The Moon had volcanoes much more recently than we thought, new study says

Fifty years ago, NASA and the Soviet space program conducted the first sample-return missions from the Moon. This included lunar rocks brought back to Earth by Apollo astronauts and those acquired by robotic missions that were part of the Soviet Luna Program.

Analysis of these rocks has revealed much about the composition, formation and geological history of the Moon. Specifically, scientists concluded that the rocks were formed by volcanic eruptions more than 3 billion years ago.

In recent years, there has been a resurgence of lunar exploration as NASA and other space agencies have sent robotic missions to the Moon (in preparation for manned missions).

For example, China has sent multiple orbiters, landers and rovers to the Moon as part of the Chang’e program, including sample return missions.

A new study led by planetary scientists from the Chinese Academy of Sciences (CAS) analyzed samples taken by the Chang’e-5 rover dating back 2 billion years.

Their research could provide valuable insight into how young volcanism shaped the lunar surface.

The research was conducted by a team from the Institute of Geology and Geophysics of the Chinese Academy of Sciences (IGGCAS), led by Su Bin, Yuan Jiangyan and Chen Yi – members of the IGGCAS Laboratory of LIthospheric Evolution and Earth and Planetary Physics.

They were joined by researchers from the Lunar and Planetary Science Institute (LPSI) at Nanjing University and the CAS Center of Excellence in Comparative Planetology. A paper describing their findings appeared in the journal Advances in Science on October 21.

Based on samples returned by the Apollo and Luna missions, scientists theorized that the Moon had been geologically dead for the past 3 billion years.

However, new lunar rock samples taken by the Chang’e-5 mission (and returned to Earth in 2021) were only 2 billion years old, indicating that volcanic activity occurred at least a billion years longer than previously expected.

As a small rocky body, the heat that fueled the volcanism on the Moon should have been lost long before these eruptions occurred.

Previously, scientists hypothesized that late-stage volcanism may have been caused by increased water content or the decay of radioactive elements in the lunar mantle. However, the many analyzes done on the samples taken by the Chang’e-5 rover have ruled out this consensus.

Based on their analysis, the CAS researchers found that minerals with low melting points in the mantle could have allowed compression, leading to young volcanism. Professor Chen explained in a recent CAS statement:

“Recent melting of the lunar mantle can be achieved by either increasing the temperature or lowering the melting point,” he said. “To better understand this problem, we will need to estimate the temperature and pressure at which the young volcanism was created.”

For their analysis, the CAS team conducted a series of simulations of fractional crystallization and melting of the lunar mantle that compared 27 basalt clasts taken by the Chang’e-5 mission to those returned by the Apollo missions.

They found that the young magma samples had higher concentrations of calcium oxide and titanium oxide than the older Apollo magma samples.

The presence of these minerals, which melt more easily than previous minerals accumulated in the lunar mantle, means that the volcanism would have been driven by gravity and caused material to tumble into the mantle.

Their analysis revealed that mantle compression could have occurred at similar depths, but under cooler temperatures that would still have provided volcanism.

This research is not unlike what planetary scientists have learned about Mars in recent years. Billions of years ago, the red planet had thousands of eruptions on its surface, some of which resulted in the largest volcanoes in the Solar System (such as Olympus Mons).

Scientists suspected that Mars became geologically dead as its interior cooled. But recent findings suggest it may still have limited volcanic activity.

This study presents the first viable explanation for young volcanism on the Moon that is compatible with the samples returned by the Chang’e-5 rover.

This study could inform future planetary studies of the Moon’s thermal and geological evolution.

As Dr. Su said:

“This is an exciting result, indicating a significant contribution of lunar magma to the late-stage ocean accretion in the Chang’e-5 volcanic formation. We found that the Chang’e-5 magma was produced at similar depths but 80 degrees Celsius cooler than This means that the lunar mantle experienced a prolonged, slow cooling of 80 degrees Celsius from about 3 billion years ago to 2 billion years ago.”

This article was originally published by Universe Today. Read the original article.