KPL/IK VIR Instrument kernel =========================================================================== This instrument kernel (I-kernel) contains Dawn VIR optics, detector, and field-of-view parameters. Version and Date --------------------------------------------------------------------------- Version 0.5 -- March 2, 2011 -- Boris Semenov, NAIF Rearranged comments and data blocks in the "FOV Definitions" section to have all FOVs defined for full and partial scan mirror sweeps described in a single comment block and defined in a single data block to more clearly separate them from actual, non-sweep FOV definitions. NO CHANGES WERE MADE TO ANY KEYWORD VALUES. Version 0.4 -- October 7, 2009 -- Dr. Federico Tosi, INAF - IFSI Boris Semenov, NAIF Changed the reference frame for the full and partial VIS sweep FOVs associated with IDs -203212, -203215 ... -203219 to DAWN_VIR_VIS_ZERO. Changed the reference frame for the full IR sweep FOV associated with IDs -203214 to DAWN_VIR_IR_ZERO. Replaced -226 with -203 in the keywords in the ``Platform ID'' section. Replaced cross-track/along-track with along-slit/cross-slit in all comments. Filled in instrument description. Version 0.3 -- July 3, 2009 -- Boris Semenov Extended comments to cover partial VIS scan FOVs added by Steve Joy. Version 0.2T2 -- June 23, 2009 -- Steven Joy Added FOVs for VIR_VIS_96 (-203218) and VIR_VIS_32 (-203219) Version 0.2T -- April 09, 2009 -- Steven Joy Added FOVs for VIR_VIS_16 (-203217) Version 0.2 -- June 24, 2008 -- Steven Joy, DSC with Boris Semenov, NAIF/JPL Added FOVs for VIR_VIS_128 (-203215) and VIR_VIS_64 (-203216). Version 0.1 -- May 9, 2005 -- Boris Semenov, NAIF/JPL Added radiator FOV. Version 0.0 -- October 12, 2004 -- Boris Semenov, NAIF/JPL Initial release. References --------------------------------------------------------------------------- 1. ``Kernel Pool Required Reading'' 2. ``C-kernel Required Reading'' 3. VIR ICD/MICD, latest version as of 10/12/04 4. Dawn Frames Definition Kernel (FK), latest version. 5. VIR CDR Presentations 6. Rosetta VIRTIS Documentation (ROS-EST-RS-30015/EID B and RO-VIR-UM-001) 7. VIR Home Page http://www.ifsi-roma.inaf.it/vir/; accessed 10/07/09 Implementation Notes -------------------------------------------------------- Applications that need SPICE I-kernel data must ``load'' the I-kernel file, normally during program initialization. Loading the kernel using the SPICELIB routine FURNSH causes the data items and their associated values present in the kernel to become associated with a data structure called the ``kernel pool''. The application program may then obtain the value(s) for any IK data item using the SPICELIB routines GDPOOL, GIPOOL, GCPOOL. Routine GETFOV may be used if the file contains instrument field-of-view (FOV) specification. See [1] for details. This file was created with, and can be updated with a text editor or word processor. Conventions for Specifying Data -------------------------------------------------------- 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 Dawn instrument ID code, constructed using the spacecraft ID number (-226) followed by the NAIF three digit ID number for VIR module. These IDs are defined in [4] as follows: Instrument name ID -------------------- ------- DAWN_VIR -203200 DAWN_VIR_SCAN -203201 DAWN_VIR_VIS -203211 DAWN_VIR_IR -203213 DAWN_VIR_VIS_SCAN -203212 (*) DAWN_VIR_IR_SCAN -203214 (*) DAWN_VIR_VIS_128 -203215 (*) DAWN_VIR_VIS_64 -203216 (*) DAWN_VIR_VIS_16 -203217 (*) DAWN_VIR_VIS_96 -203218 (*) DAWN_VIR_VIS_32 -203219 (*) DAWN_VIR_RAD -203209 (*) _SCAN, _128, _64, _16, _96 and _32 names/IDs are defined to allow specifying FOVs circumscribing full or partial side scans of the VIR scan mirror. These frames are used only for planning purposes and have nothing to do with the real angular aperture (FOV) of the VIR instrument. The remainder of the keyword is an underscore character followed by the unique name of the data item. For example, the focal length of the VIR VIS optics is specified by INS-203211_FOCAL_LENGTH The upper bound on the length of all keywords is 32 characters. If a keyword is included in more than one file, or if the same keyword appears more than once within a single file, the last assignment supersedes any earlier assignments. Overview -------------------------------------------------------- From [7]: What is VIR? The Dawn mapping spectrometer VIR is a Visual and Infrared Imaging Spectrometer that produces spectral images in the 0.25-1 mkm and 1-5 mkm ranges. VIR is a rebuild of the VIRTIS mapping spectrometer on board the ESA Rosetta mission and it also derives much design heritage from the Cassini VIMS spectrometer. The design of the instrument fully accomplishes the mission's scientific and measurement objectives with a simple space-qualified low risk approach and high performance, reliability, heritage and cost effectiveness. Some technical details VIR is a Visual and Infrared Imaging Spectrometer in a single optical head. A Shafer telescope is mated to an Offner slit spectrometer. Spectral images are formed on two matrix detectors to cover the 0.25-1 mkm and 1-5 mkm ranges. The design uses a dual arm optical and focal design with mapping ability to 5 mkm.The Dawn mapping spectrometer (VIR) is a rebuild of the VIRTIS mapping spectrometer on board the ESA Rosetta mission with an operational durations of 2y and flight time of 13y. The MS spectrometer will only use the - M channel of VIRTIS, thus allowing a great mass reduction. VIR also derives much of its design from the Cassini VIMS spectrometer with an operational lifetime of >4y and a mission life>10y. VIR modules The spectrometer consists of only three modules: the optical system, 5.0 kg mass; the proximity electronics, 3.0 kg and 5 W; the cryocooler including driving electronics, 1.3 kg and 12.6 W. A mechanical and thermal mounting of 5.0 kg mass accommodates the spectrometer subsystems. The optical system, which includes foreoptics, dispersive elements, filters, focal plane assemblies as well as the cryocooler and proximity electronics is a complete re-build of the VIRTIS M instrument The data processing unit box (DPU) is shared with the framing camera to save mass. The DPU handles the data for both camera and spectrometer, compresses and buffers them, and controls both the FCs and MS. Flight software is based on Rosetta VIRTIS and ROLIS developments. The camera is operated only when the spectrometer is not operating. As VIRTIS-M, VIR does not use beam-splitters. Two different groove densities are ruled on a single grating. The central part of the grating (about 30% of the pupil) is ruled with a higher groove density, which generate the higher spectral resolution needed in the visible channel. The infrared channel utilizes the outer 70% of the grating, which is ruled with a lower groove density. The larger collecting area in the IR compensates for the lower solar irradiance in this region. The visible detector array is based on the Thomson-CSF type TH 7896 CCD detector. The IR detector used in the MS is based on a bidimensional array of IR-sensitive photovoltaic Mercury Cadmium Telluride coupled to silicon CMOS multiplexer. This detector can operate at temperatures of the order of 75 K. For this reason cryocoolers have to be used. The calibration unit will make use of the cover, which -inside is coated. It will diffuse the light coming from two internal calibration lamps (one for the VISFPA and one for the IR-FPA), calibrated at IAS. Mounting Alignment -------------------------------------------------------- Refer to the latest version of the Dawn Frames Definition Kernel (FK) [4] for the VIR reference frame definitions and mounting alignment information. Apparent FOV Layout -------------------------------------------------------- WARNING --- the description/diagram below have not been verified This diagram illustrates the VIR apparent FOV layout for "zero" scan mirror position in the corresponding reference frame. ^ +Xvis | +Xir | | | ~0.014 degrees | | | v Pixel 1 | Pixel 256 --- +---------|---------+ | 1 line | x-------------> +Yvis --- +-------------------+ +Yir ^ 256 pixels/line | | ~3.67 degrees | |<----------------->| | | Boresight (+Z axis) is into the page This diagram illustrates the VIR apparent FOV layout resulting from a full, 256 step, +/- 1.83 degree scan mirror sweep about Y axis. For partial scans of 16, 32, 64, 96, or 128 lines the cross-slit FOV extent is proportionally decreased to 0.23, 0.46, 0.92, 1.38, and 1.84 degrees correspondingly. ^ +Xvis | +Xir | Pixel 1,1 | --- *---------|---------+ ^ | | | | ~3.67 | | | | degrees | | | | | | | | 256 lines | x-------------> +Yvis | (each for | | +Yir | a step in | | | scan seq.)| | V | | --- +-------------------+ | 256 pixels/line | ~3.67 degrees | |<----------------->| | | Boresight (+Z axis) is into the page Optical Parameters -------------------------------------------------------- The following VIR VIS and IR nominal first order optical parameters are included in the data section below, from [6]: ----------------------------------------------------------------- parameter VIR/VIS VIR/IR ----------------------------------------------------------------- Focal Length, mm 152.0 152.0 f/ratio f/5.6 f/3.2 IFOV, rad/pixel along-slit 0.00025 0.00025 cross-slit 0.00025 0.00025 Field of view (deg) along-slit 3.6669 3.6669 cross-slit 0.0143 0.0143 Field of view (deg) - scan along-slit 3.6669 3.6669 cross-slit 3.6669 3.6669 ----------------------------------------------------------------- The keywords below provide nominal values from the table above. Angular size values in the keywords are given radians, with the along-slit size being the first value and the cross-slit size being the second value in each pair. \begindata INS-203211_FOCAL_LENGTH = ( 152.0 ) INS-203211_F/RATIO = ( 5.6 ) INS-203211_FOV_ANGULAR_SIZE = ( 0.064000, 0.000250 ) INS-203211_IFOV = ( 0.000250, 0.000250 ) INS-203213_FOCAL_LENGTH = ( 152.0 ) INS-203213_F/RATIO = ( 3.2 ) INS-203213_FOV_ANGULAR_SIZE = ( 0.064000, 0.000250 ) INS-203213_IFOV = ( 0.000250, 0.000250 ) \begintext Detector Parameters -------------------------------------------------------- The nominal VIR detector parameters from [6] are: ----------------------------------------------------------------- parameter VIR/VIS VIR/IR ----------------------------------------------------------------- Detector Array Size/Physical along-slit 508 270 cross-slit 1024 436 Detector Array Size/Spatial along-slit 256 (1) 256 (2) cross-slit 1 1 Detector Array Center/Spatial along-slit 127.5 127.5 cross-slit 0.5 0.5 Pixel Size, microns/Spatial along-slit 38 (3) 38 cross-slit 38 38 ----------------------------------------------------------------- (1) VIS CCD pixels are 2x2 binned at detector level (2) assuming IR reads out the same number of pixels as VIS (3) size of a 2x2 binned pixel The values are given in microns for PIXEL_SIZE keywords and in counts for PIXEL_SAMPLES, PIXEL_LINES, and CENTER keywords. \begindata INS-203211_PIXEL_SIZE = ( 38, 38 ) INS-203211_PIXEL_SAMPLES = ( 256 ) INS-203211_PIXEL_LINES = ( 1 ) INS-203211_CCD_CENTER = ( 127.5, 0.5 ) INS-203213_PIXEL_SIZE = ( 38, 38 ) INS-203213_PIXEL_SAMPLES = ( 256 ) INS-203213_PIXEL_LINES = ( 1 ) INS-203213_CCD_CENTER = ( 127.5, 0.5 ) \begintext FOV Definitions --------------------------------------------------------------------------- This section contains definitions for the VIR FOVs. These definitions are provided in a format required by the SPICE (CSPICE) function GETFOV (getfov_c). The set of assignments in the data section below defines the VIR VIS and IR actual slit FOVs with respect to the corresponding moving frames to be a rectangles with the corners defined by the first and last pixels of the spatial line along +Y and the boresight along the +Z axis. These FOV definitions use angular extent style specification with the cross and along track angular sizes taken from the ``Optics Parameters'' section above. \begindata INS-203211_FOV_FRAME = 'DAWN_VIR_VIS' INS-203211_FOV_SHAPE = 'RECTANGLE' INS-203211_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-203211_FOV_CLASS_SPEC = 'ANGLES' INS-203211_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-203211_FOV_REF_ANGLE = ( 0.00716197 ) INS-203211_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-203211_FOV_ANGLE_UNITS = 'DEGREES' INS-203213_FOV_FRAME = 'DAWN_VIR_IR' INS-203213_FOV_SHAPE = 'RECTANGLE' INS-203213_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-203213_FOV_CLASS_SPEC = 'ANGLES' INS-203213_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-203213_FOV_REF_ANGLE = ( 0.00716197 ) INS-203213_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-203213_FOV_ANGLE_UNITS = 'DEGREES' \begintext The set of assignments in the data section below defines the VIR VIS apparent FOVs resulting from a full, 256-step and partial 128-, 64-, 16-, 96-, and 32- step scan mirror sweeps about Y axis with respect to the non-moving frame 'DAWN_VIR_VIS_ZERO' to be a rectangles with the corners defined by the first and last pixels of the spatial line in the first and last scan positions and the boresight along the +Z axis. These FOV definitions use angular extent style specification with the angular sizes taken from the ``Optics Parameters'' section above. Note that FOVs defined below are used only for planning purposes and have nothing to do with the real angular aperture (FOV) of the VIR instrument; therefore they should not be used to reproduce the geometry of real VIR acquisitions. \begindata INS-203212_FOV_FRAME = 'DAWN_VIR_VIS_ZERO' INS-203212_FOV_SHAPE = 'RECTANGLE' INS-203212_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-203212_FOV_CLASS_SPEC = 'ANGLES' INS-203212_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-203212_FOV_REF_ANGLE = ( 1.83346494 ) INS-203212_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-203212_FOV_ANGLE_UNITS = 'DEGREES' INS-203214_FOV_FRAME = 'DAWN_VIR_IR_ZERO' INS-203214_FOV_SHAPE = 'RECTANGLE' INS-203214_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-203214_FOV_CLASS_SPEC = 'ANGLES' INS-203214_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-203214_FOV_REF_ANGLE = ( 1.83346494 ) INS-203214_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-203214_FOV_ANGLE_UNITS = 'DEGREES' INS-203215_FOV_FRAME = 'DAWN_VIR_VIS_ZERO' INS-203215_FOV_SHAPE = 'RECTANGLE' INS-203215_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-203215_FOV_CLASS_SPEC = 'ANGLES' INS-203215_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-203215_FOV_REF_ANGLE = ( 0.91673247 ) INS-203215_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-203215_FOV_ANGLE_UNITS = 'DEGREES' INS-203216_FOV_FRAME = 'DAWN_VIR_VIS_ZERO' INS-203216_FOV_SHAPE = 'RECTANGLE' INS-203216_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-203216_FOV_CLASS_SPEC = 'ANGLES' INS-203216_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-203216_FOV_REF_ANGLE = ( 0.45836624 ) INS-203216_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-203216_FOV_ANGLE_UNITS = 'DEGREES' INS-203217_FOV_FRAME = 'DAWN_VIR_VIS_ZERO' INS-203217_FOV_SHAPE = 'RECTANGLE' INS-203217_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-203217_FOV_CLASS_SPEC = 'ANGLES' INS-203217_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-203217_FOV_REF_ANGLE = ( 0.11459156 ) INS-203217_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-203217_FOV_ANGLE_UNITS = 'DEGREES' INS-203218_FOV_FRAME = 'DAWN_VIR_VIS_ZERO' INS-203218_FOV_SHAPE = 'RECTANGLE' INS-203218_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-203218_FOV_CLASS_SPEC = 'ANGLES' INS-203218_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-203218_FOV_REF_ANGLE = ( 0.68754935 ) INS-203218_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-203218_FOV_ANGLE_UNITS = 'DEGREES' INS-203219_FOV_FRAME = 'DAWN_VIR_VIS_ZERO' INS-203219_FOV_SHAPE = 'RECTANGLE' INS-203219_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-203219_FOV_CLASS_SPEC = 'ANGLES' INS-203219_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-203219_FOV_REF_ANGLE = ( 0.22918312 ) INS-203219_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-203219_FOV_ANGLE_UNITS = 'DEGREES' \begintext Radiator Sun Avoidance FOV Definition -------------------------------------------------------- Sun avoidance for VIR radiator is 175 degree cone centered on spacecraft -X axis [3]. \begindata INS-203209_FOV_FRAME = 'DAWN_SPACECRAFT' INS-203209_FOV_SHAPE = 'CIRCLE' INS-203209_BORESIGHT = ( -1.000000 0.000000 0.000000 ) INS-203209_FOV_CLASS_SPEC = 'ANGLES' INS-203209_FOV_REF_VECTOR = ( 0.000000 1.000000 0.000000 ) INS-203209_FOV_REF_ANGLE = ( 87.5 ) INS-203209_FOV_ANGLE_UNITS = 'DEGREES' \begintext Optical Distortion -------------------------------------------------------- [TBD] Platform ID --------------------------------------------------------------------------- This number is the NAIF instrument ID of the platform on which the instrument mounted. All VIR components it is the spacecraft. \begindata INS-203200_PLATFORM_ID = ( -203000 ) INS-203211_PLATFORM_ID = ( -203000 ) INS-203213_PLATFORM_ID = ( -203000 ) \begintext