The researchers came to this conclusion after analyzing the rocks that the Chinese spacecraft Chang’e-5 collected from the moon at the end of 2020 and brought back to Earth.
These are the first lunar samples brought back after the Apollo missions in 1976. But they undermine the analysis of these earlier samples. The Apollo rocks, along with some samples from the Soviet Union’s Luna 24 mission, showed that the Moon had cooled and volcanoes had stopped erupting about 3 billion years ago.
“The general assumption was that the Moon is such a small body compared to, for example, Earth and Mars, so it cooled down faster and stopped producing volcanic formations,” said Bradley Jolliffe, a planetary scientist at Washington University in St. Louis, who helped carry out investigations. research, NBC News reported.
But the rocks that Chang’e-5 brought are about 2 billion years old and volcanic. This means that the lava flows must have paved the bridge over the region where the spacecraft landed, almost 1 billion years later than scientists thought.
This amazing discovery was published earlier this month in the magazine. The science… Then, on Tuesday, a new study of Chang’e-5 samples was published in the journal. Nature also determined that these rock samples are 2 billion years old.
What’s more, two companion studies this week showed that new moon samples are surprisingly low in water and radioactive elements that facilitate volcanic eruptions. Water lowers the melting point of rocks, and radioactive potassium, uranium, and thorium provide heat to melt magma. Both were present in higher concentrations in the samples of the Apollo and Moon moons.
All in all, the new articles are “a real mystery,” according to Qing-Chu Yin, a geochemist at the University of California, Davis, who was not involved in the study. Yin said The science that these studies raise questions about how a body as small as the moon could “support volcanic eruptions in later life.”
The reason the findings are confusing is that the moon does not have an atmosphere or magnetic field to hold the heat needed for volcanic activity. But there are a few ideas as to how the heat was kept for so long.
First, the Moon’s soil may have been thick enough to hold heat for a billion years longer than scientists originally thought. Another reason is that the Moon may have been heated by tidal forces from Earth, as the planet’s gravity could stretch and relax the interior of the Moon as it orbited.
A third possible explanation is the impact of a large asteroid or comet, as in some cases this can cause a volcanic eruption.
Moon samples are critical to deciphering lunar history
Chang’e 5 was launched to the moon in November. It landed near a dormant volcano in a region called Oceanus Procellarum, which is paved with a black volcanic rock called basalt. The lander then collected more than 4 pounds (2 kg) of lunar rock, taking some of the material from the surface and some from a depth of 1.83 m into the lunar crust.
Chang’e-5 then packed the samples into a capsule and launched it back to Earth. The capsule landed in Mongolia in December.
Since so few rocks have been mined from the moon in past missions, scientists expect to learn much more from future specimens, such as the Chang’e 5 rocks. China’s next lunar mission, Chang’e-6, aims to launch to the far side of the moon in 2024 and return even more samples.
“If the Moon were a continent-sized object, the samples of Apollo and the Moon would be like a sample of only one state. Imagine if this is all we know about the entire continent, ”Jolliffe said.
This article was originally published by Business Insider.
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