Vacuum Tube, Space Surveillance Fence

Display Status:

This object is not on display at the National Air and Space Museum. It is either on loan or in storage.

Collection Item Summary:

This is a vacuum tube used in the U.S. Navy Space Surveillance Fence. The system's three transmitter stations, located across the southern United States, emitted a continous wave of radio energy in a narrow fan-shaped pattern. Together the beams extended about 5,000 miles from west to east and about 15,000 miles into space. Any object passing through a beam was illuminated and the reflected signals acquired by one or more or the six receiving stations along the same latitude as the transmitting stations. Each of the receiving stations had many hundreds of these vacuum tubes to amplify the reflected signals during the early years of the system's operation. Unclassified and classified catalogs of all known objects in orbit were prepared from data from the Space Surveillance Fence and other sensors.

The Air Force assumed operation of the Space Surveillance Fence from the Navy in 2004. It was decommissioned in 2013, to be replaced by a space-based system.

RCA manufactured the vacuum tube. The Air Force transferred it to the Museum in 2014.