In 2013, the Chinese space probe “Chang’e-3″ landed in the northern part of the Sea of Rains – the third-largest moon of the sea, visible from Earth. Mare Imbrium was formed as a result of the flooding lava large impact crater about 3.85 billion years ago.
«This is a very good place to land,” – says Bradley L. Jolliffe, a professor at Washington University in St. Louis, took part in the analysis of samples of lunar soil.
Lander with the first Chinese Lunokhod “Yuytu”, which means “Jade Hare”, landed on a smooth plateau of frozen basalt near the relatively young impact crater Zi Wei, named after the ancient Chinese astronomer who lived in the V century BC.
After the US program “Apollo” lunar exploration was conducted primarily orbiters. However, the orbital sensors mainly detect regolith that covers the surface of the moon. Regolith poorly suited to scientific research, because it is a heterogeneous mixture of different breeds.
«Chang’e-3″ took in enough young basalt rocks, where the regolith layer is very thin and not mixed with rocks from other areas. Thus, the composition of the regolith in this area is similar to the composition of the basic volcanic rocks covered them. This makes the module ideal landing spot for gathering information about the lunar rocks in the formation, and then to compare it with the data orbiters.
According to Professor Jolliffe, collected samples will be reference data to orbiting satellites. Observing similar to the reference sample data with orbiters at other points of the moon, it will be possible to conclude that such areas have similar basaltic rocks.
Basalt rocks at the landing site “Chane- 3 ‘are different from samples collected missions “Apollo” and “Moon”. The difference in composition of the sample said that the upper mantle of the Moon is much less uniform in composition than Earth. By comparing the chemical composition of the rocks with their age, scientists can trace the evolution of the volcanic activity of the moon.
The research results of scientists published in the journal Nature Communications . The work involved scientists from Shandong University in Weihai (China) and the University of Washington in St. Louis (USA).
It is believed that the Moon was formed as a result of the collision with the Earth celestial body the size of Mars some 4.5 billion years ago. It was originally a liquid, and then in the process of cooling the Moon formed crust, mantle and core. However, the heat resulting from the decay of radioactive elements in the moon melted part of the mantle, which was erupting to the surface. It happened about 500 million years after the beginning of the formation of the Moon. As a result, on the lunar surface formed craters and basins, called seas. Most of the Seas is on the visible side of the Moon from the Earth.
Earlier, the American mission “Apollo” (1969-1972) and the Soviet program “Moon” (1970-1976) collected basalt rocks from the period of high volcanic activity of the moon (3-4 billion years ago). Samples collected Lunokhod “Yuytu” in the Sea of Rains include younger rocks (3 billion years old and younger).
Delivered missions “Apollo” and “moon” rock had either a high or low content of titanium. Among them there were no samples with an average grade of titanium.
The data of X-ray and infrared spectroscopy, obtained from the board Lunokhod “Yuytu” say that the basaltic rocks in place landing of the Chinese mission “Chang’e-3″ have an average titanium content and are rich in iron.
Titanium is a good source of information on volcanic activity of the moon. Its content in the samples varies very considerably – from 1 to 15 weight percent. This variation reflects the composition of basalt rocks are significant differences composition of the lunar volcanic lava different.
In the process of the formation of the Moon basaltic magma crystallized minerals in a particular type. In the early stages it was rich in iron and magnesium minerals olivine and pyroxene. In the process of crystallization of the magma ocean formed the mantle and the crust of the moon. Titanium is a member of ilmenite – a mineral formed on the later stages of hardening of lunar rocks. Thus, ilmenite was in the depths of the mantle, there is forming a region rich in titanium.
According to the scientists, the heterogeneity of the distribution of titanium on the surface of the moon suggests that the mantle of the Moon was not smooth. Perhaps at a time when the moon existed magma ocean, took place the processes that influenced the formation of the mantle.
At the same time, data from the orbiters suggest that the rocks in the landing “Chang’e-3″ also rich in olivine, like titanium.
One of the authors – Alian Wang believes this result is very strange, because the olivine crystallized at an earlier stage than the titanium-rich ilmenite, and they usually do not encountered in some formations. The scientist believes that these two minerals can mingle in the final stages of crystallization of magma ocean.
In any case, these new studies show that lunar rocks are much more heterogeneous than previously thought on the basis of “Apollo” and ” Moon ».
The module” Chang’e-3 “has carried out the second phase of China’s lunar program only partly because of some technical problems. “Yuytu” finally fell asleep February 22, 2014. Earlier, China successfully launched two lunar module to produce a topological map of the lunar surface and brought them to the lunar orbit. Next, the third stage – delivery of lunar soil to Earth – to be implemented in 2017.
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