China plans on the launch of an “Artificial Moon”.

To begin, China is in need of saving money (For some reason), so they concluded that spending less money on street lights at night would do the trick. The moon would illuminate Chengdu in China, and would save the government over $170 million dollars. This is all planned for the year 2020.

Speaking of planning, the city planning meeting must have sounded insane and should have gone something like:

Department leader: “We must save more money.”
Employee: “We can turn off the lights at night.”
DL: “Then how will people see at night?”
E: “We could… build a moon that reflects the sun’s light”

First of all, is this even possible?

Well, lets start with where this idea may have come from. It came from Russia by Russian scientists.

This project used a 5 kilometer (3.1 miles) in diameter mirror that was in low orbit above the Earth in an attempt to illuminate a part of Europe. This mirror was originally developed as a solar sail, but funding for it was cut.

Unfortunately the day of the experiment, it was a cloudy day in the place that it was illuminating. Not only was it ineffective in illuminating, it was moving at about 7+ kilometers per second (15,658+ Miles per hour) so it was just zipping across the surface.

Therefore from this experiment, we can conclude that it would be ineffective to try and build a moon to illuminate the surface to the point to where you can go about your everyday life at night.

There were more plans to use a 20 kilometer (12.42 miles) mirror, but that mirror failed to unfold so the project died.

So if that project went so poorly, what will the Chinese do?

I don’t expect it to work. I expect it to illuminate for a couple minutes. This moon would have to track with the suns position if they want it to illuminate a specific spot on the surface.

According to calculations, a 20 kilometer (12.42 miles) mirror would work for a fixed position like this only if it is much further away than Znamya ever was.

Tracking the Earth’s position and sun’s position is entirely possibly using geostationary orbit. Geostationary orbit is a path for a satellite to take that is about 36,000 kilometers (22,369.36).

Now to put this all together.

Because of the laws of physics, the reflector would be reflecting a half degree cone, which works out to 360 kilometers, given the distance of a satellite in geostationary orbit. A 600 meter reflector would do the trick for a small area, although China wants it to be as much as 10 times that.

It would indeed work, barring equinoxes.

This sounds ideal. Whats the catch?

There in fact is a catch. One problem that the Chinese government would have to overcome with this project is radiation pressure.

As something is reflecting that amount of light from the sun, it is always experiencing this pressure which is about 4µ Pa (4 micro-pascals).

This will take the moon satellite out of geostationary orbit rather quickly because just because the pressure is tiny, nearly negligible, it isn’t. The orbit will still be eccentric (circular) just shifted because of the pressure.

Think of it as the light “pushing” the object reflecting light.

This happens to all satellites, that’s why some crash land on Earth’s surface or burn up in the atmosphere.

I conclude, that China is crazy.