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Ion and Neutral Mass Spectrometer (INMS)

The INMS is a quadrupole mass spectrometer designed to measure neutral species and low-energy ions in key regions of the Saturnian system. The instrument was built by NASA/Goddard Space Flight Center.

Gases sampled by the INMS will enter the instrument through either an open or closed ionization source. The open source minimizes gas/surface interactions and is used to measure ions and reactive neutral species such as hydroxyl, while the closed source will measure nonreactive neutral species such as nitrogen and argon. The two sources are thus complementary.

The INMS will be operated in two basic modes. The Titan flyby mode is the primary acquisition mode and will be used for in-situ sampling of Titan's upper atmosphere and ionosphere. This mode requires complex sequencing of closed and open source neutral and open source ion measurements. In the Saturn mission mode, the INMS will measure both neutrals and ions in the ring environment and the wakes of the satellites, and also thermal ions in the outer magnetosphere.

Published in the Fall 1997 issue of Technology Today®, published by Southwest Research Institute. For more information, contact Joe Fohn.

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