Measurements of plasma parameters in the vicinity of the space shuttle

Abstract

A Langmuir probe flown as part of the Plasma Diagnostics Package aboard the third space shuttle flight was used to determine electron densities, temperatures and plasma potential in the vicinity of the shuttle orbiter. Measurements taken both in the cargo bay and 10 m above the cargo bay on the Remote Manipulator System arm are consistent with small satellite and laboratory results in that reduced densities and elevated temperatures are observed in the shuttle wake. The primary difference in the shuttle measurements is one of magnitude, i.e. orders of magnitude density decreases and factor of five temperature enhancements. Analysis of data taken in Δ N/ N mode (used to measure plasma density fluctuations) reveals large plasma fluctuations with a significant spectral component up through the lower-hybrid frequency. The peak amplitude of this Δ N/ N turbulence can be as high as a few percent, and the most intense turbulence seems to occur near regions with a steep gradient in plasma pressure.