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Breakthrough Propulsion Study Assessing Interstellar Flight Challenges and Prospects

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Breakthrough Propulsion Study Assessing Interstellar Flight Challenges and Prospects Breakthrough Propulsion Study Assessing Interstellar Flight Challenges and Prospects NASA Grant No. NNX17AE81G First Year Report Prepared by: Marc G. Millis, Jeff Greason, Rhonda Stevenson Tau Zero Foundation Business Office: 1053 East Third Avenue Broomfield, CO 80020 Prepared for: NASA Headquarters, Space Technology Mission Directorate (STMD) and NASA Innovative Advanced Concepts (NIAC) Washington, DC 20546 June 2018 Millis 2018 Grant NNX17AE81G_for_CR.docx pg 1 of 69 ABSTRACT Progress toward developing an evaluation process for interstellar propulsion and power options is described. The goal is to contrast the challenges, mission choices, and emerging prospects for propulsion and power, to identify which prospects might be more advantageous and under what circumstances, and to identify which technology details might have greater impacts. Unlike prior studies, the infrastructure expenses and prospects for breakthrough advances are included. This first year's focus is on determining the key questions to enable the analysis. Accordingly, a work breakdown structure to organize the information and associated list of variables is offered. A flow diagram of the basic analysis is presented, as well as more detailed methods to convert the performance measures of disparate propulsion methods into common measures of energy, mass, time, and power. Other methods for equitable comparisons include evaluating the prospects under the same assumptions of payload, mission trajectory, and available energy. Missions are divided into three eras of readiness (precursors, era of infrastructure, and era of breakthroughs) as a first step before proceeding to include comparisons of technology advancement rates. Final evaluation "figures of merit" are offered. Preliminary lists of mission architectures and propulsion prospects are provided. ACKNOWLEDGMENTS This work was supported by NASA under grant No. NNX17AE81G, under the direction of Dr. Jay Falker, Jason Derleth, and Dr. Mike LaPointe of NASA Headquarters. The authors would like to acknowledge their encouragement and support for this effort. Additional assistance came from Jim Gilland of the Ohio Aerospace Institute, Paul Gilster of the Tau Zero Foundation, Les Johnson of NASA, and the staff who helped run the 2017 Tennessee Valley Interstellar Workshop. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Aeronautics and Space Administration. pg 2 of 69 Millis 2018 Grant NNX17AE81G_for_CR.docx TABLE OF CONTENTS LIST OF TABLES .....................................................................................................................................5 LIST OF FIGURES....................................................................................................................................5 ACRONYMS ..............................................................................................................................................5 1. EXECUTIVE SUMMARY.................................................................................................................6 1.1. At-a-glance highlights in this report..............................................................................................6 1.2. Content by Section ...............................................................................................................................6 2. INTRODUCTION .............................................................................................................................8 2.1. Provocations..........................................................................................................................................8 2.2. Objective and Approach.....................................................................................................................9 2.2.1. Stage I – Defining the Problem as a Work Breakdown Structure (WBS).............................. 10 2.2.2. Stage II – Comprehensive Update to Interstellar Challenges & Prospects WBS ................ 11 2.2.3. Stage III – Remaining Analysis and Recommendations................................................................ 11 2.3. Outside Scope of Study .................................................................................................................... 11 3. PRIMER ON THE DISTINCTIONS OF INTERSTELLAR FLIGHT ......................................12 3.1. Distance................................................................................................................................................ 12 3.2. Timescales........................................................................................................................................... 15 3.3. Energy ................................................................................................................................................... 16 3.4. Infrastructure Dependence ........................................................................................................... 18 4. INTERSTELLAR TECHNOLOGY CHALLENGES (Top-DoWn)...........................................19 4.1. Payload Challenges........................................................................................................................... 19 4.2. Propulsion & Power Challenges................................................................................................... 20 4.3. Incremental and Affordable Infrastructure Creation........................................................... 21 5. PROPULSION & POWER PROSPECTS (Bottom-Up)..........................................................22 5.1. Historical Spacecraft Baselines.................................................................................................... 22 5.2. Proposed Interstellar Mission-Propulsion Architectures................................................... 23 5.3. Propulsion & Power Concepts ...................................................................................................... 24 5.4. 2017 Workshop RevieW.................................................................................................................. 27 6. PROPOSED WORK BREAKDOWN STRUCTURE (WBS) ...................................................28 6.1. WBS Hierarchical List...................................................................................................................... 28 6.2. Basic Analysis FloW Diagram ........................................................................................................ 29 6.3. List of Variables ................................................................................................................................. 31 7. MEASURING MISSION CHOICES (Top-DoWn) ....................................................................33 7.1. Destination.......................................................................................................................................... 33 7.2. Mission Ambition .............................................................................................................................. 33 7.2.1. Arrival Trajectory.......................................................................................................................................... 33 7.2.2. Science Sought ................................................................................................................................................ 34 7.3. Timing................................................................................................................................................... 35 7.4. Motive ................................................................................................................................................... 37 7.5. Figures of Merit.................................................................................................................................. 37 8. METHODS FOR EQUITABLE COMPARISONS ......................................................................39 8.1. Distinct Eras of Interstellar Flight............................................................................................... 39 8.1.1. Era of Precursors........................................................................................................................................... 39 Millis 2018 Grant NNX17AE81G_for_CR.docx pg 3 of 69 8.1.2. Era of Infrastructure .................................................................................................................................... 39 8.1.3. Era of Breakthroughs................................................................................................................................... 40 8.2. Baseline Mission & Payload Scenarios....................................................................................... 40 8.2.1. Solar Gravitational Lens ............................................................................................................................. 41 8.2.2. Deep Interstellar Medium.......................................................................................................................... 41 8.2.3. Centauri Flyby................................................................................................................................................. 41 8.2.4. Centauri Slower Flyby................................................................................................................................
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