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A fireball that struck near Hamburg, Michigan in 2018 could offer new insights into the history of the solar system, the researchers said.
The fireball, a very bright type of meteor that would even be observed in daylight, was detected in various states while flying through the sky on the night of January 16, 2018; the meteor also produced an atmospheric shock wave equivalent to a magnitude 2.0 earthquake.
Meteorite hunters quickly recovered walnut-sized fragments from Strawberry and Bass Lakes using information from scientists who had been tracking their trajectory using NASA’s weather radar.
“Finding a pebble-sized fragment in a frozen lake or blanket of snow is difficult if you don’t know where to look,” said Philipp Heck, co-author of the report and associate professor at the University of Chicago. also curator of the meteorite, rock, and mineral collection at the Field Museum of Natural History in Chicago.
Now, Heck and his colleagues have published an in-depth report examining three of the meteorite pieces housed in the Field museum.
The results reveal that the space rock is of a type known as H4 chondrite, a relatively rare subtype of a class of meteorites common in collections.
“[These] it’s only 4% of all the falls today, ”Heck said.
Heck added that initial analysis of the space rock revealed that the meteorite contained 2,600 different organic compounds. While an even larger matrix has been found in other meteorites, Heck said the findings add weight to the much-discussed idea that meteorites could have played a role in the beginning of life on Earth.
“Personally, I found it surprising how much organic compounds were still in this meteorite despite its thermal metamorphism,” Heck said.
But there were other ideas.
“We found [this meteorite] it was ejected 12 million years ago from its parent asteroid, ”Heck said, noting that this is the first evidence for that particular event.
And analysis of the argon levels in the meteorite, produced by radioactive decay, shed light on the history of the asteroid itself, with Heck pointing out that the element is released when impacts occur. “We found out that nothing else happened since [parent asteroid] it was formed 4.5 billion years ago, ”Heck said. “It was pretty boring on that asteroid.”
Heck said that when the Hamburg meteorite fell on frozen ice, it was relatively free of contamination. But to have a truly pristine sample you need to retrieve space rocks directly from asteroids – an effort that several space missions have set out to do, including NASA’s Osiris-Rex spacecraft, which will return to Earth in 2023.
Dr Katharine Joy, an expert on meteorites and lunar science at the University of Manchester, who was not involved in the report, said that space rocks like the Hamburg meteorite are exciting as they are fresh extraterrestrial samples.
“By looking at the minerals, age and chemistry of [meteorites] we can look back in time to understand how the body of its parent asteroid relates to other asteroids and small bodies that we know formed at the same time in the first million years after the sun formed, ”he said.
Joy added that the UK Fireball Network is scanning the skies for meteors and encouraged readers to report the sightings themselves to the network.
“It’s going to be an exciting day where we get the right kind of fireball and we can go out there, locate the fallen stone and analyze it to find out where it came from,” he said. “It would be completely amazing if it were a completely unique type of asteroid or a part of a large body like the moon or Mars.”
