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  • Space Mirror to Light up the North

Photonics Spectra
Nov 1998
Kevin Robinson

In February, night may become more like day in some cities across the Northern Hemisphere, as cosmonauts aboard the space station Mir deploy a giant, 25-m reflector and direct its light Earthward. The light could be as much as 10 times brighter than the moon, and officials at Space Regatta Consortium, a group of Russian space companies and organizations, hope it will prove useful in developing even larger reflectors for space illumination systems and possibly solar sails.
The spot of light reflected to Earth by the Znamya 2.5, a 25-m space reflector, will be between 5 and 7 km wide and as much as 10 times brighter than the moon. Courtesy of Energia Ltd.

The consortium was to have sent the reflector, called the Znamya 2.5, into space Oct. 15 aboard a Russian mission to supply the Mir space station. The group plans to deploy the reflector in mid-February, said Chris Faranetta, deputy managing director and project spokesman at Energia Ltd. of Alexandria, Va., a subsidiary of RSC Energia, a Russian company based in Korolev.

Once the supply mission is completed, the ship, filled with Mir's trash, will turn toward Earth and deploy the reflector. Cosmonauts aboard Mir will direct the reflected light using remote control. When the experiment is completed, the ship will be allowed to burn up in the Earth's atmosphere.

The 25-m reflector is made of a flexible aluminized plastic only 7 µm thick. Centrifugal force from the spaceship will deploy the mirror and keep it in place. "The reflector has no trusses; it is kept spinning," Faranetta said. He added that the reflector weighs only about 7 kg.

The test could have several implications for future, more permanent, applications. Faranetta said a constellation of larger reflectors could lengthen the day during the dark Arctic winter, provide artificial light for rescue workers at the scene of a disaster or reduce cities' dependence on fossil fuels to power lighting. He said it also could have military lighting applications, although, he admitted, "it is fairly easy to shoot one of these down." Further in the future, a 200-m reflector of this sort could be used, theoretically, as a solar sail to propel a spacecraft on interplanetary or even interstellar travel.

All that glitters

The experiment has run afoul of the International Dark Sky Association, a Tucson, Ariz.-based group of mostly amateur and professional astronomers dedicated to outdoor lighting that helps mitigate what astronomers call light pollution. Dave Crawford, its executive director, said the group deplores the efforts to create space illumination. He said it objects to the project on numerous grounds: light pollution, environmental impact, the potential to use the technology to create advertising in space and the inability of individuals in particular locations to choose their own type of illumination. Members have sent e-mail messages to various RSC Energia officials, and Crawford said the group is working with other associations to address their concerns politically and legislatively.

For his part, Faranetta said that space illumination systems could reduce the level of particulate air pollution caused by burning fossil fuels to power city lighting. Also, in an attempt to deflect criticism, the company plans to allow the targeted cities to vote on whether they are illuminated from space.

The opposition's present concern may be moot unless funding comes through to send the Znamya 2.5 into orbit for its November test. According to reports by The Associated Press, the Russian Space Agency may scrap plans to keep Mir operating through 1999 and bring the last crew home in June of next year. If so, only a few missions to Mir remain, and the Znamya 2.5 may have to hitch a ride with someone else.

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