MIT Project Apophis: The SET Mission Design Document 12.43/16.83 Space Systems Engineering May 18th, 2017 SET Mission Study Participants Students Andrew Adams Dylan Cohen Carlos Cruz Alissa Earle David Fellows Joseph Figura Roman Geykhman Justin Gong Jonas Gonzalez Paulo Heredia Nicholas James Diego Mundo Ellie Simonson Jeremy Stroming Max Vanatta Amy Vanderhout Emily Widder Tori Wuthrich Jim Clark Instructors Richard P. Binzel David Miller Jennifer Craig Jane Connor Christopher Jewison We would like to thank the many consultants who have patiently answered questions and provided valuable input and feedback over the semester: Farah Alibay (JPL) Cateline Lantz (MIT) Thomas Burbine (UMass) Rebecca Masterson (MIT) Dennis Burianek (MIT/LL) Jeff Mendenhall (MIT/LL) Mark Chodas (MIT) Ryan Park (JPL) Paul Chodas (JPL) Tom Roberts (JPL) Emily Clements (MIT) Christopher Semisch (MIT/LL) Mitch Ingham (JPL) Ellen Stofan (NASA) Lindley Johnson (NASA) Scott Uebelhart (MIT) Laura Kerber (JPL) Ryan Webb (JPL) Javier de Luis (Aurora) Dirk Zwemer (Intercax) 2 Contents Foreword 9 Executive Summary 10 0.1 Scientific Motivation . 10 0.2 Mission Objectives . 11 0.3 Science Payload . 11 0.3.1 LOng Range Reconnaissance Imager (LORRI) . 12 0.3.2 Ralph . 12 0.3.3 Radio Reflection Tomography Instrument (RRT) . 12 0.3.4 Thermal Emission Spectrometer (TES) . 12 0.4 Spacecraft . 12 0.5 Concept of Operations . 14 0.6 Conclusions . 14 1 Introduction & Systems Overview 15 1.1 Introduction . 15 1.1.1 Scientific Motivation . 15 1.1.2 Mission Objectives and Rationale . 16 1.1.3 Concept of Operations (CONOPS) . 17 1.2 Systems Overview . 20 1.2.1 System Requirements . 20 1.2.2 Model Based Systems Engineering (MBSE) Effort . 20 1.2.3 Block Diagrams . 22 2 Launch, Navigation, and Attitude Control 25 2.1 Subsystem Requirements . 25 2.2 Launch Vehicle . 26 2.2.1 Launch Time and Location . 28 2.3 Propulsion System . 30 2.3.1 Trades, Downselect, and Rationale . 30 2.4 Trajectory . 36 2.4.1 Planetary Safety Considerations . 36 2.4.2 Trajectory Trade Space . 37 2.4.3 End-to-End Solar-Electric Trajectory . 40 2.4.4 Station-Keeping . 50 2.5 Rendezvous and Post-encounter Maneuvers . 53 3 Instrumentation 55 3.1 Overview of Requirements . 55 3.2 Instrument Trade Space . 56 3.3 Final Instrument Choices . 59 3.3.1 Ralph . 60 3.3.2 LORRI . 63 3.3.3 RRT . 63 3.3.4 TES . 66 3.4 Instrumentation Subsystem Risks . 66 3.5 Derived Requirements . 68 1 4 Communications and Data 70 4.1 Overview of Sub-System Requirements . 70 4.2 Summary of Subsystem . 71 4.3 Data Budget . 71 4.4 Trades, Downselect, and Rationale . 72 4.4.1 Frequency band Trade . 72 4.4.2 Selected Bands and Frequencies . 73 4.4.3 Pre-Processing Discussion . 74 4.5 Spacecraft Hardware Design . 74 4.5.1 Spacecraft Hardware Overview . 74 4.5.2 Data Storage . 76 4.5.3 Redundancy . 76 4.6 Ground Stations . 76 4.6.1 Deep Space . 76 4.6.2 Near Earth . 78 4.7 Coding . 78 4.8 Link Budgets . 79 4.8.1 Link Budget Methodology . 79 4.8.2 X-band High Gain Downlink, Maximum Distance . 80 4.8.3 X-band High Gain Uplink, Maximum Distance . 81 4.8.4 X-band Low Gain Downlink, During Earth Flyby . 82 4.8.5 X-band Low Gain Downlink, Maximum Distance . 83 4.9 Downlink Planning . 84 4.9.1 Downlink Data Rate . 84 4.9.2 Downlink Schedule . 84 4.10 Tracking . 85 4.11 Subsystem Risks . 86 5 Spacecraft Bus 88 5.1 Overview of Requirements . 88 5.2 Spacecraft Bus Trade Space . 88 5.2.1 Commercial-off-the-shelf (COTS) vs. Custom bus . 88 5.2.2 Choice of Bus . 89 5.3 Technical Characteristics . 90 5.3.1 Bus Characteristics . 90 5.3.2 Fuel System Changes . 93 5.3.3 Pointing System . 93 5.3.4 Thermal Control System . 94 5.3.5 Power System . 99 5.3.6 CAD Model . 101 5.4 Testing Requirements . 102 5.4.1 Maximum Load . 103 5.4.2 Thermal Control . 103 5.4.3 Powering Components . 104 5.5 SWaP Budget . 104 5.6 Subsystem Risks . 105 6 System-Level Summary 109 6.1 Consolidated SWaP Budget . ..