Positive spacecraft charging as measured by the Shuttle potential and Return Electron experiment

Overview of APEX Project Results

“…Previous sounding rockets and spacecraft active experiments included simple electrostatic analyzers that did not allow detail studies of pitchangle distributions of charged particles in the vicinity of the beam emitting body. The space shuttle Spacelab-1/SEPAC and TSS-1/SETS active experiments (e.g., Burch, 1986;Watermann et al, 1988;Oberhardt et al, 1993) provided electron angular distributions with high time resolution but related pitch-angle distributions were not discussed. Moreover, configurations of these experiments were different from APEX.…”

Current Collection Model Characterizing Shuttle Charging During the Tethered Satellite System Missions

“…Consequently, pre-TSS-1 models were based on the assumption that ion collection at the Orbiter was dominated by the ram ion contribution. 19,30 Prior missions dealt primarily with electron collection. Effective collecting areas derived from those results did not apply to ion collection under negative charging conditions.…”

Actively produced high-energy electron bursts within the magnetosphere: the APEX project

“…During the operation of the Fast Pulsed Electron Gun (FPEG) (TSS-1 mission), the SPREE electrostatic analyzers measured intense fluxes of electrons at energies up to the energy of the emitted beam (100 mA, 1 keV). At energies above the charging peak, the shape of the electron distribution function was consistent with a simple acceleration by the electric field produced by the positively charged Orbiter (Oberhardt et al, 1993). Particle measurements up to 27 keV were performed on the TSS-1R to track the spacecraft potential and collected current.…”