The Solar System contains a large variety of objects that can find themselves on orbits intersecting the path of the Earth around the Sun. When they do, we can see these objects burn up (ablate) in the atmosphere as meteors or bright fireballs. The most massive fragments may partially survive the ablative entry in the atmosphere and can end-up impacting the Earth’s surface, after which we call them meteorites. As an Honorary Research Associate (i.e. guest-researcher) at Naturalis I study meteorites to understand what they can tell us about planet-formation and planetary evolution.
Ellemeet (1925): a Dutch diogenite with the wrong name
The agricultural fields in The Netherlands have the main stage of impacting meteorites in the pre-WWII era. I have been studying the 1925 multiple-fall near the towns of Ellemeet and Serooskerke in The Netherlands and reconstructed the conditions of the historical narrative of the impact, including the rediscovery of the original impact point. Both masses impacted near the town of Serooskerke, kilometers away from Ellemeet. One could say that due to the municipal boundaries it got the wrong name. The degradation of the ‘Serooskerke’ meteorite by local meteorological processes also caught my attention and I studied physical weathering using laboratory experiments. This involved subjecting small fragments of the meteorite to soil moisture adsorption, kinetic energy from impacts of individual rain drops (both methods are derived from the field of soil science) and freeze-thaw cycles. This allowed me to assess the susceptibility to disintegration from wetting and frost weathering and place it in the meteorological context of 1925. In addition I studied the mineralogical (X-ray powder diffraction) and spectral properties (UV-VIS-nIR reflection spectroscopy) to confirm Sersooskerke’s genetic link to the other known Ellemeet fragments. These also tell us that the meteorite originated from asteroid Vesta, a provenance that makes it a compelling specimen in the Dutch meteorite collection in relation to planet formation. Read more about this work in the peer-reviewed publication in the journal Meteoritics and Planetary Sciences.
Diepenveen (1873): priomordial chemistry of the Solar System
The ‘Diepenveen’ meteorite fell on 27 October 1873, but was not known to science until its rediscovery in a private collection in 2012. In 2019 an international consortium published the results of a thorough study of this remarkable carbonaceous chondrite in the journal Meteoritics and Planetary Science. After its terrestrial wanderings the rock is still remarkably fresh and uncontaminated, and may exhibit parallels to the regolith of asteroid Ryugu. This asteroid was the stage of several landings and sampling session of the satellite Hayabusa-2 in 2019. I contributed to the study of Diepenveen by studying the reflection spectrum (UV-VIS-NIR spectroscopy) and the links to possible spectral types that could match the regolith breccia. In addition I also measured the volume of the meteorite using 3D photogrammetry, restyled a map of the meteorological conditions in 1873 and introduced the use of the Munsell soil colour chart to describe meteorites colours more effectively.
Broek in Waterland (2017):
At a stone’s throw away from where I lived in Amsterdam-North, a meteorite impacted near the town of Broek in Waterland on 11 January 2017. The meteorite struck a small garden shed and pulverized one of the roof tiles. A motorist in Belgium was able to film the fire ball using a dashboard camera, while several eyewitnesses saw it break up into several fragments. Only the fragment that impacted the shed was recovered after extensive search efforts of the area. The rock is an ordinary chondrite (type L6), weighing in at 530 grams. Unique for this meteorite was that I could document the meteorite photographically in 3D before it was sampled for further research. You might not realize is, but many of the pre-WWII Dutch meteorites lack a proper description and photo documentation after their fall. The rendered 3D-model of the meteorite is also scientifically interesting. Using Computation Fluid Dynamics (CFD) I built a ‘virtual wind tunnel’ around the meteorite to study its aerodynamic properties during the dark flight before impact. The dimples, or ‘regmaglypts’, can also be studied using 3D surface analyses, and photogrammetry appears to be a good non-invasive approach for determining the volumes of meteorites. We are currently studying this meteorite in more depth at Naturalis.
Ongoing work in 3D photogrammetry and micro-CT scanning
Meteorites are by far the most tangible way to get in though with planetary bodies in our solar system (aside from flying there as an astronaut, of course). In addition to detailed compositional studies, the physical characteristics of meteorites can also be characterized. Within the Netherlands I am the first in developing the expertise on the 3D documentation and study of meteorites (using photogrammetry). The possible use of 3D data of meteorites can have interesting applications in the field of meteoritics, some of which I am currently testing:
- quantifying the volume (and density) of complete meteorites as an alternative to e.g. liquid immersion
- reconstructing friable meteorites that have fractured into multiple fragments.
- pairing meteorite fragments distributed across various (European) museum collections through the exchange of 3D models, eliminating the need for transport of delicate fragments.
- 3D-printing of facsimile for use as teaching aids in various educational settings at musea, science centers and schools.
A nice example of the forth application is the 3D model of the main mass of the 1843 Utrecht meteorite (aka. ‘Blaauwkapel’). It has been used by Museum for one day, a social inclusive initiative in Utrecht to bring museum objects and their stories to senior citizens. Another putative application is in ‘tactile astronomy‘ to make the shapes and sizes of meteorites more tangible for the visually impaired.
Putative micrometeorites as tracers to understand iron-fluxes in soil development
The continuous influx and spatial distribution of iron-right cosmic dust (aka. micrometeorites) enriches our ecosystems with 20,000-100,000 tons of material each year. This material may possibly give new insights in the iron stocks and development of podzolic soils that are very common in forested, sandy landscapes of The Netherlands. We studied putative micrometeorites (identified using SEM-EDX) as an internal standard to illustrate that the iron influx of podsolic soils is also derived from atmospheric sources.