Microscopic image of a metal ball that scientists say came from an interstellar body
interstellar exploration
Tiny metal balls found on the ocean floor may have come from interstellar meteorites. Researchers who recovered the globules say their composition does not match anything previously observed on Earth, a controversial claim.
Earlier this year, Avi Robe A Harvard research team accompanied an expedition off the coast of Papua New Guinea, and models predicted that the remains of an object called IM1 would make landfall. IM1 he fell to earth in 2014. Loeb and his colleagues later identified it as a possible interstellar object based on its recorded velocity. That speed, they argue, was fast enough to indicate that it hit Earth from outside the solar system. They wanted the ruins to be under the sea.
During the expedition, researchers found about 700 small iron-rich globules. They set out to analyze the composition of those globules. Of the 57 that have been investigated so far, five appear to have unusual compositions.
These five spheres are particularly rich in the elements beryllium, lanthanum, and uranium, and the researchers named them BeLaU globules. The globules also have particularly low concentrations of elements that scientists expect to evaporate in the extreme heat produced by meteors as they pass through Earth’s atmosphere. These compositions are inconsistent with the origins of Earth, the Moon, and Mars, Loeb said.
“Usually when you have globules from meteors in the solar system, their abundance varies by up to an order of magnitude,” he says. They are off by a factor of up to 1000. “Combining everything we know … I’m pretty sure these came from interstellar bodies.”
These compositions, Loeb says, indicate that the globules probably came from differentiated bodies—ones that had had enough time for the densest elements to sink to the center. But for some other researchers, it’s untraceable. “These interstellar objects are expected to leak from equivalents of Oort’s clouds around other stars…not the distinct objects he suggests.” he says Alan Rubin at the University of California, Los Angeles. “They are not what you would expect in interplanetary matter.”
Even the idea that these globules are different from the rocks we have already discovered is debatable. “He would have to compare them to all kinds of rocks and all mineral compositions on Earth, and then do the same for all mineral and meteoric rocks,” he says. Michael Bush At the SETI Institute in California. “Even if this enormous effort yields no matches, it is no evidence of an interstellar origin, as meteorites harvest only a fraction of the material in our solar system.”
“These are sleeping on the ocean floor.” [for] It will continue to accumulate pollution by reacting with sea water for at least nine years, and frankly probably thousands of years,” he said. Stephen Desh at Arizona State University. “The seafloor is littered with all sorts of things. There are natural explanations.”
The nature of IM1 itself has also come under criticism. “There are good reasons to think that these speeds, which you can’t check with no error bars, are incorrect,” says Desch. “Most of the fastest objects that appear to come from outside the solar system have some kind of anomaly in their velocities. It has never been established that they are interstellar.” He says it’s not clear if any material survived the violent passage through it.
More evidence will be needed to convince other astronomers that the globule is indeed interstellar. But Loeb said more evidence could be available soon. “We have only analyzed a tenth of the material yet, but decided to publish it now to get feedback from the community. So if we need to do something different or share the material, If you have, you can do it,” he says. He and his colleagues are already planning another expedition to search for larger pieces of IM1.
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