Method development
Since their discovery in the urban environment, the commonly used method to find micrometeorites uses strong neodymium magnets to extract micrometeorites from the rooftop sample. Although effective, these methods cause a significant loss of micrometeorites and are not always efficient enough in increasing the signal-to-noise ratio. The primary focus of my early research was therefore aimed to improve the methodology for the extraction of micrometeorites from rooftops. Using a combination of particle separation based on shape using a Faultable and on density using Laboratory Overflow Centrifuges, I have managed to significantly improve the extraction of micrometeorites from rooftops. An extensive description of these methods is given in my paper: Improved collection of rooftop micrometeorites through optimized extraction methods: The Budel collection.
Types, sizes, and abundances
The Budel collections currently consists of well over 1000 micrometeorites of all different types, sizes, shapes, and colors. While barred olivine spherules are commonly referred to as the most abundant type, the Budel collection has shown that the abundance of the various types may vary and differs with particle size. I found that porphyritic spherules in general are most abundant, especially at smaller particle sizes.
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A size-frequency distribution of the Budel collection shows the abundance of particles of a particular size. This diagram demonstrates that ~130 μm is the most common diameter for micrometeorites from rooftops. This is significantly different from collections from other locations (e.g. cold of hot deserts), which are often much older and influenced by wind patterns, weathering, etc., resulting in larger average diameters.
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When looking closely at the size-frequency distribution, one can distinguish a bimodal distribution with possibly several shoulder peaks. Suttle and Folco (2020) correlated these peaks to a variety of sources with unique normal distributions contributing to the total cosmic dust flux. As such, the distinct size distribution peaks of various cosmic spherule textures and their interrelated (shoulder) peaks within the Budel collection may reflect the specific size distributions of different sources with unique compositions and orbital parameters.
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Oxygen isotopes
In collaboration with a research group from Brussels, we analyzed the oxygen isotopic composition of 80 cosmic spherules from the Budel collection. This is the first time this kind of study has been done on young and fresh spherules, giving us a first glimpse into the composition of the modern-day influx of cosmic dust. One of the most important findings is that up to 15% of the analyzed spherules originate from a previously identified, yet unknown parental source with extremely heavy isotopic signatures. These signatures haven’t yet been observed among larger meteorites, emphasizing the importance of the study of micrometeorites. We also found a promising link between these isotopically heavy spherules and cumulate textures, which future research will continue to study. The results of our isotopic study were published in Meteoritics and Planetary Science, read the full article here.
PhD research
Starting September 2024, I will continue my research into micrometeorites as a PhD student at the VU Amsterdam. Any new findings or research publications will be updated here.