KPL/IK MSASI Instrument Kernel =========================================================================== This instrument kernel (I-kernel) contains references to mounting alignment, operating modes, and timing as well as internal and FOV geometry for the BepiColombo MMO Mercury Sodium Atmosphere Spectral Image (MSASI). Version and Date ----------------------------------------------------------------------------- Version 0.1 -- July 7, 2020 -- Marc Costa Sitja, ESAC/ESA Alfredo Escalante Lopez, ESAC/ESA Minor corrections on descriptions Version 0.0 -- July 01, 2019 -- Tomoki Kimura, Tohoku University First draft. Generated for the MSASI operation simulation study. References ----------------------------------------------------------------------------- 1. ``Kernel Pool Required Reading'' 2. ``Frames Required Reading'' 3. ``C-Kernel Required Reading'' 4. BepiColombo MMO Spacecraft Frames Definition Kernel 5. ``The Mercury sodium atmospheric spectral imager for the MMOspacecraft of Bepi-Colombo''. I. Yoshikawa. Contact Information ----------------------------------------------------------------------------- If you have any questions regarding this file contact SPICE support at Tohoku University: Tomoki KIMURA (+81) 22-795-6518 kimura@stpp.gp.tohoku.ac.jp Implementation Notes ----------------------------------------------------------------------------- This file is used by the SPICE system as follows: programs that make use of this frame kernel must "load" the kernel normally during program initialization. Loading the kernel associates the data items with their names in a data structure called the "kernel pool". The SPICELIB routine FURNSH loads a kernel into the pool as shown below: FORTRAN: (SPICELIB) CALL FURNSH ( frame_kernel_name ) C: (CSPICE) furnsh_c ( frame_kernel_name ); IDL: (ICY) cspice_furnsh, frame_kernel_name MATLAB: (MICE) cspice_furnsh ( 'frame_kernel_name' ) PYTHON: (SPICEYPY)* furnsh( frame_kernel_name ) In order for a program or routine to extract data from the pool, the SPICELIB routines GDPOOL, GIPOOL, and GCPOOL are used. See [2] for more details. This file was created and may be updated with a text editor or word processor. * SPICEPY is a non-official, community developed Python wrapper for the NAIF SPICE toolkit. Its development is managed on Github. It is available at: https://github.com/AndrewAnnex/SpiceyPy Naming Conventions ----------------------------------------------------------------------------- Data items are specified using ''keyword=value'' assignments [1]. All keywords referencing values in this I-kernel start with the characters `INS' followed by the NAIF MMO instrument ID code, constructed using the spacecraft ID number (-68) followed by the NAIF three digit ID number for one of the MSASI data item. These IDs are as follows Instrument name ID -------------------- ------ MMO_MSASI -68400 MMO_MSASI_SLIT -68401 MMO_MSASI_SSAS -68490 The remainder of the name is an underscore character followed by the unique name of the data item. For example, the MSASI boresight direction in the MMO_MSASI_SLIT frame (see [2]) is specified by: INS-68401_BORESIGHT The upper bound on the length of the name of any data item identifier is 32 characters. If the same item is included in more than one file, or if the same item appears more than once within a single file, the latest value supersedes any earlier values. Overview ----------------------------------------------------------------------------- From [5]: MSASI (Mercury Sodium Atmospheric Spectral Imager) is a spectrometer devoted to the measurement of a narrow sodium D2 emission line (589nm) against the bright surface of Mercury. A single high-resolution Fabry–Perot etalon is used in combination with an ultra-narrow band-pass filter. Full-disk images of the planet are obtained by means of a single-axis scanning mirror in combination with the spin. Science Goals: ~~~~~~~~~~~~~~ The scientific objectives of MSASI include the: - dominant release process for sodium - dusk-dawn asymmetry - sodium tail - topographic effect Source processes considered likely are thermal desorption, photon-stimulated desorption, sputtering by impacting particles in the solar wind, and meteoroid vaporisation. The target of the MSASI instrument is to observe the north–south distribution and to measure the temporal variations of the release rate of sodium atoms. Through these capabilities, it will be possible to investigate the likely source processes. Measurement Principle: ~~~~~~~~~~~~~~~~~~~~~~ A Fabry-Perot interferometer produces a circular fringe pattern on its focal plane. A part of this circular fringe (a circular arc oriented along the spin axis direction of the spacecraft) is used as a 1D image. Each 2ms, the instantaneous field of view shifts by 0.18 degrees along the spin-scan direction. Hence, using a one degree-of freedom scanning mirror (15 mm x 25 mm) to alter the line-of-sight from 25 degrees to 55 degrees, plus the spin of the spacecraft, it can obtain full-disk images of the planet and the sodium tail. The following table summarizes the instrument optics, performances and resolution: Parameter | Units | Value/Description Remarks -------------------------+---------------+---------------------------- Optics | | | | Aperture | mm | [TBW] Focal length | mm | 3.732 Focal number | | N/A Field of view | degrees | 1.8 Central obstruction | % | [TBW] Pixel IFOV | microrad | 31.4159 Spectral range | nm | ~589 Filter bandwidth | | Spectrometers | nm | [TBW] NUV channel | nm | [TBW] Spectral Channels | | [TBW] Spectral dispersion | Pix/nm | [TBW] Mirror efficiency | % | [TBW] Mirror Material | | [TBW] Mirror Grating | | [TBW] and Coating | | | | Sensor (RAE) | | | | Pixel lines | # | 16 Per detector Pixels per line | # | 1 Per detector Pixel pitch | microrad | [TBW] Peak quantum | | efficiency | | EUV | % | [TBW] FUV | % | [TBW] Full well capacity | # e- | [TBW] Scale per pixel | | At Periherm | km/px | 5 At Apoiherm | km/px | 40 Smear | px/s | [TBW] Exposure time | ms | 10 | | Resolution | | | | Spectral resolution | nm | delta(lamda) = 0.0048 Angular resolution | microrad/px | 3.14159 Spatial resolution | microm/px | 60 Mounting Alignment ----------------------------------------------------------------------------- Refer to the latest version of the BepiColombo Frames Definition Kernel (FK) [4] for the MSASI reference frame definitions and mounting alignment information. MSASI Apparent Field-of-View Layout ----------------------------------------------------------------------------- The instrument Field of View is defined by the spectrometer slit size (1000 x 60 microm). With a focal length of 3.732 mm, it corresponds to ~ 30.0 x 1.8 degrees projected on the horizon. The boresight vector is shifted by 40 degree from the y-axis in the MPO_MSASI reference frame. This diagram illustrates the MSASI apparent FOV in the MPO_MSASI (MMO_MSASI) reference frame. ^ +Zmsasi | ______|_______________________________________________________ / | \ / \ / \ / \ / \ | ___|_ | | | | | | | | | | / | \ | | | | SPECTROMETER | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +Ymsasi | | | | | |__|__ o-----------------> _________|_|___________|_|__________| | \'.'._ | | ...==========\ '. '._ /40.0 deg ======================================... /////////////\ '. /._ //////// MMO LOWER DECK //////////////////... ...============\ '/ '._ ==========================================... | \ '. '._ | | \ '. '._ MSASI-H | |____________ \ '. '.________________________________| \ _.' '. .' '._ \-' 15.0 '.-' 15.0 '._ \ deg '. deg '._ \ '. '._ \ '. '> \ '. \ '> BORESIGHT_VECTOR (+Ybore) > MSASI +X axis (+Xmsasi) is from the page FOV Definitions --------------------------------------------------------------------------- MSASI_SLIT FOV: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The MSASI FOVs are defined within a rectangle pyramid with an along slit angle of 30.0 degrees and a cross slit angle of 1.8 degrees. They are defined with respect to the MPO_MSASI reference frame. The boresight, reference, and cross-reference vectors are unit along the +Ybore that is +Ymsasi rotated by -40.0 deg around +Xmsasi, +Ymsasi, +Xmsasi frame respectively. Please note that the FOV reference and cross angles are defined with half angle values. The following FOVs definitions correspond to the NAIF Body Name: MMO_MSASI_SLIT \begindata INS-68401_NAME = 'MMO_MSASI_SLIT' INS-68401_FOV_CLASS_SPEC = 'ANGLES' INS-68401_FOV_FRAME = 'MMO_MSASI' INS-68401_FOV_SHAPE = 'RECTANGLE' INS-68401_BORESIGHT = ( 0.000000 0.766044 -0.642788 ) INS-68401_FOV_REF_VECTOR = ( 0.000000 1.000000 0.000000 ) INS-68401_FOV_REF_ANGLE = ( 15.0000000 ) INS-68401_FOV_CROSS_ANGLE = ( 0.90000000 ) INS-68401_FOV_ANGLE_UNITS = ('DEGREES') \begintext Optical Parameters ----------------------------------------------------------------------------- [TBW] Detector Parameters ----------------------------------------------------------------------------- [TBW] End of IK file.