Previous plasma imaging missions have used time-delay integration techniques that correct for uniform motion blur during integration. This was due to the assumed constant range-to-target of each pixel in the observed scene. ICON's low orbital altitude and twelve second integration time create non-uniform motion blur across the observed scene and necessitate a novel variable-range time-delay integration (TDI) algorithm be used to spatially resolve the two-dimensional images. The variable-range TDI algorithm corrects for each pixel moving at a different angular rate throughout image integration and transforms each raw image onto a surface where the spacecraft is moving at a constant angular rate with respect to every pixel in the image. Then as the raw images are co-added together the non-uniform motion of the observed scene is accounted for and will not geographically distort the final images, or any features seen within them. Through simulation using output from the SAMI3 model during plasma depletion formation it was determined that the structuring and gradients of plasma depletions can be recovered using this technique. Additionally, the effects of depletion width, solar activity level, and misalignment of the field-of-view with the local magnetic field were investigated. The variable-range TDI technique is able to recover the overall shape and depth of depletion of the depletions in all cases, however the determination of gradients observed at depletion walls is significantly degraded for very narrow plasma depletions and during periods of low solar activity. All simulated model conditions were shown to be representative of current ionospheric conditions. / Master of Science / Equatorial spread-F, also termed plasma bubbles, is a phenomenon that occurs in the equatorial region of Earth’s ionosphere, the charged region of Earth’s atmosphere. Plumes of less dense plasma, the charged material of the Ionosphere, rise through regions of higher density plasma. This causes disturbances to radio signals that travel through this region, which can lead to GPS range errors or loss of signal. ICON is a NASA Explorer mission aimed at, in part, understanding the sources of variability in the ionosphere. One instrument onboard ICON to accomplish this goal is the FarUltraviolet Imager which images airglow in the far-ultraviolet range. During nighttime, the FUV imager can observe plasma bubbles to study the instability and the mechanisms that produce it. This thesis looks at the ability of the variable-range time-delay integration (TDI) algorithm, used to produce images from ICON’s Farultraviolet imager, to spatially resolve the structure and gradients of observed plasma bubbles. However, due to the viewing geometry of ICON’s FUV imager, each pixel across the observed scene experiences a different angular rate of motion blur. The variable-range TDI algorithm removes this non-uniform motion blur by transforming each raw image onto a surface where the spacecraft moves at a constant angular rate with respect to every pixel in the image. Then raw images are integrated together such that the observed scene is not geographically distorted. It was concluded that the TDI process is able to spatially resolve a wide variety of plasma bubbles under various ionospheric conditions and imager configurations.

Die Arbeit beschäftigt sich mit laser-induzierter Plasmaspektroskopie (LIBS) im Kontext der robotischen Mars-Erkundung. Bei LIBS wird Plasma analysiert, das durch Ablation von Probenmaterial gebildet wird. Die Methode wird seit 2012 von dem Instrument ChemCam des Mars-Rovers Curiosity eingesetzt, um das Gestein und den Boden der Marsoberfläche zu untersuchen. Sie wird auch in der NASA-Mission Mars 2020 und in der chinesischen Mission HX-1 eingesetzt werden, welche im Jahr 2020 zum Mars starten sollen. Zwei Studien dieser Arbeit betrachten Emissionen von Molekülen, die sich im Plasma bilden. Diese können zur Detektion von Chlor und Fluor eingesetzt werden, die von geologischem Interesse für Mars sind. Emissionen von MgCl und CaCl werden in simulierten Marsbedingungen für die Bestimmung der Chlorkonzentration untersucht. Nur das CaCl-Signal wird als stark genug befunden. Dieses ist am stärksten bei vergleichsweise geringen Chlorkonzentrationen, was durch einen Nichtgleichgewichtszustand des Plasmas erklärt werden kann. In der zweiten Studie werden die Emissionen von CaCl und CaF verglichen. Beide können mit demselben Modell in Abhängigkeit der Konzentrationen der Reaktionspartner beschrieben werden. Allerdings werden auch starke Matrixeffekte beobachtet, die die Emissionen beeinträchtigen können. Im letzten Teil der Arbeit wird der Plasma-Imaging-Aufbau beschrieben, der aufgebaut wurde. Der Aufbau ermöglicht räumlich aufgelöste Messungen der Emissionsspektren. Es werden erste Ergebnisse vorgestellt, die mit diesem Aufbau erzielt wurden. Diese zeigen, dass CaCl und CaF nur im Plasmazentrum emittieren, was mit einer Verdünnung und Ausbildung eines Niedertemperaturbereichs im Plasmazentrum erklärt werden kann. Atomare Emissionen von Wasserstoff, Kohlenstoff und Sauerstoff sind dagegen intensiver an der Plasmafront und zeigen Verwirbelungen auf, was auf komplexe Temperaturverteilungen und auf einen starken Einfluss von Strömungen im Plasma hinweist. / In this thesis, laser-induced breakdown spectroscopy (LIBS) is investigated in the context of the robotic exploration of Mars. In LIBS, the plasma formed by laser-ablated sample material is analyzed spectroscopically. Since 2012, it is employed by the ChemCam instrument on board the Mars rover Curiosity to analyze rocks and soil on the Martian surface. The technique will also be used in NASA's Mars 2020 mission and in the Chinese HX-1 mission, which are both scheduled to launch to Mars in 2020. The first two studies are concerned with emissions of molecules that form in the laser-induced plasma. These can be used to detect chlorine and fluorine, which are of geological interest for Mars. In the first study, MgCl and CaCl emissions are investigated for the detection and quantification of chlorine in Martian atmospheric conditions. Only the CaCl signal is found to be intense enough for this purpose. The CaCl signal is found to be skewed towards low chlorine concentrations, which is explained by a non-equilibrium model of the laser-induced plasma. In the second study, the emissions of CaCl and CaF are compared. The same model is used to describe the dependence of both signals on the respective reactant concentrations. Strong matrix effects are observed that affect the observed intensities. In the final part of the thesis the plasma imaging setup that was developed in the context of this thesis is presented. It enables spatially resolved measurements of the plasma emission spectra. First results show that CaCl and CaF emissions are confined close to the plasma center, likely because rarefaction leads to a low-temperature center in which molecules can form. Atomic emissions of hydrogen, carbon, and oxygen are more stable at the plasma front and show signs of vorticity, indicating a complex temperature distribution and a strong influence of flows within the plasma.