Economic significance of platinum group elements and water in asteroids: Insights from chondritic meteorites

  • Author / Creator
    Gilmour, Cosette
  • Asteroids are considered to be rich sources of precious metals, water, and essential volatiles for life. Such a consideration has been derived from the study of meteorites and asteroid reflectance spectra which have both been vital to our understanding of asteroid compositions. The vast amount of valuable resources in asteroids that are in close proximity to Earth (Near-Earth Asteroids; NEAs) has designated such asteroids as prime targets for extra-terrestrial mining. Of the resources that can be extracted from asteroids, the platinum group elements (PGEs) and water are two of the most sought-after materials. The PGEs are highly valuable given their rarity on Earth, while having an available water source in space can help facilitate future space exploration (i.e., rocket fuel, radiation shielding, drinking water, etc.). Before mining of these resources can commence, asteroid miners must develop a detailed understanding of how the different compositions of asteroids can affect the distribution of such resources. Since it is an expensive endeavor to visit asteroids for such an assessment, meteorite studies take precedence in obtaining the necessary information for selecting an asteroid target to mine. The premise of this master’s thesis is to provide insight into the PGE and water resources that can be mined from asteroids through the study of chondritic meteorites. In the first study of this thesis, PGE concentrations have been determined in situ in ordinary chondrite metal via laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). This is the first study to provide a detailed account of in situ PGE concentrations in the metal phases among a suite of ordinary chondrites. In situ results reveal that PGE concentrations in ordinary chondrite metal are similar among the different ordinary chondrite groups (H, L, and LL). This discovery is a significant contribution to the asteroid mining industry regarding which ordinary chondrite parent body is most ideal to mine considering that previous studies have claimed that PGE concentrations vary among the three ordinary chondrite groups. The findings from this PGE study are also pertinent to understanding the formation of metal in ordinary chondrites; the minimal variability of PGEs suggest that metal was formed as nebular condensates. The second part of this thesis addresses the effects aqueous alteration has on the abundance of water in carbonaceous material. For this investigation, the unique Tagish Lake carbonaceous chondrite was selected for analysis given that variable aqueous alteration degrees have been reported for three pristine specimens (TL5b < TL11h < and TL11i; Herd et al., 2011; Blinova et al., 2014). Thermogravimetric analysis (TGA), infrared transmission spectroscopy, and X-ray diffraction (XRD) were used to quantify the extent of aqueous alteration in the Tagish Lake specimens based on how much water they contained and their phyllosilicate/olivine ratio. The findings from this study are congruent with the previously reported alteration sequence (Herd et al., 2011; Blinova et al., 2014), allowing for the addition of two new Tagish Lake specimens (TL4 and TL10a) to be incorporated into the sequence. Reflectance spectra of Tagish Lake were also acquired to re-visit the Tagish Lake parent body connection. This Tagish Lake investigation is relevant to the material processing of asteroid mining given that the TGA method records the temperatures at which minerals break down and release water. Furthermore, investigating the meteorite-parent body connection is pertinent for selecting suitable asteroid targets. The findings of this thesis provide valuable insight into the type of asteroids that are suitable for mining PGEs and water. On this basis, I propose that H chondrite parent bodies are ideal for the extraction of PGEs, while CI and CM carbonaceous chondrite parent bodies are best for water resources.

  • Subjects / Keywords
  • Graduation date
    2017-11:Fall 2017
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
  • Institution
    University of Alberta
  • Degree level
  • Department
    • Department of Earth and Atmospheric Sciences
  • Supervisor / co-supervisor and their department(s)
    • Herd, Christopher (Earth and Atmospheric Sciences)
  • Examining committee members and their departments
    • Creaser, Robert (Earth and Atmospheric Sciences)
    • Rivard, Benoit (Earth and Atmospheric Sciences)