An Imminent Impact
On February 12, 2023, Hungarian astronomer Krisztián Sárneczky was observing the sky from the Piszkéstető station of the Konkoly Observatory. Around 20:18 UT, he discovered a small asteroid approaching Earth. The object, located at 233,000 kilometers from our planet (approximately 0.61 times the Earth-Moon distance), prompted Sárneczky to report his findings to the Minor Planet Center (MPC) and request additional tracking of the asteroid.
Responding to the MPC's call for observation, observatories worldwide confirmed the potential for an imminent impact. Forty minutes post-discovery, the Višnjan Observatory in Croatia validated this concern. Leveraging a new tracking strategy from the European Space Agency's Near-Earth Object Coordination Centre (ESA NEOCC), astronomers predicted the asteroid's impact time and location with unprecedented accuracy. The anticipated entry of the asteroid into Earth's atmosphere was over the English Channel around February 13, 3:00 UT.
Such predictions are extremely rare; in human history, only seven asteroids have been detected before colliding with Earth. Fortunately, the meter-sized asteroid was too small to cause damage on the ground. Instead, it provided a unique opportunity to observe its disintegration in the atmosphere, potentially recovering some of the produced fragments (meteorites) on the ground.
A few hours prior to impact, the European Space Agency thus encouraged the population to observe the event. The news was swiftly relayed by the FRIPON and Vigie-Ciel networks1, urging residents to observe and photograph the asteroid's entry. Thanks to this efficient communication, many observers confirmed the asteroid's apparition in the night sky at 2:59 UT on February 13, 2023.
Searching for Meteorites
Numerous images, videos, and visual reports of the phenomenon were sent to scientists from France, England, Germany, and the Netherlands. The analysis of these observations, coupled with images from the professional FRIPON camera network, allowed astronomers to predict that several meteorites had fallen in Normandy, France. Thanks to the combined efforts of researchers in Canada, France, Czech Republic, Australia, and the United States, a strewn field was determined near the cities of Angiens and Saint-Pierre-le-Viger.
The FRIPON/Vigie-Ciel teams arrived on the field less than 24 hours after the event. A first team of researchers and space enthusiasts quickly explored the terrain, leading to the discovery of the first asteroid fragment only two days after its fall2. In the following weeks, more than 60 fragments of the asteroid were found, with a total mass exceeding 1.3 kg. The meteorite, an ordinary chondrite of type L5-6, was named Saint-Pierre-le-Viger (SPLV)3. Thanks to the exceptional speed of the research teams, fragments of the meteorite were sent to several European laboratories before significant Earth contamination.
An Outstanding Collaboration
The story of 2023 CX1, from its discovery in space to the analysis of the meteorites found in Normandy, is a testament to perseverance and international cooperation.
The discovery and tracking of the asteroid were made possible by the constant efforts of the professional and amateur astronomers' community, which scans the night skies for near-Earth asteroids. Effective communication from space agencies and the FRIPON/Vigie-Ciel organization alerted the population several hours before the impact, allowing the collection of numerous photographic and video observations.
These records, analyzed jointly by researchers from several countries, facilitated a quick determination of the meteorite landing location. The FRIPON/Vigie-Ciel team, with the mobilization of its network, quickly arrived on the fall area, communicated with residents, obtained permissions to explore the region, and conducted initial field searches. With the help of many volunteers, the first Saint-Pierre-le-Viger meteorite was found after a few hours of searching. This marks the first time that a meteorite found during a research campaign (i.e., not witnessed falling nearby) has been sent for analysis in a laboratory only a few days after the fall, preserving it from alterations caused by the terrestrial environment.
Creation of the 2023 CX1 Consortium
Today, the international collaboration between researchers and space enthusiasts continues for the study of this exceptional fall. Throughout history, only three asteroids discovered before impacting Earth have produced meteorites that were recovered. And only one has been accurately investigated in space, in the atmosphere, and in laboratories: 2023 CX1.
To reconstruct the history of this small asteroid, we have created the 2023 CX1 Consortium, an international and interdisciplinary research group working on the study of the Saint-Pierre-le-Viger meteorite. The consortium brings together more than 80 scientists (professionals and amateurs) from twelve different countries.