CRANFIELD UNIVERSITY William Easdown Mission ORCA: Orbit Refinement for Collision Avoidance School of Aerospace, Transport and Manufacturing Astronautics and Space Engineering MSc Academic Year: 2019 - 2020 Supervisor: Dr Leonard Felicetti March 2020 CRANFIELD UNIVERSITY School of Aerospace, Transport and Manufacturing Astronautics and Space Engineering MSc Academic Year 2019 - 2020 William Easdown Mission ORCA: Orbit Refinement for Collision Avoidance Supervisor: Dr Leonard Felicetti March 2020 This report is submitted in partial (30%) fulfilment of the requirements for the degree of Astronautics and Space Engineering © Cranfield University 2020. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright owner. William Easdown ABSTRACT The likelihood of collisions between resident space objects (RSOs) is continuously increasing, driven by spacecraft fragmentations, collisions and the increasing use of ‘mega-constellations’. This report details a space-based system proposed to address the need for space situational awareness to combat this issue. System requirements were defined based on literature review and the consideration of dependencies between spacecraft subsystems. Trade-offs during the mission design included a pivot from space debris surveillance to space traffic management, with the final mission concept supplying end users with state vectors for objects at risk of collision with their spacecraft. This switch enabled the design of the constellation, which uses a constellation of 32 12 U CubeSats, providing coverage of SSO and wider LEO between altitudes of 800 and 1400 km. This altitude range was chosen because it was found after a literature review to be most at risk from collisions. A constellation model was created in STK to allow detailed analysis of coverage and ground station passes. Spacecraft operational modes have been defined for the full mission lifetime, with payload operational modes being defined separately. These were included in a Concept of Operations (CONOPS) document used throughout the project. Areas of future development will include risk analysis, validation of component selections, and detailed design of the payload hardware and software. These will all be completed before the system Critical Design Review. Keywords: Space debris surveillance, space traffic management, space situational awareness, resident space objects, constellation, CubeSat i William Easdown Figure 0-1 - Mission ORCA logo ii William Easdown ACKNOWLEDGEMENTS I would like to thank Dr Leonard Felicetti for his supervision during this project. I would also like to thank my fellow ORCA team members for their hard work throughout the project and for the way they successfully adapted to the 2020 COVID-19 pandemic. iii William Easdown TABLE OF CONTENTS ABSTRACT ......................................................................................................... i ACKNOWLEDGEMENTS................................................................................... iii LIST OF FIGURES ............................................................................................ vii LIST OF TABLES ............................................................................................... ix LIST OF ABBREVIATIONS ................................................................................ x 1 Introduction ...................................................................................................... 1 1.1 Project Background................................................................................... 1 1.2 Brief .......................................................................................................... 7 1.3 Current State of the Art ............................................................................. 7 1.4 Business Case .......................................................................................... 8 2 Project Management ....................................................................................... 9 2.1 Team Structure ......................................................................................... 9 2.2 Meetings ................................................................................................. 10 2.3 Tools ....................................................................................................... 11 2.3.1 Slack ................................................................................................ 11 2.3.2 Trello ................................................................................................ 13 2.4 Documentation ........................................................................................ 14 2.4.1 OneDrive .......................................................................................... 14 2.4.2 File naming convention .................................................................... 16 2.4.3 Minutes ............................................................................................. 16 2.4.4 Master Central Control spreadsheet................................................. 17 2.4.5 European Space Agency (ESA) Open Concurrent Design Tool (OCDT)...................................................................................................... 18 2.4.6 Concept of Operations (CONOPS) document .................................. 19 3 Requirements Definition ................................................................................ 20 3.1 Requirements from original Brief ............................................................ 20 3.2 Debris environment research .................................................................. 21 3.3 System Requirements spreadsheet ........................................................ 22 4 Baseline Generation ...................................................................................... 23 4.1 Payload and bus trade-off ....................................................................... 23 4.2 Mission Type Trade-Off .......................................................................... 25 4.3 Current Baseline ..................................................................................... 27 4.3.1 Constellation Design ........................................................................ 27 4.3.2 Ground Segment .............................................................................. 27 4.3.3 Individual ORCA Spacecraft ............................................................. 28 5 Constellation Design ..................................................................................... 29 5.1 Constellation Requirements .................................................................... 29 5.2 Constellation Design Process ................................................................. 29 5.3 STK Model .............................................................................................. 32 v William Easdown 5.3.1 Model Limitations ............................................................................. 33 5.4 Final Constellation Design ...................................................................... 33 6 Mission Operations ........................................................................................ 35 6.1 Operations Requirements ....................................................................... 35 6.2 Operational Modes.................................................................................. 36 6.3 Ground Segment..................................................................................... 38 6.4 Mission Timeline ..................................................................................... 40 7 Other Contributions ....................................................................................... 41 7.1 CubeSat Deployer Trade-Off .................................................................. 41 8 Areas for Future Development ...................................................................... 43 8.1 Detailed payload hardware and software design .................................... 43 8.2 Completion of CONOPS ......................................................................... 43 8.3 Radiation analysis ................................................................................... 44 8.4 Detailed spacecraft failure modelling ...................................................... 45 8.5 Deployment vehicle evaluation ............................................................... 45 8.6 Star tracking mounting accuracy impact analysis ................................... 46 8.7 Full project costing .................................................................................. 46 8.8 Requirement validation and system verification ...................................... 47 9 Conclusion ..................................................................................................... 49 REFERENCES ................................................................................................. 50 APPENDICES .................................................................................................. 63 Appendix A Executive Summary: Mission ORCA: Orbit Refinement for Collision Avoidance ...................................................................................... 64 Appendix B Common Appendix .................................................................... 67 Appendix C Requirements ...........................................................................