Thanks to the people who have answered here and in email to my 
question about which countries engage in space surveillance. 
Unfortunately, I apparently didn't make the meaning of the message 
clear, since most replies have addressed satellite reconnaissance, 
rather than space surveillance 

     What I meant was _not_ which countries use satellites to look at 
the Earth (satellite reconnaissance) , but _was_ which countries have 
programs to detect and track (i.e., determine the orbital elements of) 
satellites as they pass overhead (space surveillance). 

    The US uses missile-defense radars, supplemented by a fascinating 
quasi-radar operated by the Navy, to do this for satellites in LEO, and 
electrooptical systems for objects at altitudes above 5,000 km or so. 
The FEE, I understand, does much the same thing. 

    Amateur satellite observers use eyeballs, binoculars, stopwatches 
and PCs for objects out to around 1500 km, enabling them to keep track 
of satellites for which, ah, official element sets aren't available. 
See the fascinating books by Desmond King-Hele for details, as well as 
the files in the molczan directory on kilroy.jpl.nasa.gov.  The 
material posted in my previous message suggests that Japan engages in 
optical and radar space surveillance to a modest degree, and it may be 
that other countries do also. 

    Which was the question I meant to ask: who are they, how do they do 
it, and why do they do it?


Allen Thomson                     SAIC                        McLean, VA