Graphene Found in China’s Chang’e-5 Lunar Rock Samples; What Does It Say About Early Geological Evolution of the Moon?

Scientists have made an unusual discovery while analyzing the lunar soil sample collected by Chang'e-5 from the Moon's surface.

Lunar Graphene

Chang'e-5 is China's fifth lunar exploration mission, launched on 23 November 2020 from the Wenchang Spacecraft Launch Site on Hainan Island.

A total of 3.8 pounds of the lunar samples were returned back to Earth by the probe on December 16, 2020, from some younger parts of the lunar surface, which also hosts some volcanic rocks. This made China the third country that was able to return samples from the lunar surface after the US and the Soviet Union.

A recent breakthrough by Chinese experts identified that naturally occurring graphene exists in the lunar samples brought for research by the space mission probe Chang'e-5. This was confirmed by a form of non-destructive chemical analysis known as Raman spectroscopy.

In this work, Raman spectra of high-carbon lunar soils are obtained. The quality of crystallization for graphite carbon in the lunar samples is relatively high.

The compounds of iron exist only in parts of the lunar soil samples where carbon does, which researchers believe is also tightly associated with graphene formation.

Few-layer graphene has been known to scientists as a form of graphite for carbon. Researchers now feel that minerals could have catalytically driven few-layer graphene and graphite carbon formation, perhaps by early volcanism or the solar wind on the Moon.

Other researchers from Jilin University went further to add that about 1.9% of interstellar carbon exists in graphene form, whose properties and morphology are determined by this special formation process. This would mean graphene would have great reference and information to give in connection with the geological evolution of cosmic objects.

A Look Into the Formation of the Moon

It will offer new insights into the evolutionary history and geological activities of the Moon. It may also supply some knowledge about expanding our understanding of the mineral composition of lunar soil and hence offer some resource utilization clues on our celestial neighbor.

It was for a long time believed to be the case by scientists that the Moon had formed 4.45 billion years ago from a small Mars-sized planet that had crashed into Earth, with much of the carbon probably emanating from the impact. The idea had much more support from a carbon-depleted Moon with the analysis of Apollo samples.

The discovery of graphene, however, says that carbon could be the by-product of early volcanic outbursts and solar winds that pounded the lunar surface. Yet another theory is that there existed a mechanism for carbon capture at the surface of the Moon, which progressively accumulated indigenous carbon.

Meteorite impacts could be a cause of graphitic carbon emergence on the Moon, thus suggest the researchers. Further commenting on the research, the research team said that more studies on natural graphene would be needed to understand more about the geologic evolution of the Moon.