Chinese scientists report particle size of lunar farside regolith

Chinese scientists have estimated the particle size of lunar farside regolith on the basis of the world's first in-situ temperature measurement made by Chang'e-4 spacecraft on the dark side of the Moon. This was reported by The Xinhua News Agency.

The loosely-packed rocky grains deposited on the lunar surface at the Chang'e-4 landing site are on average approximately 15 micrometers in depth, indicating an immature regolith below the surface, according to a study published in the latest edition of National Science Review.

The Chang'e-4 probe, launched on Dec. 8, 2018, made the first-ever soft landing on the Von Karman Crater in the South Pole-Aitken Basin on the far side of the moon on Jan. 3, 2019.

After landing, the Yutu-2 rover was released via the deployed two rails. Four temperature probes beneath the terminals of the rails began to measure the temperature of the local regolith every 900 seconds, allowing the researchers to calculate the particle size with a customized thermal model.

Also, they have found that the average bulk density at the landing site is about 471 kg per cubic meter and about 824 kg per cubic meter in the upper 30 cm of lunar regolith, according to the study.

"These results will provide important additional 'ground truth' for the future analysis and interpretation of global temperature observations", – said the paper's corresponding author Huang Jun who works with the China University of Geosciences in Wuhan.

"It will also shed light on the design for future in-situ temperature and heat flux probes", – said Huang.