par Tollenaar, Veronica 
Président du jury Fripiat, François
Promoteur Pattyn, Frank
Co-Promoteur Debaille, Vinciane
Publication Non publié, 2024-07-10
Président du jury Fripiat, François
Promoteur Pattyn, Frank
Co-Promoteur Debaille, Vinciane
Publication Non publié, 2024-07-10
Thèse de doctorat
| Résumé : | Meteorites are rocks that fell from space. These unique extraterrestrial samples on Earth provide crucial information for understanding the origin and evolution of our Solar System. Antarctica is the world’s most prolific site for collecting meteorites, with more than 60% of all ∼ 80,000 meteorites ever found on Earth being collected there. Antarctic meteorites are found in areas where ice is exposed, in contrast to most of the continent’s surface which is covered by snow. During Antarctic meteorite recovery missions, these typically dark meteorites are easily found while lying on the surface of the visually contrasting light-blue colored ice. Moreover, the number of meteorites in these blue ice areas can be anomalously high. This concentration of meteorites is related to the sublimation of ice layers and the flow of the ice. Meteorite finds from Antarctica were always fairly dependent on serendipity, with experts selecting sites to visit based on their experience and a limited amount of imagery and maps. In this thesis, I perform continent wide data-driven analyses to understand the potential of blue ice areas for the recovery of meteorites and project their persistence in a warming climate. The search for Antarctic meteorites can be approached with data as there is wealth of observations available from the Antarctic continent, including meteorite finds and satellite products. Moreover, techniques to analyze large amounts of data efficiently are rapidly evolving, of which machine learning the most prominent. Hence, by combining diverse satellite observations in a deep learning framework, I detected blue ice areas. Meteorites are found on blue ice, but not all blue ice areas act as meteorite trap. Therefore, I selected indirect observations of the meteorite concentrating mechanism to understand and predict the presence of meteorites. One of these observations entailed the surface temperature. Consequently, I used projections of future surface temperatures to estimate the impact of climate warming on the presence ofmeteorites. As outcome of the data analyses, in this thesis I present a map of Antarctic blue ice areas and a map of over 600 meteorite stranding zones. These meteorite stranding zones include known and unexplored areas, with an estimated accuracy of over 80%. Moreover, I estimated that, in total, there are 340,000 to 900,000 meteorites in Antarctica, implying that less than 15% of all Antarctic meteorites are recovered todate. These meteorites, however, are threatened by climate warming; an estimated 5,000 meteorites per year are currently disappearing from the surface by melting into the ice. This meteorite loss rate is a factor five larger than the recovery rate of 1,000 per year. The continent-wide studies indicate that the potential for finding meteorites in Antarctica remains largely untapped. However, with Antarctic meteorite losses due to climate warming, it is urgent to coordinate and scale up recovery efforts. The outcomes of this thesis contribute to such a coordination, i.e., the map of blue ice areas and the map of meteorite stranding zones help in identifying areas to explore. Moreover, the future projections indicate that low elevation areas should be prioritized as these are more sensitive to climate warming. To further guide recovery missions, analyses on a local scale are beneficial. These analyses could eventually also contribute to the search for the oldest ice in blue ice areas, as they can help in understanding the link between the presence of meteorites and the presence of old ice. |
