ИСТИНА

Gamma ray spectrometers (GRS) have been used to map the elemental compositions of the surface materials of Mercury, the Moon and Mars. The first Lunar GRS Th, K, and Fe maps were produced during the Apollo 15 and 16 missions, however, they provide only limited coverage of the lunar surface [10]. Since 1998, global maps detailing the elemental abundance of naturally radioactive elements (such as Th) and major refractory elements (such as Fe, Ca, Ti) have been constructed using data from Lunar Prospector, Kaguya, and Change-2 GRS, and are already publicly released. Here, we present an investigation of the Si distribution based on the 4934 keV Si gamma ray peak due to the thermal neutron interaction 28Si(n,g)29Si, which occurs between galactic cosmic rays and surface material containing Si. Our results are the first to detect Si concentrations at global scale similar to those discovered in lunar samples. This study shows that the Si abundance on the Moon ranges from about 17 to 28 wt%. Further investigation is needed to determine whether locally high Si abundances of around 30 wt% are due to calibration artifacts. Highland terrains have a higher Si content (24–28 wt%) when compared to mare regions (17-21 wt%) consisting of mafic rocks and intermediate surface types (20–24 wt%).