SAMPEX: NASA´s first small explorer satellite

The SAMPEX satellite, an international collaboration with Germany, is the first in a series of small explorer missions that NASA began in 1989 to perform astrophysics and space physics investigations with small spacecraft launched on expendable launch vehicles. SAMPEX was launched from VAFB on a Scout rocket in July 1992, just 39 months after selection by NASA. Operating in an 82° inclination orbit with altitudes between 520 and 670 km, the 350 lb spacecraft has performed flawlessly since launch. The spacecraft bus was developed by the Small Explorer project at Goddard Space Flight Center. SAMPEX carries a payload of four scientific instruments that study particles originating at the Sun, in the so-called anomalous cosmic rays, and in the magnetosphere. The SAMPEX instruments have sensitivities >100 times larger than previous low Earth orbit spacecraft, that have led to new discoveries such as a new radiation belt of interstellar material and rare hydrogen and helium isotopes trapped in the radiation belts. SAMPEX provides routine global maps of the magnetosphere, and has given new insights into the processes by which radiation levels through the entire magnetosphere can become greatly enhanced, leading to operating spacecraft anomalies. The authors give an overview of the SAMPEX scientific goals, instrumentation, and mission development approach