Moonlighting: a novel approach to streetlights
By Rory Clarke | Nov 24 2018
As winter sets in, the days are getting shorter and the ever-oppressive darkness seems to reign supreme. Modern society has come up with varied solutions to the problem that sunlight-less mornings and evenings present us with. From turning back the clocks to streetlights, mankind has been creative in trying to keep the darkness at bay. However, these efforts are nothing as compared to the recent proposal in Chengdu, China where a group of scientists have a rather more ambitious goal. Chengdu Aerospace Science and Technology Microelectronics System Research Institute Co. Ltd want to augment the faint light of our existing Moon with a second man-made moon, more powerful and controllable than that which nature has provided us with.The proposals were reported earlier this year in People’s Daily, one of the largest publications in China with direct links to the ruling Communist party. Although officially termed an “illumination satellite”, the proposed project has cultivated notoriety as a “fake moon”. If constructed, the giant mirror-oriented satellite would be “designed to complement the Moon at night” with light reportedly eight times as bright, according to Wu Chunfeng, the chairman of the Institute. Wu, speaking at a national innovation and entrepreneurship conference in Chengdu revealed that they hope to have the satellite in place by 2020.As for its capabilities, Wu has claimed that the satellite will be able to illuminate an area 10 to 80 kilometers in diameter, the exact location of which can be controlled to within several dozen meters.If constructed, the giant mirror-oriented satellite would be “designed to complement the Moon at night with light reportedly eight times as bright
The original conceptualisation of an artificial moon has been credited to a French artist, who reportedly imagined a cosmic reincarnation of the famous Hall of Mirrors in Versailles. The anonymous artist boldly suggested placing mirrors in space to create perennial sunshine through Parisian streets and markets.Although this plan may seem audacious and almost surreal, there is a precedent for artificial illumination in space. Three computerised mirrors were installed in the sky above a Norwegian town previously veiled in near constant winter darkness, Rjukan. These mirrors were programmed to track the movement of the Sun and reflect its illuminating rays down onto the town square. Although this was but a small and isolated example, it demonstrates that neither the concept nor the technology is entirely untested.Additionally, in the 1990s, a group of Russian scientists launched a satellite from Znamya into space with the aim of reflecting sunlight back to Earth. Their stated aim was to “test the feasibility of illuminating points on Earth with light equivalent to that of several full moons” according to the New York Times. They succeeded only to the extent that Earth was briefly illuminated by a beam 5 kilometres in diameter (not quite several Moons), but the overall concept was demonstrated admirably.This is not just a astronomer’s pet project. There are many who believe that this has the potential in the long-term to be financially profitable. Mr Wu has been quoted as saying that substituting artificial lunar light for streetlights in an area of 50 square kilometres could save up to 1.2bn yuan ($173m) a year in electricity costs. Although the initial research and production costs of the “fake moon” may be much greater, there is potential for getting a solid return on the investment. This mindset is one certainly shared by Dr Matteo Ceriotti, a lecturer in Space Systems Engineering at the University of Glasgow, who told the BBC to “think of this as sort of an investment. Electricity at night is very expensive so if you could say, have free illumination for up to 15 years, it might work out better economically in the long term.”Furthermore, as ludicrous as it may sound, there is actually limited space, in space
From a science perspective, the fake moon is plausible. To serve its purpose, the satellite would have to remain in permanent orbit over Chengdu. This would require it to be located at around 37,000 feet in geostationary orbit. This presents several difficulties for the project. Firstly, the satellite’s pointing direction system would have to be extremely accurate, as any micro-errors in space would disproportionately affect the direction on Earth. Secondly, the reflecting mirror would have to be colossal to have any impact at that range. Furthermore, as ludicrous as it may sound, there is actually limited space, in space. According to international standards, all satellites in geostationary orbit should, for safety reasons, be separated by 1000 km. Consequently, the project would face a fight with telecom operators and governments for one of 1800 global “parking spaces” for their “fake moon”. Indeed, the allocation system, administered by the International Telecommunications Union, is based on a first-come, first-served basis. Although spaces can be bought/leased, this is usually at exorbitant cost. For example, in 1988, Tonga auctioned five orbital slots for $2m per year, which equated to a daily cost of approximately $5,480.There is a degree of uncertainty surrounding the political capital behind the project, with neither the city of Chengdu nor the Chinese government having yet been announced publicly as backers. This could prove problematic, in terms of generating the vast capital investiture required to get this project off the ground. Concerns about disturbing the long-established routines of nocturnal animals and others should not be given too much credence according to Kang Weimin, director of the Institute of Optics, School of Aerospace, Harbin Institute of Technology. Weimin is confident that the “dusk-like” quality of the light will ensure that it does not disturb the animal populations of China. For similar reasons, the field of astronomical exploration would not be unduly affected by the project, were it to go ahead. This has not stopped several Chengdu residents complaining that this will only add to the light pollution they face daily.Nearly 20 years ago, celebrated science editor of the BBC, Dr David Whitehouse, famously said, in response to the Znamya experiments, that there was “not the slightest chance that the Earth will be girdled with space mirrors in the foreseeable future.” While it may no longer be possible to say this with such conviction, the city of Chengdu faces significant challenges before its artificial moon joins the cosmic club.