SCI/NEWS: space-based mirror to illuminate some cities today (2/4/99)

Han Huang (hhuang@MIT.edu)
Thu, 4 Feb 1999 07:49:13 -0500

http://www.skypub.com/news/special/znamya.html 

             Up in the Sky!
             It's a Bird,
             It's a Plane, 
             It's Znamya!

             By J. Kelly Beatty

             Six years ago Russian space officials conducted an
orbital test of a 20-meter-wide (65-ft) reflector called Znamya, the Russian word for banner. The spinning space mirror directed a 4-km-wide (2=-mile) spot of reflected sunlight along a swath of Europe that lay in predawn darkness. Although much of the target area was blanketed by clouds, a few observers reported seeing a 1-second-long flash nearly as bright as the full Moon.

Buoyed by this success, the Russians will attempt to deploy another giant reflector, dubbed Znamya 2.5, on February 4th. With a diameter of 25 meters, this version incoporates design improvements that should spread the aluminized 5-micron-thick plastic sheet more evenly when it is spun out at 1= revolutions per second. Furthermore, Mir cosmonauts Gennady Padalka and Sergei Avdeyev will orient the reflector by remote control, keeping it trained on ground targets for one or two minutes at a time.

If all this works as planned, during the 16-hour test several cities in North America and Europe could find themselves briefly bathed in artificial light 5-10 times brighter than the full Moon in the hours after sundown. Observers far outside Znamya 2.5's directed beam will see the spacecraft outshining virtually every star as it coasts across the sky in an orbit 360 km (225 miles) high. The spacecraft should be separated by a few hundred meters, which means they should look like a dazzling "double star? when viewed through binoculars.

The following timetable was supplied by the Space Regatta Consortium in Moscow on January 31st. However, since then the orbit of the Mir space station has been adjusted three times. Consequently, Sky & Telescope believes these times may be in error by as much as 10 minutes. For example, our predictions show that Mir will pass over Calgary from 6:21 to 6:23 p.m. local time. Therefore, we suggest that you check our predictions for the passages of Mir and Znamya over your location. (Click here if you are in North America and here if you are elsewhere worldwide.) If those predictions show that the spacecraft are passing nearly overhead any time on the evening of February 4th, you could potentially see the flash of Znamya?s reflected light. 

                           Znamya Timetable
                         4 February 1999 ( * = 5 February)
                        (courtesy Space Regatta Consortium) 

              Moscow
              time 
                     UT
                     (GMT)
                            Local
                            time 
                                   Event 
              13:04
                     10:04
                              
                                   Progress M-40
                                   undocks from
                                   Mir 
              14:34
                     11:34
                              
                                   Znamya 2.5
                                   reflector
                                   deploys 
              16:12
                     13:12
                            6:12
                            pm 
                                   beam on
                                   Karaganda,
                                   Kazakhstan 
              17:45
                     14:45
                            5:45
                            pm 
                                   beam on
                                   Saratov, Russia 
              19:20
                     16:20
                            7:20
                            pm 
                                   beam on
                                   Poltava,
                                   Ukraine 
              20:54
                     17:54
                            6:54
                            pm 
                                   beam on Liege,
                                   Belgium 
              20:56
                     17:56
                            6:56
                            pm 
                                   beam on
                                   Frankfurt,
                                   Germany 
              2:54*
                     23:54
                            5:54
                            pm 
                                   beam on
                                   Winnipeg,
                                   Manitoba 
              2:56*
                     23:56
                            6:56
                            pm 
                                   beam on Quebec
                                   City, Quebec 
              4:30*
                     1:30*
                            6:30
                            pm 
                                   beam on
                                   Calgary,
                                   Alberta 
              4:32*
                     1:32*
                            7:32
                            pm 
                                   beam on Devil's
                                   Lake, North
                                   Dakota 
              5:13*
                     2:13*
                              
                                   Test ends,
                                   reflector is
                                   released 



             This cosmic klieg light is the brainchild of the Space
Regatta Consortium (SRC), a partnership involving seven Russian aerospace management and engineering organizations. Vladimir Syromyatnikov, SRC's general director, hopes the Znamya test will lead to whole constellations of space mirrors orbiting 1,500 to 4,500 km
(1,000 to 3,000 mi) up. With a diameter of 200 meters (650 feet), each
satellite could beam down a disk of light as wide as a city and 100 times the Moon's brightness. Syromyatnikov imagines such spacecraft being used to illuminate high-latitude regions of Earth in the hours after sunset or before sunrise, ostensibly to improve the spirits and productivity of those forced to endure long, dark winters. The orbiting beacons might also provide emergency lighting for cities during disasters. Syromyatnikov even envisions using SRC's solar-sail technology to propel interplanetary spacecraft using sunlight alone or to power orbiting observatories.

However, the prospect of an armada of giant space mirrors hardly comes as a delight to astronomers. "We're having enough trouble battling light sources on the ground," contends Daniel W. E. Green
(Harvard-Smithsonian Center for Astrophysics). "To have to deal with
sources from the sky is very disheartening." Some preemptive action has already been taken by radio astronomer Woodruff T. Sullivan
(University of Washington). In his role as General Secretary of the
International Astronomical Union (IAU), Johannes Andersen (Univ. of Copenhagen) is trying to persuade the United Nations to recognize the night sky as an important part of Earth's environment and to protect it from encroachment by artificial satellites. An international symposium on the subject will be held in July.

All this negative reaction is not lost on SRC officials. According to Chris Faranetta, a spokesman for SRC partner Energia Ltd., the consortium has pledged to conduct a full environmental-impact assessment prior to full-scale development. Faranetta also points out that few observatories exist in the far-northern regions that the SRC hopes to illuminate. An open letter to astronomers on SRC's Web site (http://src.space.ru) offers the hope that these "extremist experiments" will someday provide scientists with "unique tools for real exploration of the farthest corners of the universe."