POLITECNICO DI TORINO Dipartimento di Ingegneria Meccanica e Aerospaziale Corso di Laurea Magistrale in Ingegneria Aerospaziale Tesi di Laurea Magistrale Lunar Nano Drone for a mission of exploration of lava tubes on the Moon: Navigation System Relatore Candidato Prof. Paolo Maggiore Gael Latiro Co-relatori Matricola Ing. Piero Messidoro 257622 Gen. Roberto Vittori Ing. Nicolas Bellomo Dicembre 2020 Acknowledgment There are many people whom I would like to thank for their contributions, both directly and indirectly, to this thesis. I would first to like to thank my supervisor prof Paolo Maggiore which allowed me to carry out this thesis and make contacts with leading figures in the sector. I also want to thank Eng. Piero Messidoro for his precious help both in terms of logistics and for the experience he shared with us. To Nicolas Bellomo who helped us enormously despite his constant commitment to work. Finally, I want to thank the astronaut as well as General Roberto Vittori for his precious help both as a reference and contact figure and as the creator of the project. To my parents and friends, in particular to my best friend Matteo Lertora who has always supported me and has always been there since I can remember. To my grandmother, who helped me a lot and unfortunately is no longer with us. To my aunt, my cousin and my girlfriend, who have always supported and helped me. I also want to thank my roommates who have accompanied me in these 5 years of university and have also been my colleagues for this thesis project. To all the people, whom I have not specifically mentioned, but who supported me and believed in me. Thank you all. Abstract On October 5th, 2017, USA Administration announced the USA President plan to return astronauts to the Moon. Looking to the long-term, NASA and several other space agencies are also intent on establishing a permanent lunar base there. This base will not only provide opportunities for lunar science but will also facilitate missions to Mars and beyond. The main question is, where should such a base be built? For many years, NASA, ESA and other agencies have been exploring the possibility of stable lava tubes as a potential site. According to new study by a team of international scientists, the presence of such a tube has now been confirmed in the Marius Hills region. This location is likely to be the site of future lunar missions and could even be the site of a future lunar habitat. This study aims to achieve the preliminary design of a Lunar drone and its mission feasibility, focusing mainly on the problem of navigation. The main purpose is to explore the lunar caves and to provide pictures of them, all taking into consideration the use, if possible, of Italian technologies that have directed many of the choices in the system design made to the detriment of a purely theoretical treatment. This thesis at first provides a purely theoretical overview of the systems used for autonomous navigation in an environment without GPS and in lack of lighting. Consequently, there is a discussion concerning the research for the components necessary for autonomous navigation. In particular, the two methods chosen: visual navigation and LiDAR, are then compared in terms of performance, masses, dimensions and energy consumption. The autonomous navigation inside tunnels is finally treated by focusing on the problems of maximum speed and lighting. Always taking into consideration the comparison in terms of masses, dimensions, consumption and performance of the two architectures taken into account. Finally, a discussion on the CAD of the individual components that will make up the drone is carried out in order to reach a possible configuration. 3 Index Figures .............................................................................................................................................................. 8 Tables .............................................................................................................................................................. 11 Nomenclature ................................................................................................................................................. 12 Applicable and reference documents ........................................................................................................... 13 1 Context and objectives of the study ...................................................................................................... 14 1.1 Mission statement and objectives ................................................................................................... 14 1.2 Observational evidence and characteristics of lunar lava tubes ..................................................... 15 1.3 State-of-the-art mission concepts ................................................................................................... 18 1.4 Challenges ........................................................................................................................................ 18 1.5 Summary .......................................................................................................................................... 19 1.6 Possibly supporting missions ........................................................................................................... 19 2 LuNaDrone mission design .................................................................................................................... 21 2.1 Mission overview ............................................................................................................................. 21 2.2 Spacecraft overview ........................................................................................................................ 25 3 Literature of the Navigation System ..................................................................................................... 27 3.1 SLAM ................................................................................................................................................ 27 3.2 Elements of vSLAM .......................................................................................................................... 28 3.2.1 Base Modules .............................................................................................................................. 28 3.2.2 Additional modules for stable and accurate vSLAM ................................................................... 28 3.2.3 Summary ...................................................................................................................................... 29 3.3 Related Technologies....................................................................................................................... 29 3.3.1 Visual odometry .......................................................................................................................... 29 3.3.2 Structure from motion ................................................................................................................ 30 3.3.3 MonoSLAM .................................................................................................................................. 30 3.3.4 PTAM ........................................................................................................................................... 30 3.3.5 Comparison between MonoSLAM and PTAM ............................................................................. 31 3.3.6 Techniques on global map optimization ..................................................................................... 31 3.3.7 Summary ...................................................................................................................................... 32 3.4 Direct methods ................................................................................................................................ 32 3.4.1 DTAM ........................................................................................................................................... 32 3.4.2 LSD-SLAM ..................................................................................................................................... 33 3.4.3 SVO and DSO ............................................................................................................................... 33 3.4.4 Summary ...................................................................................................................................... 33 3.4.5 RGB-D vSLAM ............................................................................................................................... 34 3.4.6 KinectFusion ................................................................................................................................ 34 3.4.7 Slam ++ ........................................................................................................................................ 34 3.4.8 Techniques on RGB-D VO and global map optimization ............................................................. 34 3.5 Open problems ................................................................................................................................ 35 4 3.5.1 Pure rotation ............................................................................................................................... 35 3.5.2 Map initialization ........................................................................................................................