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Title: Ion mass spectrometer measurements from the space shuttle
Authors: Grebowsky, J M
Schaefer, A
Issue Date: Apr-1990
Publisher: NISCAIR-CSIR, India
Abstract: Ion mass spectrometer measurements, made as part of the University of Iowa’s Plasma Diagnostic Package, on the STS-3 and Spacelab 2 Space Shuttle missions sampled a variety of positive ion composition perturbations in response to gas emissions from the vehicle. The only other shuttle ion composition measurements were made by AFGL quadrupole spectrometer flown on STS-4. Gas emissions change the distribution of th ambient plasma through scattering and charge transfer processes. A background of contaminant ion species (mostly relating to water) always exists in the vicinity of the shuttle. The measured number fluxes of the contaminant ions vary differently from those of the ambient ions in response to changes in the spectrometer and spacecraft angles of attack. There is a near shuttle wake cavity in the contaminant ion distributions which has a different spatial configuration than the wake of the ambient ions. Although water dumps produce the longest term ion perturbations, the most well defined effects were observed from measurements taken during the short firings of the reaction control system thrusters. Contaminant ion perturbations associated with such firings were observed to persist for the order of a second after the cessation of the firings. The dense thruster plumes are efficient collisional, charge exchange barriers to the passage of ambient ions. Near spacecraft ion perturbations were more evident for firings of the rear verniers, whose plumes scatter off projecting surfaces, than for the nose thrusters. The contaminant ion distributions depended on the orientation of the local terrestrial magnetic field with respect to the shuttle velocity, indicative of production of the ions within the neutral gas cloud about the vehicle and the pickup of the ions by the magnetic field.
Page(s): 49-61
ISSN: 0975-105X (Online); 0367-8393 (Print)
Appears in Collections:IJRSP Vol.19(2) [April 1990]

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