To save energy, is it possible to illuminate cities at night with space-based mirrors that would beam reflected sunlight to them?
A crazy idea, but during the 1990s, a group of Russian scientists and engineers devised a gadget that redirected sunlight back to Earth. Acting like a giant mirror, the device was intended to lengthen daylight hours, provide solar energy for power, and possibly one day power spaceships. And believe it or not, it almost worked.
The project to build ZNAMYA - meaning “Banner,” as it was known, 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. The brains behind this nightmarish fantasy was Vladimir Syromyatnikov, an expert at designing docking mechanisms that are still used on shuttles that fly to the International Space Station.
Soviet leaders at the time were obsessed with extending the work day to maximize productivity, so Syromyatnikov pitched these solar sails as a means to redirect sunlight back towards the Earth, to extend daylight for an hour or two. Even after the fall of the Soviet Union, Syromyatnikov continued to work on the project, and in 1993 he got his chance to put Znamya to the test. He constructed a 20 meter-wide sheet of Mylar that could be unfurled from a central mechanism and launched from the Mir space station. (Mir was a space station that operated in low Earth orbit from 1986 to 2001, run by the Soviet Union and later by Russia. Mir was the first modular space station and was assembled in orbit from 1986 to 1996.)
When the Znamya satellite was deployed the night of February 4, 1993, it orbited at an altitude of about 350 km, and it directed a beam of light kilometers wide down to Earth, passing across the Atlantic ocean, over Europe, and into Russia. 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 re-entered the atmosphere. The engineers had predicted the luminosity would be equal to several full moons, but actually it was equivalent to a single full moon's. Unfortunately, excessive cloud cover prevented the effect from being seen much on land; as the BBC reported, some Europeans reported noticing a flash of light as it glanced by, but that was about it.
Image courtesy of: Znamya Space Mirror
They planned another Znamya - this time, 25 meters wide, but when they tried to launch it, got caught on one of Mir’s antennae, which ripped the delicate sail and the mission was scrapped. The plan was to launch dozens of such reflectors* but there was a lot of opposition. Opposition to the project arose immediately. Astronomers opposed the idea because it would mean light pollution for most earth-based space observation. Scientists and environmentalists declared it would have detrimental physiological consequences for both animals and humans, in that the absence of regular alternations between night and day would disrupt various metabolic patterns, including sleep. There were also protests from cultural and humanitarian groups, who argued that the night sky is a commons to which all of humanity is entitled to have access, and that the ability to experience the darkness of night and observe observe the stars is a basic human right that no corporation can nullify.
- At an altitude of 350 km - like the ISS - the reflector can 'see' the sun for about an hour or so after sunset, and it will 'pass' over a city in about five minutes or so. That is the reason why the Russians planned to launch dozens of reflectors. At best, they could have extended the 'daylight' for an hour or so; but it may not have been continuous. They had plans to launch the reflectors to orbit at a higher altitude, with larger sails, but the idea was too far-fetched, so the whole thing was shelved.
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