The moon is seen near a Chinese national flag in
The Chinese government has unveiled plans to build a permanently manned radar station on the moon to monitor the earth.
The feasibility study which would cost $2.4 million is being funded by China's National Natural Science Foundation.
The proposed facility, which may include quarters for astronauts and a powerful radar antenna array at least 50 meters high, could monitor wider areas of the earth than conventional satellites, according to scientists involved in the study.
The base, which would be used for scientific research and defence monitoring, could also produce more powerful and clearer images of earth as the high-frequency microwaves emitted by the radar station could not only penetrate cloud, but also the earth's surface, allowing it to monitor areas on land, under the sea and underground.
Leading space scientists in China have joined the radar station project.
The team held a two-day brainstorming session at the Fragrant Hill Hotel in Beijing last month.
Those taking part included Yan Jun, the director of the National Astronomical Observatories; Professor Lin Yangting, a planetary researcher whose team discovered evidence of coal-like carbon in an asteroid; and senior scientists from China's unmanned lunar exploration missions.
The team leader is Professor Guo Huadong, a top radar technology expert at the Chinese Academy of Sciences.
Guo initially proposed the moon-based radar station in a research paper in the journal Science China Earth Sciences three years ago.
He suggested that the moon had numerous advantages over satellites or a space station as an earth observation platform, including stability and the unlimited durability of any complex on the lunar surface.
The data collected by lunar radar would help with a wide range of scientific research issues such as monitoring extreme weather conditions, global earthquake activity, agricultural production and the collapse of the polar ice caps, he wrote.
To generate high intensity radio beams that could reach earth, the radar station would need an enormous amount of power so a solar or nuclear power plant would have to be built, Guo said in the paper.
The radar would generate at least 1.4 gigabytes of data each second, a volume far exceeding the bandwidth of current long-distance space communications technology, but this would not be a problem if the station was manned by astronauts who could process the information on site, he added.
Guo gave no precise estimate on costs for the project, but cautioned it would be "very expensive".
China is not the first nation to draw up plans for a manned extraterrestrial base; the US and Russia are exploring the possibilities of creating habitable space bases.
The lunar radar project comes as China shows signs of wanting to play a leading role in a renewed race to the moon, according to some space experts.
The design of a giant rocket the same size as the Saturn V in the US Apollo missions will be completed by 2020 to pave way for large scale activities in space including a "manned moon landing", according to a scientific and technological innovation plan announced by the Chinese government earlier this month.
The country landed a rover called Chang'e 3 in 2013, making it the third nation behind the US and Russia to successfully complete a soft landing on the moon. It was also the first moon landing in almost four decades.
'A lunatic idea'
Many researchers, however, expressed scepticism about the scheme, arguing that it was a waste of money, time and human resources.
"It's a lunatic idea," one scientist not involved in the project told the South China Morning Post on the condition of anonymity. He added that the cost would be "higher than filling the sky with a constellation of spy satellites," which would "do the same job at only a fraction of the cost."
"Either the radar has to be extremely powerful, or the antenna extremely large, otherwise it won't be able to pick up the radio waves bouncing back from the Earth," said Professor Zhou Yiguo, a radar technology researcher at the Chinese Academy of Sciences.
"It is an important subject of research, but whether its advantage over satellite constellations can adjust the high cost and risk will need careful evaluation."