What is the "artificial moon" planned in China?

Artificial moons could replace street lights in urban areas. (Reuters photo / File)

Last week, Chinese media announced plans for a private institute to launch an "artificial moon" on Chengdu City, Sichuan Province, by 2020. L 'goal is to provide an alternative way of street lighting and save electricity. Since then, the idea has not only been widely covered (including in The Indian Express of October 19), but has also been viewed with some skepticism.

What we know up to now

Information on the project is so far incomplete. The online People's Daily online, the first to report it, said the artificial moon would be a mirror orbiting Chengdu, at an altitude of 500 km. It would reflect the sunlight at night and complete the street lighting of Chengdu, which has 1.6 million inhabitants.

The Peoples Daily Online reported that the brightness of the artificial moon will be eight times greater than that of the moon, while the China Daily reported that the brightness would be a fifth of that of a street lamp . The online newspaper People's Daily said that the moon would illuminate an area of ​​diameter between 10 and 80 km. According to an AFP report, an illuminated area of ​​50 square kilometers would save about 1.2 billion yuan ($ 170 million) a year in electricity costs for Chengdu.

READ | China will launch an artificial moon to illuminate the night sky

If the experiment succeeds, two other moons of this type could be sent by 2022, according to the China Daily report citing Wu Chunfeng, president of Chengdu Aerospace Science and Technology Microelectronics. System Research Institute Co Ltd, and the head of the new regional science company Tian Fu who manages the project

What the Chinese media did not specify is whether the project is officially supported by the government. Several other publications indicated that they could not confirm the project independently with Wu.

Challenges

At an altitude as low as 500 km and considering a diameter small enough to be economically viable, precision is essential. Missing a few degrees at the angle of reflection would miss Chengdu by several kilometers, a scientist would have said. "If you want to illuminate an area with a 10-kilometer error, even if you miss a hundredth of a degree, you'll have light directed to another place," said Dr. Matteo Ceriotti, a professor at Space Systems. Engineering at the University of Glasgow as indicated.

Again, there must be a sufficient glow, but if this glow covers a large area, it could potentially affect the daily cycle of animals and plants, and even affect the human circadian system – the clock of body. "Many people are in a circadian fog where our physiology is confused," said Richard Stevens, a cancer epidemiologist at the University of Connecticut's School of Medicine at the New York Times.

Is this possible?

The idea of ​​having a satellite reflecting light at night is not new. In 1993, Russia sent Znamya 2, a 65-foot-diameter plastic mirror. He managed to reflect a narrow beam of light and astronauts from the Mir space station would have filmed a spot of light on the surface.

"The beam of a width of two and a half miles traveled about eight minutes across part of the Atlantic Ocean, then from Europe, including Russia", reported the NYT in 1993. For people on the ground, light was seen as pulses from a star-shaped object.

Six years later, Russia launched Znamya 2.5, supposed to be a bigger mirror, but not deploying properly. The idea of ​​sending a giant mirror in the sky is dead with it. Until now.

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