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Thermal-Mechanical Design of the Balloon-Borne Aerosol Limb Imager

Date

2022-10-03

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Thesis

Degree Level

Masters

Abstract

The balloon-borne Aerosol Limb Imager is a prototype of a satellite-borne atmospheric remote sensing instrument being developed at the University of Saskatchewan in collaboration with the Canadian Space Agency. It is a multispectral imager designed to capture images of the atmospheric limb across a wide band of wavelengths and in two orthogonal polarization states. These images are used to retrieve vertical profiles of aerosol particle properties in the upper troposphere and lower stratosphere. Aerosols have been identified as an important atmospheric constituent for study due to their net negative radiative forcing effect. Stratospheric aerosol properties are difficult to predict as they are modulated by volcanic eruptions and wildfire. Knowledge of stratospheric aerosol properties therefore requires continuous measurement. Most space-borne instruments currently producing measurements of aerosol are nearing or beyond their designed lifetimes. Continued measurement of aerosols requires a new generation of space-borne instruments. This work is concerned with the thermal-mechanical design of the third balloon-borne prototype of the Aerosol Limb Imager. The core component of the instrument is an acousto-optic tunable filter. In flights of previous prototypes, this component fell to temperatures outside of its operational range. This requires that detailed design be performed on the thermal design of the instrument. The work also aims to build on previous experience in the thermal-mechanical design of balloon payloads to begin to develop a general design procedure. The prototype flew aboard a high altitude balloon from Esrange, Sweden in August, 2021. All design requirements were met while the instrument was operating at float altitude. Analysis of engineering data from the flight indicates that significant cooling occurred during the ascent of the balloon. Weather conditions at the time of flight support the hypothesis that this was driven by icing early in ascent. Experience gained through the work facilitated the development of a process for the thermal-mechanical design of balloon payloads. This process is iterative and relies on the accurate characterization of operational environments for use in finite element analysis simulations. The success of the thermal design in all operational environments provides confidence for future flights and will inform the development of a satellite-borne Aerosol Limb Imager.

Description

Keywords

thermal, mechanical, design, aerosol, balloon

Citation

Degree

Master of Science (M.Sc.)

Department

Physics and Engineering Physics

Program

Physics

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