The first lunar rocks sent back to Earth in almost 40 years have indicated that the Moon was volcanically active later in its history than scientists previously assumed.

An international team of scientists led by Chinese Academy of Geological Sciences experts analyzed lunar samples obtained by China's Chang'e 5 mission, which retrieved more than 4 pounds of materials from the lunar surface.

The findings provided a more thorough picture of how the Moon evolved and may help scientists determine how the inner solar system's planet originated approximately 4.5 billion years ago.

Chang'e 5 was the Chinese first lunar sample-return mission since 1976 and China's first lunar material probe. It is one of at least eight phases of China's lunar mission to study the entire Moon. The country launched the probe in late November and returned in early December 2020.

The researchers published the study, titled "Age and Composition of Young Basalts on the Moon, Measured From Samples Returned by Chang'E-5," in the journal Science on Thursday.

Science Times - Chang’e 5 Spacecraft Decelerates, Enters Lunar Orbit
(Photo : Kaynouky on Wikimedia Commons)
Elevation map of the Moon with the localization of the landing sites of successful sample return missions and the designated landing region of Chang'e 5. The darker regions have low elevation, while the brighter regions have high elevation. The map was made by NASA.

Moon Used To Volcanically Active

Moon was volcanically active for a longer period than scientists had previously thought, the Chang'e 5 samples show. Bradley Jolliff, study co-author and a planetary scientist at Washington University in St. Louis, said in Astronomy.com that the Chinese samples were produced by magma that erupted about 2 billion years ago.

Scientists believe that radioactive uranium and thorium penetrate deep into the guts of such bodies while they are young. These slowly decompose and emit heat, maintaining the mantle molten for billions of years in a big body. However, simulations show that the material as tiny as the Moon would rapidly lose all of its heat.

The Chang'e 5 spacecraft landed in the Oceanus Procellarum, or Ocean of Storms, a volcanic plain on the Moon. The samples, taken from the surface and 6 feet into the lunar crust, are likely to fill up key gaps in our understanding of the Moon's past.

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Latest Vocanic Activity In Moon Happened Sometime 3 to 4 Billion Years Ago

Moon rocks from NASA's Apollo program (per Space.com) and the former Soviet Union's Luna 24 mission (per Popular Mechanics) indicated that most volcanic activity occurred between roughly 3 billion and slightly earlier than 4 billion years ago.

Jolliff said in an NBC News report that volcanism on the Moon appeared to decline after that. However, scientists have noticed places of the Moon that are less extensively pockmarked with impact craters in the decades after the Apollo and Luna flights, suggesting that materials on the surface are newer due to volcanic eruptions.

Crater counting is a technique used by scientists to determine the age of planetary surfaces. Based on the known ages of materials from the Apollo moon missions, researchers can estimate the chronology of craters.

Crater counts revealed that regions of the Moon's surface with less impact craters were between 1 billion and 2 billion years old, Jolliff pointed out.

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