Credit: Chinese Academy of Sciences

Credit: Chinese Academy of Sciences

A special issue of Research in Astronomy and Astrophysics has been dedicated to the early results from China’s Chang’e 3 lander mission to the Moon.

On December 14, 2013, the Chang’e 3 (CE-3) landed on the Mare Imbrium basin in the east part of Sinus Iridum (19.51◦W, 44.12◦N). It was China’s first soft landing on the Moon. The achievement made China the third country to achieve a soft landing on the lunar surface.

China’s first lunar surface exploration mission made use of a heavily instrumented lander and a rover

“The mission is part of the second phase of China’s Lunar Exploration Program (CLEP) that has the ultimate goal of launching manned flights to the Moon,” one of the scientific papers reports.

Previously, the first phase of China’s robotic lunar exploration program had two orbital probes, Chang’e 1 (CE-1) and Chang’e 2 (CE-2), which were launched in 2007 and 2010, respectively.

Credit: Chinese Academy of Sciences

Credit: Chinese Academy of Sciences

Lunar dust

In the journal, an array of scientists from the Laboratory of Lunar and Deep Space Exploration, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, present initial findings from the lander and its lunar rover, Yutu.

According to the papers, an analysis of the effect of the CE-3 engine plume on the lunar surface was done by comparing images before and after the touchdown using data from the craft’s landing camera.

For example, during the landing process of CE-3, lots of lunar dust was blown away by the engine plume. Furthermore, the scope of influence is about 60 meters from east to west and 135 meters from south to north. “Thus, this leads to a redistribution of lunar dust and changes in space weathering on the lunar surface,” one of the research papers notes.

The landing site of CE-3 was found to be a high titanium basalt stratum, and its geological age is young Eratoshenian – the longest period of the lunar timescale, thought to range from about 3.2 to 1.1 billion years old.

Ultraviolet eyes

A Moon-based Ultraviolet Telescope (MUVT) is one of the payloads on the CE-3 lunar lander.

Because of the advantages of having no atmospheric disturbances and the slow rotation of the Moon, long-term continuous observations of a series of important celestial objects in the near ultraviolet band were possible, as were sky surveys of selected areas, observations that cannot be completed on Earth.

Reported in one paper, the results from the MUVT demonstrate that the methods used for data collection and preprocessing are effective, and conducive to follow-up scientific research.

Also, the Extreme Ultraviolet Camera (EUVC) obtained the first global image of the plasmasphere from the Moon. After an image of the plasmasphere was acquired, the EUVC was rotated away from the Earth to take a dark image of the background. Then the background was removed from the image of the plasmasphere. The result was that the plasmasphere, plasmapause, airglow and the Earth’s shadow were clearly seen in imagery.

“Data from the EUVC will provide useful images for researchers to investigate how the plasmasphere responds to solar activities,” another research paper states.

Radar scans

Along with its camera gear, the Yutu lunar rover carried Lunar Penetrating Radar (LPR) equipment. After the lunar rover was dispatched on the Moon’s surface, the LPR started to work on December 15.

“A large amount of scientific data about exploring the lunar regolith and subsurface were successfully obtained,” it is reported.

After preliminary analysis, one channel of the LPR equipment clearly detected information about the shallow layer of the lunar crust along the path of the lunar rover. Another LPR channel detected the layer structure of lunar regolith.

“These observations have revealed the configuration of regolith where the thickness of regolith varies from about 4 meters to 6 meters. In addition, one layer of lunar rock, which is about 330 meters deep and might have been accumulated during the depositional hiatus of mare basalts, was detected,” one of the group of scientific papers states.

The regolith on the Moon’s surface is a highly comminuted surface layer, it is reported, which was formed by billions of years of collisions. The regolith is not uniform and structures with multiple layers have been observed. Working with the LPR, the data collected shows that the regolith around the landing place in Mare Inbrium is about 4 meters to 6 meters in depth.

“Since the Yutu rover had severe problems during its second lunar day, it is pity that the Yutu rover only transversed a limited distance. Nevertheless, the LPR worked successfully and performed the first on-site exploration of structure under the lunar subsurface,” one paper explains.

Looking around the landing site

Other items noted:

— The landing site of the Chinese spacecraft lies on the edge of a plateau in a flat plain with a declining trend from west to east. The topographic slope and waviness of the area are low, which is typical for terrain in lunar mare.

— The crater next to the landing site has a lower difference in elevation from east to west, but has a higher difference in elevation from south to north. There are thousands of rocks distributed in the southern and western parts of the crater wall.

— The distance from the landing point to the western edge of the crater is 40 meters. The adjacent area is flat terrain, with landforms such as craters, domes, strata and rocks with different albedos, which are good targets for scientific exploration.

To take a look at the full range of papers, go to:

http://www.raa-journal.org/raa/index.php/raa/issue/view/81

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