After two years on the moon, a Chinese lunar rover named “Yutu,” has uncovered a new type of moon rock on a long-dead lava flow. According to a new study published in the journal Nature Communications, the unique composition of the recently discovered rocks is revealing new insights into the moon’s origins.

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The rover is part of China’s Chang'e lunar mission, which conducted the first lunar “soft landing” in almost 40 years. The Chang’e-3 lander and Yutu touched down smoothly on the surface of the moon in January 2013.

But while Yutu now holds the record for the longest stay by a lunar rover, it hasn’t actually done all that much roving, Jeff Foust reports for SpaceNews. The rover started experiencing problems just a few lunar days into its mission, causing many of its systems to lock up.

Luckily, Yutu could still analyze the rocks immediately around it in the moon's giant dark spot, Mare Imbrium. Scientists believe that this large lunar “sea” is actually a crater created by space debris. Then lava repeatedly flooded the massive pockmark for the next two billion years. The resulting landscape is one of the smoothest regions on the moon’s surface, Becky Ferreira writes for Motherboard.

When Yutu finally began sending back data, the mix of minerals the rover uncovered surprised planetary scientists. While the moon rocks uncovered during the American and Soviet moon missions in the 1960s and ‘70s contained either extremely high or low titanium levels, the samples Yutu dug up sat almost right in the middle, Tim Radford writes for The Guardian. The rocks were also surprisingly rich in iron oxide and an igneous rock called olivine, Ferreira reports.

While the Earth’s upper mantle is more or less made of consistent materials throughout, the regolith that makes up the moon’s surface varies greatly from region to region, planetary scientist Bradley Joliff, who was the only American member of the Chinese group that analyzed the rover’s findings, tells Radford.

Plus, a smaller crater in Yutu’s range was created only about 100 million years ago, giving the plucky rover plenty of material to study rocks from different periods of the moon’s history.

“The CE-3 landing site and in situ analyses of the rocks and soils derived from the fresh crater near the landing site provide key new ground truth for some of the youngest volcanism on the Moon,” the study’s authors note.

As it turns out, Yutu couldn’t have picked a better place to break down.