The Courier program was one of the first attempts to evaluate the possibility of communications via satellite. Managed by the Army Signal Research and Development Laboratory, Courier was the successor to that agency's 1958 Score satellite, the first communications spacecraft.
Courier had one launch failure before a successful mission in October 1960, lasting 17 days. The satellite's primary purpose was to test basic techniques in communications. Courier could actively receive and transmit signals, or, using tape recorders, it could "store-and-dump" information as the satellite passed from one ground station to the next as it proceeded along its orbit.
The Museum's artifact is a prototype and was transferred from the U.S. Army to the Smithsonian in 1965. Notice the solar cells (the blue rectangles) on the exterior of the satellite--they helped to provide power essential for satellite operations. The exterior is partially cut away to reveal the satellite's electronics.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.