Planetary Radio Interferometry and Doppler

Delft University of Technology Planetary Radio Interferometry and Doppler Experiment (PRIDE) for radio occultation studies A Venus Express test case Bocanegra Bahamon, Tatiana DOI 10.4233/uuid:738b9b01-d130-4ae4-bc51-c989824a8760 Publication date 2019 Document Version Final published version Citation (APA) Bocanegra Bahamon, T. (2019). Planetary Radio Interferometry and Doppler Experiment (PRIDE) for radio occultation studies: A Venus Express test case. https://doi.org/10.4233/uuid:738b9b01-d130-4ae4-bc51- c989824a8760 Important note To cite this publication, please use the final published version (if applicable). Please check the document version above. Copyright Other than for strictly personal use, it is not permitted to download, forward or distribute the text or part of it, without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license such as Creative Commons. Takedown policy Please contact us and provide details if you believe this document breaches copyrights. We will remove access to the work immediately and investigate your claim. This work is downloaded from Delft University of Technology. For technical reasons the number of authors shown on this cover page is limited to a maximum of 10. Planetary Radio Interferometry and Doppler Experiment (PRIDE) for radio occultation studies A Venus Express test case Planetary Radio Interferometry and Doppler Experiment (PRIDE) for radio occultation studies A Venus Express test case Proefschrift ter verkrijging van de graad van doctor aan de Technische Universiteit Delft, op gezag van de Rector Magnificus Prof.Dr.Ir. T.H.J.J. van der Hagen, voorzitter van het College voor Promoties, in het openbaar te verdedigen op dinsdag 19 maart 2019 om 10:00 uur door Tatiana Marcela BOCANEGRA BAHAMÓN Ingenieur Luchtvaart en Ruimtevaart, Technische Universiteit Delft, Nederland, geboren te Bogotá, Colombia This dissertation has been approved by the: promotor: Prof.Dr. L.L.A. Vermeersen promotor: Prof.Dr. L.I. Gurvits Composition of the doctoral committee: Rector Magnificus chairperson Prof.Dr. L.L.A. Vermeersen Technische Universiteit Delft Prof.Dr. L.I. Gurvits Joint Institute for VLBI ERIC (JIVE) and Technische Universiteit Delft Independent members: Prof.Dr. C. Jackson ASTRON Prof.Dr. V. Dehant Royal Observatory of Belgium Prof.Dr.-Ing.Habil. R. Klees Technische Universiteit Delft Dr. D.V. Titov ESA-ESTEC Dr.Ir. D. Dirkx Technische Universiteit Delft Prof.Dr.Ir. P.N.A.M. Visser Technische Universiteit Delft (reserve member) The work presented in this dissertation was performed with support from the NWO (GBE) project 614.011.501 on Dutch-Chinese cooperation in Very Long Baseline In- terferometry, implemented by the Joint Institute for VLBI European Research Infras- tructure Consortium and Shanghai Astronomical Observatory of the Chinese Academy of Sciences. Keywords: Doppler and VLBI spacecraft tracking, planetary missions, radio science applications, radio occultation, planetary atmospheres. Printed by: Ridderprint. Front & Back: Schematic representation of a radio occultation experiment with Venus Express orbiter conducted with radio telescopes on Earth. Image copyright: ESA (Venus Express), JAXA/ISAS/DARTS/Damia Bouic (Venus) and Harm-Jan Stiepel/ASTRON (Westerbork). Copyright © 2019 T.M. Bocanegra Bahamón ISBN 978-94-6375-341-8 An electronic version of this dissertation is available at http://repository.tudelft.nl/ Contents Preface ix Summary xiii References. xvii Samenvatting xix References. xxiii 1 Introduction 1 1.1 Thesis goal and research questions . 3 References. 5 2 Introduction to Radio Interferometric Techniques for Spacecraft Tracking 9 2.1 Introduction to VLBI . 12 2.1.1 Technical implementation of VLBI. 13 2.1.2 Mathematical treatment of VLBI . 15 2.2 VLBI measurement techniques for spacecraft tracking . 19 2.2.1 Involvement of the VLBI networks in spacecraft tracking . 21 References. 25 3 Description of the PRIDE technique: signal processing pipeline and analysis methodology 27 3.1 Experiment design, data acquisition and logistics . 29 3.2 Correlation. 33 3.2.1 Correlation of quasi-monochromatic electromagnetic ra- diation . 33 3.2.2 Baseband conversion and sampling. 34 3.2.3 Geometrical delay compensation and fractional delay error correction . 35 3.2.4 Cross-correlation and normalization . 36 3.2.5 JIVE’s software correlator SFXC . 36 v vi Contents 3.2.6 Delay models . 37 3.3 Broadband reference source signal processing . 43 3.3.1 Data Processing Path in AIPS . 45 3.4 Narrowband spacecraft signal processing . 51 3.4.1 Software spectrometer (SWSpec). 52 3.4.2 Phase-stop polynomial fit . 53 3.4.3 Spacecraft multi-tone tracking . 53 3.4.4 Digital Phase-Locked Loop . 54 3.4.5 Phase delay of the carrier line . 54 3.5 Broadband correlation of the spacecraft signal: group delay estimation . 55 3.6 Phase-referencing and estimation of the spacecraft angular po- sition corrections . 56 3.6.1 Imaging . 57 3.6.2 Solving the fundamental astrometric equation . 57 References. 58 4 On the performance of the Doppler component of PRIDE 61 1 Introduction . 63 2 PRIDE Doppler observables. 66 2.1 Observed values of the Doppler observables . 66 2.2 Computed values of the Doppler observables . 68 3 MEX Phobos Flyby: GR035 experiment . 72 3.1 Instrumental noise . 74 3.2 Medium propagation noise . 76 3.3 Noise budget for the Doppler detections of GR035 . 80 4 Conclusions . 81 5 Acknowledgements . 82 References. 82 5 Radio occultation experiments with PRIDE 87 1 Introduction . 90 2 The radio occultation experiment . 91 2.1 Theoretical background and approximations . 92 2.2 Observation model . 92 2.3 Relation to atmospheric properties . 95 3 PRIDE as an instrument for radio occultation studies: a test case with Venus Express . 97 3.1 Observations and experimental setup . 98 3.2 Derived atmospheric profiles . 99 3.3 Error propagation analysis . 105 4 Conclusions . 112 5 Acknowledgements . 113 References. 114 Contents vii 6 Conclusions 119 1 Recommendations and outlook . 124 1.1 Calibrator sources in the ecliptic plane survey . 124 1.2 Improvements to the radio occultation software . 125 1.3 Preparations for radio occultation experiments with PRIDE- JUICE . 126 References. 127 Curriculum Vitæ 135 List of Publications 137 Preface The thesis that you are about to read deals with the implementation of a technique to study atmospheres of planets or moons in the Solar System. We use radio telescopes on Earth to track spacecraft that are orbiting planets, and use the signal the spacecraft emits, as it crosses the planet’s atmosphere, to investigate its physical characteristics. Amazing, isn’t it? Often, we get lost in our daily routines and we lose sight of the overall picture. We forget how truly astounding the experiments we are able to undertake are, using the universe as our lab. I feel very privileged to have been able to do this as part of the work that led to this dissertation. Looking back to my personal journey and to how it all started, I think of Ellie. Yes, I’m a kid of the 90s (85 rounds off to 90) influenced by American pop culture, and yes, I’m one of those who became obsessed with space because of the movie Contact. That, the series from the Earth to the Moon and a visit to the Kennedy Space Center sparked my interest. All of this was years before my first physics class, but already then it was clear to me that I wanted to pursue a career in space exploration. There are many wonderful people that helped me along in the process of moving from dreaming about space to being able to perform experiments with planetary spacecraft. First and foremost, I would like to thank my mentor and PhD supervisor Leonid Gurvits, the person who introduced me to this amazing field and the person who has constantly given me the opportunity, from my bachelor’s through to my PhD, to join multiple projects and broaden my research experience. Thank you very much for your guidance and support. I would also like to thank Bert Vermeersen, my master’s thesis supervisor and PhD promotor, for giving me the freedom and support to find a research topic to my interest, and for providing guidance throughout this process. Over these years it has been a pleasure to be able to work in different environ- ments, various countries, and among very intelligent and inspiring people. To my colleagues and friends from the group of Astrodynamics and Space Missions in the faculty of Aerospace Engineering at TUDelft, Boudewijn, Ejo (also my bachelor’s supervisor), Erwin, Ron, Marc, José, Eelco, Wim, Daphne, Kevin, Imke, Wouter, Loïc, Vidhya, Stephanie, Elisabetta, many thanks for the lively and stimulating working ix x Preface atmosphere. Special thanks to Relly for all the support and for ensuring everything runs smoothly in our department. To Pieter, for his support and very valuable input when reviewing my thesis. To Dominic, my friend, colleague and collaborator, I’ve always valued your opinion about my work very much, I have learnt a great deal from you. To Joao, for all the good advice and saving my thesis with Zambujeira. To my fellow PhD colleagues and friends, Bart, Hermes, Kartik, Guido, Mao, Black, Bas, Haiyang, Teresa, Günther, Jacco, Svenja, Tim, Gourav, Yuxin, for all the fun times inside and outside work. Certainly, we have a wide spectrum of unique and extraordinary characters among us. To Jinglang, my office-mate and dear friend, for all the great times we had together. To my second home institute JIVE and all the colleagues I had the pleasure to spend time with over the past years. Special thanks to Giuseppe, Guifré, Dima, Sergei and Dora, the Space Science and Innovative Appli- cations Group at JIVE, for giving me a fascinating first-hand experience with all the tracking experiments we conducted, all the knowledge you passed on to me and for your invaluable friendship.

Load more