Recently, news on ‘man-made moon’ has drawn wide attention both at home and abroad. According to Tianfu System Science Society in Chengdu Si Chuan, the mission of ‘man-made moon’ participated in by the science society is to be tentatively realized in 2022 – In 2022, the first ‘man-made moon’ will complete the overall system demonstration and verification process from its launching, to entering its orbit, to unfolding and to illumination and will be launched. In the same year, a total of 3 ‘man-made moons’ will complete the overall system demonstration and verification experiment from their launching to illumination.
The conceptualization and application of the idea of ‘man-made moon’ is one of the most advanced technologies in Aerospace Science and Technology. This article believes that scientific research and technological innovation and advancement with the purpose of enhancing human welfare should be scrupulously analyzed, proved and then carried out under the principle of respecting the nature, understanding the nature and obeying the rules of the nature. Will the artificial lighting created by ‘man-made moon’ become a source of light pollution so that it will exert an adverse impact on the ecosystem directly under or close to its lighting spectrum? The Dark & Starry Sky Committee of China Biodiversity Conservation and Green Development Foundation (CBCGDF), as a persistent mainstream force advocating the scientific control and management of light pollution and working for the protection of dark night, has been continually attentive to the preservation of the dark night environment and biodiversity and the safety of the ecosystem. Accordingly, the purpose of the Star Working Committee writing this article is to expound on several of its opinions on the project of ‘man-made moon’ from the perspective of preserving biodiversity and the dark night environment.
[The existence of potential risks for astronomical observation]
Since ancient time, a series of momentous scientific and cultural breakthroughs have been reached from astronomical observation by our mankind. But with the rapid spread of light pollution, night lighting has rendered it too bright for human eyes to observe certain celestial phenomena, which can only be seen within a dark environment.
It is claimed that the luminance of ‘man-made moon’ is almost eight times that of the Moon and artificial satellite can be approximated as a point light source because of the Moon being an area light source with a diameter of half of a degree. Such an intensive artificial light source will inevitably produce extensive light pollution. Similar to the phenomenon of stars surrounding a bright Moon being greatly obscured by the latter, the intensive light source created by ‘man-made moon’ outside the atmosphere will eclipse the stars after the diffuse reflection of the atmosphere.
Currently, many observatories are out of use or massively disrupted by light pollution, causing the disappearance of the sky resources observed by mankind for thousands of years and their associated culture. The ‘man-made moon’ will undoubtedly exacerbate the spreading of light pollution.
[The existence of potential risks for the night environment and ecosystem]
For billions of years, life on the Earth relies heavily on regular alteration of day and night, and this characteristic can be found in the gene sequence of almost all the animals and plants. However, due to brightening of dark sky because of artificial lighting, such a cycle has been severely disrupted by human activities. The worsening light pollution has imposed serious environmental hazards on the dark night environment and ecosystem.
As is widely known, most wild species depend on the cyclic rhythm between day and night on the Earth to perform their survival behaviors, including reproduction, foraging activities, sleeping and avoiding predators, or even migration. Plants undergo the process of photosynthesis under daylight and breathe at night. There has been scientific evidence that the artificial light source at night will become a life-threatening risk factor for many creatures such as the survival of amphibians, birds, mammals, insects and plants.
“When we are artificially bringing light to the natural environment, we are likely to destroy natural reserves, just like using the bulldozer to demolish natural landscapes”, said by Chad Moore, former national park service in the USA.
Birds migrating or foraging at night use moonlight or stars for navigation. Artificial light sources will cause these birds to divert away from their right route and fly instead towards dangerous cities. It is reported that millions of birds die from colliding with high-rise buildings and high towers, and all these buildings all have unnecessary lighting. Migratory birds rely on the time and space information from the reasonable alternation of four seasons, but artificial light will mislead them to migrate too early or too late, or miss the best environmental conditions for nesting, foraging and other important survival activities.
Many insects have the instinct of phobophototaxis, but artificial light can be a life-threatening misleading factor for them. The reduction in the number of insects will adversely affect species dependent on them to for food and pollination. Some predators take advantage of artificial light and initiate an unpredictable development of the food chain.
[The existence of potential risks for human health]
“Many animal species including the human being need a dark environment to rest”, said the Public Health Committee of the American Medical Association.
Light pollution will be a health risk factor for human beings as well. Human beings during their biological evolution have become accustomed to the alteration between day and night, and artificial light means it is no longer necessary for human beings to experience dark environment. Researchers have found that a series of adverse health symptoms will emerge from artificial lighting, such as increasing obesity rate, depression, sleeping disorder, and diabetes. Darkness is indispensible for most ecosystems on the Earth. If ‘man-made moon’ is launched to the sky, as is planned, the light intensity by then can be expected to be maintained at a constant level. In other words, night will no longer be night, and such a consequence may simply be dooming for our mankind.
[The scientific feasibility and practicality of the technology of ‘man-made moon’]
Even without light pollution, writers of this article, as amateurs of astronomy, seriously doubt the practicality of the ‘man-made moon’ project based on information released so far.
The ‘man-made moon’ project is based on the theory of the reflection of sunlight by satellites. The Iridium satellite currently orbiting around the Earth is one of the favorites of amateurs of astronomy exactly because the shape of its antennas resembles a flat mirror. The maximum luminance of the Iridium satellite can be as high as the level of 8, so it is extremely luminous at twilight. The luminance of the so-called ‘super moon’ will be 600 times that of the Iridium satellite. We can do a simple calculation as follows:
The orbital altitude of the Iridium satellite is 780 km, and the orbital altitude of ‘man-made moon’ is 500 km (or below). If the Iridium satellite was hypothetically placed to an orbital altitude of 500 km, with the inverse relationship between luminance and distance, and if we take the logarithm of star magnitude (notes: a 1 degree decline in star magnitude is equal to a decline of 2.512 in luminance difference), then our “new Iridium satellite would be of a star magnitude of 9, which is sill 251 times lower than the star magnitude of the promoted ‘man-made moon’. So this implies that we have to increase the size of our reflector. The size of the Iridium satellite is approximately 1 meter order of magnitude. Suppose that the area of the antennas of the Iridium satellite is about 0.5 square meter, then the ‘man-made moon’ will require a reflector with an area of 100 square meter to be able to reach its claimed luminance. Technically speaking, this can be extremely challenging.
Even if such a technique could be realized, the efficiency of lighting remains a problem. For satellites at an orbital altitude of 500 km, they can travel around the Earth within 2 hours. Man-made satellites move in the sky at a speed observable by human eyes, if they reflect in the same way as the Iridium satellite, the same spot on the Earth will receive perpendicular incidence from the brightest reflection light for only seconds every night. In the meantime, the prerequisite for satellites to reflect light is that they are exposed to sunlight first, which means that this can happen only after sunrise or before the setting of the sun. At night, when satellites move into the shade of the Earth, there will be no light reflection at all. ‘Man-made moon’ are satellites still, so it has to conform to the law of Physics.
To conclude, it is highly recommended that related departments conduct careful scientific research and hold public hearing, for the common goal of improving the well-being of humanity.
We deeply appreciate the advice from Mr. Dai Jianfeng (the Dark & Starry Sky Committee of China Biodiversity Conservation and Green Development Foundation) for the revising of this article.
(Photo source: Internet)
(Photo: CBCGDF)
Relevant media report:
https://mp.weixin.qq.com/s/-7rvyww1NR1JJn40Rsy7RA
Original Chinese article:
https://mp.weixin.qq.com/s/rmWqEi0x0nd0Nw2IyTSgmQ
By / Lei Proof / Linda