Science & Technology
Chinese scientists say the man-made moon, which is essentially an illuminated satellite, will be in orbit by 2020. It will be eight times brighter than Earth's moon and will shine down on the city of Chengdu, the capital of the southwestern Sichuan province.
It's hoped the innovation will replace the need for streetlights and will reduce annual electricity costs by up to 1.2 billion yuan ($173 million).
Residents shouldn't worry that it will "light up the entire night sky," Wu Chunfeng, chief of the Tian Fu New Area Science Society, said to China Daily. "Its expected brightness, in the eyes of humans, is around one-fifth of normal streetlights," he said, adding that it could even assist emergency services during blackouts and natural disasters.
The 'moon' will only illuminate a 50-square-kilometer area, as it's much closer to Earth than our real moon. It will sit about 500km (310 miles) away, compared to the moon's 380,000km (236,000 miles).
If the project proves successful, China plans to launch three more moons around the country by 2022. "The first moon will be mostly experimental, but the three moons in 2022 will be the real deal with great civic and commercial potential," Wu said.
Before it makes its city debut, however, the moon will have to be tested in an uninhabited desert so that its light beams don't to interfere with people or Earth-based space observation equipment.
Reader Comments
Also, OurManFlint has a good point. Most people in the world don't have access to a place where you can clearly see the stars.
If the "moon" is intended to remain over a particular city (Chengdu, in this case), it will have to be in a geosynchronous orbit. The altitude of such an orbit is nearly 36,000 km, while the article states that the "moon" will be at an altitude of ~500 km. With an orbit at that altitude, it will NOT remain above a particular location on the Earth's surface.
If it is placed into a geosynchronous orbit, the reflecting area of the satellite will have to be extremely large (many km in extent) in order to illuminate a particular extended area on the earth's surface in any discernible manner. If it is at an altitude of ~500 km, it can be much smaller but it will be in the earth's shadow during most of the nighttime of the area which it overflies, and will thus not be able to reflect sunlight during those times.
T he real moon is built with super-reflective rock (as can be verified from astrononts on the moon) - but what are they going to use here
What sort of lights would be visible from 500KM ...
one of the biggest problems with long distance laser measuring is the disbursement of the beam