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        A solar mirror is an object with a reflective surface that is used to reflect the light of the Sun. Solar mirrors have many uses such as concentrating solar radiation for heating or the generation of electricity. When placed in orbit around the Earth, solar mirrors are referred to as Space Reflectors (SR) and could provide illumination at night for a specific area.
        In 1992, Russia began a series of experiments on SRs made from solar sails with the intention of providing illumination for far northern cities that receive much less sunlight in the winter months. None of the experiments were successful in illuminating the Earth’s surface and the Russians gave up in 1999.
      Last January, Rocket Lab, a private U.S. space company launched a reflective mini-satellite into orbit around the Earth to create an artificial star which they called Humanity Star. It is a sphere about three feet in diameter and has a surface with seventy-six reflective panels. It was launched into a polar orbit and circled the Earth once every ninety-two minutes. The orbital distance varied between one hundred and eighty and three hundred and twenty miles.
       The satellite was intended to orbit for nine months but it burned up on reentry after orbiting for only a couple of months. Humanity Star was bright enough to be seen by the naked eye from the surface of the Earth. The website for Humanity Star says, “the Humanity Star was designed to be a bright symbol and reminder to all on Earth about our fragile place in the universe.”
        Astronomers were critical of the Rocket Lab project. They complained that reflective objects in orbit can interfere with astronomical observations. Supporters of the project pointed out that flares of light from the International Space Station and other satellites are much brighter than the light from Humanity Star.
        China has just announced plans to send an ‘artificial moon’ into Earth orbit in 2020 to provide night time illumination in urban areas. Their first SR will orbit above the city of Chengdu which is the capital of the Sichuan province. If the first SR is successful, then another three will be launched by 2022.
        Chinese scientists estimate that the SR will about eight times as luminous as the actual moon when it is full. It will only orbit at around three hundred and ten miles above the Earth. The actual light provided for city streets will only be about one fifth of the illumination currently provided by street lights.
       It is estimated that the SR could save the city about one hundred and seventy-three million dollars by reducing the cost of electricity currently used for street lights. It could also help first responders to natural disasters when the power grid goes down and there are no street lights.
       Wu Chunfeng, chief of the Tian Fu New Area Science Society, has been interviewed
about the plan. He called for more testing to be sure that the plan is viable and that such artificial illumination will not cause problems for the natural environment. He also said, “We will only conduct our tests in an uninhabited desert, so our light beams will not interfere with any people or Earth-based space observation equipment.”