .2 V.2.1 V.2.2 V .2. 3 V. 2. 4 V. 2. 5 V. 2. 6 V. 2. 7 V. 2. 8 Table of Contents (continued) CHAPTER V - ENVIRONMENTS Introduction Life Requirements Radiation . Atmosphere Temperature and Humidity Food Waste Recycling Light .... . Rotation of Environment Acoustic Levels .. V.3 Operation and Comfort Requirements V.3.1 Pseudogravity . . . . ... . V.3.2 Living Space ..... . VI. l VI. 2 VI. 3 CHAPTER VI - SYSTEMS Introduction Design Method The First Hull VI.3.1 General Remarks VI.3.2 Assumptions .. VI.3.3 Design Philosophy VI.3.4 Candidate Hulls . VI.3.5 Dimensions of Hull VI .4 Shielding, Sunlight, and Windows VI.4.1 General Remarks ....... . VI.4.2 Shielding Requirement .... . VI.4.3 Sunlight, Windows, and Cutouts VI.4.4 Shield Configuration VI.4.5 The Sunlight Beam .. VI.5 The Precession/Nutation Problem VI.5.1 VI. 5 .2 VI. 5. 3 VI. 5. 4 VI. 5. 5 VI. 5. 6 VI. 5. 7 VI. 5. 8 General Remarks ... The Hull as Gyroscope Uncontrolled Variations in the Hull Spin Axis The Shield Around the Hull The Despun Shield Option The Slowly Spun Shield Option Shield Option Decision Docking System . . . . . . . vi 5.1 5.1 5.1 5.3 5.7 5.7 5.8 5.8 5.11 5.11 5.12 5.12 5.13 6.1 6.2 6.2 6.2 6.2 6. 4 6.5 6.7 6.14 6 .14 6.14 6.17 6.18 6.21 6.26 6.26 6.26 6. 31 6.32 6.32 6.36 6.44 6.44

VI. 6 VI. 6 .1 VI. 6. 2 VI. 6. 3 VI. 7 VI. 7 .1 VI. 7. 2 VI. 7. 3 VI. 7 .4 VI. 7. 5 VI. 7 .6 VI. 8 VI. 8.1 VI.8.2 VI. 8. 3 VI. 8. 4 VI. 8. 5 VI.8.6 VI.9 VI. 9 .1 VI. 9. 2 VI. 9. 3 VI. 9. 4 VI. 9. 5 Table of Contents ( continued) First Overall Configuration General Remarks The Hull The Shield Air Composition and Pressure General Remarks . . . . . . Advantages to Low Pressure Inert Gas Content Risk of Fire Decision Leakdown Analysis Energy Flow in the First Configuration General Remarks ..... . Description of Inputs ...... . Output by Passive Radiation through the Shield ............. . Output by Passive External Radiator Output by Active External Radiator Heat Pipes through the Shield Configuration Change Reasons for Changes . . . . . Changes .......... . Parabolic Mirror and Electrical Generating System ....... . Docking Svstem ....... . Flat Mirror and Shadow Reflector VI.10 Temperature and Humidity Control VI.10.1 General Remarks ......•.. VI.10.2 Solar Heat Gain - Sensible and Latent Heat VI.10.3 Electrical Heat Gain - Sensible and Latent VI.10.4 Environmental Control Process .. VI.11 Food Production and Waste Recycling VI.11.1Summary. . . . . . . . . . . . . VI.11.2 Nutritional Requirements VI.11.3 Food Production - Nutrients and Growth Medium VI.11.4 Food Production - Temperature, Light, and Humidity VI.11.5 Food Production - Yields VI.11.6 Agricultural Area Design VI.11.7 Waste Recycling . vii 6 .44 6.44 6.47 6.47 6.50 6.50 6 . 50 6.50 6. 50 6.50 6.51 6.53 6.53 6.53 6.55 6.57 6.65 6.67 6.68 6.68 6. 72 6. 77 6.81 6.84 6. 86 6.86 6.87 6.91 6.95 6.109 6.109 6.110 6.110 6 .111 6 .114 6 .119 6 .119

Table of Contents (continued) VI.12 Living Space Design ....... . VI.12.1Summary . . . . . . . . . . . . . VI.12.2 Image of the Prototype Community VI.12.3 Activities and Facilities Program VI.12.4 Habitable Space Program VI.12.5 Landuse Plan VI.12.6 Building Systems APPENDIX VI.A - RADIATION SHIELDING VI.A.l The Problem. VI.A.2 The Radiation Environment VI.A.2.1 The Solar Wind VI.A.2.2 Solar Particle Events . VI.A.2.3 The Galactic Background Radiation VI.A.3 Dosimetry ....... . VI.A.4 Shielding ....... . VI.A.5 Simpleminded Calculation of Shielding Mass APPENDIX VI.B - THE GYROSCOPE VI.B The Gyroscope .... APPENDIX VI.C - ESTIMl\.TES OF MOMENT OF INERTIA VI.C.l Estimate of Moment of Inertia about Spin Axis of 6.120 6.120 6.121 6.123 6.124 6 .134 6.136 6.Al 6 .Al 6 .A2 6 .A2 6 .A2 6 .A7 6.Al4 6.Al6 6.Bl First Hull Design . . . . . . 6. Cl VI.C.2 Estimate of Moment of Inertia about Transverse Axis of First Hull Design . . 6 .C4 VI.C.3 Estimate of Moment of Inertia of First Shield Design about its Axis of Symmetry . . . . . . 6 .C7 VI.C.4 Estimate of Moment of Inertia of First Shield Design about Transverse Axis 6 .C9 APPENDIX VI.D - LEAKDOWN ANALYSIS VI.D.l List of Symbols .. VI.D.2 Analysis VI.E APPENDIX VI.E - ESTIMATE OF THE ELECTRICAL ENERGY REQUIREMENTS OF THE SPACE COLONY Estimate of the Electrical Energy Requirements of the Space Colony . . . . . . . viii 6.Dl 6.Dl 6.El

Table of Contents (continued) APPENDIX VI.F - POWER FLOW FROM HULL THROUGH SHIELD FOR FIRST CONFIGURATION VI.F.l List of Symbols VI.F.2 Analysis APPENDIX VI.G - DENSITIES OF TYPICAL RADIATOR STRUCTURES VI.G Densities of Typical Radiator Structures APPENDIX VI.H - THE BRAYTON HEAT PUMP CYCLE VI.H.l List of Symbol~ and Constants .. VI.H.2 Description of Brayton Heat Pump Cycle VI.H.3 Analysis VI.H.4 Constraints on the Parameters VI.H.S Numbers . APPENDIX VI. I - THE RANKINE HEAT PUMP CYCLE VI.I.l List of Symbols and Constants . . VI.I.2 Description of Rankine Heat Pump Cycles VI. I. 3 Analysis . . . . . . . VI.I.4 Choice of Refrigerants VI.I.5 Numbers . VI.I.6 Water .. VI.I.7 Refrigerant 11 VI.I.8 Refrigerant 12 VI. I. 9 Remarks . . APPENDIX VI.J - TRANSPIRATION OF PLANTS VI.J VII. l VII. 2 Transpiration of Plants .... CHAPTER VII - STRUCTURAL DESIGN Operational Requirements of the Colony Structure Loads ... VII.2.1 General Remarks . VII.2.2 Normal Operations ~1 • .,,,ee,•d""'"'" ix 6.Fl 6 .Fl 6.Gl 6.Hl 6 .H3 6.H6 6 .Hll 6.Hl2 6.Il 6.I2 6.I4 6.I9 6. Il0 6. Ill 6. I12 6. Il4 6. Il6 6.Jl 7.1 7. 2 7.2 7. 3

Section Table of Contents (continued) VII.2.3 Construction and Spin-up VII.2.4 Damage-Induced Loads VII.3 Configuration and Materials-Alternatives VII.3.1 General Remarks ... . VII.3.2 Materials ...... . VII.3.3 Fabrication Techniques VII.3.4 The Hull Concept VII. 4 Stress Analysis and Sizing VII.4.1 List of Symbols VII.4.2 General Remarks VII.4.3 Inner Hull VII.4.4 Outer Hull VII.4.5 Bulkheads ... VII.4.6 Interior Structure VII.5 Fatigue and Operational Safety Limits 7. 4 7. 5 7. 9 7. 9 7. 9 7.15 7.17 7.22 7. 22 7.23 7. 24 7.27 7. 28 7. 36 7. 39 VII.5.1 General Remarks . . . . . . . . . 7.39 VII.5.2 Fracture Mechanics Considerations in Component Design . . . . . . . . 7. 41 VII.5.3 Choice of Design Points . . . 7.56 VII. 6 VII. 7 General Configuration ..... Conclusions and Recommendations APPENDIX VII.A - DERIVATIONS OF HOOP STRESS EQUATIONS 7. 61 7. 68 VII.A.l General Remarks . . . 7.Al VII.A.2 Determination of Hoop Stresses in a Single Hull 7.Al APPENDIX VII.B - DYNAMIC LOADS VII.B.l List of Symbols VII.B.2 General Remarks VII.B.3 Torsion VII.B.4 Bending VII.B.5 Conclusions VII.C APPENDIX VII.C - METEOROID IMPACT Meteoroid Impact X 7.Bl 7 .Bl 7.B2 7 .B6 7.B10 7 .Cl

Table of Contents (continued) APPENDIX VII. D - LEAK BEFORE BREAK DESI GN VII.D. l List of Symbols VII. D. 2 General Remarks VI I. D. 3 Analysis VII.E APPENDIX VII. E - MASS PER UNIT AREA OF HULL, BULKHEAD, SHIELD, AND AGRICULTURE Mass Per Unit Area of Hull, Bulkhead, Shield, and Agriculture . . . . . . . . APPENDIX VII. F - RAYLEIGH- RITZ ANALYS I S OF SQUARE CLAMPED PLATE VII. F . 1 List of Symbols VII. F . 2 General Remarks VII.F.3 Analysis APPENDIX VII.G - EXAMPLE OF INTERIOR STRUCTURE VII. G. 1 General Remarks VII.G . 2 Analysi s APPENDI X VI I . H - STRUCTURAL ANALYSIS OF ENDCAP WINDOI~ VII.H VIII . l VI II . 2 Structural Analysis of Endcap Window CHAPTER VIII - CONSTRUCTION AND MAINTENANCE Introduction Materials . VIII.2.1 Materials Availability VIII. 2 . 2 Materials Requirements VI II. 3 Refining VIII. 3.1 Refining Processes VI II . 3 . 2 Process Mass , Power , and Labor VIII. 4 Manufacture . . . . . VII I. 4. 1 General Comments on Space Manufacture VIII.4.2 Material Flow ... .. . VIII . 4. 3 Rolling Mi lls and Related Equipment VIII. 4 . 4 Light Machine Tools . . . xi 7. Dl 7 . D2 7. D2 7 . El 7 .Fl 7 . F2 7. F2 7 .Gl 7 .Gl 7 . Hl 8 .1 8 . 1 8. 1 8. 3 8. 6 8. 6 8. 6 8. 9 8 . 9 8. 9 8 . 11 8 . 16

Section Table of Contents (continued) VIII.4.5 Additional Manufacturing Equipment and Procedures VIII.4.6 Conclusion VIII. 5 Fabrication. VIII.5.1 Outline of Fabrication Technique VIII.5.2 Electron Beam Welding ..... . VIII.5.3 Detail of Section and Bulkhead Fabrication VIII.5.4 Conclusion ....... . VIII. 6 Work Environment and Summary VIII. 6 .1 Work Shacks . . . . . . VIII.6.2 Mass and Power Summary VIII. 7 Assembly . . . . . . . VIII.7.1 Overall Plan VIII.7.2 The Construction Site VIII.7.3 Colony Assembly Process VIII.7.4 Design of Construction Site Structure VIII.7.5 Conclusion VIII. 8 Inspection and Repair VIII.B.l Overall Scenario VIII.8.2 Inspection Methods VIII.8.3 Component Quality Assurance VIII.8.4 Assembly Inspection .... VIII.8.5 Overall Structural Proof Testing VIII.8.6 Structure Monitoring and Leak Detection VIII. 8. 7 Repair VIII. 9 Work Force, Mass, and Power . VIII.9.1 Work Force ....... . VIII.9.2 Mass and Power Consumption VIII.10 Conclusions and Recommendations 8.18 8 .19 8.20 8.20 8. 21 8.22 8.26 8. 27 8.27 8. 29 8.30 8. 30 8. 30 8. 40 8. 45 8.47 8. 4 7 8.47 8.48 8.51 8.53 8.53 8. 55 8. 56 8. 57 8.57 8. 58 8. 58 APPENDIX VIII.A - CHAR-1\CTERISTIC RELATIONS OF MACHINE TOOLS VIII.A.l General Remarks .. VIII.A.2 Light Machine Tools VIII.A.3 Rolling Mills ... APPENDIX VIII.B - EB WELDING RATE VIII.B EB Welding Rate ... xii 8.Al 8. Al 8.A2 8.Bl

Table of Contents (continued) CHAPTER IX - TRANSPORTATION, SCHEDULING, AND COST IX.l IX.1.1 IX .1. 2 IX.1 . 3 IX.1.4 IX .1. 5 IX.2 IX.3 IX. 4 IX.5 IX. 6 Transport Systems ...... . Earth Surface-Low Earth Orbit Transportation Interorbital Transfer Vehicle Lunar Landing Vehicle .... Transport Linear Accel~rator Interlibration Point Transfer Vehicle Transportation Costing Rationale Project Scheduling Transport Scheduling Program Cost Rationale Program Costs . .... CHAPTER X - CONCLUSIONS AND SUGGESTED RESEARCH X.l X. 1.1 X. l. 2 X. l. 3 X.l. 4 X. l. 5 X. l. 6 X.2 XI X.2.1 X. 2 . 2 X. 2 . 3 x. 2. 4 X.2. 5 X.2.6 X.2.7 Conclusions .. ... General Conclusions Thermal Effects .. Structures Construction Inspection and Repair Cost Suggested Research General Remarks . Human Physiology Ecology ..... Location and Logistics Structures ..... . Systems . . . . . . . . Construction and Maintenance CHAPTER XI - REFERENCES References xiii 9 . 1 9.1 9. 4 9.17 9.20 9.26 9.27 9.33 9.37 9.37 9.42 10.l 10.l 10.1 10.1 10.3 10.3 10.4 10.5 10.5 10.5 10.6 10 . 7 10.8 10. 8 10.8 11.1

1.1 2.1 2. 2 2. 3 2.4 2.5 2. 6 2. 7 2.8 4.1 4. 2 5.1 5.2 5.3 5. 4 6.1 6.2 6.3 6.4 6. 5 6. 6 6. 7 6.8 6. 9 6 .10 6 .11 6 .12 6.13 LIST OF FIGURES CHAPTER I Space Colony Designs CHAPTER II General Configuration of the MIT Prototype Space Colony ........... . Outside View of Colony Cutaway View of the Colony Cylindrical Section Compartment Flow of Material from Ingots to Final Parts Construction Site Colony Scheduling ..... . Yearly Cumulative Cost CHAPTER IV The Lagrangian Points in the Earth-Moon System Velocity Increments between Locations CHAPTER V Hypoxia Effects due to Reduced Partial Pressure of Oxygen .................. . Effects of Oxygen Toxicity due to Raised Partial Pressure of Oxygen .............. . Tolerable Pressures of Oxygen-Inert Gas Mixtures for Human Breathing .......... . Spectral Distribution of Human Visibility .... CHAPTER VI Flowchart of First Hull Design Candidate Hull Shapes ..... Torus with Central Docking Section Cross-Sections of Candidate Hulls . Radius of Gyration Versus Spin Rate Interior Configuration of First Hull Flowchart of Shielding, Sunlight, and Windows Possible Free Relative Orientation Design. Possible Windowless Cutout Design ..... Effect of Small Cutouts and Window on Free Relative Orientation Design . . . . . . . . Possible Fixed Relative Orientation Design Areas and Masses of Shields Versus Hull-Shield Spacing ............. . Cassegrain Two-Mirror Configuration .. ... . xiv 1. 6 2.2 2.4 2.5 2.8 2.10 2.12 2.14 2.15 4. 2 4.3 5.4 5.5 5. 6 5.10 6.3 6.6 6.8 6.9 6.10 6 .13 6.15 6.16 6 .19 6.20 6.22 6.23 6.24

6.14 6.15 6.16 6 .1 7 6.18 6.19 6.20 6.21 6.22 6.23 6.24 6.25 6.26 6 .27 6.28 6. 29 6.30 6.31 6 . 32 6.33 6. 34 6.35 6.36 6. 3 7 6. 38 6. 39 6.40 6.41 6.42 6 .Al 6 .A2 6 .A3 6 .A4 6 .AS 6.A6 6.Bl 6.BZ 6.B3 6.B4 List of Figures (continued) Desired Orientation of First Configuration Geometry and Effect of Precessive Torque on Hull Schematic of Active Open Bearing System. Wheel Bearing . . . . . . . . . . . . . . Schematic of Active Closed Bearing System. Docking System for First Configuration Cutaway View of First Hull Configuration Cutaway View of First Shield Configuration Leakdown Parameters .......... . Power Flow from Hull through Shield ... . Power Flow Versus Thermal Conductivity of Shield Possible External Radiators . . ....... . Sunward-Side Cylindrical Radiator Configuration Power Flow in Active External Radiator System Cutaway of Heat Pipe ...... . Colony Cross-Sections . . . . . . . . . . Cross-Section of Final Hull Configuration Orientation of Final Colony Configuration Possible Thermal Engine Configurations Parabolic Mirror and Solar Cell Array Configuration ........... . Docking Port and ~ransfer Pod ... . Final Overall Colony Configuration Environmental Control Design Process Psychrometric Chart . . . . . . . . . Psychrometric Chart; Design and Supply Points Psychrometric Chart; Typical Cooling Coil Performance . . . . . . . . . . . . . . . . . Schematic of Cooling Coil Process ..... . Diurnal Variations in Plant Water Parameters Landuse Plan . . . . . . . . ..... APPENDIX VI.A Solar Wind Characteristics at 1 AU Ion Species in Solar Wind near 1 AU Probabilities of Solar Proton Exposure Galactic Cosmic Ray Protons and Electrons RBE's of Various Radiation Components Shielding Effect of Atmosphere ..... APPENDIX VI.B Untorqued Gyroscope at LS ........ . Effect of Torque Along Spin Axis .... . Effect of Torque Perpendicular to Spin Axis Deflection of Spin Axis due to Torque ... 6.27 6.29 6.34 6.40 6.41 6.46 6.48 6.49 6.52 6.56 6.58 6.62 6.64 6.66 6.69 6. 71 6.73 6.76 6.78 6. 79 6.82 6.85 6.97 6.100 6.102 6.103 6.105 6 .113 6.140 6 .A3 6 .A4 6.A6 6 .A8 6.Al2 6.Al7 6.B3 6.B4 6.B5 6.B7

List of Figures (continued) APPENDIX VI. C 6. Cl Spin Axis !'1oment of Inertia Model for First Hull Configuration: Cross-Section . . 6 . C2 6. C2 Transverse Axis Moment of Inertia Model for First Hull Configuration: Cross- Section 6. CS 6 . C3 Moment of Inertia Model for First Shield Configuration: Cross-Section . 6 .cs APPENDI X VI . F 6 . Fl Power Flow Versus Thermal Conductivity of Shield 6 .FS 6 .Hl 6 .H2 6 .H3 6 .H4 6 . HS APPENDIX VI. H T-S Diagram of Ideal Brayton Heat Pump Cycle Schematic of Brayton Heat Pump Power Balance using Brayton Heat Pump Cycle Envelope for Brayton Temperatures . Brayton Heat Pump Parameters Versus T 2 APPENDIX VI.I 6 . I l T-S and p-h Diagrams for Ideal Rankine Heat Pump 6 . H4 6 .HS 6. H9 6 .Hl3 6 .Hl S Cycle . . . . . . . . . . . . . . . . 6.I3 6. I2 Schematic of Rankine Heat Pump 6. I S 6. I3 Power Balance using Rankine Heat Pump Cycle 6 . I 7 7 .1 7. 2 7. 3 7. 4 7. 5 7. 6 7. 7 7. 8 7. 9 7 . 10 7 . 11 7 .12 7 .13 7 .14 7 .15 7 .16 7 . 1 7 7 .18 CHAPTER VII Assumed Damage Scenario . . . . Failure Induced Loads .... . t Versus Steel Thickness . Detail of Crack Stopper/Stiffener Longitudinal Hull Section . . . Transverse Hull Section . . . . Major Stiffener-Joint Detail Log a 8 Versus t for I nner Hul 1 t~i l~~ur~~:~~ in!~;a~~f~~ ~u~l. ~~fe~io~e~~~~din!~r L!~~~~e!~~ Atta;h~e~t · Window Detail . . . . . . . . . . . . . . Fail Safety Criteria ... .. .... . Fail Safe/Stiffener Construction Stress Intensity Solution for Reinforced Plate Types of Fastener Failure Log cr 8 Versus t for Inner Hull .... , . . . xvi 7. 7 7. 8 7 .11 7 .13 7 . 19 7 . 20 7. 21 7 . 26 7. 29 7 . 31 7. 35 7. 38 7. 40 7. 42 7. 44 7. 51 7. 53 7. 57

7.19 7. 20 7.21 7. 22 7.23 7.24 7.25 7.26 List of Figures (continued) Log 0 8 Versus t for Outer Hull Log 0 8 Versus t for Bulkheads Major Stiffener Configuration . General Configuration ..... Cylindrical Section Compartment Hemispherical Section Compartment Major and Minor Stiffener Details Window Detail ..... . APPENDIX VII.A 7. 58 7. 59 7.62 7.63 7.65 7.66 7.67 7. 69 7.Al Free Body Diagram of Hull Cylindrical Section ... 7.A2 APPENDIX VII.B 7. Bl 7 .Cl Vibratory Mode Shapes .. APPENDIX VII.C Probability of Meteoroid Impact APPENDIX VI I. D 7 .B3 7 .C2 7.Dl Growth of Surface Flaws to Critical Size, a 7.D3 7.D2 Flaw-Shape Parameters for Surface and Internal Flaws . . . . . . . . . . . . .. . . . 7.D5 7.D3 Deep Flaw Magnification Factor Curves 7.D6 7.D4 Relative Efficiencies of Al and Steel to Meet Leak Before Break Criterion 7.D9 7 .El 7.Gl 8.1 8.2 8.3 8.4 8. 5 8.6 APPENDIX VII.E Schematic Layout of Hull APPENDIX VII. G Floor Thickness Required for Buildings CHAPTER VIII Flowchart of Colony Construction and Maintenance Chemical Process Flowchart .... . .... . Flow of Material from Ingots to Final Parts .. Arrangement of Rollers in Two Common Mill Types Hold Down Bed ..... . Flowchart of Fabrication xvii 7.E2 7. G3 8.2 8. 7 8.10 8.14 8.23 8. 25

8.7 8.8 8.9 8.10 8 .11 8.12 8.13 8.Al 8.A2 8 .A3 9.1 9.2 9. 3 9. 4 9. 5 9. 6 9.7 9.8 9.9 9.10 9 .11 9.12 List of Figures (continued) Colony Construction Site Construction Site; Plan View Cross-Section of Hull and Frame Pivoted Crane ........ . Arrangement of Workshacks .. . Construction Site Deployment Organizational Chart; Workforce per Shift APPENDIX VI II. A Power Versus Weight of Light Machine Tools Weight Versus Volume of Light Machine Tools Power Versus Mass of Rolling Mills CHAPTER IX Low Earth Orbit Delivery Systems ..... . Empty Orbital Transfer Vehicle Configuration Deploy Only Launcher Propellant Launch Configuration ............... . Cargo Orbital Transfer Vehicle Configuration . Personnel Orbital Transfer Vehicle Configuration Lunar Landing Vehicle Empty Configuration ... . Lunar Landing Vehicle Cargo Configuration ... . Lunar Landing Vehicle Personnel Configuration .. Conceptual Launch Configuration of LLV Components Colony Scheduling ..... Yearly Program Expenditures Yearly Cumulative Costs .... xviii ~ 8.31 8.33 8. 34 8.35 8. 37 8.41 8. 59 8.A3 8.A4 8.AS 9.3 9.10 9.11 9.14 9.16 9.21 9.22 9.23 9.35 9.38 9.46 9.47

Table 3. 1 3.2 5.1 5. 2 5. 3 6.1 6. 2 6.3 6.4 6.5 6. 6 6. 7 6.8 6 .9 6.10 6 .11 6. 12 6.13 6.14 6.15 6.16 6.17 6.18 6 .19 6.20 Course Personnel Research Teams . LIST OF TABLES CHAPTER III CHAPTER V Relative Biological Effectiveness of Radiation and Human REM Allowances ...... . Recommended Dietary Allowances for Men and Women (18-35 years) in the United States Living Space Standards .... CHAPTER VI Docking Allowances . . . . . . . . . . . . . . . Dimensions of Docking Port and Transfer Pod Components . . . . . . . . . . Rates of Heat Gain from Occupants of Conditioned Spaces .................... . Estimate of the Average Heat Gain to Colony due to Presence of Occupants ...... . Total Heat Gains from Occupants Distribution of Solar Radiation Distribution of Electrical Consumption Distribution of Total Heat Gain ..... Symbols used in the Environmental Control Design Process ........ . ........ . Data used in the Production of the Psychrometric Chart . . . . . . . . . . . . . . . . . . Values for Variables in the Environmental Control Problem ............. . Environmental Control Calculations . Sample Nutrient Solution .. Comparison of Candidate Meat Animals Major Components of Proposed Diet Leisure Activities ... Lifestyle Activities .. Habitable Space Program Area Calculations Allocation Plan APPENDIX VI.A 6.Al Values Near 1 AU and Radial Dependences for Solar 6 .A2 6 .A3 6.A4 Wind Parameters . . ........... . Electron Components and Proton Components Intensity Ratios of the Twelve Most Abundant Cosmic Ray Nuclei to Protons Human REM Allowances . xix 3.3 3.4 5. 2 5.9 5.15 6. 45 6.83 6. 89 6.90 6.92 6.93 6. 94 6.96 6. 9 8 6. ;; 6.106 6.107 6 .112 6.116 6.118 6.125 6.126 6.127 6.135 6.137 6 .AS 6 .A9 6 .AlO 6.Al3

List of Tables (continued) APPENDIX VI.E 6.El Average Power Consumption Per Day for Residents of the U.S. in 1967 . . . . . . . . . . . . 6.E3 6.E2 Prototype Colony Lifestyle Energy Demand (Per Person) . . . . . . . 6. ES CHAPTER VII 7.1 Nominal Mechanical Properties and Composition of HY-80, HY-100, and AISI 4130 Steels 7.14 7.2 Dimensions, Stress Levels, Masses . . . . . . . 7.70 CHAPTER VIII 8.1 Composition of Lunar Rock and Soil . . . . . 8.4 8.2 Alloy Compositions of Structural Steels 8.5 8.3 Mass and Power Requirements for Construction Site 8.60 CHAPTER IX 9.1 Orbiter DOL Component Masses 9.2 Nominal OTV Component Masses 9.3 Lunar Landing Vehicle 9 .4 Scheduling Summary ..... 9.5 Transport Vehicle Schedules 9.6 Program Line Item Costing xx 9.12 9.15 9.19 9.39 9.40 9.44

CHAPTER I INTRODUCTION I.l THE CONCEPT OF SPACE COLONIES "A number of rockets orbiting the Earth, with all the equipment needed to enable rational beings to exist, might serve as a base for the further dissemination of humanity." So wrote Konstantin Eduardovich Tsiolkovskiy in 1911, in one of the earliest articles on rocketry (1.1). In the sixty-five years since then, the development of mankind's technical abilities has permitted spectacular successes in our space efforts--indeed, many rockets have orbited the Earth. But it is only now that we can conceptually include "all the equipment needed to enable rational beings to exist" in our space hardware. To do so, we have modified Tsiolkovskiy's concept, replacing his "number of rockets" by a space colony. A space colony is a large self-sufficient, self-sustaining, life-supporting structure. Once built, it provides its inhabitants with air, food, water, light, gravity, housing, constant temperature and humidity, protection from radiation a~d meteorites, and facilities for recreation and cultural development. Its material imports are few, and these it obtains by work or barter. The colony recycles its wastes, keeps stable its animal and vegetable populations, and maintains and repairs its structures, It has survival potential, based on a margin of ability beyond mere self-maintenance: it can improve its own design, modify itself, adapt to unexpected situations. And, most important, it can expand, building more space hardware and improved replicas of itself, "for the further dissemination of humanity." We are now able to design and evaluate space colonies from an engineering point of view. This report presents one such design and evaluation.

1. 2 I.2: PROJECTED USES OF SPACE COLONIES I.2.1: General Remarks: Space colonies need economic as well as philosophical justification. The establishment of a space colony program is financially one-sided. The mother planet, Earth, provides research and development, construction facilities and materials, manpower, training, and transportation; the initial investment is considerable. Once the major systems (transportation, materials procurement) are operational, and the first colony is complete (becoming the trained manpower supply and the construction facility), the program costs are greatly reduced. However, material imports and services from Earth to the colony still add to the bill. To offset the mother planet's expenditures, space colonies are expected to provide economic returns in the form of specialized goods and services, taking advantage of the colonies' unusual location and environment. This section describes the principal anticipated products of space colonies. The list will grow and change as our abilities in space and our requirements for space products become better defined. Though it is not the purpose of this study to evaluate the benefits of space colonies, the design of any space colony must be based in part on the requirement for such economic returns. I.2.2: Manufacture: A number of manufacturing processes benefit from a zero-g environment. In a gravity field, density and temperature effects cause sedimentation and convection currents in fluids, thus affecting crystal growth, refining of substances, and separation of components in fluid mixtures. The Skylab missions performed fourteen experiments to determine how the absence of sedimentation and convection affected processes such as float-zone refining, growth or ultrapure crystals from liquid melts and vapors, production of infrared optical materials, and doping of electronic semiconductors by liquid diffusion. The results of these tests (1.2) demonstrate a significant improvement in the desired properties of the spaceprocessed products over their Earth-produced counterparts. Space processing extends the metallurgist's or crystallographer's control over his materials down to the microscopic-even molecular-level.

1.3 Zero-g also improves the microbiologist's ability to separate components from fluid mixtures, such as live lymphocyte cells for cancer research. This points the way to the production of certain pharmaceuticals at lower costs. A space colony can serve as a base for continuous space processing operated by trained personnel. The availability of pollutionfree energy from solar radiation further reduces the operating costs or the manufacturing operations. I.2.3: Large Space Structures: Large-scale human utilization of space rests in part on the fabrication and assembly of large structures such as Satellite Solar Power Stations (SSPS's), optical telescopes, antenna arrays for radio telescopes, and large mirrors to reflect sunlight to Earth (1.3). Prefabricating these on Earth and transporting them into space for assembly requires designs tough enough to withstand launch stresses, and specialized packaging techniques, such as folding trusswork, to fit the structures into transport vehicles. The assembly requires logistical support for a trained work force. A space colony can provide facilities and manpower for the fabrication and assembly of these large space structures. The designs can be simpler and less massive, due to the low transportation stresses, the absence of special packaging techniques, and the improved properties of space-processed materials. If the raw materials come from the Moon, the transportation costs are decreased by avoiding the Earth's gravitational well, and the refining and fabrication costs are reduced by the use of solar energy. The manpower and logistical support for the assembly site is provided by the colony. So are later inspection, maintenance and repair teams. I.2.4: Long-Term Uses: As the availability of minerals on Earth decreases, and as the energy and environmental cost of refining these minerals increases, the possibility of mining the asteroids, particularly for rare metals, will become cost-effective. A space colony, due to its location high in the Earth's gravity field, and because it is not surrounded by an atmosphere, has easier access to the asteroids than Earth does. At first, a colony can send mining

1.4 teams out after the minerals. Later, the asteroids themselves can be brought to the colony, using part of their mass as propellant. The principal cost savings is in the refining, with the use of solar energy. The finished products, either as pure minerals or space-processed components, can be sold to Earth. An early use of propelled space colonies might be as selfsufficient observatories and laboratories orbiting the Sun, Mars, Venus, the gas giants and their satellites. Such observatories, moving outward within the Solar System, would extend the astronomer's baseline for deep-space measurements. Eventually, colonies independent of solar energy could leave our Solar System. As their number, size, and rate of production increases, space colonies can provide living space for a significant percentage of Earth's population (1.4). Although it is unlikely that emigration to the space colonies could stabilize the mother planet's population (1.5), it would establish a new frontier much like Great Britain's American colonies in the seventeenth and eighteenth centuries. Space colonies would be the vehicles of mankind's renewed outward motion. I.3: HISTORY The concept of the space colony is a blend of ideas gathered together over a number of centuries. To the early thoughts on manned space travel and artificial satellites were added spinning for artificial gravity, a recycled food system for life support, the use of solar energy, and the mining of the Moon for materials. Robert Salkeld (1.6) reviews the growth of the space colony from its contributing themes, as gestated and explored by science-fiction authors and scientists. In 1969 Professor Gerard K. O'Neill and a group of Princeton University students began a more systematic investigation of the space colony concept, defining its potential uses, and developing a potential colony design, called the O'Neill Model 1. These ideas, published in Physics Today (1.4), generated considerable interest in

1.5 space colonies, and sparked several studies and conferences on the subject. The Marshall Space Flight Center reviewed space colonization and the O'Neill designs in an assessment dated January 1975 (1.5). This study presented a set of program requirements (smaller stations, simulation facilities, transport systems, lunar and libration point bases) to develop the technologies required for the establishment of space colonies. The Princeton University conference of May 1975, titled "Space Manufacturing Facilities" (1.7), gathered 130 participants to explore the problems and benefits of space colonization. Their discussions covered a wide range of issues: transportation systems, construction sites, materials procurement and processing, fabrication techniques, human physiology, ecology, social and cultural factors, solar energy, and program organization. In the summer of 1975, Stanford University, the American Society for Engineering Education, and the NASA Ames Research Center sponsored a ten-week study session on space colonies. This group investigated human physiology, life-support, and economics, further defined the overall concept of space colonization, and produced a colony design called the Stanford Torus, with a lower spin rate than the O'Neill Model 1 (1.8). Both these designs are shown in Figure 1.1. Together with other proposed designs (1.9) (1.6), these concepts set the stage for this study, and for other research on space colonies as well. In particular, during the writing and editing of this report, NASA Headquarters sponsored a 1976 Summer Study at NASA Ames Research Center. This six-week research effort concentrated on the Transport Linear Accelerator, orbital mechanics, materials processing, and space construction systems (1.10).

Sunlight Sunlight - FIGURE 1.1 SPACE COLONY 1. 6 O'Neill Model 1 Stanford Torus

II.l: INTRODUCTION 2.1 CHAPTER II SUMMARY OF RESULTS This Chapter describes the final design of the MIT Prototype Space Colony. The design history leading to the configuration presented is the subject of Chapter VI. The structural issues associated with the colony are investigated in Chapter VII. Chapter VIII describes the colony construction and maintenance, and Chapter IX,the scheduling and cost. II.2: OVERALL CONCEPT The space colony designed in this study is a prototype. As such, it combines a small size--its population is 1000--with the design features anticipated in later, larger models. Its purpose is to investigate the viability of the space colony concept,while keeping the program costs down by becoming operational sooner and by providing some economic return through the manufacture of specialized goods. II.3: COLONY CONFIGURATION AND SYSTEMS II.3.1: Major Components: Figure 2.1 presents the three major components (flat mirror, shadow reflector, and the colony itself) of the MIT Prototype Space Colony. These components are located in a stable orbit around the trailing Lagrange point LS. The q-axis shown in the figure is perpendicular to the plane of the Earth's orbit around the Sun. The section labeled "colony" spins to provide pseudogravity. Its spin axis is lined up with the q-axis. The elliptical flat mirror is a low-mass trusswork supporting a reflective surface. It redirects direct sunlight to the colony's parabolic mirror. Attitude-control systems on the flat mirror

2. 2

2. 3 maintain the required geometry as the entire configuration orbits about the Sun. Since sunlight beams are virtually parallel at LS, the distance between the flat mirror and the colony can be as large as necessary for safety. The rectangular shadow reflector, also a low-mass trusswork supporting a reflective surface, intercepts sunlight before it can impinge on the colony and increase its thermal input. Attitude control systems maintain its position between the colony and the Sun. Its distance from the colony is large (2 km) so that it does not interfere with the thermal radiation of the colony's waste heat into space. II.3.2: The Colony: Figure 2.2 presents a closer view of the colony itself, with dimensions. In its general details, the colony is symmetrical around its spin axis. Agriculture and habitation take place within a double-hull, consisting of a cylindrical section with length of 100m and outer radius 105 meters, capped by hemispherical endcaps. At the tip of one endcap is a docking port providing access to the colony interior through an air lock. A transfer pod brings cargo to or from the docking port. Both transfer pod and cargo air lock are sized to handle a Space Shuttle payload {a cylinder Sm in diameter and 18m long). The elliptical flat mirror shown in Figure 2.1 reflects parallel beams of sunlight at the colony. The outer beams of this reflection impinge on the colony's annular solar cell array. These solar cells generate 9.3Sxl0 6 watts of electrical power for the colony's consumption. Light from the flat mirror also shines on the colony's parabolic mirror (whose support structure is not shown in Figure 2.2). This mirror concentrates the sunlight towards a second mirror. The second mirror in turn reflects the light as a concentrated parallel beam along the spin axis. This beam enters the colony through a 20-meter-radius window. This sunlight path is illustrated in Figure 2.3, a cutaway view of the colony. Once inside, the concentrated light is dispersed by a set of mirrors onto the colony's agricultural area.

2 . 4 le------240 m---------•----l?B m------ir•- 62 m-f Solar cell array T 105 m ~ 100 m f Hull 105 m 1 ~ing port I.---- 210 ~------- Transfer pod I Spin I axis FIGURE 2.2: OUTSIDE VIEW OF COLONY

Tension cable Second mirror array Inner Outer Bulkheads 2. 5 Docking port Sunl ght mirror Workshop area FIGURE 2.3: CUTAWAY VIEW OF THE COLONY

2.6 The double-hull, parabolic mirror, solar cells, docking port, and transfer pod (when docked) spin together at 2 to 3 RPM, to provide a pseudogravity of .5g to lg on the inner hull in the cylindrical section. This cylindrical section, with area 6.28xl0 4 m 2 , is allocated for Earth-variety agriculture and the care of animals. The diet produced includes meat, fruits, vegetables, grain products, milk, and eggs. Crops are grown in a 30 cm deep layer of lunar dirt enriched by a nutrient solution and separated from the inner-hull surface by a 4-mil-thick layer of polypropylene. The agricultural illumination is 400 watts/m 2 . Workshops (not shown in Figure 2.3) are located in low-g areas near the spin axis, to take advantage of low-g or zero-g conditions for research and manufacturing of specialized products. The higher-g areas of the endcaps near the agricultural areas are filled by human housing and community facilities for the population of 1000 (which includes about 260 children). Housing space is divided into townhouse-model units, includes outdoor space in each unit, and provides considerable flexibility of lifestyle. Community facilities include administrative offices, shops, maintenance rooms, performing arts studios and auditoria, sports facilities, a guest hotel, a hospital, places of worship, and entertainment buildings and areas. The colony's atmosphere is a half-and-half mixture of oxygen and nitrogen at a pressure of 40530 N/m 2 (2/5 of Earth sea-level pressure), Its temperature is 295°K (72°F) and its relative humidity is 60%. These levels are maintained by a temperature and humidity control system which recirculates the total atmospheric volume every 20 minutes. This system also transfers the heat gain of the colony (3.35xl0 7 watts from sunlight and electrical consumption) to a refrigerant, and circulates this refrigerant to warm the outer hull. The outer hull in turn radiates the waste heat into space. II.4: STRUCTURAL DESIGN II.4.1: Hulls and Compartments: The separation between inner and outer hulls is 5 meters. The hulls are connected by continuous bulkheads, which run lengthwise between the tips of the endcaps

2.7 and circumferentially around the hulls, forming a distorted checkerboard pattern of 510 compartments. Typical compartment dimensions are 20m x 20m x Sm. Shielding from solar and galactic radiation is provided by lunar dirt and slag--by-product of the colony construction's refining process--packaged in bags and stacked inside the hull compartments. Thus the shielding material spins with the colony. Its area density is 5000 kg/m 2 ; its depth in the compartments is 2.5 meters. Figure 2.4 depicts a cylindrical section compartment. All compartments are assembled from prefabricated hull sections (roughly 20m x 20m) and bulkhead sections (roughly Sm x 20m). The prefabrication procedure uses electron beam welding to assemble lm x lm plates of AISI 4130 steel, separated by minor stiffeners of HY-80 or HY-100 steel, into the needed hull and bulkhead sections. Both hulls have plate thickness 4 cm; the bulkhead plates are 3 cm thick. The prefabricated sections are assembled by joining them to major stiffeners with threaded fasteners. Holes for the fasteners are drilled through the sections and the major stiffeners during prefabrication. Once assembled, compartments are sealed airtight. II.4.2: Damage Tolerance: The plate thickness of hulls and bulkheads satisfies the structural leak-before-break criterion, allowing detection of flaws before complete failure of a plate by a simple system of pressure measurements between the interior atmosphere and the compartments (the compartments are kept at different pressures). The Plate/Stiffener design is a Fail-Safe structure, avoiding large-scale structural failures by containing the spontaneous growth of cracks beyond the critical crack length. The tolerable damage scenario is the sudden loss of four lm x lm plates in a 2m x 2m square. The compartmentalization of the hull, leak-beforebreak criterion, and fail-safe structure permit inspection and repair schemes which require only simple technology and do not interfere with normal colony operations. In case of unexpected problems, some of the colony's buildings are designed as airtight emergency shelters.

2. 8 L..------ Welds along minor stiffeners + • 4 cm FIGURE 2.4: CYLINDRICAL SECTION COMPARTMENT = 0 N

2. 9 II.5: COLONY CONSTRUCTION II.5.1: Materials and Refining: The colony structure requires l.98xl0 8 kg of steel, of which 75% is AISI 4130 steel for the plates and 25% is HY-80 or HY-100 steel for stiffeners. Ninety-nine percent of this mass is available from iron, manganese, silicon, and chromium processed from l.46xl0 9 kg of lunar rock delivered unprocessed to LS. Only 2.50xl0 6 kg of alloying elements (carbon, molybdenum, and nickel) are transported from Earth. By-products of the steel production are l.70x10 8 kg of oxygen for the atmosphere and for propellant, 9.9xl0 7 kg of silicon for solar cells, and 9.9xl0 8 kg of slag suitable for radiation shielding. The refining process uses hydrogen reduction, carbon reduction, centrifuge separation, and distillation to produce the required metals. Reducing elements are recovered and recycled. The electrical power consumption of the refining process is 4.57xlo 7 watts. II.5.2: Manufacture and Fabrication: The one-ton steel ingots produced by the refinery are then manufactured into stock parts for the colony by sequences of machinery. This process is schematized in Figure 2.5. The total output of the manufacturing sequences is 600,000 lm x lm hull and bulkhead plates, 1,200,000 lm-long minor stiffeners, pieces for 3,090 major stiffener assemblies, and 3,353,000 nut-and-fastener pairs. The stock parts are then fabricated into the 20m x 20m hull sections and Sm x 20m bulkhead sections described in Section II.4.1. This procedure uses an automated layup bed which positions plates and stiffeners, electron-beam welds the plates to the minor stiffeners and the pieces of the major stiffener assemblies to~ether, drills fastener holes in the welded sections and major stiffeners, and attaches the major stiffeners to the sections. The total output of this prefabrication process is 1020 hull sections and 1050 bulkheads. The electrical power consumption of manufacture and fabrication is l.17xl0 7 watts. An automated control system regulates the production schedules of the refining, manufacture, and fabrication processes, and sets the specifications on each piece produced by the machinery.


2.11 II.5.3: Assembly and Testing: Figure 2.6 depicts the major components of the colony construction site. The largest element is the power plant, a square solar-cell array 661m on each side, generating 60 Megawatts. From its support structure extend four 150m-long trusswork booms, connecting the power plant to a rectangular trllsswork frame. This frame, 310m long and 220m wide, brackets the assembly volume for the colony's double hull. Along this frame move two circular trusswork cranes, 220 meters in diameter. Their motion along the frame sweeps out a cylinder surrounding the assembly volume. One width of the frame forms the center of a 400m-long trusswork mast, which provides attachment points for the work crew's living quarters and the construction cylinders (called 'shacks') which contain the machinery described in Sections II.5.1 and II.5.2. Along the mast runs a hoist to move people and material between the living quarters, assembly volume, and work shacks. The 20m x 20m hull sections and Sm x 20m bulkhead sections produced by the work shacks are grabbed by manipulators on the hoist, moved along the mast, and transferred to a crane. The crane moves the section to its assembly point and positions it while workers fasten it in. Once the hull is completed, the parabolic mirror, the solarcell array, and the docking port are added, and the construction apparatus is detached from the colony and moved away. The total mass of the construction site (frame, cranes, mast, booms, power array, living quarters, work shacks and machinery) is 10,946 metric tons, and its total electrical power consumption is 60,298 kilowatts. The work force builds up from an initial crew of 50 people to a peak of 160 workers during assembly. The component quality is assured during manufacturing and fabrication by ultrasonic and eddy current inspection techniques. Samples are also sent to Earth for proof testing. The structure is reinspected after assembly with the same ultrasonic and eddy current techniques. To supplement these component inspections, the completed structure is also given two proof tests: overpressure and overspin. Any failures detected are repaired before the final installation of agriculture and inhabitants.

2.12 Towards the Sun (normal to the ecliptic plane) Mast Living quarters Cranes array shown) FIGURE 2.6: CONSTRUCTION SITE

2.13 II.6: SCHEDULING AND COSTS II.6.1: Schedule: The program schedule derived for the prototype space colony project falls rather naturally into four.divisions: research, development, and procurement; construction site setup; colony construction; and testing, spin-up, and interior finishing. Starting from program go-ahead, six years are spent in research and development of new systems, such as the colony structure and lunar electromagnetic launcher; and in procurement of vehicles and equipment necessary. The only orbital operations in this initial period consist of four space shuttle flights in program year 6, to assemble the orbital transfer and lunar landing vehicles. The next three years are spent assembling the construction and lunar material transport apparatus, with initial operational capability of the entire construction system at the end of program year 9. Actual colony construction takes five years, with proof testing in the first quarter of program year 15. The remainder of that year and the next are spent outfitting the interior and starting the ecosystem, resulting in overall colony completion at the end of program year 16. This schedule is illustrated in Figure 2.7. II.6.2: Costs: Costs are extrapolated on a system-by-system basis, based on cost information available on comparative systems already operational. Twenty-eight line items are identified, divided into research and development, production and procurement, and operations cost groups. Costing for each line item is done on a year-by-year basis. The overall prototype colony project is found to cost $64.5 billion, of which $13.7 billion are research and development costs, and $44.1 billion are operational costs. Application of a 10% discount rate results in a net future program value of $147.7 billion at completion. The cumulative discounted and undiscounted costs are presented in graphical form in Figure 2.8.


'2 3 ..... -,-< .Q ~ .µ Ill 0 u 150 140 130 120 110 100 90 80 70 60 so 40 30 20 10 2.15 1 2 3 4 5 6 7 8 9 10 1112 13 14 15 16 Program year FIGURE 2.8: YEARLY CUMULATIVE COST

III.l: THE COURSE 3.1 CHAPTER III THIS STUDY III.1.1: Course Announcement: The MIT Prototype Space Colony Study, whose results are presented in this report, was done as a course project for 16.86: Advanced Systems Engineering, offered by the Department of Aeronautics and Astronautics of the Massachusetts Institute of Technology under the supervision of Professor John F·. McCarthy, Jr., Director of MIT's Center for Space Research, and Dr. Oscar Orringer, Lecturer in the Department of Aeronautics and Astronautics. The following course announcement was posted on bulletin boards prior to registration for the course. 16.86 ADVANCED SYSTEMS ENGINEERING Design of a Space-Based Community Spring 1976 It has been suggested that space colonies could be built at stable points in the Earth/Moon/Sun systel'\. An artificial planetoid could be constructed from raw materials from the Moon or an asteroid. One concept of the planetoid would be a modular cylinder 16 miles long, and 4 miles wide, housing 10,000 people. It would be used to provide solar power for the F.arth and for manufacturing in space. The project this spring will be an engineering investigation of the design, fabrication, and test of such a space-based community. Design requirements and system specifications will be derived from space-colonization concepts which have been suggested by various investigators. A derivative of the space shuttle system will be assumed for transportation. Emphasis will be placed on the engineering aspects of the space-based community itself culminating in a master plan for its development including engineering tradeoffs and economic considerations. Technical aspects of the study will be supported by lectures given by staff specialists and guest lecturers. The project will be a team effort, but the students will form into groups by task and specific technical areas. Tasks will be considered in parallel and iterated to obtain feasible system approaches. A final report will be prepared. Each student will contribute according to his/her interest and assignment. Grading will be on the basis of net value to the project and effort expended. JOHN F. McCARTHY, JR. Professor in Charge