Air Force Space Surveillance System

It is a component of the U.S. space surveillance network, and according to the U.S. Navy was able to detect basketball sized (75 cm (30 in)) objects at heights up to 30,000 km (19,000 mi).

[3] The operation's headquarters were at Dahlgren, Virginia, and radar stations were spread out across the continental United States at roughly the level of the 33rd parallel north.

In 1965, the "Fence" system was modernized with the operating frequency doubled to 216.98 MHz (just above Channel 13 in the VHF TV broadcast band) to obtain higher resolution and to locate smaller objects.

On 30 September 2011, Five Rivers Services was awarded a US$7,022,503 firm fixed price with cost reimbursable line items contract modification to manage, operate, maintain, and logistically support the nine Air Force Space Surveillance System field stations, presumably for Fiscal Year 2012.

Alternate operating modes for radars at Cavalier Space Force Station and Eglin AFB were devised to fulfill the mission to provide uncued data for new objects.

[15] "It appears they pulled the plug at 00:00 UTC (6 a.m. Local MDT) on September 1st", reports engineer Stan Nelson, who was monitoring the radar using an antenna in Roswell.

[16] The shutdown only affects the original Space Fence, not the new one contracted to be built by Lockheed Martin for deployment in Australia and the Marshall Islands.

[18] In 2014 Lockheed Martin won the contract to build the new S band space fence system at Kwajelein with an option for another radar site in Western Australia.