Artificial Moon to be Launched

[Wayne]

And you thought your neighbor's floodlight was bad.

China plans to launch an illumination satellite in 2020 that will reflect the Sun's light. Eight times brighter than the moon, it is intended to replace the need for street lights in the city of Chengdu (population 10 million). Someone pointed out that it could have an adverse affect on animals and astronomical observation, so initial testing will be done on an uninhabited desert.

http://en.people.cn/n3/2018/1016/c90000-9508748.html
http://time.com/5429288/china-chengdu-artificial-moon/

[BradNasset]

Seems like a really, really bad idea! Hmmmm….. if a magnifying glass can start fires, wonder if this will become a weapon? Or at least light up the enemy on the battlefield? Jeez, until I wrote this, never thought I was a conspiracy thinker. Seen enough in my life so far not to think this. Will be interesting.

[merle]

Article on military use of solar weapons:

https://militaryhistorynow.com/2013/09/ ... t-weapons/


In part:

As was reported on MilitaryHistoryNow.com on Sept. 28, 2012: “During the Roman siege of Syracuse in 212 BCE, the Greek inventor Archimedes put his considerable genius to work helping to shore up defenses. According to contemporary accounts, one of his schemes involved placing giant parabolic mirrors at various points atop the city’s walls that could be used in concert to focus the sun’s ray’s onto distant targets (in this case, Roman warships). Other historians from antiquity suggested that it wasn’t actually mirrors Archimedes used but rather large magnifying glasses. In any case, the inventor’s beam weapon supposedly did set some of the invaders’ ships on fire.

Over the years, a number of historians and scientists have tried to reproduce Archimedes’ death ray. Most recently, both the American television program Mythbusters and a group of students and faculty at MIT attempted to replicate the heat ray. The latter were able to ignite a simulated wooden ship hull using the mirrors after some initial setbacks.

[Dave Venne]

From the Time article:

Scientists estimated that it could be eight times more luminous than the actual, original moon. It will also orbit much closer to Earth; about 500 km (310 miles) away, compared to the moon’s 380,000 km (236,000 miles).

This is a low orbit with a period of 1h 34m. Much of the night it will be in the earth's shadow while over the target area and not provide any illumination at all. And it will only be in the target area's sky for the duration of each overhead pass. Doesn't seem like it would be at all effective.

Perhaps something has been lost in translation?

[Wayne]

Another source (https://www.cbsnews.com/news/china-to-l ... night-sky/) reports it is the first of four similar satellites.

Per Wikipedia (Sun-synchronous orbit):

If one wants a satellite to fly over some given spot on Earth every day at the same hour, it can do between 7 and 16 orbits per day....

At the altitude given, this near polar orbit puts any one satellite in a position to provide light for perhaps 25 minutes (at least ~45 degrees above the horizon). Three additional satellites would fill the gap until the first is in position again. But after a full orbit the earth would have rotated, requiring not only 25 minutes of steady mirror adjustment for the changing Sun/mirror/Chengdu angle, but the mirrors must shift angle for every orbit over the night side. And Dave hit the biggest problem, a low orbit satellite would be in Earth's shadow for most of the night.

Just in case Merle is on the right track:

The satellite will be able to light an area with a diameter of 10 to 80 kilometers, while the precise illumination range can be controlled within a few dozen meters.

Since the mirrors apparently have adjustable focus (at least to some degree), how intense would the beam be if focused on a small area? Assuming a 10km circle is 8 times the moons brightness, a 10 meter spot would be 8 million times as bright as the moon. Let see, full moon is about 1 lux, Sun is about 100,000 lux. Thus about 80 times as bright as the Sun. So if it could focus that tight and maintain pointing accuracy, it seems like it could be an Archimedes death ray.

[Deane Clark]

If this happens, I think I’ll just move - to another planet.