Tracking all the active satellites and orbital debris around the Earth is a challenging task, even for the US Defense Department. (credit: NASA)Occasionally on this blog I write up information on some of the more interesting military satellite information that crosses my desk. In those write ups you will see mention of the NORAD Space Catalog number, International Designator, and other information on the object's orbit.
I have come across a most interesting article online that describes the creation and maintenance of satellite catalogs and a lot more by a knowledgeable author, Brian Weeden.
http://www.thespacereview.com/article/1417/1
If you would like to learn more about how NORAD tracks stuff in orbit, this is a must read.