China's lunar rover has discovered a pair of enigmatic glass balls on the Moon's surface, the nation's researchers revealed in a study published this week.
Yutu-2 rover's panoramic camera photographed the semi-transparent spheres, which measure up to four centimeters across. The strange objects, according to the research, are on the Moon's far side, which the rover has been studying since it landed there.
The researchers noted, however, that the rover was unable to determine the chemical composition of the "spherules." They have been identified as potential research targets since they could shed light on the Moon's early history.
Still, such tiny glass spheres, which are typically smaller than three millimeters in diameter, are a regular sight on the Moon. They are made when silicate material is heated to extremely high temperatures, which are both abundant on the Moon.
Two confirmed (upper row) and two possible (bottom row) glass globules found along the route of Yutu-2
© Photo : Science China Press
According to the study, spherules are typically leftovers from the Moon's volcanic activity or are generated by meteorite strikes. And the balls discovered by Yutu-2 were most likely caused by the tremendous heat created by the latter.
"Transparent and translucent glasses on the Moon are less than 1 mm in diameters, and larger ones are dark and opaque," the researchers stated, adding that these globules "simply blow our mind," given their uniqueness.
Dr. Zhiyong Xiao, an associate professor at the Planetary Environmental and Astrobiological Research Laboratory at Sun Yat-sen University and lead author of the study, added in a statement that "the first discovery of macro-sized translucent glass globules on the Moon confirms that lunar anorthosites are excellent raw materials to manufacture glasses with good light-admitting quality."
"Their existence on the Moon indicate that impact events on the other planetary bodies could also form tektite-like impact glasses. Such glass globules should be commonly produced by ancient impact basins on the Moon, so their compositions and isotopic ages will be highly valuable to understand the early impact history," he said. "Also, at the dawn of constructing human bases on the Moon, lunar anorthosites are promising and widespread resources to produce glasses in-situ."
As the researchers underscore, the potential that these glass globules have of being terrestrial tektite equivalents is currently unknown because of a lack of compositional data. On Earth, tektites were created by craters larger than 10 km in diameter that originated in a water-rich target.
The clear glass globules are a valuable sampling target for future lunar surface studies, as Apollo astronauts reported easy recognition when collecting centimeter-sized glassy globules on the Moon.
Yutu-2 has produced a number of rather strange discoveries in the past. China's space agency released an image of a "mysterious house" acquired by the rover on the Moon's far side in December.
As can be seen in the pictures, a cube-shaped object stands out from the lunar horizon. Scientists were unable to agree on what it was, so Yutu-2 had to close in on the object and take a better picture after a few weeks. Experts eventually deduced that it was a strangely formed rock.