fc> Modern, 
fc> ground-based, visible light astronomy (what these proposed
fc> orbiting billboards would upset) is already a dying field: The
fc> opacity and distortions caused by the atmosphere itself have
fc> driven most of the field to use radio, far infrared or space-based
fc> telescopes. 

 Here's one radio astronomer quite concerned about 
 radio-frequency interference from portable telephones, etc.

