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Title: The interpretation of space shuttle measurements of ionic species

Journal Article · · Journal of Geophysical Research; (United States)
;  [1];  [2]
  1. Physical Sciences, Inc., Andover, MA (United States)
  2. Massachusetts Inst. of Tech., Cambridge (United States)

Measurements of ionic species made in the space shuttle bay area during low-earth orbit are interpreted within the framework of a kinetic analysis that incorporates shuttle cloud/ambient interactions, flow, and electromagnetic phenomena. This analysis indicates that a pressure of water vapor near the shuttle surface of 10{sup {minus}6} torr is consistent with (H{sub 2}O{sup +})/(O{sup +}) and (H{sub 3}O{sup +})/(H{sub 2}O{sup +}) ratios of 0.1 and 0.2, respectively, and the latter ratio is within the range of measurements. For CO{sub 2} the analysis shows that a (CO{sub 2}{sup +})/(O{sup +}) ratio of 0.01 is consistent with a CO{sub 2} pressure near the shuttle of 8 {times} 10{sup {minus}8} torr. For these conditions the dominant formation of ions is by charge exchange from ambient O{sup +} ions, and the dominant loss of ions is by parallel flow along the magnetic field lines. In addition, Monte Carlo calculations of the slowing of the incident O{sup +} ions indicate that charge exchange with H{sub 2} molecules occurs before the ions have lost a significant amount of energy when the H{sub 2}O pressure near the shuttle surface is less than 10{sup {minus}6} to 10{sup {minus}5} torr.

OSTI ID:
5875603
Journal Information:
Journal of Geophysical Research; (United States), Vol. 92:A1; ISSN 0148-0227
Country of Publication:
United States
Language:
English