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dc.contributor.authorDouglas, Ewan S.en_US
dc.date.accessioned2016-12-19T18:27:48Z
dc.date.available2016-12-19T18:27:48Z
dc.date.issued2016
dc.identifier.urihttps://hdl.handle.net/2144/19717
dc.description.abstractThis work explores remote sensing of planetary atmospheres and their circumstellar surroundings. The terrestrial ionosphere is a highly variable space plasma embedded in the thermosphere. Generated by solar radiation and predominantly composed of oxygen ions at high altitudes, the ionosphere is dynamically and chemically coupled to the neutral atmosphere. Variations in ionospheric plasma density impact radio astronomy and communications. Inverting observations of 83.4 nm photons resonantly scattered by singly ionized oxygen holds promise for remotely sensing the ionospheric plasma density. This hypothesis was tested by comparing 83.4 nm limb profiles recorded by the Remote Atmospheric and Ionospheric Detection System aboard the International Space Station to a forward model driven by coincident plasma densities measured independently via ground-based incoherent scatter radar. A comparison study of two separate radar overflights with different limb profile morphologies found agreement between the forward model and measured limb profiles. A new implementation of Chapman parameter retrieval via Markov chain Monte Carlo techniques quantifies the precision of the plasma densities inferred from 83.4 nm emission profiles. This first study demonstrates the utility of 83.4 nm emission for ionospheric remote sensing. Future visible and ultraviolet spectroscopy will characterize the composition of exoplanet atmospheres; therefore, the second study advances technologies for the direct imaging and spectroscopy of exoplanets. Such spectroscopy requires the development of new technologies to separate relatively dim exoplanet light from parent star light. High-contrast observations at short wavelengths require spaceborne telescopes to circumvent atmospheric aberrations. The Planet Imaging Concept Testbed Using a Rocket Experiment (PICTURE) team designed a suborbital sounding rocket payload to demonstrate visible light high-contrast imaging with a visible nulling coronagraph. Laboratory operations of the PICTURE coronagraph achieved the high-contrast imaging sensitivity necessary to test for the predicted warm circumstellar belt around Epsilon Eridani. Interferometric wavefront measurements of calibration target Beta Orionis recorded during the second test flight in November 2015 demonstrate the first active wavefront sensing with a piezoelectric mirror stage and activation of a micromachine deformable mirror in space. These two studies advance our ``close-to-home'' knowledge of atmospheres and move exoplanetary studies closer to detailed measurements of atmospheres outside our solar system.en_US
dc.language.isoen_US
dc.rightsAttribution-NonCommercial 4.0 Internationalen_US
dc.rights.urihttp://creativecommons.org/licenses/by-nc/4.0/
dc.subjectAstronomyen_US
dc.subjectCoronagraphsen_US
dc.subjectDebris disksen_US
dc.subjectExtreme ultravioleten_US
dc.subjectIonosphereen_US
dc.subjectSounding rocketsen_US
dc.subjectWavefront sensingen_US
dc.titleAdvancing spaceborne tools for the characterization of planetary ionospheres and circumstellar environmentsen_US
dc.typeThesis/Dissertationen_US
dc.date.updated2016-12-04T02:06:44Z
etd.degree.nameDoctor of Philosophyen_US
etd.degree.leveldoctoralen_US
etd.degree.disciplineAstronomyen_US
etd.degree.grantorBoston Universityen_US


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Attribution-NonCommercial 4.0 International
Except where otherwise noted, this item's license is described as Attribution-NonCommercial 4.0 International