[ad_1]
An eight-hour search of the seabed off the coast of Washington on Monday revealed two tiny fragments of molten rock that scientists suspect to be remnants of the meteor that exploded in a fireball and was collapsed in the sea in March. "I could not be happier," said Mark Fries, conservator of cosmic dust at NASA, Tuesday morning at a phone news briefing. from the EV Nautilus the nonprofit vessel that conducted the research. "It has been the experience of a lifetime."
If the discovery takes place, it will be the first time anyone will retrieve fragments of a known meteorite from the ocean.
A trolley-sized space rock hit the atmosphere the evening of March 7 was widely seen, heard and felt along the Washington coast.
If the meteor had exploded on Seattle, he would probably have broken the glass and caused injuries like the spectacular meteor that shook the Russian city of Chelyabinsk Oblast in 2013, said the astronomy professor of the city. Washington University Don Brownlee. was the largest detected in the United States in more than 20 years, said Fries. He estimates that about 2 tons of broken rock have survived the fiery dive. With the aid of a weather radar, he followed the main impact zone to a corridor half a mile in diameter about 16 miles off the coast. coast
. sediment samples. They also used a shovel and a shaped magnetic wand for the mission to scan the sediment for magnetic meteorites.
The sample that contained the two fragments was the last of the day, collected in a small pit on the seabed.
"The bottom of the sea was like a pool table, and there was this little pit where there seemed to be something falling in," said Fries
. 300 feet deep, was soft and muddy. Any large fragment of meteorite would probably have been swallowed up by the mud at impact. Surface bumps of up to 12 feet also boiled water during the operation, reducing visibility.
The two pieces of rock are about 2 to 3 millimeters in diameter, about one tenth of an inch. French fries have said that they are probably what's called a melting crust – a melted layer like pottery glaze etched on the surface by the blast furnace heat of the descent of a meteor in l & # 39; atmosphere.
Fries hopes to determine the chemical composition of the fragments. The meteor was unusual as it was divided into several large fragments, indicating that it was composed of harder materials than any other space rock that it followed.
"You can explain this anomaly if the meteor is of a different composition than we now have samples in hand to test that hypothesis," he says.
Although the Washington expedition was the first to track down a particular meteorite, this is not the first time that extraterrestrials have been mined. from the bottom of the ocean. British scientists from the HMS Challenger expeditions of 1872-76 who laid the foundation for modern oceanography, propelled magnets through the sediments of the seafloor and extracted tiny metal spherules that were found in the sea. they had correctly detected the space. 19659002] In 1979, Brownlee and his colleagues dragged a 600-pound magnetic sledge that they called the Cosmic Muck Rake across the bottom of the Pacific in water at more than 3 miles deep. They recovered more than 100,000 spherules – the smallest of the fragments discovered by Nautilus .
Brownlee's space particle quest finally culminates in NASA's Stardust mission. 2 and brought them back to earth in 2006. These samples are now stored in the NASA collection that Fries manages.
Fries consulted Brownlee before the Washington expedition. But towing a mighty magnet over the bottom of the sea would not fly in the protected waters of the National Marine Sanctuary of the Olympic Coast.
Yet, Brownlee is impressed by the ingenuity of the crew and its apparent success
. Meteorites are invaluable to astronomers because they are remnants of the primordial material that formed the solar system. "They are our main source of information on the early solar system," said Brownlee. "They are the only documents we have of what has really happened."
After examining samples from the Washington Coast, Fries will hand them over to the Smithsonian Institution, which houses the National Meteorite Collection. If it is confirmed that they come from space, it will be up to an international group called the Meteorological Society to decide if the specimens contain enough material to be officially certified as a new meteorite.
If accepted by society, the meteorite needs a name. Fries and staff at the Olympic Coast National Marine Sanctuary have asked members of the Quinault Indian Nation, which is the closest community to the landing site, to suggest opportunities.
When he returns to his laboratory at NASA's Johnson Space Center, Fries plans to sift the sediment samples, looking for fragments of space rocks, no matter how small.
"I'm sure we'll find more than two small fragments," he said. "Small is not a problem.We have a habit of processing samples that are literally stains."
Source link
