The Yutu happened to break down in a very interesting spot.
China's Yutu rover just passed its two year anniversary of living on the Moon, and what a ride it has been. The robotic explorer has gone from writing its own death notes to recently becoming the longest-lived rover ever to grace the lunar surface.
Now, Yutu has padded out its resume further by discovering a new type of basalt rock in its unique home of Mare Imbrium, one of the largest lunar maria, or "seas," formed by ancient volcanic activity. The research, led by planetary scientist Zongcheng Ling and published today in Nature Communications, provides the first detailed glimpse of the Moon from its surface since the Soviet Luna 24 lander touched down in 1976.
"Our analysis indicates that this young lunar mare region has unique compositional characteristics, and represents a new type of mare basalt that has not been sampled by previous Apollo and Luna missions and lunar meteorite collections," Ling's team wrote in the study.
Scientists think that Mare Imbrium—which forms the right eye in the pareidolic image of the Man in the Moon—was created by a massive impact in our satellite's infancy, which was then repeatedly flooded by lava flows over the course of two billion years. As a result of this prolonged series of molten baths, Mare Imbrium is one of the smoothest regions of the Moon, and an ideal site for exploring its volcanism. The crew of Apollo 15 was even able to bring some of the mare's basalt-rich rock back with them after visiting its eastern edge in 1971.
But according to Ling and his colleagues, the new basalt rock Yutu found is distinct in composition from anything turned up by any other landing mission. It is especially rich in olivine, a common igneous silicate, as well as iron oxide, calcium oxide, and titanium dioxide.
All of these compounds are relatively normal for a geological region with a volcanic past, but Yutu has a unique vantage point that sets it apart from past Mare Imbrium excursions. The rover's mothership, the Chang'e 3 lander, happened to land in a small crater called Zi Wei, which translates to the Purple Palace—named for ancient Chinese star map designations—formed by an impact within the last 100 million years.
This collision kicked up a lot of ejecta and material from several periods in the Moon's history, so Yutu has a wide range of sample ages to study.
"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," Ling's team noted.
Given that the rover was rendered immobile by multiple malfunctions back in January 2014, it's very lucky that it happened to break down in such an interesting spot. The new research is a great start to the little robot's third year in Mare Imbrium, and hopefully, it won't be the last we hear from Yutu.