If the discovery pans out, it will be the first time anyone has recovered fragments of a known meteor from the ocean bottom. "I could not be happier," said NASA's curator of cosmic dust.
An eight-hour search of the seafloor off the Washington coast Monday yielded two tiny fragments of molten rock that scientists suspect are remnants of a meteor that exploded in a fireball and plummeted into the sea in March.
The fragments must be analyzed microscopically to confirm that they came from space, but the NASA scientist who led the hunt is optimistic.
“I could not be happier,” Mark Fries, NASA’s curator of cosmic dust, said Tuesday morning in a telephone briefing from the EV Nautilus, the nonprofit ship that conducted the search. “This has been the experience of a lifetime.”
If the discovery pans out, it will be the first time anyone has recovered fragments of a known meteor from the ocean bottom.
The fireball and sonic boom created when the golf-cart-sized space rock slammed into the earth’s atmosphere the evening of March 7 were widely seen, heard and felt along the Washington coast. If the meteor had exploded over Seattle, it probably would have shattered glass and caused injuries like the spectacular meteor that jolted the Russian city of Chelyabinsk Oblast in 2013, said University of Washington astronomy professor Don Brownlee.
The Washington meteor was the largest detected in the U.S. in more than 20 years, Fries said. He estimates about 2 tons of shattered rock survived the fiery plunge. Using weather radar, Fries tracked the main impact zone to a half-mile-diameter swath about 16 miles off the coast.
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The crew of the EV Nautilus used underwater robots equipped with a suction tube to slurp up samples of sediment. They also used a scoop and a magnetic wand fashioned for the mission to rake through the sediment for magnetic meteorites.
The sample that contained the two fragments was the final one of the day, collected from a small pit on the seafloor.
“The seafloor was like a billiard table and there was this one little pit where it looked like something fell into it,” Fries said.
Crew members said the search was challenging because the seafloor at about 300 feet in depth was soft and muddy. Any large meteorite fragments would likely have been swallowed up by the muck on impact. Surface swells of up to 12 feet also roiled the water during the operation, reducing visibility.
The two bits of rock are about 2 to 3 millimeters in diameter, or about a tenth of an inch. Fries said they are probably from what’s called a fusion crust — a molten layer like pottery glaze seared onto the surface by the blast-furnace heat of a meteor’s descent into the atmosphere.
Fries hopes to determine the chemical composition of the fragments. The meteor was unusual because it broke into several large fragments, indicating that it was made up of harder material than all of the other space rocks Fries has tracked.
“You can explain that anomaly if the meteor is of a different composition from the normal, most common types of meteors and now we have samples in hand to test that hypothesis,” he said.
Though the Washington expedition was the first to stalk a particular meteorite, it’s not the first time extraterrestrial material has been extracted from the ocean bottom. British scientists on the 1872-1876 HMS Challenger expeditions, which helped lay the foundation for modern oceanography, ran magnets through seafloor sediment and extracted tiny, metallic spherules that they correctly surmised had fallen from space, Brownlee said.
In 1979, Brownlee and his colleagues dragged a 600-pound magnetic sled they called the Cosmic Muck Rake, across the bottom of the Pacific in water more than three miles deep. They pulled up more than 100,000 of the spherules — most far smaller than the fragments discovered by the EV Nautilus.
Brownlee’s quest for particles from space eventually culminated in NASA’s Stardust mission, which collected samples from comet Wild-2 and returned them to earth in 2006. Those samples are now stored in the NASA collection that Fries manages.
Fries consulted with Brownlee before the Washington expedition. But towing a heavy magnet across the seafloor wouldn’t fly in the protected waters of the Olympic Coast National Marine Sanctuary.
Still, Brownlee is impressed with the crew’s resourcefulness — and apparent success.
“It’s fantastic that they may have found something,” he said.
Meteorites are invaluable to astronomers because they’re remnants of the primordial material that formed the solar system. “They’re our major information source about the early solar system,” Brownlee said. “They are the only records we have of what really happened.”
After Fries examines the samples from the Washington coast, he’ll hand them over to the Smithsonian Institution, which houses the national meteorite collection. If they are confirmed to be from space, it will be up to an international group called the Meteoritical Society to decide if the specimens contain enough material to be officially certified as a new meteorite.
If accepted by the society, the meteorite will need a name. Fries and the staff of the Olympic Coast National Marine Sanctuary have asked members of the Quinault Indian Nation, which is the closest community to the splashdown site, to suggest possibilities.
When he gets back to his lab at NASA’s Johnson Space Center, Fries plans to sift through the sediment samples again, looking for additional bits of space rock, no matter how small.
“I’m certain we’re going to find more than two little fragments,” he said. “Small isn’t a problem. We’re used to dealing with samples that are literally specks.”