China's Plan to Launch an Artificial Moon - ScienceNerds

Guess what? China has announced plans to launch an “artificial moon” into our skies by 2020 or 2021! And, as crazy as that sounds, it’s not actually the first time something like this has been attempted. But first China’s new plan.

                                                  

As per the report of China Daily, China plans to launch an "illumination satellite" into orbit over the city of Chengdu. Well, actually four lighting satellites. The first as a proof of concept in 2020 and the next three as a real deal in 2022.

There are not yet many details about the satellites themselves, how big they are or what they will be made of, but do we know that they will be covered with a " coating that reflects Moon's Surface"? Whatever that is supposed to mean. At the proposed distance of 500 km, a single satellite is expected to illuminate an area between 10 and 80 km, the light being about eight times brighter than the moons.

If everything goes according to plan, the scientists hope that the moons will replace the street lamps in urban areas and save the city millions in electricity costs every year. They could also help illuminate roads in the event of natural disasters and blackouts. The same advantages led Russia to try something similar 20 years ago in the so-called Znamya project. In 1993, Russia successfully deployed its own prototype lighting satellite, such as a 20-meter reflective film that unfolded in space. For several hours it circled a few hundred meters above the earth and shone a 5 km wide spotlight over Europe. However, this light only moved at about 8 km / h, which means that most people only saw a flash of lightning in the sky as they passed. Eventually, it fell out of orbit and burned when it reentered. The Russians tried again a few years later, this time with a 25-meter mirror.

However, the satellite could not be deployed and quickly fell out of orbit. There were plans to launch a third, larger mirror, but the project faced serious budget problems and was later abandoned. So China's plan is essentially to continue where Russia stopped acknowledging its mistakes and doing something that actually works, right? Well, as critics have quickly emphasized, this doesn't seem to be the case.

The first and probably biggest problem with China's proposed scheme is the orbit height. For a satellite to track a single city on Earth, it must be in geostationary orbit, approximately 36,000 km above Earth. On the proposed 500 km, China's satellites would have the same problem as Russia when it whipped around the world, quickly illuminating random locations for a split second - which is not exactly the goal. And even if 500 km were a typo and meant 36,000, a satellite at that height would have to be extraordinarily large - hundreds of meters in diameter - to reflect much back to Earth. And yet we don't know how big China's Sats will be, launching something big enough could be prohibitively difficult. Critics also pointed out that the plan does not mention any engines or fuels onboard these satellites. And that would probably be a necessity since the satellites - like the Russian mirrors - will experience aerodynamic drag and solar radiation in space, which will eventually bring them out of orbit. The cost of the primary fuel and the subsequent refuelling missions could outweigh the savings in electricity costs on Earth. Researchers at several universities and institutes have reportedly reviewed the plan and given approval for the trial. Maybe we just don't have all the details. If this is the case and the plan works, should we worry? Many scientists have expressed concerns that these satellites will exacerbate existing light pollution problems. Excessive light from cities today changes the night cycles of animals, the sleep cycles of people and disturbs the astronomers' view of space. And a project of this size is likely to make these problems worse. It is not clear in the reports whether the Chinese government has officially supported these plans. I assume we just have to wait and see if new moons brighten the sky.

~sciencefreak