Active Vehicle Charging Measurements in Sounding Rocket and Space Shuttle Orbiter Environments at Low Earth Orbit (LEO) Altitude,
UTAH STATE UNIV LOGAN CENTER FOR ATMOSPHERIC AND SPACE SCIENCES
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Several collaborative experiments on active space vehicle charging, involved use of low power electron guns to charge the vehicle, and a variety of diagnostics to monitor the electrical potential of the electron gun platform, and perturbations to the charge sheath around the vehicle. The physical processes involved in the acquisition of the steady state electrical potential of a vehicle at LEO altitudes under passive and active conditions is reviewed. Sounding rocket results show that for daytime experiments the vehicle potential rarely exceeds 10v for beam currents up to 80mA. At nighttime both low vehicle charging conditions and somewhat higher charging into the 100s of volt range are observed. The space shuttle orbiter appears to carry a cloud of out-gassing material with it which can become partially ionised thereby providing additional charge carriers for vehicle return currents. The return current flow to the Orbiter is restricted to a small percentage of the vehicle surface area engine nozzles and is thereby subject to pronounced plasma wake effects, however the total area is large enough that low electron beam currents can readily be balanced by electron collection at a fairly low potential if the engines have access to typical LEO mid-latitude ionospheric plasma concentrations.
- Unmanned Spacecraft
- Electricity and Magnetism