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Scientists have found pieces of a meteorite that fell near Berlin just after midnight on Jan. 21. It is a rare find, from an asteroid that was identified just before it entered Earth\u2019s atmosphere. Only a handful of such events in the recent past have allowed astronomers to trace an incoming rock\u2019s origin in the solar system.<\/p>\n
Early analysis of the fragments has shown something equally rare. The meteorite is an aubrite, a class with unknown origins that some scientists argue may be pieces of the planet Mercury. They are so rare that they made up just 80 of the 70,000 or so meteorites that were collected on Earth before last month\u2019s event.<\/p>\n
\u201cIt\u2019s really exciting,\u201d said Sara Russell, a meteorite expert at the Natural History Museum in London. \u201cThere are very, very few aubrites.\u201d<\/p>\n
The asteroid that became the meteorite (or rather fragments of meteorite) was initially spotted by Kriszti\u00e1n S\u00e1rneczky, a Hungarian astronomer, three hours before it hit Earth\u2019s 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 made a brilliant flash that cameras in many parts of Europe picked up.<\/p>\n<\/div>\n<\/div>\n
As soon as he heard the news of the meteorite fall, Peter Jenniskens, an astronomer at the SETI Institute in California, bought a plane ticket.<\/p>\n
\u201cOn Saturday afternoon I learned about it,\u201d he said. \u201cOn Saturday late evening I was on a plane to Berlin.\u201d<\/p>\n
During a nine-hour layover in Newark, Dr. Jenniskens calculated where pieces of the meteorite might be found so that, when he landed early on Monday morning, he and nearly two dozen students and volunteers could start looking for fragments immediately.<\/p>\n
For days they trawled through fields around Ribbeck. \u201cWe couldn\u2019t find anything,\u201d he said.<\/p>\n
But that Thursday, Jan. 25, a Polish team of meteor hunters announced that it had found the first piece of the meteorite. \u201cThey could show us what to look for,\u201d Dr. Jenniskens said. The meteorites weren\u2019t black, as expected from the passage through the atmosphere, but light, like terrestrial rocks.<\/p>\n
With this information, in just two hours a member of Dr. Jenniskens\u2019 team, a student at Freie Universit\u00e4t Berlin named Dominik Dieter, found a meteorite just sitting on top of the soil. More were quickly spotted.<\/p>\n
\u201cIt was incredible,\u201d Dr. Jenniskens said. \u201cWe found over 20 fragments.\u201d<\/p>\n<\/div>\n<\/div>\n
Researchers at the Natural History Museum in Berlin analyzed the minerals in the fragments using an electron microprobe. That revealed that the rocks appeared to be aubrites. It was the first time such meteorites had been collected in a tracked fall.<\/p>\n
The source of aubrites, named after the French town of Aubres near where they were first found, remains mysterious, as their composition does not match other known sources of meteorites in the solar system. Some research has suggested they are fragments of the planet Mercury, but not all scientists support that origin story.<\/p>\n
If aubrites came directly from Mercury, 2024 BX1 should have originated in the inner solar system. However, tracing back its path, it appears that the asteroid\u2019s initial orbit was much wider and outside Earth\u2019s orbit.<\/p>\n
\u201cTherefore this object could not have come to us directly from Mercury,\u201d said Marc Fries, a planetary scientist at NASA\u2019s Johnson Space Center.<\/p>\n<\/div>\n<\/div>\n
It is possible, though, that 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 rule out this idea completely, although Dr. Fries remains skeptical.<\/p>\n
Whatever their origin, 2024 BX1\u2019s fragments will prove scientifically fascinating. \u201cI\u2019m sure it\u2019s going to be a priority to find out what its composition is and how it compares to other meteorites,\u201d Dr. Russell said.<\/p>\n
Tracking asteroids as small as this before they hit Earth\u2019s atmosphere is also crucial for defending the planet from asteroids. Davide Farnocchia, from NASA\u2019s Center for Near Earth Object Studies, said smaller objects from space go undetected all the time but can pose problems to people on the ground, such as the 65-foot-wide Chelyabinsk meteor that exploded over Russia in 2013 and injured hundreds of people. Knowing the trajectories in advance could give people time to reach safety.<\/p>\n
\u201cIf you could send a warning, nobody would get hurt,\u201d he said.<\/p>\n<\/div>\n<\/div>\n