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Scientists believe they have found the oldest known rock on Earth – on the moon



Almost 48 years after its collection, scientists believe that a sample of the rock taken during the flight of Apollo to the Moon was obtained from Earth about four billion years ago.

From Apollo 11 – the first mission to Earth to the final mission of Apollo 17, astronauts visiting the moon were assigned many scientific tasks, including collecting stones for analysis.

A team of scientists has published their results in the journal Earth and Planetary Science Letters and the use of a new technology for studying a two-gram sample of moonstone collected by the Apollo 14 astronauts in 1971. Their results show that instead of a stone originating on the moon, it came from Earth four billion years ago.

This is a fragment of rock, returned by the Apollo 14 mission. Scientists analyzed its composition of the two-gram test. (David A. Kring)

Researchers believe that the rock sample is a type of felzite, which consists of feldspar, quartz and tiny zircon. It looks like granite, which is a type of rock that forms continents. Scientists believe that this is due to plate tectonics, as the outer crust of the Earth moves. It is very unusual to find him on the moon.

The results show that the best explanation for the existence of this type of stones on the moon is that they are not from the moon at all. This is from Earth.

Surviving many explosions

Chemical analysis of the fragment showed that it crystallized. Scientists suggest that conditions on Earth, about 20 kilometers from the surface, about four or four billion years ago, could trigger this process.

“It was a confirmation that we had something granite and that we had a large enough impact impact to launch objects from Earth,” says co-author David A. Kring, principal researcher at the Center for Lunar Sciences and Research at the Lunar and Planetary Institute , "Surprisingly, the stone survived."

This is surprising because this particular pattern has undergone three significant impacts. The solar system was rife with large bodies that spread around the sun when planets and moons were formed. At about the same time — from the period of the late heavy bombardment — it is believed that the Earth was blown up by debris.

Soon after the formation of our planet, several large bodies, such as an asteroid or a comet, crashed into Earth, eventually moving the rock and sending it into space. He reached the lunar surface. The moon would be 2.8 times closer to Earth than today.

Once there, the theory claims that it experienced subsequent shock events, including one approximately 3.9 billion years ago, when a large impact partially melted the stone, and it was probably buried under the surface of the moon in the Imbrium basin.

The moon was much closer to Earth than today, when a fragment of rock was extracted. (LPI / David A. Kring)

But it will not stay there.

There was another strong blow in the region, which sent a fragment about 200 kilometers from the landing site.

Finally, the researchers suggest that about 26 million years ago, an asteroid was working on the moon, creating a Cone crater with a diameter of 340 meters, returning it to the surface, where it was discovered by astronauts.

Less likely explanation

There may be other explanations, albeit less likely, considered by scientists.

The stone could crystallize on the moon. However, it should have been 130 kilometers below the surface, which would place it in the lunar mantle, which would require a completely different understanding of the moon than we currently have.

Gordon (Oz) Osinsky, director of the Canadian Lunar Research Network and a professor at the departments of Earth Sciences, Physics and Astronomy at Western University, considers the explanations of the researchers most plausible.

“This is quite doable, and over the past few decades there have been several papers confirming that this is possible, and this document certainly presents some convincing evidence,” he says.

“I hope this will spur interest in people who look to other similar [samples] in the Apollo collection. "

Most of the stones on Earth are younger than four billion years, and both scientists say that finding the older stones is key to determining how our planet formed.

Given the recent attention of NASA to the return of people to the moon, Kring hopes that more samples will be collected. And this, he said, will help us learn about our early solar system and, therefore, about ourselves.

“The more samples we find, the better the picture of the early Earth will be,” says Kring. “And I think that we are all interested in the origin and early evolution of our planet. And there is no doubt that the best record of these processes on the moon. "


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