Last Updated on 2020/12/06
A few days ago the Chinese media (and others) talk about the project of launching a “fake moon” in orbit to illuminate the streets of Chengdu during the night.
UPDATE: According to ABC, the project would consist of three artificial moons that will be sent starting in 2020. The mirrors made of reflecting materials should work alternately in order to significantly reduce the city’s electricity consumption, especially during the winter months.
This idea, which should be implemented by 2020, was designed to allow the municipality of Chengdu, Sichuan, to save some money in night lighting, while also allowing to illuminate the darkest corners of the Chinese metropolis, that however, like most of the Chinese metropolis is already heavily affected by night light pollution.
This news was released for the first time last week by the People’s Daily, commenting on an innovation conference by Wu Chunfeng, head of the Chengdu Aerospace Science Institute, the Microelectronics System Research Institute Co., Ltd.
In Wu’s words, the launch should be launched in 2020. Other “giant mirrors” should be launched by 2022.
It is not clear if this project has obtained public funding.
How should it work?
The artificial “moon” should therefore be a kind of mirror that reflects light back onto the earth and should orbit about 500 km above the ground, at the same height as the ISS.
Not having been disclosed many details, we only know that the “artificial moon” should illuminate an area between 10 and 80 km, with a power 8 times higher than that of the moon.
According to the project, it should save a lot of money from the local municipality. According to the China Daily, illuminating an area of 50 square miles, it would be possible to save up to 170 million dollars a year of electricity.
So where is skepticism born?
The project could theoretically be possible.
But to work, the fake moon should geostate over Chengdu. But this is not possible because the geostationary orbit is more than 35,000 km from Earth to allow a satellite to “synchronize” the period of revolution with the rotation period of the earth.
The geostationary orbit is therefore much sought after by artificial satellites (weather forecasts, telecommunications, etc.) and is also very crowded.
It goes without saying that at that distance, not at 500 km in height, but at almost 40,000 km, the mirror should have colossal dimensions and should have an extremely accurate pointing system, said Dr. Matteo Ceriotti of the University of Glasgow at the BBC.
According to Ceriotti, therefore, a small error would suffice to illuminate a completely different area.
Moreover, despite the director of the Harbin Institute of Technology told the People’s Daily that the lights will be like a glow in the fog and that they will not disturb the routine of the animals, it may somehow interrupt the night cycle of nature.
In 1993 the Russian space agency sent a 20 m diameter reflector (Znamya 2) to the Mir space station, which orbited between 200 and 420 km from the earth.
Znamya 2 for some moments illuminated an area of about 5 km in diameter on the earth before the satellite burned back.
Later in the 1990s, the Russians tried to create a bigger model, but the project failed.