D2.1 VLEO Aerodynamics Requirements Document Project acronym: DISCOVERER Grant Agreement: 737183 Project Duration: 1 January 2017 – 31 March 2021 (51 months) Version: 1.0 Date: 23/03/2018 WP Leader: Jonathan Becedas [DEIMOS] Authors: Gerardo González [DEIMOS] Rosa M. Domínguez [DEIMOS] Irene Vázquez [DEIMOS] Álvaro Braña [DEIMOS] Nicholas H. Crisp [UNIMAN] Jonathan Becedas [DEIMOS] Due date of deliverable 31/03/2018 Actual submission date 31/03/2018 Horizon 2020 DISCOVERER TABLE OF CONTENTS Acronyms and Abbreviations .................................................................................................................. 6 1. Introduction ...................................................................................................................................... 7 2. VLEO Aerodynamics ....................................................................................................................... 8 2.1. Principles of Orbital Aerodynamics ............................................................................................ 8 2.2. Aerodynamic Control ................................................................................................................ 10 2.2.1. Aerostability .................................................................................................................... 10 2.2.2. Aerodynamic Attitude Control Manoeuvres ................................................................... 14 2.2.3. Orbit Control ................................................................................................................... 16 2.2.4. Aeroassisted Manoeuvres ............................................................................................. 18 3. Aerodynamic Technologies ........................................................................................................... 20 3.1. Aerodynamic Geometries ......................................................................................................... 20 3.2. Materials ................................................................................................................................... 21 3.3. Application of Aerodynamic Technologies to Earth Observation ............................................. 22 4. Earth Observation Applications ..................................................................................................... 23 4.1. Benefits of VLEO ...................................................................................................................... 23 4.1.1. Increased Resolution of Optical Payloads ..................................................................... 23 4.1.2. Increased Radiometric Performance ............................................................................. 26 4.1.3. Increase in available launch mass ................................................................................. 26 4.1.4. Non disposal manoeuvre is required at EOL ................................................................. 27 4.1.5. Low risk of collision with space debris ........................................................................... 27 4.1.6. Increase of Geospatial Position Accuracy ..................................................................... 28 4.1.7. Disruptive Propellant Systems ....................................................................................... 28 4.1.8. Low Radiation Levels ..................................................................................................... 28 4.2. Challenges of flying in VLEO ................................................................................................... 29 4.2.1. Earth’s Atmosphere ....................................................................................................... 29 4.2.2. Communication Windows .............................................................................................. 30 4.2.3. Revisit Time ................................................................................................................... 30 4.3. EO Applications of VLEO ......................................................................................................... 31 5. Earth Observation Operations ....................................................................................................... 34 5.1. Mission concepts ...................................................................................................................... 34 5.1.1. Optical coverage concept .............................................................................................. 34 5.1.2. Optical VHR high performance concept ........................................................................ 36 5.1.3. Optical VHR low cost concept ........................................................................................ 38 5.1.4. Synthetic Aperture Radar (SAR) concept ...................................................................... 39 5.2. Orbit control operations ............................................................................................................ 43 5.2.1. Orbit maintenance .......................................................................................................... 43 5.2.2. Collision avoidance ........................................................................................................ 46 5.2.3. Nominal orbit insertion ................................................................................................... 46 5.2.4. Rephasing ...................................................................................................................... 47 D 2.1 Page 2 of 83 Horizon 2020 DISCOVERER 5.2.5. Deorbiting ....................................................................................................................... 47 5.3. Attitude control operations........................................................................................................ 47 5.3.1. Agility .............................................................................................................................. 48 5.3.2. Pointing accuracy ........................................................................................................... 49 5.3.3. Stability ........................................................................................................................... 49 5.3.4. Other control performances ........................................................................................... 49 5.4. Operations summary ................................................................................................................ 56 6. Analysis of EO with enhanced aerodynamics and technologies ................................................... 61 6.1. Applications for earth observation ............................................................................................ 61 6.2. Aerodynamic technologies applied to in orbit operations ......................................................... 63 6.2.1. Aerodynamic geometries ............................................................................................... 63 6.2.2. Materials ......................................................................................................................... 64 6.3. Enhanced aerodynamics and technologies performance ........................................................ 64 6.4. Aerodynamic technologies applied to the mission concepts.................................................... 66 7. Aerodynamic Requirements for EO Applications and Platform Concepts .................................... 69 8. Acknowledgement and disclaimer ................................................................................................. 75 9. References .................................................................................................................................... 76 10. Annex A: requirements management Manual and Tool ................................................................ 80 10.1. Acronyms.................................................................................................................................. 80 10.2. Introduction ............................................................................................................................... 80 10.3. Requirements Management Tools ........................................................................................... 80 10.3.1. Identification ................................................................................................................... 81 10.3.2. Selection ........................................................................................................................ 81 10.4. DISCOVERER requirements tool – Brief User’s manual ......................................................... 81 10.4.1. General view .................................................................................................................. 82 10.4.2. Requirement fields ......................................................................................................... 82 10.4.3. Other functionalities ....................................................................................................... 83 10.5. Conclusions .............................................................................................................................. 84 10.6. References ..............................................................................................................................