Date of Graduation

12-2010

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Space & Planetary Sciences (PhD)

Degree Level

Graduate

Department

Space & Planetary Sciences

Advisor/Mentor

Sears, Derek W.

Committee Member

Lacy, Claud H.S.

Second Committee Member

Paul, David W.

Third Committee Member

Ulrich, Richard K.

Fourth Committee Member

Zachry, Doy L.

Keywords

Pure sciences; Earth sciences; Asteroids; Chondrites; Evaporites; Meteorites; Phyllosilicates

Abstract

Asteroids are one group of the bodies that can provide insights into the origin and early history of the solar system. Asteroids are considered to be fairly pristine, with alterations only occurring to their surface from the space environment. Studying them provides opportunities to learn about the primordial solar system, its materials, and processes and how it evolved into the current condition. Many asteroids have been discovered, but few have their surface compositions determined. The C and X complexes provide a difficulty in determination because their near infrared spectrum is featureless.

The C asteroids have been long associated with the carbonaceous chondrites because of similar albedos and matching spectra. The carbonaceous chondrites do not look like the major minerals that compose their matrix. Phyllosilicates are the primary mineral in the matrix and evaporites are also in high quantity. Heat treatment investigation has been conducted on terrestrial analogs to simulate heat implanted into the surface of asteroids by micrometeorite impacts.

The mineralogical interesting region of the spectrum is the near infrared region. The featureless spectrum of the C and X asteroids and carbonaceous chondrites in this region require the use of continuum slopes to compare the three groups to one another. For investigation, the continuum slope is broken down into two regions and plotted against each other. The short wavelength region is 1.0-1.75µm and the long wavelength region is 1.8-2.5µm. The break at 1.75µm is the result of a discontinuity in the spectrum of the phyllosilicates. The meteorites and asteroids plot in small fields that overlap each other showing that they are related. The phyllosilicates and phyllosilicate-evaporite mixtures plot in a large field below the asteroids, suggesting no connection. Heating the phyllosilicates and phyllosilicate-evaporite mixtures causes the resulting data to plot among the asteroids, giving an insight to the surface composition of C and X asteroids. The surface is likely composed of a decomposed mixture of 40wt% phyllosilicate-60wt% evaporite. It is plausible that when opaque materials are taken into account that the serpentine in the mixtures would still retain its structural water, but still provide a spectrum similar to the C asteroids.

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