Prototype satellite payload built at the University of Iowa designed to provide refined data on the Earth's Van Allen radiation belts over an extended period of time measuring electron and proton fluxes. The payload illustrates manufacturing techniques and standards prevalent in about 1960 in one of the leading university space research departments. From this prototype a flight model eventually became Explorer S-46 (NASM Catalogue #A19740876000), built by the Jet Propulsion Laboratory. This small octahedral-shaped spacecraft is equipped with solar cells on four of its faces. Explorer 46 was launched from Cape Canaveral on March 23, 1960 atop a Juno 2 vehicle. It failed to achieve orbit because the upper stage of the vehicle did not ignite. Elements of the S-46 payload have subsequently been donated to the collection by George Ludwig, the designer of the payload (NASM Catalogue numbers A20060086 - 012; 013; 014). The object was donated to NASM in March 1993 by James A. Van Allen who directed Ludwig's PhD work at Iowa.