China: samples from the near and far sides of the Moon are different
Scientists studying the lunar samples brought back from China’s Chang’e-6 mission to the far side of the Moon have determined that the different environments create differences in the surface material.
The study found that the solar wind exposure time of the Chang’e-6 samples was close to the minimum observed in the Apollo 11 samples, lower than that of the other Apollo samples, and slightly shorter than that of the Chang’e-5 samples. However, surprisingly, the npFe⁰ grain sizes in the Chang’e-6 samples were larger. “This might suggest that solar wind radiation in this region leads to more pronounced segregation and aggregation of iron,” she noted. These exciting new results add to the growing evidence that space weathering on the lunar farside may differ from that on the nearside, and, contrary to previous findings from Apollo and Chang’e-5 samples, solar wind radiation plays a more dominant role in the space weathering process on the lunar farside.
There are differences in the solar wind’s influence on different regions of the Moon. During each synodic month, the near side of the Moon enters Earth’s magnetotail, where the protection afforded by Earth’s magnetic field reduces its exposure to the solar wind; in contrast, the farside is continuously exposed to direct solar wind radiation. Moreover, due to orbital dynamics, different locations on the Moon experience varying impact velocities from cometary and asteroidal meteoroids. The relative velocity between the Moon’s surface and impacting meteoroids changes with the lunar phase: during a full moon, when the Moon and meteoroids move in the same orbital direction, the relative velocity increases; the opposite occurs during a new moon.
That there are differences between samples from the Moon’s two hemisphere should not a surprise. Confirming and characterizing those differences however is good.
Scientists studying the lunar samples brought back from China’s Chang’e-6 mission to the far side of the Moon have determined that the different environments create differences in the surface material.
The study found that the solar wind exposure time of the Chang’e-6 samples was close to the minimum observed in the Apollo 11 samples, lower than that of the other Apollo samples, and slightly shorter than that of the Chang’e-5 samples. However, surprisingly, the npFe⁰ grain sizes in the Chang’e-6 samples were larger. “This might suggest that solar wind radiation in this region leads to more pronounced segregation and aggregation of iron,” she noted. These exciting new results add to the growing evidence that space weathering on the lunar farside may differ from that on the nearside, and, contrary to previous findings from Apollo and Chang’e-5 samples, solar wind radiation plays a more dominant role in the space weathering process on the lunar farside.
There are differences in the solar wind’s influence on different regions of the Moon. During each synodic month, the near side of the Moon enters Earth’s magnetotail, where the protection afforded by Earth’s magnetic field reduces its exposure to the solar wind; in contrast, the farside is continuously exposed to direct solar wind radiation. Moreover, due to orbital dynamics, different locations on the Moon experience varying impact velocities from cometary and asteroidal meteoroids. The relative velocity between the Moon’s surface and impacting meteoroids changes with the lunar phase: during a full moon, when the Moon and meteoroids move in the same orbital direction, the relative velocity increases; the opposite occurs during a new moon.
That there are differences between samples from the Moon’s two hemisphere should not a surprise. Confirming and characterizing those differences however is good.
