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Cambianica, Pamela (2019) Morphological and compositional analysis of boulder distributions on comet 67P/Churyumov-Gerasimenko. [Ph.D. thesis]

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Abstract (italian or english)

The European Space Agency's Rosetta mission consisted of the orbiter spacecraft Rosetta and the lander Philae. Launched in 2004, the space probe reached the comet 67P/Churyumov-Gerasimenko after a journey lasted more than ten years. The objectives of the mission were to map the comet, to study its composition, to investigate the chemical and thermal properties, and to monitor the activity during its journey in the inner Solar System. Rosetta was the first mission to rendezvous with a comet, and to deploy a lander on a comet's surface. From a wider prospective, the Rosetta mission allowed to investigate the origin of comets, and to define the implication for the origin of the Solar System. We used OSIRIS Narrow Angle Camera with a spatial scale smaller than 2 m=pixel to analyze the surface of comet 67P. The surface reveals a variety of terrains and geological features, suggesting to be a very active and complex environment. In the first part of the thesis, a detailed quantitative analysis of isolated boulder fields is provided. We used different techniques to supply a method for analyzing the morphology of the boulders, which represent one of the ubiquitous and most important geological features on the comet. In the second part, a method to measure the seasonal evolution of Hapi's deposit is described, providing an upper limit for Hapi's water ice fraction. Measuring the evolution of the heights of some boulders, we fixed the pristine 67P ice content, and we compared the results with the Inter-Stellar Medium and CI-Chondrites. Finally, we investigated the macroscopic thermomechanical behavior of a 40 meter boulder located on the Imhotep region by modeling its response to diurnal thermal forcing. Preliminary results reveal that stresses occur in the boulder's exteriors due to the sudden variation in temperature during sunset and sunrise. We explored whether the simulated stress is enough to propagate preexisting cracks, discussing the implications for rock breakdown.

EPrint type:Ph.D. thesis
Tutor:Naletto, Giampiero
Supervisor:Cremonese, Gabriele
Data di deposito della tesi:01 December 2019
Anno di Pubblicazione:05 November 2019
Key Words:comets, data analysis, FEM simulation, heat propagation modeling, solar system, planetary science, statistical analysis, boulders, cometary dust
Settori scientifico-disciplinari MIUR:Area 02 - Scienze fisiche > FIS/05 Astronomia e astrofisica
Struttura di riferimento:Centri > Centro Interdipartimentale di ricerca di Studi e attività  spaziali "G. Colombo" (CISAS)
Codice ID:12247
Depositato il:22 Jan 2021 10:43
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