Large fluxes of energetic heavy ions (M / q ≈ 16) were observed in the inner magnetosphere during the geomagnetic storm of December 17, 1971. The observations were made by a set of energetic‐ion mass spectrometers covering the energy range 0.7–12 kev on board the polar‐orbiting satellite 1971‐089A (800‐km altitude, ≈0300 LT). Significant heavy‐ion fluxes were observed for a period of approximately 48 hours during the main phase of the storm. The heavy‐ion fluxes frequently exceeded the proton fluxes in the 0.7‐ to 12‐kev energy range. The heavy‐ion spectrums were highly variable and frequently contained a peak of several kev. The heavy ions were observed over a wide latitudinal range (2.4 ≲ L ≲ 9) and generally extended to somewhat lower latitudes than the protons. The peak energy flux of these ions was approximately 0.4 erg/cm² sec ster, which is substantial in terms of expected observable ionospheric effects. They may also contribute significantly to the storm‐time magnetic‐field depression (Dst), since at the same flux they represent an energy density greater by a factor of 4 than that of the protons.

A satellite‐borne energetic ion mass spectrometer experiment has detected fluxes of O+ and H+ ions flowing up out of the ionosphere in the auroral and polar regions. The observed ions have energies in the keV range, narrow pitch‐angle distributions aligned along the magnetic field direction and peak flux intensities of the order of 108 (cm²‐sec‐sterad‐keV)−1. The observations were made at altitudes between 5000 and 8000 km on both the day and nightsides of the earth.

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0+ ions with energies of approximately 1 keV have been observed flowing upward out of the ionosphere with a pitch angle distribution having a minimum along the magnetic field direction and maxima in about the 130°–140° range. The measurements were obtained with an energetic ion mass spectrometer experiment on the satellite 1976‐65B at an altitude of about 7600 km in the northern dayside polar cusp. The data are interpreted as resulting from a mechanism which accelerates ambient ionospheric ions in a direction perpendicular to the geomagnetic field.

Upward flowing fluxes of energetic (0.5‐16 keV) H+ and O+ ions are frequently observed by the ion mass spectrometer on the polar‐orbiting S3‐3 satellite. Data obtained on the first ∼370 orbits have been used to derive the occurrence frequency of these fluxes. The upward acceleration of ionospheric ions to keV energies is a persistent phenomenon generally occurring in a zone closely associated with the statistical auroral oval. Upward flowing ion events with flux above ∼2 × 106 keV/(cm² sec ster keV) are observed in more than 60% of the orbits. A strong dawn‐dusk asymmetry is found in the frequency of occurrence with the maximum in the dusk sector. The probability of observation increases with altitude up to apogee (8000 km) indicating that the main energization takes place preferentially at altitudes above ∼1 R E.