Electrostatic charge generation on dielectric surfaces at low pressures

The surface charge generated on solid dielectrics placed in contact with granular materials at low gas pressures has been measured for several solid dielectrics. Induction sensors embedded in the dielectrics were used to measure the amount of charge that was induced on a metal electrode that had been exposed to some external distribution of electrostatic charge. These sensors have sensitivities in the picocoulomb per cm/sup 2/ range, achieved by adjusting circuit component values as well as the total electrode area. Environments such as the one described for these experiments are encountered on the surface of Mars. These studies serve to characterize the response of different dielectrics to the Martian environment, with applications to the near future exploration of the planet.