Damaged moon rocks persuade researchers to rethink lunar history
NASA Astronaut Harrison Schmitt uses a scoop to retrieve lunar samples during the Apollo 17 mission. Image courtesy of NASA
New research reveals that even lunar samples once believed to be pristine have been extensively altered by meteorite impacts, challenging long-held assumptions about the moon’s formation and early history.
A team of scientists from Arizona State University, the University of Rochester and UCLA has developed a groundbreaking analytical tool. This tool, a fundamental principle in lunar science, analyzes aluminum content in zircon crystals and compares it with surrounding glass in lunar samples. The result is a powerful method that determines whether these materials formed together or were later assembled through impacts.
“We designed this aluminum-in-zircon method specifically to test the ‘pristine rock’ hypothesis that has shaped lunar science for decades,” said Melanie Barboni, assistant professor at ASU’s School of Earth and Space Exploration and lead author of a paper detailing their findings, recently published in Nature Communications.
The "pristine rock" hypothesis posits that certain lunar rocks, believed untouched by impact events, provide a direct record of the moon’s early history.
“We discovered that zircon crystals and their surrounding materials don’t match chemically — proving they didn’t form together. This means what we thought were untouched igneous rocks are complex mixtures created by repeated impact events,” Barboni said.
For billions of years, the moon’s surface has been bombarded by asteroids and comets, forming the craters we see today. Scientists had believed specific rock fragments collected during Apollo missions had escaped this violent history, preserving an unaltered record of the moon’s origins.
The findings have profound implications. Many theories about the moon’s formation and early evolution are based on these supposedly pristine samples. With this new evidence, researchers are now faced with the task of revisiting key aspects of lunar science, including the timing of the moon’s formation and the development of its early crust.
“Our study highlights the need for advanced geochemical tools tailored to different lunar rock types,” Barboni said. “The aluminum-in-zircon method works for zircon-bearing samples, but researchers must develop similar techniques for other crucial lunar materials.”
The study was funded by NASA and utilized samples collected during the Apollo missions.
As NASA prepares to return humans to the moon with the Artemis program, this research underscores the importance of specialized analytical techniques and collecting samples from areas far from significant impact basins — particularly the lunar far side, where truly pristine rocks may still exist.
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