China’s lunar rover unveils underground secrets on far side of moon
UNTV News • February 27, 2020 • 339
China’s lunar rover Yutu-2, or Jade Rabbit-2, has helped scientists unveil the secrets buried deep under the surface on the far side of the Moon, enriching human’s understanding about the history of celestial collision and volcanic activities and shedding new light on the geological evolution on the Moon.
China’s Chang’e-4 probe made the first-ever soft landing on the eastern floor of the Von Karman Crater within the South Pole-Aitken Basin on the far side of the Moon on Jan 3, 2019. After its landing, the spacecraft immediately deployed its Yutu-2 rover, which uses Lunar Penetrating Radar (LPR) to investigate the underground it roams.
A study conducted by a research team led by Li Chunlai and Su Yan at the National Astronomical Observatories of China (NAOC) reveals what lurks below the lunar surface.
As a result of the tidal locking effect, the Moon’s revolution cycle is the same as its rotation cycle, and the same side always faces Earth.
The research team used the LPR on Yutu-2 to send radio signals deep into the surface of the Moon, reaching a depth of 40 meters by the high-frequency channel of 500 MHz – more than three times the depth previously reached by the Chang’e-3 lunar probe, which was sent to the near side of the Moon at the end of 2013.
The results of the radar data collected by the LPR during the first two lunar days (a lunar day equals 14 days on Earth) of operation provide the first electromagnetic image of the subsurface structure of the far side of the Moon and the first “ground truth” of the stratigraphic architecture of an ejecta deposit, said Li Chunlai, deputy director of the NAOC.
“The first layer is a fine 12-meter soil layer below the surface. The second layer between 12 and 24 meters under the ground has a lot of stones and the strongest radar echo. It even forms a stone layer and stacks of loose stones. There are three gravel stacks. The third layer is 24-40 meters under the surface. Radar echo shows its dark and bright parts, so there are granules and scattered stones,” said Su Yan, a researcher from the NAOC.
The scientists analyzed the radar image with tomographic technique, and the result shows that the subsurface is essentially made by highly porous granular materials embedding boulders of different sizes.
The content is likely the result of a turbulent early solar system, when meteors and other space debris frequently struck the Moon. The impact site would eject material to other areas, creating a cratered surface atop a subsurface with varying layers, said Li.
“We find the ejecta have many layers and each layer is different from each other. It may mean the place has lots of ejecta from impact sites, so history of meteorite impacts here is very complicated. It also shows the Moon was frequently struck by small celestial bodies, and debris will be ejected to bottom of the Von Karman Crater. The ejecta have recorded history of meteorite impact on the Moon,” said Li.
As the Yutu-2 rover has walked about 300 meters, Li said his team expects new discovery in the future.
“We hope it can walk out of the ejecta-covered area. If it can enter a basalt zone, maybe we can better understand distribution and structure of ejecta from meteorite impacts. The distance may be 1.8 kilometers. I think it may take another one year for the rover to walk out of the ejecta-covered area,” Li said.
The study was published Wednesday in the latest issue of Science Advances. (Reuters)
China’s National People’s Congress’ third session closed on Thursday (May 28) after parliament members voted on a proposal to implement Hong Kong’s national security legislation.
“The session made a decision to establish a legal system and enforcement mechanism for the national security of Hong Kong’s Special Administrative Region,” chairman of the standing committee of the NPC, Li Zhanshu, told delegates at the closing ceremony.
“It will uphold and improve the ‘one country, two systems’ policy. It is in line with the Constitution and Hong Kong’s Basic Law and is in the interest of all Chinese people including Hong Kong people,” he added.
The legislation received 2,878 votes while one voted against and six abstained. The draft national security law has received international criticism with the US Secretary of State Mike Pompeo declaring that Hong Kong is ‘no longer autonomous.’
Hong Kong, which has freedoms not granted in the mainland such as freedom of assembly and freedom of the press, has experienced months-long anti-government protests which sparked from a now-withdrawn extradition bill. (Reuters)
Hong Kong leader Carrie Lam said on Tuesday (May 26) that Beijing’s proposed national security laws would not trample on the city’s rights and freedoms and called on its citizens to wait to see the details of the legislation.
Beijing unveiled plans last week for national security legislation for Hong Kong that aims to tackle secession, subversion and terrorist activities. It could see Chinese intelligence agencies set up bases in the city.
Thousands poured onto the street of Hong Kong on Sunday (May 24) in a mass protest against the planned new security laws.
Police fired tear gas and water cannons to disperse the crowd and arrested almost 200 people.
More protests are expected in Hong Kong on Wednesday (May 27). (Reuters)
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