Jenniskens' collaborators at the Nature Museum have officially announced that the first examinations of one of these objects using an electron microprobe demonstrate the typical mineralogical and chemical composition of operite-type achondrite.
The official classification now matches what many suspected just by looking at photos of the strange meteorites that fell near Berlin on January 21, 2024. They belong to a rare group called “operetta.”
“They were very difficult to find because from a distance they look like other rocks on Earth,” said Dr. Peter Jeniskens, a meteorite astronomer at the SETI Institute. “Up close, not much.”
Jenniskens traveled from San Francisco to Berlin to research the fields just south of the village of Reebeck with Museum Naturalist (MfN) researcher Dr. Lutz Hecht, guiding a team of students and staff from the MfN, Free University of Berlin, and the German Center. für Luft und Raumfahrt, and the Technical University of Berlin in the days following the fall.
“Even with the wonderful guidance provided by meteor astronomers Dr. Pavel Sborny, Jiri Borovicka, and Lukas Sherbiny of the Astronomical Institute of the Czech Academy of Sciences, who calculated how the meteorites were blown by strong winds, speculated that these could be rare enstatite-rich meteorites based on the light emitted by the fireball, and our research team could not initially detect them easily. “They are on the ground,” Jeniskens said.
Unlike other meteorites that have a thin crust of black glass due to the heat of the atmosphere, these meteorites have a mostly transparent glass crust.
“We discovered the meteorites only after a Polish team of meteorite hunters identified the first discovery and could show us what to look for,” Jeneskens said. “Then, our first discoveries were quickly made by Freie University students Dominique Dieter and Kara Wehe.”
The importance of meteorite clusters
The meteorites are fragments of the small asteroid 2024 BX1, which was first observed using a telescope at the Konkoli Observatory in Hungary by astronomer Dr. Krysztian Szarnieczky, and its impact on Earth's atmosphere was then tracked and predicted by NASAImpact Risk Assessment Systems for ESA's Meerkat Scout and Asteroid Sentinel, with Davide Farnocchia of Jet Propulsion Laboratory/Caltech provides frequent path updates, finally causing the bright fireball seen and photographed. This was Jeneskens' fourth wave recovery of such a small asteroid impact, following a 2008 impact in Sudan, a 2018 impact in Botswana, and a 2023 impact in France.
Today, Jenniskens' collaborators at the Museum Für Naturkunde officially announced that the first examinations of one of these objects using an electron microprobe prove the mineralogical and chemical composition typical of operetta-type achondrite. This finding was submitted to the International Nomenclature Committee of the Meteorological Society on 2 February 2024 for examination and confirmation.
The name of the meteorite comes from the village of Aubris in France, where a similar meteorite fell on September 14, 1836. The museum has part of that in the collection.
“Based on this evidence, we were able to make an approximate classification relatively quickly,” said Dr. Ansgar Griszak, scientific head of the museum's meteorite collection. “This underscores the enormous importance of the collections for research. To date, there is only material from eleven other observed falls of this type in meteorite collections around the world.”
“The operite stones do not look like what people generally imagine meteorites to look like. The operite stones look more like gray granite and are composed mainly of magnesium silicates enstatite and forsterite,” said Christopher Hamann of the Museum of Nature, who participated in the initial classification and participated in the research. Almost no iron, and the glassy crust, which is usually a good way to identify meteorites, looks very different from most other meteorites. Therefore, it is difficult to discover operettas in the field.
“Devoted student. Bacon advocate. Beer scholar. Troublemaker. Falls down a lot. Typical coffee enthusiast.”