urn:nasa:pds:context:instrument:mimi-chems.co 1.0 1.20.0.0 Product_Context MIMI CHEMS 2023-07-05 1.0 Initial version describing MIMI CHEMS as a unique instrument, rather than as a component of the MIMI instrument. urn:nasa:pds:context:instrument_host:spacecraft.co::1.0 instrument_to_instrument_host Krimigis, S.M., D.G. Mitchell, D.C. Hamilton, S. Livi, J. Dandouras, S. Jaskulek, T.P. Armstrong, J.D. Boldt, A.F. Cheng, G. Gloeckler, J.R. Hayes, K.C. Hsieh, W.-H. Ip, E.P. Keath, E. Kirsch, N. Krupp, L.J. Lanzerotti, R. Lundgren, B.H. Mauk, R.W. McEntire, E.C. Roelof, C.E. Schlemm, B.E. Tossman, B. Wilken, and D.J. Williams, Magnetosphere Imaging Instrument (MIMI) on the Cassini Mission to Saturn/Titan, Space Sci Rev. 114, 233-329 (2004). https://doi.org/10.1007/s11214-004-1410-8 reference.KRIMIGISETAL2004 Kusterer, M.B., L.M. Burke, Level 1A File Layouts, Cassini/MIMI Data Analysis Center Level 1A File Layouts, The Johns Hopkins University Applied Physics Laboratory Document, Revision 18, December 2003. reference.KUSTERER-BURKE2003 Manweiler, J.W., W.A. Rasmuss, and S. Joy, MIMI Standard Data Products and Archive Volume Software Interface Specification, v2.1, JPL Document D-31634, Cassini document IO-AR-006, 2005. reference.MANWEILERETAL2005 MIMI Charge/Energy Mass Spectrometer Charged Particle Detector not applicable not applicable The text of this instrument description has been abstracted from the instrument paper [KRIMIGISETAL2004]: Krimigis, S.M., Magnetosphere Imaging Instrument (MIMI) on the Cassini Mission to Saturn/Titan, in Space Science Reviews, Springer Science and Business Media, B.V., formerly Kluwer Academic Publishers B.V., Vol. 114, No. 1-4, pp. 233-329, December 2004. Calibration: ============ Calibration processes are accomplished via both flight software and ground processing software. Flight software is used primarily to accommodate variations in measurements due to spacecraft motion. Ground based calibration is accomplished through a combination of calibration data values (see COMIMI_0000) coupled with various algorithms to generate particle flux from measured count rates. Operational Considerations: =========================== The MIMI power consumption is nomially ~19.0 W. Typical operations include the capability to sense 6-7 orders of magnitude in particle flux over a dynamic energy range for electrons of 30 KeV to 5 MeV and for ions from 3 KeV to 160 MeV. Data quality is affected by direct sun exposure into the instruments. Sensors: ========== The MIMI experiment consists of three independent sensors: Charge Energy Mass Spectrometer (CHEMS), Ion Neutral Camera (INCA), and Low Energy Magnetospheric Measurements (LEMMS). Each sensor has specific targeted energies and populations to be examined and collectively provide the ability to fully characterize the energetic charged and neutral particle population in the Saturnian Magnetosphere as well as the Solar Wind, the Jovian Magnetosphere, and the Earth Magnetosphere. Each sensor is a combination of geometric components, silicon detectors, micrpchannel plates, and electronics/software components that give them the ability to fully answer the missions scientific objectives. When the spacecraft is spinning the MIMI sensors obtain measurements over a full four pi steradians. The different MIMI sensors share common electronics and provide complimentary measurements of energetic plasma distributions, composition, and energy spectrum, and the interaction of that plasma with the extended atmosphere and moons of Saturn. The CHEMS sensor is mounted on the particles and fields instrument pallet with a field of view of approximately 160 degrees in latitude (bisected by the spacecraft x-y plane) by 4 degrees in azimuth centered on the spacecraft -x axis. CHEMS measures ions from approximately 3 to 220 KeV/e. Frames diagram -------------- All MIMI telescope directions are described in terms of the spacecraft fixed frame. CHEMS latitudinal field of view of 160 degrees is bisected by the spacecraft x-y plane and its azimuthal field of view of 4 degrees is centered on the spacecraft -x axis. There are no otherwise specifically defined Cassini MIMI frames. Electronics: ============ Signals from the sensors are first processed by the analog electronics and then by the digital processing unit (DPU). Analog data are placed into the digital system and with respect to CHEMS minimal processing is done. The CHEMS sensor has a variable high voltage potential to determine selection of particle based upon energy and to then subsequently place particles into energy, mass, and/or mass/charge bins. The DPU unit's primary function is to catalog incoming particle measurements based upon underlying logic and to count events in accumulation bins. The DPU also packages the data along with the instrument housekeeping data (instrument states) and then integrated into telemetry for broadcast to ground station. Parameters that control the high voltage supplies, the selection of priority counters etc, are expected to be updated periodically under normal operating conditions. Data compression and sampling techniques are used to maximize data return within the bandwidth allocated to the experiment.