lunar Dust Reveals Ancient Asteroid Impacts, Hints at Moon’s Watery Past
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A groundbreaking analysis of dust collected from the far side of the Moon has revealed the first confirmed evidence of a rare, water-bearing meteorite type – a CI chondrite – impacting the lunar surface. This discovery, made possible by China’s Chang’e-6 mission, suggests that these fragile asteroids played a notable role in delivering water and other volatile compounds to the early Earth and Moon.
this is particularly surprising revelation given their tendency to disintegrate during atmospheric entry on Earth.
Unearthing a Lunar Treasure
Researchers, led by geochemists Jintuan Wang and Zhiming Chen of the Chinese Academy of Sciences, meticulously examined over 5,000 fragments of material retrieved by the Chang’e-6 mission. The sample originated from a crater-within-a-crater – the Apollo Basin nestled within the expansive South Pole-Aitken Basin, a region covering nearly a quarter of the lunar surface and considered a prime location for ancient impact debris.
The team focused on olivine, a common mineral found in volcanic rock, impact melts, and meteorites. Through advanced analytical techniques – including scanning electron microscopy, electron probe microanalysis, and secondary ion mass spectrometry – thay identified seven fragments exhibiting chemical characteristics identical to olivine found in CI chondrites, also known as Ivuna-type carbonaceous chondrites.
The Importance of CI Chondrites
CI chondrites are exceptionally rare and valuable to scientists. They are the most primitive and water-rich meteorites known, containing up to 20% of their mass as water bound within hydrated minerals. Their composition closely resembles that of asteroids like Ryugu and Bennu, offering a glimpse into the building blocks of the early solar system.
However, their porous and crumbly nature makes them particularly vulnerable to destruction when entering Earth’s atmosphere. Fewer than 1% of meteorites discovered on Earth are classified as CI chondrites, highlighting their scarcity. “These meteorites are incredibly fragile,” one analyst noted, “and rarely survive the journey through Earth’s atmosphere intact.”
Why the Moon is a Preservative
Surprisingly, the Moon’s habitat appears to be more conducive to preserving these delicate meteorites. Unlike earth, the Moon lacks an atmosphere to burn up incoming space rocks. While impacts still occur at high velocity, the lunar surface offers a stable environment where fragments can remain relatively undisturbed for billions of years.
The analysis suggests that CI chondrites could account for as much as 30% of the Moon’s meteorite collection, a considerably higher proportion than found on Earth. This finding has profound implications for understanding the early bombardment history of both the Earth and the Moon.
A Window into the Solar System’s Past
The identified fragments exhibited porphyritic structures – olivine crystals embedded in a glassy matrix – indicative of rapid cooling after an impact melt event. crucially, the chemical and isotope ratios within these fragments did not align with those expected from lunar or terrestrial sources. Instead, they perfectly matched the signature of CI chondrite material.
“This is the first direct, physical evidence that CI chondrites bombarded the Moon early in the Solar System’s history,” a senior official stated. “And it’s the first evidence that remnants of that bombardment can actually survive and be detected.”
Scientists have long theorized that CI chondrites played a crucial role in delivering water and other volatile compounds to the early Earth and Moon, perhaps contributing to the formation of oceans and the emergence of life. These seven tiny grains of dust from the Moon’s far side provide compelling support for this hypothesis.
future lunar sample return missions will be essential to further explore this possibility and refine our understanding of the Moon’s composition and history. “Given the rarity of CI chondrites in Earth’s meteorite collection, our integrated methodology…offers a valuable tool for reassessing chondrite proportions in the inner Solar System,” the researchers conclude.
