UnEX (University-class Explorer) is the lowest-cost type of Explorer satellite. The UnEX Program is designed to provide frequent flight opportunities for highly focused and relatively inexpensive science missions whose total cost to NASA is limited to $13 million. The first mission in the program to be developed was CHIPSat (Cosmic Hot Interstellar Plasma Spectrometer atellite). Another proposed mission, IMEX (Inner Magnetosphere Explorer), was cancelled. The program is managed by the Goddard Space Flight Center.