Measurements made by the Voyager 2 spacecraft during its flyby of Uranus in 1986 found warm stratospheric and hot thermospheric temperatures that cannot be explained by solar heating alone. This contributes to what has become known as the “giant planet energy crisis”: there is a fundamental lack of understanding of the energy balance of the giant planets in the solar system. Uranus has the coldest stratospheric temperatures, the hottest thermospheric temperatures at some altitudes, and yet the weakest internal heat flux of all four giant planets. Moreover, the Voyager 2 temperature profiles are at odds with the many contemporaneous Earth-based stellar occultation observations. This unresolved tension impedes efforts to compare atmospheres in the solar system to one another and to exoplanet atmospheres. In this dissertation, I present an investigation into the upper atmospheric temperatures of Uranus using archival Earth-based stellar occultation observations. I begin with an overview of planetary atmospheres and remote-sensing measurements of Uranus in Chapter 1. In Chapter 2, I derive and explain how stellar occultations are predicted, observed, processed, and analyzed, emphasizing my contributions. Chapter 3 describes how I validated these techniques on an archival Mars occultation. In Chapter 4, I present the results of comparing the Voyager 2 measurements to 26 archival Earth-based stellar occultations by Uranus. In Chapter 5, I present new temperature profiles from reprocessing these 26 occultations and a new one-dimensional atmospheric model based thereon. Chapter 6 outlines a low-Earth orbit mission concept to observe many new stellar occultations. Chapter 7 contains conclusions and summaries. My primary finding is that the lower thermosphere of Uranus is much cooler than reported by Voyager 2. I find that the mesopause is likely higher in altitude than previously believed and the stratosphere of Uranus has a nearly isothermal section, in alignment with the other giant planets. My new atmospheric model suggests Uranus has a significant source of heat dissipation in the stratosphere, which might be supplied by gravity waves. This work can contribute to planning for any Uranus Orbiter and Probe mission by helping to revise Uranus’ representative temperature profile and improving our understanding of Uranus’ energy balance.

La thèse porte sur le rôle de la rotation planétaire dans la structure globale de l'interaction vent solaire/magnétosphère à partir de simulations magnétohydrodynamiques (MHD). Les magnétosphères planétaires du système solaire présentent une incroyable diversité, et notamment dans leurs configurations respectives de l'inclinaison de leur axe magnétique par rapport à leur axe de rotation. La durée des périodes de rotation par rapport au temps de relaxation de chaque magnétosphère diffère aussi d'une planète à l'autre. On distingue ainsi les rotateurs lents (Mercure et la Terre), pour lesquels le temps de relaxation est plus court que la période de rotation, des rotateurs rapides (Jupiter, Saturne, Uranus et Neptune). Dans le cas du rotateur lent Mercure, on s'intéresse à l'influence des paramètres du vent solaire sur la structure globale du champ magnétique et de l'écoulement. En appui à la mission spatiale BepiColombo, nous présentons des simulations effectuées pour deux modèles différents de champ magnétique herméen. Nous détaillons le rôle des fronts d'onde MHD stationnaires, en particulier les fronts stationnaires de mode lent dans la magnétogaine. Saturne présente la particularité d'avoir un axe magnétique parfaitement aligné avec son axe de rotation. C'est donc un cas de rotateur rapide stationnaire, qui nous permet d'étudier la structure globale du champ magnétique et de l'écoulement pour différentes orientations de l'IMF, mais aussi pour différentes vitesses de rotation de la planète. Enfin, le cas d'une configuration quelconque, avec un grand angle entre l'axe magnétique et l'axe de rotation planétaire, est étudié en présence d'un vent solaire magnétisé en s'inspirant de la configuration d'Uranus au solstice et à l'équinoxe. Dans la configuration « solstice », c'est à dire lorsque l'axe de rotation pointe vers le Soleil, on montre qu'une structure de nature alfvénique se développe en hélice dans la queue de la magnétosphère, et que les zones de reconnexion entre le champ magnétique planétaire et l'IMF, qui forment aussi une double hélice, ralentissent la progression de la structure alfvénique. A l'équinoxe, lorsque l'axe de rotation est toujours dans le plan de l’écliptique mais perpendiculaire à la direction Soleil-Uranus, la structure en hélice disparaît. / The topic of the thesis is the part of planetary rotation in the global structure of the solar wind interaction with planetary magnetospheres using MHD simulations. We discuss the distinction between slow and fast rotators from a MHD point of view. In the case of a non-rotating magnetosphere (as is the one of Mercury), the part of standing MHD modes is studied, along with a method to identify them in simulations. A fast-rotating but stationary magnetosphere (inspired by the case of Saturn) is presented in details and provides a good test to validate the new version of the AMRVAC code allowing for any configuration regarding the respective directions of the planetary spin axis, planetary magnetic axis, solar wind inflow direction, and IMF orientation. Finally, a random configuration, with a large angle between the planetary spin and magnetic axis, is analyzed for the first time in presence of a magnetized solar wind, using configurations inspired from the planet Uranus at solstice and equinox.

Project Upsilon is a proposed NASA Flagship Class, Uranus Orbiter and Probe mission concept to investigate Uranus' planetary magnetic field and atmosphere. Three spacecraft - the Upsilon-0 Propulsion Module, the Upsilon-1 Science Orbiter, and the Upsilon-2 Atmosphere Probe - shall be implemented to meet needs, goals, and objectives as stated by the NASA Solar System Planetary Science Decadal Survey 2013-2022. Upsilon-0 shall be expended in order to complete orbital capture about Uranus. Upsilon-1 shall study Uranus' planetary magnetic field, obtaining real-time measurements for nominally 20 months within the first two years of arrival; and for as long as possible after the first two years, as part of an extended science mission. Upsilon-2 shall be descended into Uranus' cloud tops to obtain physical data and imagery well into the atmosphere's depths. Chemical propulsion is employed in place of solar-electric propulsion, with regard to the interplanetary system-level trade tree. The interplanetary trajectory requires a single un-powered flyby of Jupiter, selected among several flyby node configurations. The science orbit produces nearly repeating latitude-longitude tracks over a rotating Uranus. The statistical estimation method combines an orbit determination model with respect to Uranus' flattening, and a simple magnetic dipole model for field line modeling. A 7-year period is allotted for the technology research and development, and the testing and verification stages of the project life cycle; the interplanetary journey to Uranus requires 21 years; and the nominal in-situ operation lifetime is 2 years. The Project Upsilon spacecraft launch in 2021 to "revolutionize our understanding of ice giant properties and processes, yielding significant insight into their evolutionary history"; contributing to the Planetary Science Decadal Survey's, and NASA's, key planetary science and deep space exploration visions. / text

Submitted by Andre Amarante Luiz null (amarante@feg.unesp.br) on 2018-02-11T19:52:31Z No. of bitstreams: 1 A_Amarante__O_C_Winter__M_Tsuchida.pdf: 9049058 bytes, checksum: a87f695e2060e08b5657bf5c4106d282 (MD5) / Approved for entry into archive by Pamella Benevides Gonçalves null (pamella@feg.unesp.br) on 2018-02-14T10:49:37Z (GMT) No. of bitstreams: 1 amarante_a_dr_guara.pdf: 9049058 bytes, checksum: a87f695e2060e08b5657bf5c4106d282 (MD5) / Made available in DSpace on 2018-02-14T10:49:37Z (GMT). No. of bitstreams: 1 amarante_a_dr_guara.pdf: 9049058 bytes, checksum: a87f695e2060e08b5657bf5c4106d282 (MD5) Previous issue date: 2017-09-19 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A origem e estabilidade de satélites planetários estão, intimamente ligadas à origem do nosso Sistema Solar e à formação de planetas. Portanto, é apropriado estudar alguns casos peculiares para nossa compreensão atual sobre a formação do Sistema Solar e para entender a criação dos sistemas de satélites. Tendo isso em vista um estudo da estabilidade dos satélites internos de Urano é realizado procurando viabilizar um cenário estável para tal sistema. Nós encontramos um provável cenário que possa nos dar indícios de que o sistema de satélites internos de Urano possa ser estável. Outro cenário importante para compreender a formação de satélite é o estudo de nosso próprio satélite natural, a Lua. O estudo da origem a Lua é realizado através de uma rápida revisão bibliográfica das teorias de origem da Lua e com isso tentamos analisar qual seria o cenário mais provável de colisão dentro da teoria do Grande Impacto que favorece a formação do nosso satélite, levando em conta suas características físicas, químicas e petrológicas. O cenário mais provável foi aquele em que colisões com massas comparáveis são usadas para se originar a Lua. O estudo da estabilidade de coorbitais dos pequenos satélites do sistema binário Plutão-Caronte é importante visto que também é um caso de cenário de formação de satélites peculiares no Sistema Solar. O estudo dessa estabilidade nos levou a indícios de que o sistema não possui coorbitais à suas pequenas luas, fato comprovado até agora pela missão New Horizons. / The origin and stability of planetary satellites are closely linked to the origin of our Solar System and the formation of planets. Therefore, it is appropriate to study some peculiar cases to our current understanding of the formation of the Solar System and to understand the origin of satellite systems. In order to study the stability of the internal satellites of Uranus, in order to provide a stable scenario for such a system. We have found a probable scenario that allows the internal uranian system get stable. Another important scenario for the formation of satellites is the moon scenario. The study of the origin of the Moon is made through a revised bibliographical revision of the theories of origin of the Moon and with this we try to analyze which forming the most probable collision within the theory of Great Impact that favors a formation of our satellite, taking into account its physical, chemical and petrological characteristics. The most likely scenario was that collisions with comparable masses are used to originate the Moon. The study of coorbital stability of the small satellites of the Pluto-Charon binary system is important since it is also a case of a peculiar satellite formation scenario in Our Solar System. The study of stability has led us to evidence that the system is not coorbitary in its small moons, a fact proven so far by the New Horizons mission

The Thesis objective is the design and implementation of the universal control system for a flying robot, quadrotor concept. The first part deals with ways of solving program for microcontrollers. The special attention is given to the FreeRTOS real-time operating system, which is designed for microcontrollers. The second part of the Thesis is focused on the description of the chosen microcontroller LM3S8962 and the hardware solution. One chapter is devoted to the integration of the robot to the Cassandra-WPF robotic control system. The third part deals with the identification of the new robot construction and the mathematical model creation. Using the model controllers for stabilization pitch and roll are designed and their functionality is verified on a physical model. The last part of the Thesis is focused on the FreeRTOS implementation and the control application creation.

No description available.

The ice giants, Uranus and Neptune, are the two outermost planets in our solar system. With only one satellite flyby each in the late 1980’s, the ice giants are arguably the least understood of the planets orbiting the Sun. A better understanding of these planets’ atmospheres will not only help satisfy the natural scientific curiosity we have about these distant spheres of gas, but also might provide insight into the dynamics and meteorology of our own planet’s atmosphere. Two new ground-based, near-infrared datasets of the ice giants are studied. Both datasets provide data in a portion of the electromagnetic spectrum that provides good constraint on the size of small scattering particles in the atmospheres’ clouds and haze layers. The broad extent of both telescopes’ spectral coverage allows characterisation of these small particles for a wide range of wavelengths. Both datasets also provide coverage of the 825 nm collision-induced hydrogen-absorption feature, allowing us to disentangle the latitudinal variation of CH4 abundance from the height and vertical extent of clouds in the upper troposphere. A two-cloud model is successfully fitted to IRTF SpeX Uranus data, parameterising both clouds with base altitude, fractional scale height, and total opacity. An optically thick, vertically thin cloud with a base pressure of 1.6 bar, tallest in the midlatitudes, shows strong preference for scattering particles of 1.35 μm radii. Above this cloud lies an optically thin, vertically extended haze extending upward from 1.0 bar and consistent with particles of 0.10 μm radii. An equatorial enrichment of methane abundance and a lower cloud of constant vertical thickness was shown to exist using two independent methods of analysis. Data from Palomar SWIFT of three different latitude regions.

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The giant planets exhibit banded zonal jet streams that have maintained theirstructures over decades. There are long-standing questions: how deep the windstructures extend? What mechanisms generate and maintain the observed winds?Why are the wind structures so stable? To answer these questions, we performedthree-dimensional numerical simulations of the atmospheric flow using the primitiveequations.First, we use a simple Newtonian cooling scheme as a crude approach to gener-ate atmospheric latitudinal temperature differences that could be caused by latentheating or radiation. Our Jupiter-like simulations show that shallow thermal forcingconfined to pressures near the cloud tops can produce deep zonal winds from thetropopause all the way down to the bottom of the simulated atmosphere (a fewhundred bars). These deep winds can attain speeds comparable to the zonal jetspeeds within the shallow, forced layer; they are pumped by Coriolis accelerationacting on a deep meridional circulation driven by the shallow-layer eddies.Next, we explicitly include the transport of water vapor and allow condensationand latent heating to occur whenever the water vapor is supersaturated. Our simu-lations show that large-scale moist convection associated with condensation of watervapor can produce multiple zonal jets similar to those on the gas giants (Jupiterand Saturn) and ice giants (Uranus and Neptune). For plausible water abundances(3-5 times solar on Jupiter/Saturn and 30 times solar on Uranus/Neptune), oursimulations produce about 20 zonal jets for Jupiter and Saturn and 3 zonal jetson Uranus and Neptune. Moreover, these Jupiter/Saturn cases produce equatorialsuperrotation whereas the Uranus/Neptune cases produce equatorial subrotation,consistent with the observed equatorial jet direction on these planets. Sensitiv-ity tests show that the water abundance is the controlling factor; modest waterabundances favor equatorial superrotation, whereas large water abundances favorequatorial subrotation. This provides a possible mechanism for the existence ofequatorial superrotation on Jupiter and Saturn and the lack of superrotation onUranus and Neptune.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23007号 / 理博第4684号 / 新制||理||1672(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 嶺重 慎, 准教授 前田 啓一, 教授 太田 耕司 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM