SAMPEX was designed to study the energy, composition and charge states of four classes of charged particles that originated beyond the Earth: (1) galactic cosmic rays (from supernova explosions in the Milky Way Galaxy); (2) anomalous cosmic rays (from the interstellar gas surrounding our solar system); (3) solar energetic particles (from explosions in the solar atmosphere); and (4) magnetospheric electrons (particles from the solar wind trapped by the Earth's magnetic field).

SAMPEX was the first of NASA's Small Explorer (SMEX) missions. SAMPEX observations were designed to provide new information on the cosmic abundances of elements and their isotopes, the composition of local interstellar gas, the solar composition and the mechanisms responsible for solar atmospheric heating, and electron energy injection into the Earth's upper atmosphere.

The single string architecture satellite used a momentum-bias control system with 1 momentum wheel and 3 torque rods for vehicle pointing. Attitude knowledge was better than 2 deg (3 sigma). Attitude sensing was via sun sensors, star sensors, and a magnetometer. Two deployable, articulated solar panels with GaAs cells provided 102 W orbit average power (no eclipse) and recharged one 9 A-hr NiCd battery. The aluminum structure bus used passive thermal control. Two omni antennas and near-Earth 5 W S-band transponders provided communications. The payload used solid-state memory and a fiber optic Mil-Std 1773 data bus.

SAMPEX carried 4 instruments:

• HILT (Heavy Ion Large Area Proportional Counter Telescope) measured heavy ions from 8 to 220 MeV/nucleon for oxygen.
• LEICA (Low Energy Ion Composition Analyzer) measured 0.5 to 5 MeV for solar and magnetospheric ions. LEICA and HILT were originally designed and constructed as Get-Away-Specials for shuttle flight.
• MAST (Mass Spectrometer Telescope) measured isotropic composition of elements from Li to Ni in the range of 10 MeV to several hundred MeV.
• PET (Proton/Electron Telescope) complemented MAST by measuring the energy spectra and relative composition of protons (18 to 250 MeV) and helium nuclei (18 to 350 MeV/nuclei) of solar, interplanetary, and galactic origins, and the energy spectra of solar flare and precipitating electrons from 0.4 to 30 MeV.

Design Life: 1 year, 3 year goal. Typical orbit: 520 x 670 km, 82 deg inclination. Length: 1.50 m (4.90 ft). Maximum Diameter: 0.86 m (2.82 ft). Mass: 158 kg (348 lb). Associated Launch Vehicle: Scout G.

• 1992 July 3 - SAMPEX - Program: Small Explorer. Launch Site: Vandenberg. Launch Vehicle: Scout. Mass: 158 kg (348 lb). Perigee: 506 km (314 mi). Apogee: 670 km (410 mi). Inclination: 81.70 deg. Period: 96.50 min.

  First Small Explorer mission; Solar Anomalous and Magnetospheric Particle Explorer. Spacecraft engaged in research and exploration of the upper atmosphere or outer space (US Cat B).