July 9 (UPI) -- Scientists have identified the 'gel-like' substance the Yutu-2 rover mission discovered on the far side of the moon a year ago, according to a study published this week in Earth and Planetary Science Letters.
Through an analysis of the images and comparison with Apollo samples on earth, researchers found that the substance was rock -- and more specifically, rock that likely melted together from a meteorite impact.
"Chang'e 4 rover discovered a dark greenish and glistening impact melt breccia in a crater during its traverse on the floor of Von Karman crater within the South Pole Aitken (SPA) basin on the lunar farside," researchers wrote in the study. "It was formed by impact-generated welding, cementing and agglutinating of lunar regolith and breccia."
The Chinese Yotu-2 rover team made the discovery in a small crater on a Chang'e 4 mission to explore the far side of the moon on July 2019.
The next month, in a study about the finding, researchers described the substance as dark greenish and glistening "gel-like" material, measuring 20 inches by 6 inches, possibly indicating presence of glass from impact melt or volcanic eruptions.
The substance was similar to samples retrieved by Apollo 15 and Apollo 17 missions, the researchers said. Those samples were retrieved from impact craters and classified as breccia, chunks of rock cemented together by finer material to form larger rocks.
The cement for lunar regolith was black glass in both cases, researchers said.
The paper noted that analysis was limited due to poor lighting and lack of an actual sample to analyze.