Instrument Information
IDENTIFIER urn:nasa:pds:context:instrument:inms.co::1.2
NAME Ion and Neutral Mass Spectrometer for CO
TYPE Spectrometer
DESCRIPTION The Cassini Ion and Neutral Mass Spectrometer (INMS) is designed to analyze the mass composition and number densities of neutral species and low-energy ions in the Saturn system, focusing primarily on Titan's upper atmosphere and its interactions with Saturn's magnetosphere. The study targets high-altitude regions where methane and nitrogen photochemistry leads to the formation of complex hydrocarbons and nitriles, potentially creating lakes or oceans on Titan's surface. The INMS will also investigate Saturn's rings and icy moons, identifying positive ions and neutral species within the inner magnetosphere. The instrument consists of a closed and open ion source, focusing lenses, a quadrupole mass analyzer, and dual detectors, operating in three modes to measure non-reactive neutrals, reactive neutrals, and positive ions. Calibration was conducted at Goddard Space Flight Center, and real-time operational considerations are being defined.Key scientific objectives include determining the thermal structure and chemical composition of Titan's upper atmosphere, studying its magnetospheric interactions, and investigating the neutral environments of Saturn's ring system and icy satellites. Measurement strategies are organized into detailed sequences tailored to different scientific inquiries, varying by data rates and sampling requirements. These include default sequences, exploratory sequences for Titan, and sequences for measuring the outer and inner magnetospheres as well as the ring system. Overall, the INMS instrument aims to enhance our understanding of Titan's complex atmospheric processes and the Saturn system's dynamics.
MODEL IDENTIFIER
NAIF INSTRUMENT IDENTIFIER
SERIAL NUMBER not applicable
REFERENCES Fox, J.L., and R.V. Yelle, Hydrocarbon ions in the ionsphere of Titan, Geophys. Res. Lett., 24, 2179, 1997.

Kasprzak, W., H. Niemann, D. Harpold, J. Richards, H. Manning, and 2 others, Cassini orbiter ion and neutral mass spectrometer instrument, Proc. SPIE, 2803, 129-140, 1996.

Keller, C.N., V.G. Anicich, T.E. Cravens, Model of Titans ionosphere with detailed hydrocarbon ion chemistry, Planet. Space Sci., 46, 9-10, 1157-1174, 1998.

Mahaffy, P.R., and K. Lai, An electrostatic quadrupole deflector for mass spectrometer applications, J. Vacuum Sci. & Tech. A, 8, 4, 3244-3246, 1990.

Strobel, D.F., M.E. Summers, and X. Zhu, Titan's upper atmostphere - Structure and ultraviolet emissions, Icarus, 100, 2, 512-526, 1992.

Waite, J.H., W.S. Lewis, W.T. Kasprzak, V.G. Anicich, B.P. Block, T.E. Cravens, G.G. Fletcher, W.-H. Ip, J.G. Luhmann, R.L. McNutt, H.B. Niemann, J.K. Parejko, J.E. Richards, R.L. Thorpe, E.M. Walter, and R.V. Yelle, The Cassini Ion and Neutral Mass Spectrometer (INMS) Investigation, Space Sci. Rev. 114, 113-231, 2004.