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A rebadysis of the lunar materials collected during the Apollo 14 mission comes to a rather surprising conclusion: One of the reported rocks appears to contain a small piece of Earth dating back about four billion years ago. 39 years . According to research, the rings of Saturn could disappear in 100 million years only
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A new research published this week in the document indicates that a rock fragment included in the lunar sample 14321 – a 0.9 kilo rock known as the Big Bertha – is of terrestrial origin. The fragment probably hit the moon's surface after an asteroid or comet collided with the Earth, throwing debris into space. The leading authors of the new study, Jeremy Bellucci of the Swedish Museum of Natural History and Alexander Nemchin of Curtin University in Australia, say that this happened about four billion years ago, in
Big Bertha was recovered by NASA astronauts Alan Shepard and Edgar Mitchell in 1971, during the Apollo 14 mission in the formation of Fra Mauro. This rock, along with other lunar samples, is stored at the Johnson Space Center's Lunar Curative Facility in Houston, Texas. The 14321 sample is special because it is a network rich crystalline space.
"In simple terms, it means that it is a rock made up of a mixture of rocks and rock fragments already existing, as well as fusion materials and of impact formed during a major impact or series of impacts on the moon, "said James Day, professor at the Scripps Oceanographic Institute, who was not badociated with the new study. "The sample has been described as a" treasure "containing an infinity of rock fragments."
Lunar sample 14321 with an arrow indicating the location of the apparent fragment of the Earth. Katie Robinson, a postdoctoral fellow at the Center for Science and Lunar Exploration JPI-JSC and co-author of the study, said that sample 14321 had been recognized as unusual for a long time and that we are only now. appreciate how unusual it is. In this lunar breach is a felsite clasto of two grams – a fine-grained volcanic rock – with fragments of felsito, including quartz, feldspar and zirconium. These materials are usually found on Earth but are very unusual on the Moon. In fact, a chemical badysis of the sample suggests that it has formed in terrestrial conditions rather than moles.
"We used the composition of minerals in the fragment to show that it was formed under conditions that only occur on Earth," Robinson told Gizmodo. "For example, the composition of some minerals is sensitive to temperature and pressure, they contain more or less diverse elements that crystallize in hot or cold environments and / or in deep or shallow environments." other minerals may indicate if the rock formed in the presence of too much oxygen or in a very low oxygen environment Our data show that this fragment is formed in an environment under pressure higher, with greater oxygen and temperature lower than that found on the moon.Basically, it had to come from an environment similar to the Earth. "
Obviously, it happens that the Moon had an environment similar to the Earth next door, more precisely in … the Earth! The idea that an old asteroid impact threw pieces of terrestrial debris into the space and on the surface of the moon is not ridiculous. During the Asean era, asteroids regularly produced craters several thousand kilometers in diameter. Impacts of this magnitude have made it possible to extract materials from the depths of the earth's surface. The apparent land fragment found in the Big Bertha was formed about 20 kilometers below the surface of the Earth – a depth that is not within the reach of these ancient asteroids.
A version of the artist for an Earth struck by asteroids during the Hajj era. Simone Marchi
Another possibility, according to research, is that the fragment crystallized on the Moon, otherwise the material should have formed in the deepest part of the Moon. its lunar mantle, and there is no reason for it to reach the surface.
Speaking of lunar surface, it seems astonishing that the Apollo astronauts could find this flaw so easily. The simplest explanation, according to the researchers, is that it comes from the Earth. In fact, billions of years of constant accumulated lunar dust, known as the Regolith, should have obscured the remains of this rock. But, as Robinson explains, Big Bertha was covered with regolith, but not enough to bury it completely. To explain her presence on the lunar surface, she said the ditch had already been buried but had been restored to the surface after the impact of the Cone, a 300 meter crater located near the landing site. Apollo 14 – a "very common process on the moon."
A fascinating aspect of this discovery is that this lunar sample of apparent terrestrial origin is really old. The terrestrial zirconium mineral in the sample, which is estimated at between 4 billion and 4.1 billion years old, is now one of the oldest known. A press release from the Association of Space Research Universities (USRA) has gone so far as to claim that it was the "oldest rock on Earth", but that is not entirely accurate, as the explained Matthew Dodd, a geologist at the University. "The age of the zirconium mineral present in the lunar sample would be about 4.01 billion years, making it a very old piece of Earth (if this research is correct), but it's not the oldest, "Dodd told Gizmodo. "There is zirconia on Earth dating from 4.4 to 4.3 billion years ago from Western Australia.
The authors of the new study have presented two possibilities to explain the abnormal sample: either he formed on Earth (probably) or on the bottom of the moon (very unlikely).
"(This third possibility) is that these unusual features are the result of processes impacting the moon, without the need for these rocks to come from the earth," he said. Day in Gizmodo. "During the formation of the impact cast, conditions can be met to generate the unusual chemistry of zirconium element traces, but the authors do not consider this possibility, even if these felsite clasts have textures consistent with the fact that they are molten rocks
Mr. Day said that his scenario seemed more plausible compared to the "chain of events required to (break) the Earth's felsito to very high impact pressures to allow it to escape from its Earth orbit. and then blend into a molten rock of lunar impact. "The clasts of Felsite," he said, "are almost the right age to figure among" some of the first major impacts recorded on the moon, making lunar origin more likely. "
For the authors of The new study, this kind of reaction or criticism is not unexpected.As stated in the USRA press release, the researchers predicted that "the completion of an origin ground for the rock fragment would be controversial. "
When contacted for comment, Bellucci stated that some of his colleagues were simply skeptical, because the samples were found on the moon. stated that "the best explanation of our data presented in the article is a terrestrial source for the badyzed clasto," adding that, after what he and his colleagues know, "we did the best job that either. "We could have done it for conf confirming an earthly origin. "
In addition, Robinson explained:" Dynamic calculations have taught us that Earth samples were ejected at impact and reached the Moon, but the challenge is to recognize, "he said. she "This is only the first rock identified as an earth meteorite.The more we will find, the better we can identify them!"
Despite the reservations of Day, he declares that the new study is important because it highlights the need for future missions to study the formation of the Moon.
"Back to the Moon to understand how it was formed and how our own planet would be a scientific stimulus, just like the Apollo American and Luna missions, from the Soviet Union to the Moon, to the late 1960s and early 1970s, "he added. "After all, as this article in 2019 shows, we continue to make discoveries on the moon from rocks collected 48 years ago."
[Earth and Planetary Science Letters]
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