Scientists have found pieces of a meteorite that fell near Berlin shortly after midnight on January 21. It’s a rare find, from an asteroid spotted just before it entered Earth’s atmosphere. Only a few such events in the recent past have allowed astronomers to trace the origin of an incoming rock to the solar system.
Early analysis of the fragments showed something equally rare. The meteorite is an aubrite, a class of unknown origin that some scientists believe may be fragments of the planet Mercury. They are so rare that they made up just 80 of the roughly 70,000 meteorites collected on Earth before last month’s event.
“It’s really fascinating,” said Sarah Russell, a meteorite expert at the Natural History Museum in London. “There are very, very few aubrites.”
The asteroid that became the meteorite (or rather meteorite fragments) was first spotted by Krisztián Sárneczky, a Hungarian astronomer, three hours before it hit Earth’s atmosphere. A network of cameras tracked the incoming rock, 2024 BX1, as it fell near Ribbeck, a village outside Berlin. Estimates suggest the rock was tiny, less than three feet in size. It still produced a brilliant flash that was caught on camera in many parts of Europe.
Upon hearing the news of the meteorite crash, Peter Jenniskens, an astronomer at the SETI Institute in California, bought a plane ticket.
“Saturday afternoon I found out,” he said. “Late Saturday night I was on a plane to Berlin.”
During a nine-hour wait in Newark, Dr. Jeniskens calculated where pieces of the meteorite could be found so that when it landed early Monday morning, he and nearly two dozen students and volunteers could begin searching for fragments immediately.
For days they passed through the fields around Ribbeck. “We couldn’t find anything,” he said.
But that Thursday, January 25, a Polish group of meteorite hunters announced that they had found the first piece of the meteorite. “They could show us what to look for,” Dr. Jeniskens said. The meteorites were not black, as expected from passing through the atmosphere, but light, like terrestrial rocks.
With this information, within just two hours a member of Dr. Jenniskens, a student at Berlin’s Freie Universität named Dominik Dieter, found a meteorite sitting on top of the soil. More were quickly spotted.
“It was incredible,” Dr. Jeniskens said. “We found over 20 fragments.”
Researchers at the Natural History Museum in Berlin analyzed the minerals in the fragments using an electron microprobe. This revealed that the rocks appeared to be auvrites. It was the first time such meteorites had been collected in a tracked fall.
The source of the aubrites, named after the French town of Aubres, near where they were first found, remains a mystery as their composition does not match other known sources of meteorites in the solar system. Some research has suggested that they are fragments of the planet Mercury, but not all scientists support this origin story.
If the aubrites came directly from Mercury, 2024 BX1 would have to come from the inner solar system. However, by tracing its path, it appears that the asteroid’s original orbit was much wider and outside of Earth’s orbit.
“Therefore, this object could not have come to us directly from Mercury,” said Marc Fries, a planetary scientist at NASA’s Johnson Space Center.
It is possible, however, that the aubrites were ejected from Mercury long ago into the asteroid belt between Mars and Jupiter, forming a group called E-type asteroids. The orbit of 2024 BX1 does not completely rule out this idea, although the Dr. Fries remains skeptical.
Whatever their origin, the fragments of 2024 BX1 will prove scientifically fascinating. “I’m sure it will be a priority to find out what its composition is and how it compares to other meteorites,” said Dr. Russell.
Tracking such small asteroids before they hit the Earth’s atmosphere is also vital to the planet’s defense against asteroids. Davide Farnocchia, of NASA’s Center for Near-Earth Object Studies, said smaller objects from space are not constantly detected but can cause problems for people on the ground, such as the 65-foot-wide Chelyabinsk meteorite that exploded over Russia in 2013 and injured hundreds of people. Knowing the trajectories in advance could give people time to get to safety.
“If you could send a warning, no one would get hurt,” he said.
