Plasma diagnostics package initial assessment of the Shuttle orbiter plasma environment

A primary objective of the Plasma Diagnostics Package (PDP) on the third Space Shuttle flight (STS-3) was to assess aspects of the orbiter's induced gaseous, plasma and electrical environment with respect to the conduct of scientific investigations. Instrumentation temperatures were found to be within predicted limits, payload bay pressure varied from ambient (10 super(-7) Torr) up to almost 10 super(-3) Torr with thruster firings, electromagnetic interference (EMI) levels were found to be below worst-case estimates but included Orbiter-induced electrostatic noise, and Orbiter potential was consistent to first order with V x B motional potentials varying plus or minus 5 V with respect to the plasma. Electrostatic noise, neutral pressure and potential all exhibited orbit-period modulation. Payload bay plasma varied in density and composition from ambient to a rarefied mixture with Orbiter-produced H sub(2)O super(+). Energetic electrons and ions with energies up to 10's of electron volts were observed occasionally.