When the glacier left the volcano: Behaviour and fate of glaciovolcanic glass in different planetary environments

Volcano-ice interactions and associated landforms have been studied in Iceland since 1900 and this research gained a new dimension after similar landforms were observed in 1979 on planet Mars. Our current understanding of a volcano’s response to the overlying ice mass shows that these eruptions are governed by complex processes that affect the properties of glassy eruption products. Recent observations on Mars show that these types of materials are highly abundant. The aim of this dissertation is to fill gaps in our knowledge of physical erosion properties and transport thresholds of these ‘glaciovolcanic glasses’. By combining field and laboratory studies of Icelandic volcanic glass, wind tunnel experiments under low atmospheric pressures and using observations from the Mars Exploration Rovers it becomes possible to determine the fate of these materials in the present-day Martian surface environment

Urban Meteor Map: a map-based forecast of hourly rates for visual observers

The visible rate of meteors is dependent on various local viewing condition during shower peak nights. The interrelationship of the visible fraction of the night sky, radiant elevation and effects of the light pollution on sky brightness confounds outreach efforts to manage realistic expectations for visual meteor observations by the public. The Urban Meteor Map offers a map-based forecast of hourly rates to help make the effects of local viewing conditions more insightful. The project generates maps based on raster data for parameters in the Zenithal Hourly Rate formula. A Digital Surface Model (DSM) covering the Netherlands was used to generate maps of the visible percentage of the sky. At 5 m resolution this DSM offers insights into obstruction by buildings, vegetation and topography. To incorporate effects of light pollution, a national sky brightness map for cloudless nights was converted into Naked Eye Limiting Magnitudes (NELM). Combined with known shower parameters such as population index and radiant height, maps were generated with hourly rates forecasts at local and national scales. Ultimately, observing conditions will remain dependent on the individual observers, their night adaptation and local light interference. The Urban Meteor Map aims to helps raise awareness for the effects of light pollution, and thus promotes exploration of local living environment to seek the best viewing spots for meteor showers.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Planetary Exploratio

Delft Meteorite Lab: a virtual environment to explore meteorites and meteorWrongs

Assessing and classifying rocks on the basis of their visual traits has been a long standing practise for geoscience fields. For planetary geoscience the interaction with astrogeological materials such as meteorites and impactites contributes to the comprehension of their properties, alteration and, ultimately, solar system formation processes. In the wake of the SARS-CoV-2 (COVID-19) pandemic we explored alternative options to involve meteorites and impactites in remote teaching. Simultaneously, this opened up the integration of meteorites in teaching activities for large groups of learners. We have developed a workflow using Structure from Motion (SfM) photogrammetry to render high-resolution digital 3D models of meteorites and impact rocks. This procedure was used to create a virtual collection with tens of examples that were made publicly accessible in an online environment. The digital 3D models can be inspected by rotating and zooming, while annotations in clickable pop-ups direct users to key features or provide background information and data. We evaluated the user experience and discuss how virtual collections can be created and used for blended learning. Meanwhile, we have explored the use of models in the ‘Delft Meteorite Lab’ in academic teaching, public outreach and science applications. The virtual collection also offers a potential resource to aid the identification of putative meteorite finds by the general public. Looking towards the future, a new ‘Dutch Meteorite Lab’ aims become a national hub for education and research to explore meteorites and meteorite taxonomy based on specimen available in various study collections across the Netherlands.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Planetary Exploratio

Aeolian contributions to the development of hillslopes and scree sediments in Grænagil, Torfajökull, Iceland

Scree cones and slopes are common sedimentary landforms created by rock fall and rock particle fall in mountainous environments. These formative processes are attributed to various weathering and particle detachment mechanisms. However, the aeolian contributions to the weathering of rock faces and formation of scree sediments are poorly understood and often underestimated. A case study in the southern highlands of Iceland provided a geological setting in a subarctic environment where the contribution of various erosion and deposition mechanisms to the development of scree deposits could be studied. Here, moderately-cohesive subglacial volcanic eruption products are continuously undercut by local streams, creating exposed and steep-sided canyon walls where scree cones and slopes are formed by dominant influences of freeze-thaw cycles and the wind on rock particle fall. The stratigraphy and the morphometry of these sedimentary landforms indicate that wet formative processes can contribute but are not as dominant. Avalanching of accumulated material occurs in dry conditions and creates distinct stratified sediments. The aeolian contribution to the scree development was studied by determining the physical requirements of particle detachment using wind tunnel simulations. Simulated threshold wind speeds of the removal of fines show that these wind and gust conditions are common in these areas in Iceland. A detailed particle analysis of the sediment from an isolated scree cone and the contributing rock face showed that sediments were depleted in the silt fractions. Field observations confirmed the influence of deflation where fine material is removed by the wind from exposed sediments whereas larger particles are excavated by the deflation of the surrounding matrix on the overlying rock face. The outcomes highlight the role that aeolian processes can fulfil in subarctic environments. As similar glassy materials are also found on other planets, the studied processes can for example offer insights in hillslope processes at the surface of planet Mars