They recover and analyze for the first time a meteorite that has fallen in Galicia

On January 18, 2021, in the midst of a pandemic, the Traspena meteorite, about 20 km from the city of Lugo. It happened shortly after a huge fireball, cataloged as SPMN180121, crossed the sky and its shock wave (produced by its entry into hypervelocity and disruption 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 the videos sent by several fans to the Research Network on Fireballs and Meteorites (SPMN). The images were used to determine the atmospheric trajectory of this meteoroid that generated sound waves detected in three seismic stations.

A team of researchers from the University of Santiago de Compostela, led by the researcher Manuel Andradeand three CSIC centers (the Institute of Space Sciences ICE, Geosciences Barcelona GEO3BCN and the National Museum of Natural Sciences MNCN) worked side by side in the study of this meteorite.

The study, accepted in Monthly notices from the Royal Astronomical Societystarted from the analysis of videos compiled from four stations of the SPMN network and eleven contributed by casual witnesses of that luminous event.

The original meteoroid had a diameter of around 1.15 meters and a mass of around 2,620 kg, making it technically a small asteroid.

Two months after the fireball crossed the sky and in the midst of USC’s recovery campaign, a farmer located the meteorite near Traspena. Scientists confirmed that it was a common chondritic of 527 gramswho has already been officially appointed by the Meteoritic Society.

From the ICE-CSIC, researchers Josep M. Trigo Rodríguez (coordinator of the SPMN network) and Eloy Peña Asensio contributed to the astrometric analysis of part of the audiovisual material obtained and, in addition, carried out an independent verification of the heliocentric orbit of Traspena with the software 3D-FireTOC, developed in ICE-CSIC.

Likewise, Josep M. Trigo, from ICE Meteoritics and Returned Samples Clean Room, participated in the petrographic characterization of the rock, finally identified as a common L5 chondrite.

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

The mineralogical characterization carried out at the X-Ray Diffraction Service of the Institute of Geosciences of Barcelona (GEO3BCN-CSIC), directed by the materials scientist Jordi Ibáñez-Insaallowed to complement the petrographic study of the meteorite.

“X-ray diffraction provided very valuable structural and compositional information about the meteorite’s key minerals. The results obtained show excellent agreement with the microanalyses performed for their petrological characterization”. This is not trivial, as diffraction provides information on a macroscopic average of the meteorite, while microanalysis allows the study of only a few mineral grains”, highlights Ibáñez-Insa.

Likewise, from MNCN, Javier Garcia Guinea he handled geochemical and petrographic analysis. “During the summer of 2021, we carried out an analysis on the destructiveness of the 527-gram fragment to determine the apparent density, the internal density and the morphology by micro-computed tomography of X-rays”, explains the geologist, who was the first to access the interior of the rock.

“As with all meteorites, the interior is very different from the outer fusion crust, so we used a diamond disk with the thinnest possible section to make two cuts and extract a sample section,” says García Guiné. 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. ICE and 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, in addition to several thin sections used for its characterization and microscopic study.