Scientists have completed data processing of the GPR Rover’s Chinese mission “Chang’e-4” studying the dark side of the moon. It turned out that the soil in the landing area consists of a thick surface layer of fine porous regolith, under which there are large boulders, and rich in iron and titanium oxides. While subject to the basalt layer is so deep that can’t be fixed by radar. Work published in the journal Science Advances.
Third January 2019 Chinese station “Chang’e-4” Rover “WiTu-2” on Board made the first ever soft landing in the crater of Pocket — one of the oldest and largest craters on the back side of the moon. The reverse side is interesting because it is covered with hills and craters are much stronger than the visible, but because of difficulties with communication all the missions still sit only facing the Earth half. Last year aboard the the mission was able to grow cotton, which became the first plant on the moon. Now Chinese scientists a few GPR “UTU-2” explored the depths of the reverse side.
GPR is one of the best tools for the study of planetary cores. It emits radio waves of different frequencies deep into the surface, and looking at how they are absorbed or reflected, it is possible to get a picture of the internal structure down to depths of several tens of meters. Ground penetrating radars are being widely used on Earth in the search of archaeological sites and exploration and for space exploration can be located on the artificial satellite, and on the descent module. They were equipped with the orbiters missions “Apollo-17” and “Kaguya”, as well as the previous Chinese Rover mission “Chang’e-3”.
The key characteristic of an antenna is its working frequency. Longer wavelengths penetrate deeper, but short give a much more detailed picture. “Chang’e-4” can use the waves of frequency 60 and 500 MHz, but, unfortunately, the body creates too much interference for low frequency research and his data is too serious defects, and therefore was not used by the authors. Two lunar day (approximately 30 earth days) Rover scanned the surface at a distance of about one hundred meters.
For the interpretation of the data Canli Lee (Chunlai Li) from the National astronomical Observatory, Chinese Academy of Sciences and his colleagues used a technique similar to computer tomography. They made up three-dimensional model of the overlying soil on the basis of multiple shots at different angles.