China's artificial moon
China has announced plans to launch an “artificial moon” into our skies by 2020. 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 reported in China Daily, China plans to launch an “illumination satellite” into orbit above the city of Chengdu. Well actually, four illumination satellites. The first as a proof of concept in 2020 and the next three as the real deal in 2022. There aren’t a ton of details about the satellites themselves yet, like how big they are or what they will be made of, but we DO know they’ll be covered with a “reflective coating similar to the moon’s”? Whatever that’s supposed to mean.
At the proposed distance of 500 km, a single satellite is expected to illuminate an area between 10 and 80 km, with light around “8times brighter” than the moon’s. If all goes to plan, the scientists hope the moons will replace streetlights in urban areas and save the city millions in electricity costs annually. They could also help light up streets during natural disasters and blackouts. Those same benefits are what prompted Russia to try something similar 20 years ago, in what was called Project Znamya. In 1993, Russia successfully deployed their own prototype of an illumination satellite, about a 20-meter reflective film that unfolded in space. For a few hours, it orbited a couple hundred meters above earth, beaming a 5 km wide spotlight over Europe. But, that light only moved at about 8 km/hour, meaning most people just saw a flash in the sky as it passed. Eventually, it fell out of orbit and burned up on reentry. The Russians tried this again a few years later, this time with a 25-meter mirror. However, the satellite failed to deploy, and it quickly fell out of orbit. There were plans to launch a third, even bigger mirror, but the project faced serious budgeting issues and was later abandoned.
So China’s plan is essentially picking up where Russia left off, taking note of their mistakes and making something that will actually work, right? Well, as critics have been quick to point out, that doesn’t appear to be the case. The first and probably biggest, issue with China’s proposed scheme concerns the height of orbit. In order for a satellite to track a single city on earth, it would need to be in a geostationary orbit, about 36,000 km above earth. At the proposed 500 km, China’s satellites would face the same problem that Russia’s did, whipping around earth, quickly lighting up random places for a fraction of a second as they go- which isn’t exactly the goal. And even if 500 km was a typo, and they meant to say 36 thousand, a satellite at that height would need to be extraordinarily large - hundreds of meters across- to reflect much back to earth. And while the article doesn’t specify how big China’s sats will be, launching something big enough could be prohibitively difficult. Critics also pointed out the plan has no mention of any sort of thrusters or fuel onboard these satellites. And that would probably be a necessity since out in space, the satellites-- like the Russian mirrors-- will experience drag and solar radiation that will eventually push them out of orbit. The cost of the initial fuel and subsequent refueling missions could outweigh any savings in electricity costs on Earth.
Reportedly, researchers at several universities and institutes have looked over the plan and have given it the okay for trial, so maybe we just don’t have all the details. If that’s the case, and the plan does work, should we be worried? Many scientists have expressed concerns that these satellites will amplify the light pollution problems we already have. Excess light from cities today alters night cycles of animals, the sleep cycles of humans, and disrupts astronomers’ view of space. And a project of this scale will likely make those problems worse. It’s not clear in the reports whether the Chinese government has given these plans any sort of official backing, So, I suppose for now, we’ll just have to wait and see if any new moons light up the sky.
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