China’s artificial moon satellites could replace streetlamps, saving energy and night fighting advantage to PLA

Rajesh Uppal April 14, 2019 Space Comments Off on China’s artificial moon satellites could replace streetlamps, saving energy and night fighting advantage to PLA 401 Views

China is planning to launch its own ‘artificial moon’ by 2020 to replace streetlamps and lower electricity costs in urban areas, state media reported. The Tian Fu New Area Science Society plans to launch the so-called “illumination satellite” would orbit above the Chinese city of Chengdu and glow in conjunction with the actual moon, but shine eight times brighter. At that intensity, this satellite won’t brighten the entire sky, but it should give off what one Harbin Institute of Technology scientist described as a “dusk-like” glow. It would reflect the sun’s light at night, and supplement street lighting in Chengdu, which has a population of 1.6 million.

The organization says it will launch three more satellites in 2022 — potentially replacing streetlights in urban areas. The plans were announced by Wu Chunfeng, head of the society, at an innovation conference in Chengdu on October 10. Chunfeng told China Daily that the satellite, launching from the Xichang Satellite Launch Center, will orbit about 300 miles (500 kilometers) above the city and use its mirror-like coating to reflect sunlight down to Earth.

Chungfeng says the object is able to focus its reflected light onto a very specific portion of the Earth’s surface, illuminating a small area with a diameter of 6.2 to 50 miles (10 to 80 kilometers). That won’t be nearly enough to cover Chengdu, which encompasses 4,787 square miles (12,400 square kilometers). But by Chungfeng’s estimate, if the satellite illuminates just 19 square miles (50 square kilometers) of the city, Chengdu could scale back its urban lighting infrastructure and thus save 1.2 billion yuan — or $173 million — annually. The extraterrestrial source of light could also help rescue efforts in disaster zones during blackouts, he added.

The three follow-up moons, though, will be able to cover much more ground. The trio will take turns, based on who’s facing the Sun, beaming light on the city streets. Working together, they’ll be able to illuminate 2,000 to 4,000 square miles (3,600 to 6,400 square kilometers) for up to 24 hours.

Despite shining light in a similar way, the satellite boasts one advantage that the moon doesn’t — human control. Chunfeng says that both the location and brightness of the human-made moon can be changed, and that it can be completely shut off if necessary. And since the satellite is mobile, it can assist in disaster relief by beaming light on areas that lost power.

In addition to Tian Fu New Area Science Society, other universities and institutes, including the Harbin Institute of Technology and China Aerospace Science and Industry Corp, are involved in developing Chengdu’s illumination satellites.

If China’s researchers could really control the location and brightness, then PLA might be able to have nighttime advantage over their adversaries, by having the power to illuminate the locations and activities of their adversaries.

The challenges

The current plan is to have the craft revolve in low-Earth orbit at an altitude of 310 miles (500 kilometers). At an altitude as low as 500 km, and considering a diameter small enough to be economically viable, accuracy is key. Missing the angle of reflection by even a few degrees would miss Chengdu by miles, a scientist has reportedly said. “If you want to light up an area with an error of say 10 km, even if you miss by one 100th of a degree you’ll have the light pointing at another place,” BBC quoted Dr Matteo Ceriotti, a lecturer in Space Systems Engineering at the University of Glasgow, as saying.

Again, there must be sufficient glow, but if this glow covers a large area, it could potentially affect the daily cycle of animals and plants, and even affect the human circadian system — the body clock. “Many people are in a circadian fog where our physiology is confused,” Richard Stevens, a cancer epidemiologist at the University of Connecticut School of Medicine, told The New York Times.

Chunfeng also said that people have concerns about the moons’ impact on the sleep patterns of humans and animals, but from the sounds of it, the group thinks that the burden will be minimal.

China is not the first country to try beaming sunlight back to Earth. In the 1990s, Russian scientists reportedly used giant mirrors to reflect light from space in an experimental project called Znamya or Banner.

How a Russian Space Mirror Briefly Lit Up the Night

The project to build Znamya or “Banner,” as it was called, began in the late 1980s to test technology that would increase the length of a day with the goal of boosting productivity in farms and cities in the then Soviet Union.

Funded by a collection of Russian state-owned corporations, Syromyatnikov constructed a 65-foot-wide sheet of mylar that could be unfurled from a central mechanism and launched from the Mir space station, Warren E. Leary wrote for the New York Times at the time.

“During the tests, Russian engineers say the small reflector should cast light equivalent to three to five full moons over an area of Earth measuring about three miles in diameter,” Leary wrote.

As odd as the idea may seem, the test was successful. When the Znamya satellite was deployed the night of February 4, 1993, it directed a beam of light about two or three times as bright as the moon and two-and-a-half miles wide down to Earth’s night sky, passing across the Atlantic ocean, over Europe, and into Russia, Leary reported at the time. While observers on the ground only reported seeing a bright pulse as if from a star, astronauts in orbit said they could see and follow a faint light across the sky below. A few days later, the mirror burned up as it reentered the atmosphere.

Six years later, Russia launched Znamya 2.5, which was meant to be a larger mirror, but it did not deploy properly. The project cost too much money, and a follow-up satellite got caught on one of Mir’s antennae, which ripped the delicate sail and the mission was scrapped.

Critics worry about the extra light pollution this may cause. Will the manmade moons frustrate astronomers by blocking out the view of the stars in certain areas? And how will they affect animals like birds and sea turtles whose movements are guided by natural moonlight? Chungfeng says that such points are being considered. He claims the satellites have been in development for several years and they’ll be tested in “an uninhabited desert,” where he hopes the light beams won’t affect urbanites or astronomical observatories.