Testing EVA Equipment for Polar Orbit Operations

Polar orbit extravehicular activity (EVA) will expose EVA equipment to the conditions in which charging of Defense Meteorological Satellite Program (DMSP) satellites has been measured. Charging can occur when you have darkness, incident energetic electrons, and low neutralizing plasma density. Fluxes of precipitating keV to tens-of keV electrons, which also cause optical auroras, may be encountered in the high latitude auroral zone. In addition, a large body such as the Shuttle sweeps out the ambient ionospheric plasma to produce a cavity in its wake. Laboratory test results will be presented that confirm charging and subsequent arc discharge of EVA equipment material samples. Induced current and radiated radio frequency electromagnetic interference (EMI) were measured from the arc discharges. Such EMI could cause potentially dangerous EVA equipment anomalies. Ground tests of subsystems and the complete EVA equipment system are needed. Orbital tests to validate model predictions and understanding of polar orbit Shuttle wake charging will be proposed.