(no subject)

jbarker@arinc.com
Fri, 5 Jan 1996 10:22:05 -0500

     I found this short description in the Army Space Reference Text 
     (1993).
     
     In an earlier message, it was mentioned that the Moon is detected 
     passing through the beam.  If the beam is projected vertically along 
     the 33rd parallel, then the Moon's orbit would have to have an 
     inclination greater than 33 deg.  Something doesn't sound right.
     
     jbarker@arinc.com
     --------------------------------
     
      Navy Space Surveillance (NAVSPASUR) System
     
        The NAVSPASUR  system consists of three transmitters and six 
     receivers located along the 33d parallel in the U.S.  The transmitters 
     emit a vertical continuous beam which forms an electronic fence.  When 
     an object passes through one of the transmitter's waves in space and 
     two or more geographically separated receivers detect the reflected 
     energy, the object's location can be determined by triangulation 
     derived by interferometric techniques.  This is essentially the same 
     process that bistatic radars use.  It does not track, it only detects. 
     Once the object's location and general direction of movement are 
     determined, NAVSPASUR operators notify the Space Surveillance Center, 
     which can then notify a tracking radar to make more precise 
     determinations of the object's characteristics.  The range of this 
     fence is 5,000 miles in length and can detect satellite sized objects 
     up to 15,000 miles out in space.  The space object in orbit must have 
     an inclination of greater than 33 degrees in order to pass through the 
     electronic fence.  More than one million detections are made every 
     month.
     
        Transmitters are located at Gila River, Arizona; Lake Kickapoo, 
     Texas; and Jordan Lake, Alabama.  Receivers are located at Fort 
     Stewart, Georgia; Hawkinsville, Georgia; Silver Lake, Mississippi; Red 
     River, Arkansas; Elephant Butte, New Mexico; and San Diego, 
     California.  
     
        NAVSPASUR headquarters is at Dahlgren, Virginia.  The headquarters 
     is also the Alternate Space Defense Operations Center and the 
     Alternate Space Surveillance Center.