We have surveyed measurements taken by the Shuttle Potential and Retur
n Electron Experiment (SPREE) in the shuttle payload bay during the sa
tellite deployment phase of the Tethered Satellite System (TSS 1) miss
ion. The shuttle was flying in an inverse airplane mode with its engin
e bells facing the ram direction to facilitate ion current collection.
SPREE ion spectral measurements indicate that with no thrusters firin
g, the shuttle charged to, at most, a few tens of volts negative. We i
dentified 13 intervals during which the tether was electrically connec
ted to the shuttle by a low-impedance shunt and thruster firings occur
red. In previously reported examples of neutral gas releases from char
ged spacecraft the magnitude of the vehicle potential decreased. Thrus
ter firings during our events either left the TSS circuit unchanged or
caused the current measured in the tether to diminish and the shuttle
to become more negatively charged. In the latter case it appears that
thruster gas impeded access of ambient ions to the current collecting
surfaces of the shuttle. The changes in the distribution of the motio
nally induced potential between the tether and sheath calculated using
Ohm's law are in agreement with SPREE measurements.