SAMPEX was the Solar Anomalous and Magnetospheric Particle Explorer. It was launched on July 3rd 1992 from Vandenberg Air Force Base in California on a Scout Rocket (and was RIP Nov 13, 2012).
SAMPEX’s instruments were far more sensitive than those of previous similar missions, which allowed a great deal of new information to be gathered on the composition of interstellar gas, the mechanism of solar atmospheric heating and the relative abundance of various isotopes.
As you can see from the photograph, SAMPEX was quite dinky. This is because it was an early success of NASA’s Small Explorer Program, or SMEX. (Why not SEX? They could have improved their hit rate on Google by loads.)
SMEX funds projects costing no more than $120m.