In 2023, two meteorites were discovered in the Sahara Desert: Northwest Africa 15915 (NWA 15915) and Ksar Ghilane 022 (KG 022). These specimens have attracted scientific interest due to their potential link to Mercury, the innermost planet of our solar system.
Researchers have analyzed the mineral composition of these meteorites, noting the presence of olivine, pyroxene, and oldhamite—minerals that align with predictions for Mercury's surface composition. Additionally, their oxygen isotopic compositions are similar to those found in aubrites, a rare class of meteorites previously proposed as originating from Mercury's shallow mantle.
However, certain discrepancies have been observed. Both meteorites contain only trace amounts of plagioclase, whereas Mercury's surface is estimated to be over 37% plagioclase. Moreover, the estimated age of these meteorites is approximately 4.5 billion years, which is older than Mercury's youngest recognized surface units, estimated to be around 4 billion years old.
Confirming the origin of these meteorites remains challenging. Direct sample return missions to Mercury are complex and costly. The BepiColombo mission, a collaboration between the European Space Agency and the Japan Aerospace Exploration Agency, is currently in orbit around Mercury and is expected to provide high-resolution data that may help determine the ultimate origin of NWA 15915 and KG 022.
If these meteorites are indeed from Mercury, they could offer valuable insights into the planet's formation and evolution, shedding light on its geological history and composition.