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First probe to explore far side of the Moon reveals secrets of lunar surface

Andrew Griffin
Lunar rover Yutu-2, taken with the Chang'e 4 lander's terrain camera on the far side of the moon on 11 January 2019: EPA

The first probe ever to explore the far side of the Moon has revealed new informaton about its surface.

The Chinese probe has revealed that the distant side – which cannot be seen from Earth since it always faces away from us – is covered with a layer of rock and dust.

It marks the first time that scientists have been able to confirm important information about the Moon's far side, which had only ever been explored from orbit until the Chinese Chang'e 4 spacecraft landed almost a year ago.

The layer of deposits was formed over billions of years as meteorites constantly smashed into the Moon's surface.

The findings, published in the journal Science Advances, reveal some of these loose deposits to be up to 39ft (12m) thick.

As most of the knowledge on lunar regolith comes from Nasa's Apollo and the Soviet Union's Luna missions to the near side of the Moon, scientists were, until now, uncertain whether these observations would hold true elsewhere on the lunar surface.

Dr Elena Pettinelli, a professor in the mathematics and physics department of Roma Tre University in Italy and one of the study authors, told the PA news agency: "These series of ejecta or deposits came from different impact craters that were created during the evolution of the Moon's surface.

"It is quite interesting because we can see quite clearly the geological sequences of these events 40 metres below the surface."

The Chang'e 4 (CE-4) spacecraft landed on the Von Karman crater on January 3 2019.

Its rover, Yutu-2, which can climb 20-degree hills and 8in (20cm) tall obstacles, was deployed 12 hours later to explore the landing site.

Previous landings have been on the near side of the Moon, which faces Earth.

The far side, which cannot be seen because it faces away from Earth, has been observed many times from lunar orbits but never explored on the surface.

Using data gathered from the first two days of Yutu-2's exploration, the researchers identified coarse granular materials up to a depth of 79ft (24m) below the lunar surface.

They were able to combine the rover's high-resolution images and ground-penetrating radar scans from 131ft (40m) below the surface to create a picture of the Moon's "internal architecture".

Although the radar signal could not be detected below 131ft (40m), the researchers speculate that these granular materials might extend deeper.

Dr Petrenelli said the information gathered from the Yutu-2 rover, along with the data from the previous near-side Moon explorations, could help shed light on the geological history of the lunar surface.

She added: "Maybe we can reconstruct historically the sequence of events in different areas on the Moon."

Additional reporting by agencies

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