They find for the first time a fallen meteorite in Galicia

On January 18, 2021, the Traspena meteorite fell in Galicia, about 20 km from the city of Lugo, shortly after a huge fireball, cataloged as SPMN180121, crossed the sky and the shock wave produced by its entry to hypervelocity and rupture in the atmosphere was heard by hundreds of people.

This is the first fall of a meteorite recovered in this autonomous community thanks to the cameras of the University of Santiago de Compostela (USC) and other videos received thanks to citizen participation by the Research Network on Fireballs and Meteorites, which served to determine the atmospheric trajectory of this meteoroid that generated sound waves detected at three seismic stations.

A team of researchers from the University of Santiago de Compostela, led by researcher Manuel Andrade, and three centers of the Higher Council for Scientific Research (CSIC) – the Institute of Space Sciences (ICE-CSIC), Geociencias Barcelona (GEO3BCN) and the National Museum of Natural Sciences (MNCN-CSIC) – worked side by side in the study of the Traspena meteorite, whose fall occurred in the middle of the pandemic.

The study, accepted in Monthly Notices of the Royal Astronomical Societywas based on the analysis of the videos compiled within the framework of the Research Network on Fireballs and Meteorites (SPMN), both from four stations belonging to this research project and from another eleven contributed by casual witnesses of this luminous event.

Meteorite

The original meteoroid had a diameter of about 1.15 meters and a mass of about 2,620 kg, making it technically a small asteroid. Two months after the fireball crossed the sky and in the middle of the USC recovery campaign, a farmer located the Traspena meteorite, an ordinary 527-gram chondrite, which has already been officially named by the Meteoritical Society.

The Fireball and Meteorite Research Network (SPMN)which has been monitoring large fireballs that have fallen in Spain since 2003 and is coordinated by the ICE-CSIC astrophysicist Josep M. Wheat, provided the researchers from the University of Santiago de Compostela with the videos captured and compiled from various witnesses to the fireball in order to undertake their astrometric study in order to calculate the trajectory.

Throughout this process, from the ICE-CSIC, Josep M. Trigo Rodríguez and Eloy Pena Asensio contributed to the astrometric analysis of part of the audiovisual material obtained and, in addition, carried out an independent corroboration of the heliocentric orbit of Traspena with the 3D-FireTOC software, developed at the ICE-CSIC. Likewise, Josep M. Trigo, from the ICE Meteoritics and Returned Samples Clean Room, participated in the petrographic characterization of the rock, finally identified as an ordinary L5 chondrite.

“In addition to participating in the astrometric reduction of the videos, verifying the orbit calculated from the USC and, from it, in the search for a progenitor asteroid for the meteoroid that produced Traspena, identifying and evaluating its possible origin in the asteroid potentially dangerous minos”, says Josep M. Trigo-Rodríguez, astrophysicist at ICE-CSIC and member of the Institute for Space Studies of Catalonia (IEEC). The connection with that asteroid, however, was finally ruled out after the final evaluation of the evolution of both orbits.

Mineralogical characterization

The mineralogical characterization carried out in the X-Ray Diffraction Service of the Barcelona Geosciences Institute (GEO3BCN-CSIC), directed by the materials scientist Jordi Ibáñez-Insa and close collaborator of Trigo in recent years, made it possible to complement the petrographic study of the meteorite.

“X-ray diffraction provided very valuable structural and compositional information about the major minerals in the meteorite. The results obtained present an excellent agreement with the microanalyses carried out for its petrological characterization”. This is not trivial, since diffraction provides information on a macroscopic average of the meteorite, while microanalysis only allows us to study a few mineral grains”, adds Jordi Ibáñez-Insa.

Likewise, from the MNCN, Javier Garcia Guinea he dealt with geochemical and petrographic analyses. “During the summer of 2021 we performed non-destructive analysis of the 527-gram fragment to determine the apparent density, internal density and morphology by X-ray micro-computed tomography”explains the CSIC researcher, who was the first to access the interior of the rock.

“As with all meteorites, the interior is very different from the outer melt crust, so we used a diamond blade with the thinnest section possible to make two cuts and extract a sample section”, indicates Garcia Guinea. The researcher and his team also created two copies of the meteorite.

The Institute of Space Sciences and the National Museum of Natural Sciences will act as an international repository for the meteorite, as in other previous falls. The ICE and the MNCN will house complete and exact replicas of the meteorite, as well as two thick sections of its interior weighing 24 and 29 grams, respectively, as well as several thin sections used for its characterization and microscopic study.

Font: ICE-GEO3BCN-CSIC Communication

Reference article: https://www.csic.es/es/actualidad-del-csic/recuperan-por-primera-vez-un-meteorito-caido-en-galicia