Graphene discovery in lunar soil challenges Moon's origin theory
What's the story
Chinese scientists have found graphene, a pure carbon form, in lunar soil samples collected by the Chang'e-5 mission four years ago.
This finding could potentially challenge the widely accepted theory of the Moon's origin.
The researchers from Jilin University argue that this presence of carbon, contradicts the prevalent belief that the Moon was formed from a collision between Earth and another small planet.
Challenge
Carbon presence contradicts giant impact theory
The researchers explained that the "prevalent giant impact theory has been strongly supported by the notion of [a] carbon-depleted moon derived from the early analysis of Apollo samples."
They also referenced a recent Japanese study that questioned this theory, showing carbon ion emission fluxes across the Moon, indicating indigenous carbon.
Analysis
Study of young lunar samples could unravel mystery
The Chinese research team suggested that studying young lunar samples, approximately two billion years old, could help to "unravel the crystalline structure of the indigenous carbon" present on the Moon.
After analyzing the graphene in their sample, they proposed a potential carbon capturing process on the Moon's surface.
This team included scientists from Shenyang National Laboratory for Materials Science and China's Deep Space Exploration Laboratory.
Lunar history
Discovery could reinvent lunar history understanding
The researchers believe their findings "may reinvent the understanding of chemical components ... and the history of the Moon."
They acknowledged that meteorite impacts could also lead to graphitic carbon formation, as proposed by NASA researchers who found graphite in lunar samples collected by the Apollo 17 mission.
The Chinese scientists emphasized that further investigation into natural graphene would offer more information on lunar geological evolution.
Study method
Graphene microstructure and composition studied in lunar soil
The study is reportedly "the first ... to verify the presence of natural graphene in lunar soil samples by examining its microstructure and composition."
The researchers used Raman spectroscopy and other microscopy techniques, to study a lunar soil sample of around 2.9x1.6mm, retrieved by the Chang'e-5 mission from a volcanic region on the Moon's near side.
Formation process
Graphene formation linked to volcanic eruptions
The researchers found graphene in form of individual flakes and as part of a "carbon shell" enclosing elements like magnesium, sodium, aluminium, silicon, calcium, tin, and iron.
They suggested that iron found in the sample played a role in graphitization of carbon as catalyst for carbon-rich precursor materials.
The graphene's structure indicates it was formed due to "high-temperature processes resulting from volcanic eruptions," which may have allowed iron-carrying lunar soil to interact with carbon-containing gas molecules in solar winds.