China's exploration of the far side of the moon has come to a halt after the discovery of a mysterious gel-like substance.
The Yutu-2 rover made the find, prompting scientists to divert their attention to figuring out just what the material is.
Scientists describe it as having an "unusual colour", and suggest it may be melted glass from a meteor strike. It was found in a small crater.
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The find came on day eight of Yutu-2's exploration of the moon's far side, which never faces the Earth. Each moon day is nearly a month long.
Once analysis of the substance is complete, Yutu-2 is expected to keep rolling on west.
Yutu-2 landed on the moon in January, the first from any country to touch down on the far side.
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"The idea of setting up mining operations on the moon in the future, that's really part of this project in the long-term," Auckland Astronomical Society president Grant Christie told Newshub in January.
"Where they've landed was once the site where a big asteroid crashed into the moon, buried itself deep inside and melted all that part of the moon, and presumably brought interior material up near the surface."