Preliminary results from the P78-2 satellite

Several particle instruments and a pair of spherical probes on three meter booms, built by The Aerospace Laboratories are in orbit aboard the P78-2 spacecraft. The experiments are briefly described and several examples of preliminary observations are presented and discussed. The probe measurements have shown that the P78-2 spacecraft frame potential changes as it rotates because the area of the illuminated grounded conductors varies as different portions of the spacecraft become sunlit. The probes have also measured the spacecraft potential during several onboard accelerator operations. The particle analyzers have observed the acceleration of the ambient plasma during artificially induced spacecraft charging events. The particle experiments have also measured the natural environment. One set of observations shows the occurrence of field aligned ions at energies of a few hundred eV/q. The angular distributions of these ions peak near 0 deg and 180 deg in pitch angle. These and other observations will be discussed.