Development and Definition of a CubeSat Demonstrator for a Water Propulsion System Entwicklung und Definition eines CubeSat Demonstrators für ein Water Propulsion Antriebssystem Master Thesis of cand. aer Colum Walter IRS-20-S-046 Supervisors: Prof. Dr. Stefan Schlechtriem M.Sc. Marius Wilhelm M.Sc. Malte Wurdak Institute of Space Systems, University of Stuttgart January 2021 Abstract ArianeGroup is currently developing the innovative semi-electric Water Propulsion System (WPS) based on the in-orbit production of the propellants, hydrogen and oxygen, by a polymer electrolyte membrane (PEM) electrolyzer. The propulsion system is composed of new technologies and components that shall be tested in their operational environment to verify their functionality in space. Therefore, a demonstrator system concept is developed which shall be tested on a CubeSat platform. An examination of the current developments of the WPS is performed in the first step followed by a description of the CubeSat mission by a project breakdown structure and a design and development plan for the Demonstrator Water Propulsion System (DWPS). The outcomes hereof combined with the results of a literature study on suitable CubeSat platforms result in the definition of technical requirements on the demonstrator system. These technical requirements form the foundation for the development of a concept of the DWPS which is analyzed by a Matlab calculation on the behavior of the gases produced by the electrolyzer. For the demonstrator propulsion system, a preliminary mission is defined in a last step. It provides an overview of the expected performance of the system, reviews orbit and launch possibilities and defines the operational procedure in space. Furthermore, a link budget is calculated that gives the data rate transmittable during a ground station flyby of the CubeSat. IV Table of Contents TASK DESCRIPTION ...................................................................................................................................... II AFFIDAVIT .................................................................................................................................................. III ABSTRACT ................................................................................................................................................. IV TABLE OF CONTENTS .................................................................................................................................. V LIST OF SYMBOLS ..................................................................................................................................... VII LIST OF FIGURES ..........................................................................................................................................X LIST OF TABLES ..........................................................................................................................................XII ABBREVIATIONS ...................................................................................................................................... XIV 1 INTRODUCTION .................................................................................................................................. 1 2 BACKGROUND & STATE OF THE ART ................................................................................................... 2 2.1 WATER PROPULSION SYSTEM STATE OF THE ART ......................................................................................... 2 2.1.1 Electrolyzer & Electrolyzer Control Unit ....................................................................................... 2 2.1.2 Thruster ........................................................................................................................................ 4 2.1.3 Current Development Status ........................................................................................................ 6 2.2 CUBESAT TECHNOLOGY DEMONSTRATION .................................................................................................. 8 2.3 CUBESAT PROPULSION SYSTEMS ............................................................................................................ 12 2.3.1 Solid Propellant .......................................................................................................................... 12 2.3.2 Mono-propellant ........................................................................................................................ 12 2.3.3 Bi-propellant ............................................................................................................................... 14 2.3.4 Overview..................................................................................................................................... 15 3 CUBESAT PLATFORM FOR THE IN-ORBIT TECHNOLOGY DEMONSTRATION ....................................... 16 3.1 CUBESATS – GENERAL COMPOSITION ...................................................................................................... 16 3.1.1 Dispenser .................................................................................................................................... 16 3.1.2 CubeSat Subsystems ................................................................................................................... 17 3.2 CUBESAT PLATFORMS .......................................................................................................................... 24 3.2.1 CubeSat Platform Requirements ................................................................................................ 24 3.2.2 ISIS .............................................................................................................................................. 26 3.2.3 NanoAvionics .............................................................................................................................. 27 3.2.4 GOMSpace .................................................................................................................................. 28 3.2.5 Conclusion .................................................................................................................................. 30 4 TECHNICAL REQUIREMENTS ON THE DWPS ...................................................................................... 31 4.1 FUNCTIONAL ANALYSIS ......................................................................................................................... 32 4.1.1 Functions .................................................................................................................................... 32 4.1.2 Constraints ................................................................................................................................. 33 4.2 GENERIC REQUIREMENTS ...................................................................................................................... 34 4.2.1 Mission Objective ....................................................................................................................... 34 4.2.2 General Design Requirements .................................................................................................... 34 4.3 TECHNICAL REQUIREMENTS - DWPS SYSTEM ........................................................................................... 38 4.3.1 Functional Performance Requirements ...................................................................................... 38 4.3.2 Design & Manufacturing Requirements ..................................................................................... 41 4.3.3 Environmental Requirements ..................................................................................................... 41 4.3.4 Interface Requirements .............................................................................................................. 43 4.3.5 Verification Requirements .......................................................................................................... 44 4.4 TECHNICAL REQUIREMENTS - THRUSTER .................................................................................................. 46 4.4.1 Functional Requirements ............................................................................................................ 46 4.4.2 Design & Manufacturing Requirements ..................................................................................... 48 4.4.3 Environmental Requirements ..................................................................................................... 49 V 4.4.4 Interface Requirements .............................................................................................................. 49 4.5 TECHNICAL REQUIREMENTS - WATER TANK ASSEMBLY ............................................................................... 50 4.5.1 Functional Performance Requirements ...................................................................................... 50 4.5.2 Design & Manufacturing Requirements ..................................................................................... 51 4.5.3 Environmental Requirements ..................................................................................................... 51 4.5.4 Interface Requirements .............................................................................................................. 51 4.6 TECHNICAL REQUIREMENTS - ELECTROLYZER AND GAS TANKS ASSEMBLY ......................................................