Date of Award

2007

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Bioinformatics & Computational Biology

First Advisor

Malay K. Mazumder

Abstract

Martian dust characterization is important for minimizing the effects of abrasion, adhesion, corrosion, and damage to mission hardware, and also to reduce the effect on human health during future robotic and human exploratory missions. Characterizing the particle size and charge on Mars dust will help in the development of techniques for dust mitigation. Presently there is no miniature instrument which is capable of in-situ and real time measurements on Mars. In order to simultaneously analyze the particle size and charge of Mars dust, a Dust Particle Analyzer (DPA) has been developed and tested which is based on a Laser Doppler Velocimeter (LDV), the dust particles passing through the sensing volume of the LDV undergo oscillations depending upon the applied field, the phase lag between the field and the particle oscillation gives the size, whereas the amplitude ratio gives the electrostatic charge. Using different test aerosols, the DPA has proved to provide accurate and precise results. Both theoretical analysis assuming the predicted environmental conditions of Mars and experimental data on the development of the DPA show that the instrument has an excellent potential for its application to measure the size and charge distributions of dust particles on the surface of Mars. The performance of the prototype instrument was tested with JSC-1 Mars dust simulant under both laboratory conditions and in a vacuum test chamber to simulate the Martian atmospheric parameters. The DPA with the electric drive is capable of measuring size and charge distributions of only charged particles, whereas with an acoustic field, the DPA is capable of measuring size distribution of all particles irrespective of their charge, but the charge information is not available. Therefore, for simultaneous measurement of charged and uncharged particles, both the acoustic and electric excitation fields were superimposed and driven synchronously in phase. Typically, airborne particles are either neutral or have low charge, so with the simultaneous application of acoustic and electric fields, the entire size and charge profile of the aerosol cloud can be rapidly analyzed.

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