Author's School

Graduate School of Arts & Sciences

Author's Department/Program

Earth and Planetary Sciences

Language

English (en)

Date of Award

January 2010

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Chair and Committee

Raymond Arvidson

Abstract

Orbital observations, rover-based remote-sensing and in-situ observations, and terramechanics modeling can be used collaboratively to examine the interplay between material properties, scientific setting, and mobility issues facing rovers on other worlds. In this thesis, these types of observations are used concurrently to identify the surface properties on a regional scale for the Gusev Crater Spirit landing site, to understand how the rover interacted with these materials while driving, and as a look ahead to a candidate new landing site, Aram Chaos, with exposed materials that contain key evidence for past environmental conditions. Comparison of rover-based and orbital spectral reflectance data over Spirit's traverses show that cratered plains in Gusev Crater are dominated by nanophase ferric-oxide-rich dust covering weakly altered basaltic sands. Comparison of Mars Odyssey THEMIS-derived thermal inertia values with Mars Express OMEGA-derived spectral parameters shows that although the dust cover can be optically thick: 0.4 to 2.5 μm wavelength region) in some areas, it is not thick enough: ~1 cm) to mask the thermal inertia of the underlying substrate. Mobility in the above materials with a five-wheeled rover--Spirit's right front drive actuator is non-functioning--is analyzed in a modeling environment to assess mobility issues facing current and future rovers, specifically how to minimize the effect of an inoperable wheel on rover mobility and determining the rolling resistance of an embedded rover. This includes generation and use of mobility hazard maps as a tactical planning tool. A detailed stratigraphic and mineralogical description of a candidate new landing site, Aram Chaos: ~3┬░N, 339┬░E), is presented based on orbital data primarily from the Mars Reconnaissance Orbiter. Two sedimentary units overlie the basement chaos material representing the original plains fill in Aram Crater: the first and oldest is comprised of ferric hydroxysulfate intercalated with monohydrated-sulfate-bearing materials, monohydrated sulfates, and a capping unit with nanophase ferric oxides and monohydrated sulfates. After a period of wind erosion, these deposits were partially and unconformably covered by the second sedimentary unit, a discontinuous unit containing crystalline hematite and polyhydrated sulfate material. These sedimentary deposits were formed by evaporite deposition during at least two distinct rising groundwater episodes fed by regional-scale recharge.

Comments

Permanent URL: http://dx.doi.org/10.7936/K7WD3XMT

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