A team of international space scientists has found new evidence of a low-altitude meteorite impact that hit Antarctica 430,000 years ago.
Extraterrestrial particles (condensation spherules) recovered on the summit of Walnumfjellet (WN) within the Sør Rondane Mountains, in eastern Antarctica, indicate unusual impact, where a jet of molten and vaporized meteorological material resulting from the atmospheric entry of an asteroid with at least 100 meters hit the surface at high speed.
This type of explosion caused by a single asteroid impact is described as intermediate, as it is larger than an air explosion, but smaller than a crater impact event.
The main chondritic volume, the trace element chemistry and the high nickel content of the debris demonstrate the extraterrestrial nature of the recovered particles. Their unique isotopic oxygen signatures indicate that they interacted with oxygen derived from the Antarctic ice sheet during their formation in the impact plume.
The results indicate a much more dangerous impact than the events of Tunguska and Chelyabinsk on Russia in 1908 and 2013, respectively.
This investigation, published by Science Advances, guides an important discovery to the geological record where the evidence of such events is scarce. This is mainly due to the difficulty in identifying and characterizing the impact particles.
The study highlights the importance of reevaluating the threat of medium-sized asteroids, as similar impact events are likely to produce similar particles. Such an event would be totally destructive in a large area, corresponding to the area of interaction between the hot jet and the ground.
Dr. van Ginneken, in a statement, stated that “in order to complete the recording of the impact of Earth’s asteroids, we recommend that future studies focus on identifying similar events on different targets, such as rocky or shallow ocean basements, since the layer of Antarctic ice covers only 9% of the Earth’s surface. Our investigation can also be useful for the identification of these events in sediment cores of the seabed and, if the expansion of the plume reaches land masses, the sedimentary record.
The extraterrestrial particles (condensation spherules) examined in this study were found during the Belgian Antarctic Meteorite (BELAM) 2017-2018 expedition based on the Princess Elisabeth Antarctica Research Station in Belgium and funded by the Belgian Scientific Policy (Belspo).
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