The transient potential response of a large spacecraft structure in low Earth orbit due to electron generator emissions has been investigated experimentally using the Tethered Satellite System on NASA's Space Shuttle and by equivalent-circuit-model simulations. The model simulations of this highly distributed and complex structure demonstrate that useful predictions of high-speed potential behavior and charging levels can be made. Our experimental results were obtained when an electron generator emitted pulses into the surrounding nighttime ionospheric plasma. Because of the surrounding plasma's low density, the electron generator modified the Shuttle's potential quickly and by several volts. Our experimental system measured the resulting voltage transients by selectively sampling the system voltage in high-speed bursts. The model simulations show that the transient potential response of the system is due to a combination of the system's electrical circuit and the modification of the Shuttle's potential due to the electron generator emissions. Computer simulations also were used to perform parametric studies of transient spacecraft potential modification for varying plasma densities, electron-beam currents, and electron collection areas. These results have implications for the use and simulation of electron generators that actively modify the potential of their host spacecraft.
All Science Journal Classification (ASJC) codes
- Aerospace Engineering
- Space and Planetary Science