Geotechnical Properties of Fillite -- Simulant for Planetary Rover Mobility Studies


TitleGeotechnical Properties of Fillite -- Simulant for Planetary Rover Mobility Studies
Publication TypeJournal Article
Year of Publication2016
AuthorsEdwards, MB, Dewoolkar, MM, Huston, DR
JournalJournal of Aerospace Engineering
Date Published2016/03
ISSN0893-1321
Abstract

Physical model studies on rovers are conducted first on Earth, often on granular simulants, before they are deployed to Mars, the Moon, or other planetary bodies. Researchers at the NASA Glenn Research Center developed a large test bed called the “sink tank” specifically to simulate rover mobility in high-sinkage, high-slip situations similar to the ones encountered by the Spirit rover on Mars. For the test bed, they selected a granular material called Fillite, which is composed of alumino-silicate hollow microspheres harvested from the pulverized fuel ash of coal-fired power plants. Fillite is available in large quantities at a reasonable cost and it is chemically inert. The particle size distribution of Fillite (grade 500W-LF, off-white in color, made by Tolsa USA Inc.) is uniform with particles ranging mostly between 0.075 mm and 0.42 mm (mean particle size of about 0.2 mm). Its unit weight on Earth is 3.9 – 4.8 kN/m3. This is similar to that of Martian regolith on Mars (about 3.7 – 5.6 kN/m3) and close to the range of the unit weight of lunar regolith on the Moon (about 1.4 – 2.9 kN/m3). The focus of the work presented in this paper is to summarize geotechnical characterization of Fillite, specifically its mechanical properties such as shear strength parameters, elastic modulus, Poisson’s ratio and small-strain shear modulus. These properties of Fillite are compared to the known and estimated properties of Martian and lunar regoliths as well as of other commonly used simulants. The data presented here support that Fillite has many physical and mechanical properties that are similar to what is known about Martian regolith. These 6 properties are also comparable to lunar regolith. Fillite is quite dilatant; its peak and critical angles of internal friction are smaller than those of most other simulants. Smaller shear strength, coupled with much smaller bulk unit weight as compared to other simulants, results in smaller bearing and shearing resistances allowing for better simulation of the intended high-sinkage, high-slip behavior for rover mobility studies.

URLhttp://ascelibrary.org/doi/abs/10.1061/%28ASCE%29AS.1943-5525.0000613
DOI10.1061/(ASCE)AS.1943-5525.0000613
Refereed DesignationRefereed
Status: 
Published
Attributable Grant: 
RACC
Grant Year: 
Year5 StatusChanged
Acknowledged VT EPSCoR: 
Ack-No