Study reveals composition of 'gel-like' substance discovered by Chang'e-4 rover on moon's far side

July 21, 2020

The unusual dark greenish and glistening "gel-like" substance in a crater on the far side of the moon has attracted widespread interest following its discovery by the Chang'e-4 rover in July 2019.

A research team led by Prof. DI Kaichang from the Aerospace Information Research Institute (AIR) of the Chinese Academy of Sciences and their collaborators analyzed the substance in detail by using multiple datasets from the rover's panoramic camera (Pancam), hazard avoidance camera (Hazcam), and the visible and near-infrared spectrometer (VNIS).

The researchers found that the unusual substance is actually an impact melt breccia, and the provenance of the rover measured surrounding regolith might originate from a differentiated melt pool or from a suite of igneous rocks. Their findings were published in Earth and Planetary Science Letters.

China's Chang'e-4 probe, including a lander and a rover, successfully touched down within the 185-km-wide Von Kármán crater inside the South Pole-Aitken (SPA) basin on January 3, 2019, making the first-ever soft landing on the lunar far side.

The gel-like substance was discovered in a crater (Fig. 1) during the eighth lunar day of the rover's mission. Detailed measurements on the breccia and surrounding regolith were conducted during the ninth lunar day.

The discovered breccia, measuring 52 by 16 centimeters, resembles the lunar impact melt breccia samples 15466 and 70019 (Fig. 2) returned by the Apollo missions. It was formed by impact-generated welding, cementing and agglutinating of lunar regolith and breccia.

Clods surrounding the breccia-hosting crater were crushed into regolith powders by the rover's wheels (Fig. 3), indicating the regolith may be compacted slightly and becomes blocky and friable. Hapke model-based spectral unmixing results showed that plagioclase was abundant, and pyroxene and olivine had almost equal fractions, indicating the regolith was likely the weathering products of noritic rocks.

The regolith measured by Chang'e-4 rover was actually a mixture of multiple sources, with ejecta from Finsen crater being primary and possible contributions from Alder crater. Finsen and Alder craters are on the margin of the proposed impact melt pool produced by the SPA basin-forming event. Therefore, the provenance of the regolith might originate from a differentiated melt pool or from a suite of igneous rocks.
-end-


Chinese Academy of Sciences Headquarters

Related Crater Articles from Brightsurf:

Study reveals composition of 'gel-like' substance discovered by Chang'e-4 rover on moon's far side
A research team led by Prof. DI Kaichang from the Aerospace Information Research Institute (AIR) of the Chinese Academy of Sciences and their collaborators analyzed the substance discovered by Chang'e-4 rover on Moon's far side in detail and revealed its composition.

Photos may improve understanding of volcanic processes
The shape of volcanoes and their craters provide critical information on their formation and eruptive history.

Here be methane: Skoltech scientists investigate the origins of a gaping permafrost crater
Researchers from Skoltech and their colleagues spent more than two years studying a 20-meter wide and 20-meter deep crater in the Yamal Peninsula in northern Russia that formed after an explosive release of gas, mostly methane, from the permafrost.

Hayabusa2's big 'impact' on understanding asteroid Ryugu's age and surface cohesion
After an explosive device on the Hayabusa2 spacecraft fired a copper cannonball a bit larger than a tennis ball into the near-Earth asteroid Ryugu, creating an artificial impact crater on it, researchers understand more about the asteroid's age and composition, they say.

Impact crater data analysis of Ryugu asteroid illuminates complicated geological history
Analysis of the impact craters on Ryugu using the spacecraft Hayabusa2's remote sensing image data has illuminated the geological history of the Near-Earth asteroid and revealed 77 craters.

Wolfe Creek Crater younger than previously thought
Wolfe Creek Crater, one of the world's largest meteorite craters, is much younger than previously thought.

Karla crater confirmed to be an impact structure
The Karla crater, one of the about 150 large impact structures on Earth, is situated near the border of the Republic of Tatarstan and Chuvash Republic, about 163 kilometers from Kazan Federal University.

ASU researchers study largest impact crater in the US, buried for 35 million years
About 35 million years ago, an asteroid hit the ocean off the East Coast of North America.

Mass anomaly detected under the moon's largest crater
A mysterious large mass of material has been discovered beneath the largest crater in our solar system -- the Moon's South Pole-Aitken basin -- and may contain metal from the asteroid that crashed into the Moon and formed the crater, according to a Baylor University study.

NASA finds possible second impact crater under Greenland ice
A NASA glaciologist has discovered a possible second impact crater buried under more than a mile of ice in northwest Greenland.

Read More: Crater News and Crater Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.