China’s lunar rover unveils underground secrets on far side of moon
UNTV News • February 27, 2020 • 225
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)
As the whole world is struggling to fight the coronavirus pandemic, one of the unexpected outcomes for Chinese people is more clean skies.
China had a significant decrease in nitrogen dioxide pollution in cities like Beijing during February, when factories and streets were closed as authorities attempted to stop the spread of the virus, according to the European Space Agency (ESA) Copernicus satellite image.
Analysis by Greenpeace shows that the pollutant emissions in Beijing and its surrounding areas dropped by more than 40% year-on-year in February.
Compared to previous years, the air in the capital has seen a big improvement during the outbreak. Streets and landmarks are no longer covered in smog.
Beijing resident Liu Chuan takes this as a potential health benefit, saying that he could even see stars at night after work.
“It feels like the air is overall much less polluted than it used to be. It also improves people’s mood, and indirectly strengthens the immunity. It’s good for fighting the virus,” added Liu.
However, expert warns the air pollution and carbon emissions may soon reappear as Chinese factories are ramping up output in an effort to offset the economic hit of coronavirus.
“We can’t rule out the possibility that it may cause air pollution frequently if a large scale of high-polluting industries resume production,” said Lyn Liu, a Greenpeace climate and energy campaigner. (Reuters)
China’s foreign ministry is advising foreign diplomats to stop coming to Beijing, after the country temporarily banned most foreigners from entering to prevent a resurgence of a coronavirus epidemic, a spokeswoman said on Friday (April 3).
Foreign ministry spokeswoman Hua Chunying told reporters during a daily briefing that the ministry was aware of confirmed coronavirus cases among foreign diplomats in China.
Mainland China reported 31 new confirmed coronavirus cases, 29 of which were imported from overseas, the country’s National Health Commission said on Friday.
The total number of infections now stands at 81,620 and 3,322 deaths have been reported from mainland China to date. (Reuters)
A massive forest fire in southwestern China has killed 19 people, according to a state media report on Tuesday (March 31).
Eighteen firefighters and a local guide were confirmed dead, from a group of 21 firefighters who went to fight the blaze that had spread over more than 1,000 hectares of land near Xichang, a city in Sichuan province.
The fire started on a farm on Monday (March 30) afternoon and quickly spread to nearby mountains due to strong winds, according to local reports.
Flames and heavy smoke were seen drifting into the sky, posing a threat to a nearby town — including a gas storage station about 70 meters away from parts of the fire.
“This place (the gas station) is by far the most dangerous place in this forest fire in Xichang,” said Zhang Shanhu, a member of the local fire and rescue team.
Police have evacuated more than 1,200 people from the area, and local authorities have organized over 2,000 people to fight the blaze. (Reuters)
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