Nearly 48 years after the collection, scientists believe that a rock sample taken during the Apollo mission for the moon originated from the Earth for about four billion years.
From Apollo 11 – the first mission that landed on the moon – until the last mission Apollo 17, the astronauts on a visit to the moon were tasked with many scientific purposes, including gathering rocks to return to analysis.
Announced a team of scientists their findings in the Earth and Planetary Science Letters and used a new technology to study two grams of moon samples collected by the astronauts Apollo 14 in 1971. Their findings show that, rather than the rock originating from the moon, the Earth four billion years ago.
The researchers believe that the rock sample is a type of feltite, composed of feldspar, quartz and a small zircon. It is similar to granite, which is the type of rock formed by the continents. Scientists believe it is produced through a fertile tectonics, how the external bark of the Earth moves. It is very unusual to find the moon.
The results show that the best explanation for the existence of this rock type on the moon is that it is not from the moon at all. It's from the Earth.
He survives many explosions
The chemical analysis of the fragment showed that it crystallized. Scientists suggest that on Earth about 20 kilometers below the surface about 4 to 4.1 billion years ago could cause this process.
"It was a confirmation that we had some granite and that we had big enough events to start working from the Earth," says co-author David A. Kring, chief researcher at the Center for Lunar Science and Research at the Moon and Planet Institute. "It's incredible that the rock survived."
It's incredible because this sample went through three significant influences. The solar system was surrounded by large bodies that were sealed around the sun while planets and moons were formed. About this time – referring to the late heavy period of bombardment – it is believed that the Earth was destroyed by debris.
Shortly after the formation of our planet, several large bodies, such as an asteroid or comet, hit the Earth, which finally moved the rock and sent it into space. It reached the surface of the moon. The moon would be 2.8 times closer to Earth than today.
After there, according to the theory, the following events survived, including one about 3.9 billion years ago, when the great influence was partially melted by the rock, and probably buried under the moon's surface in the Imbrium Basin.
But it will not stay there.
There was another major impact in the region that sent the fragment about 200 kilometers from its landing location.
And finally, researchers theorize that some 26 million years ago, the asteroid hit the moon, creating a cone crater of 340 meters, returning it to the surface where the astronauts found it.
A less likely explanation
There may be another explanation, although less likely, say scientists.
The stone can be crystallized on the moon. However, it should be 130 kilometers below the surface, which would put it in the moon of the moon, something that would require a completely different understanding of the moon than we currently have.
Gordon (Oz) Osinsky, director of the Canadian Moon Research and Professor of the Department of Science and Physics and Astronomy at the Western University, believes that the explanation of researchers is most plausible.
"It's completely feasible, and in the last few decades there have been several papers that this is possible, and this is definitely some convincing evidence," he says.
"I hope this will foster interest for people who see other similar ones [samples] in the Apollo collection. "
Most rocks on earth are under four billion years old, and both scientists say that finding out how our planet is formed is finding the older rocks crucial.
With NASA's recent attention to return people to the moon, Krung hopes to collect more samples. And that, he says, will help us to find out about our early solar system, and hence ourselves.
"The larger the number of samples we find, the better the picture we will paint from the wounded Earth," says Krung. "And I think we are all interested in the origin and early evolution of our planet. And there's no doubt that the best record of those processes is on the moon."