<p>A large multi-aperture telescope has the potential to reach the diffraction limit corresponding to its baseline. To do so, Adaptive Optics (AO) and beam combination are critical to good performance. Operation as an interferometer is a complicated mode for the telescope. The system now has much tighter tolerances and is difficult to align. The alignment process needs to be planned in multiple steps, and tolerance and sensitivity analysis needs to be performed for each step. Alignment tools can be prepared based on the resolution found in the sensitivity analysis in each step. </p><p> Random fluctuation is another critical factor that reduces system performance. If noise sources near the telescope are characterized and identified, image quality can be improved by post-image processing. </p><p> Measuring the outer scale of atmosphere is also helpful for understanding the system performance. The fringe tracking method in the Large Binocular Telescope Interferometer (LBTI) system provides optical path difference (OPD) variation, and the power spectral density of the OPD variation is used to estimate the size of the outer scale. However, this method is limited by the baseline of the LBTI by 5[special characters omitted] B, where B is the baseline, and by this equation the outer scale size which is able to be estimated should be more than 125 m. </p><p> AO simulation can provide an understanding of new AO system concepts and parameter variations before they are applied to the real system. In this dissertation study, we simulated an LBTI system with structural vibration of 10 Hz and 20 Hz and with various amplitudes. From the simulation, we learned that the slower bandwidth of piston-correcting systems allows stars as faint as ~13^the magnitude to be observed. If there is significant vibration on the structure, the increased bandwidth will limit the phasing stars to 10~11^th magnitudes. This demonstrates the limits of the LBTI system regarding structural vibration. </p><p> An alternative phasing sensor for the LBTI system, the pseudo phasing sensor, can be used for more than 1000 m of outer scale of atmosphere. If the direct phasing sensor embedded in the LBTI system cannot be used for a very faint star, the pseudo phasing sensor, which approximately estimates the phase difference by AO wavefront sensor, can be useful for atmospheric conditions with estimated outer scale of about 1000 m. </p><p> The analyses in this dissertation provide a partial guide for developing large-scale telescopes and astronomical instruments.</p>

<p> The Kuiper belt is a population of small bodies located outside Neptune's orbit. The observed Kuiper belt objects (KBOs) can be divided into several subclasses based on their dynamical structure. I construct models for these subclasses and use numerical integrations to investigate their long-term evolution. I use these models to quantify the connection between the Kuiper belt and the Centaurs (objects whose orbits cross the orbits of the giant planets) and the short-period comets in the inner solar system. I discuss how these connections could be used to determine the physical properties of KBOs and what future observations could conclusively link the comets and Centaurs to specific Kuiper belt subclasses. </p><p> The Kuiper belt's structure is determined by a combination of long-term evolution and its formation history. The large eccentricities and inclinations of some KBOs and the prevalence of KBOs in mean motion resonances with Neptune are evidence that much of the Kuiper belt's structure originated during the solar system's epoch of giant planet migration; planet migration can sculpt the Kuiper belt's scattered disk, capture objects into mean motion resonances, and dynamically excite KBOs. Different models for planet migration predict different formation locations for the subclasses of the Kuiper belt, which might result in different size distributions and compositions between the subclasses; the high-inclination portion of the classical Kuiper belt is hypothesized to have formed closer to the Sun than the low-inclination classical Kuiper belt. I use my model of the classical Kuiper belt to show that these two populations remain largely dynamically separate over long timescales, so primordial physical differences could be maintained until the present day. </p><p> The current Kuiper belt is much less massive than the total mass required to form its largest members. It must have undergone a mass depletion event, which is likely related to planet migration. The Haumea collisional family dates from the end of this process. I apply long-term evolution to family formation models and determine how they can be observationally tested. Understanding the Haumea family's formation could shed light on the nature of the mass depletion event.</p>

<p>Earth and Mars have nearly the same axial tilt, so seasons on these two bodies progress in a similar manner. During fall and winter on Mars, the primarily CO₂ atmosphere (~95% by volume) condenses out onto the poles as ice. Approximately 25% of the entire Martian atmosphere condenses, and then sublimes in the spring, making this cycle a dominant driver in the global climate. Because the water and dust cycles are coupled to this CO₂ cycle, we must examine seasonal CO₂ processes to understand the global (seasonal) distribution of H₂O on Mars. The density of the ice may indicate whether it condensed in the atmosphere and precipitated as &ldquo;snow&rdquo; or condensed directly onto the surface as &ldquo;slab&rdquo;. Variations in density may be controlled by geographic location and surface morphology. The distribution and variations in densities of seasonal deposits on the Martian poles gives us insight to the planet&rsquo;s volatile inventories. Here we analyze density variations over time on Mars&rsquo; Northern Polar Seasonal Cap (NPSC) using observational data and energy balance techniques. </p><p> We calculate the bulk density of surface CO₂ ice by dividing the column mass abundance (the mass of CO₂ per unit area) by the depth of the ice cap at a given location. We use seasonal rock shadow measurements from High Resolution Imaging Science Experiment (HiRISE) images to estimate ice depth. The length of a rock&rsquo;s shadow is related to its height through the solar incidence angle and the slope of the ground. </p><p> From differences in the height of a rock measured in icy vs. ice-free images, we estimate the depth of surface ice at the time of the icy observation. Averaging over many rocks in a region yields the ice depth for that region. This technique yields minimums for ice depth and therefore maximums for density. </p><p> Thermal properties of rocks may play an important role in observed ice depths. Crowns of ice may form on the tops of rocks with insufficient heat capacity to inhibit ice condensation, and may cause an artificial increase in shadow length. This increases the apparent height of a rock and thus decreases the apparent surface ice depth. Additionally, moats may form around rocks with sufficient heat capacity to sublime ice as it is deposited. Moating will also artificially increase the shadow lengths (decreasing apparent surface ice depth). We correct for these effects in our depth-estimation technique. </p><p> We balance incoming solar flux with outgoing thermal radiation from Thermal Emission Spectrometer (TES) observations to calculate the column mass abundance. TES thermal bolometer atmospheric albedo and temperature observations are a good proxy to the surface bond albedo and effective surface temperature. These parameters are needed to balance the incoming and outgoing flux. </p><p> Mars&rsquo; atmosphere is tenuous so we assume homogeneous radiance from the surface to the top of the atmosphere, no lateral diffusion of heat, and that any excess heat goes into subliming surface ice in our flux balance. Using a Monte Carlo model, we integrate the net flux until reaching the time where Cap Recession Observations indicate CO₂ has Ultimately Sublimed (the CROCUS date) to obtain the column mass abundance. </p><p> We study seasonal ice at three distinct geomorphic units: plains, dune fields, and craters. Two plains regions, four dunes regions, and two crater regions are analyzed over springtime sublimation. Data for these regions spanned three Mars Years. </p><p> Our results indicate that the evolution of seasonally deposited CO₂ ice on the Northern Polar Cap of Mars is highly dependent on complex relationships between various processes. The grain size, dust contamination, water doping, and density vary dramatically over time. The initially deposited material varies according to local geomorphic features and topography, as well as latitude and longitude. The inter-annual variability of ice may play a role in its evolution over sublimation, but likely plays a smaller role than anticipated. Low normalized initial and time-averaged densities suggest that NPSC deposits are initially low and remain relatively low throughout spring. These densities are very similar to estimates made by previous studies. Thus, we conclude that the NPSC is indeed pervaded by low density deposits. These deposits densify over time, but rarely reach typical characteristics for pure slab ice. </p>

<p> A significant portion of the process of detecting pulsars from radio sky surveys remains a largely manual task. The visual inspection of data in order to detect and validate potential pulsar candidates is by far the most time consuming portion of the overall process. Coupled with the fact that well over a Petabyte of pulsar survey data has been archived, the task of identifying these valuable phenomena is tedious and time consuming.</p><p> Using data from a survey performed with the National Radio Astronomy Observatory&rsquo;s (NRAO&rsquo;s) Green Bank Telescope (GBT) in 2007, this thesis explores the application of machine learning techniques to mitigate the manual efforts involved in pulsar candidate detection. The performance of three different classifiers is explored - Naive Bayes, C4.5 (J48) Decision Tree, and Support Vector Machine. Preprocessing and feature extraction methods are described and a framework for applying the classifiers to the survey data is presented. Multiple features were extracted from the survey data and used to train the classifiers. Cross-validation results of the various feature sets and classifiers are documented. Experiments suggest the potential of the proposed framework in rapidly detecting pulsars from large amounts of survey data.</p>

<p> Astronomy is becoming a forgotten science, which is evident by its relatively low enrollment figures compared to biology, chemistry, and physics. A portable inflatable planetarium brings relevance back to astronomy and offers support to students and educators by simulating realistic astronomical environments. This study sought to determine if learning is improved in an inflatable planetarium by adhering to the design principles of the cognitive theory of multimedia learning (CTML), specifically the coherence principle, in an authentic classroom. Two groups of 5^th grade students of similar ability were purposefully assigned using a 1-teacher-to-many-students format with mean lesson lengths of 34 minutes. The experimental group was differentiated with <i>seductive details</i>, defined as interesting but irrelevant facts that can distract learning. The control group (<i> n</i> = 28), with seductive details excluded, outperformed the experimental group (<i>n</i> = 28), validating the coherence principle and producing a Cohen's effect size of medium practical significance (<i>d</i> = 0.4). These findings suggest that CTML, when applied to planetarium instruction, does increase student learning and that seductive details do have a negative effect on learning. An adult training project was created to instruct educators on the benefits of CTML in astronomy education. This study leads to positive social change by highlighting astronomy education while providing educators with design principles of CTML in authentic settings to maximize learning, aid in the creation of digital media (astronomical simulations/instructional lessons for planetariums) and provide valuable training for owners of inflatable planetariums with the eventual goal of increasing student enrollment of astronomy courses at the local level.</p>

This thesis presents theoretical and numerical studies of the radial diffusion of relativistic radiation belt electrons. The research has been focused particularly on the radiation belt phase space density profile, and radial diffusion due to particle drift resonance with ULF waves. Observations have shown a strong connection between magnetospheric ULF oscillations and electron flux enhancements. I investigate radial diffusion coefficients based on theoretical analysis of particle diffusion in ULF perturbation electric and magnetic fields. The analytical diffusion coefficients consist of two terms: a symmetric term and an asymmetric term. The symmetric term agrees with earlier works, and the asymmetric terms are new. Both terms show good agreement with numerical test particle simulations. The asymmetric terms have higher L dependence, which indicates they might be more important at higher L-shells or at times when the magnetospheric field is highly asymmetric. A numerical radial diffusion model has been developed which can take into account: dynamic boundary locations and values, plus effects of losses and sources. Several test cases are considered to study the effects of different diffusion coefficients, internal sources, external sources, and loss. A method of converting observational particle flux to phase space density is also presented. Identifying the source and loss processes using observational data is currently one of the key issues for understanding and modeling radiation belt dynamics. We present a new measurement technique which utilizes two GOES satellites located at different local times to calculate the radial gradient of phase space density at geostationary locations. The result shows positive gradient at geomagnetic quiet periods. To further study the high energy electron transport, especially the ULF related acceleration during storm times, I use the numerical radial diffusion model for the September 24-26, 1998 storm and compare the results with an MHD test particle simulation. The diffusion result using ULF-wave diffusion coefficients and a time-dependent outer-boundary condition can reproduce the main features of the MHD-particle results quite well. Using wave driven diffusion coefficients gives better results than using power law or Kp-dependent diffusion coefficients.

Observations of solar wind temperatures near the Earth indicate that heating of the solar wind plasma exists. An alternate approach to finding explicit heating terms for the energy equation is to use a polytropic approximation. Using data from the Helios 1 spacecraft, an empirical value for the polytropic index of the solar wind is found to be independent of speed state, within statistical error, and has an average value of 1.47. Application of this empirically derived index to a solar wind computer model is examined by comparing the MHD energy equation and the polytropic relation. The result is obtained that the polytropic index can replace the adiabatic index in the MHD energy equation to simulate the effects of heat conduction if the assumptions are made that the heat conduction flux has a specific form and the particle pressure has no explicit time dependence. Justifications and limitations of this approach are discussed.

The Pioneer Venus observations show a peak in the O$\sb2\sp+$ concentration at $\sim$170 km altitude in the dayside ionosphere of Venus. In this thesis, the 2-dimensional MHD equations are solved in a self-consistent manner, as an extension to the 1-dimensional model by Cloutier et al. (1987), to present a global model of the Venus dayside ionosphere for solar zenith angles (SZA) $\leq$ 60$\sp\circ$. The model describes, by calculating vertical profiles at different SZA, ion densities, magnetic field magnitudes, and ion velocities. The model shows that the O$\sb2\sp+$ peak, at $\sim$170 km altitude, occurs throughout the dayside ionosphere as observed by the Orbiter Ion Mass Spectrometer (OIMS). The velocity field, which affects the ion distributions, is mainly tangential near the ionopause and radial for altitudes below 200 km. The downward flow accelerates, near 170 km altitude, due to collisional interactions with the neutral atmosphere, and removes the O$\sb2\sp+$ densities to lower altitudes, thus, producing the bump observed in the altitude profile.

Strong 8-$\mu$m infrared hot spots in the polar regions of Jupiter exhibit different behaviors: the northern polar hot spot (hereafter, NPHS) tends to remain fixed in System III longitude while the southern polar hot spot (SPHS) drifts. Joule heating associated with Pedersen currents that are generated by the spinning magnetized ionosphere (the Faraday disc dynamo) is proposed as a possible power source for the hot spots. A quantitative perturbation model is used to show that the NPHS is confined by a steep longitudinal magnetic-field gradient to a System III longitude of approximately 175$\sp\circ$, in agreement with observations. The model also shows that a Joule heating power of about $10\sp{14}$-$10\sp{15}$ Watts can be dissipated in the hydrocarbon layer, significantly larger than particle-precipitation power and the radiated power of the hot spots. The drift of the SPHS is hypothesized as being caused by gravity waves. The total energy provided by Joule heating and by the dissipation of the waves constitutes the power for the hot spot; propagation of the waves causes the location of the total energy deposition to move, thus causing the drift of the SPHS. Because of the asymmetry in the polar magnetic field configurations between the two hemispheres, these gravity waves are more likely to deposit energy comparable to the Joule heating energy in the south to heat up the hydrocarbon layer where IR emission originates. The ranges of wavelength and frequency are investigated for waves that propagate mainly in north-south direction. These waves can cause the SPHS to drift at the observed speed of $\sim$5km/s and dissipate heat that is comparable to Joule heating in the south but less important than the Joule heating in the north. The current-driven joule-heating model, with the presence of wave modulation, can thus account for the primary features of the Jovian polar hot spots: their power output, the fixed location of the NPHS, and the drift motion of the SPHS.

Can the average bulk flow of an ensemble of charged particles in Earth's plasma sheet still be described by adiabatic theory even if the ensemble contains a significant number of particles executing non-adiabatic motion? This is part of a broader spectrum of questions which ask if chaotic microscopic processes can be parametrized as macroscopic ones when ensemble averaged. Wolf and Pontius (1993) have shown that at least for a simple 2D, tail-like magnetic field configuration, the average particle drift speed of an appropriately chosen ensemble of particles, including those executing chaotic motion, is given correctly by the simple adiabatic guiding-center drift formula. Here, we extend the proof to 2${1\over2}$D magnetic fields (3 component, 2 spatial dependences) and include the effects of an electric field. The results of numerical test-particle simulations further show that the dispersion of particles about the mean drift speed tends to decrease due to the presence of chaotic particle scattering. Thus, we have shown that the standard way of representing particle transport in the inner magnetosphere, namely the isotropic pitch angle, bounce averaged drift formalism, is valid for the central plasma sheet despite the presence of non-adiabatic particle motion.