KPL/IK Hayabusa2 NIRS3 Instrument kernel ============================================================================== This instrument kernel (I-kernel) file contains detector, optical, and field-of-view parameters for the Hayabusa2 Near Infrared Spectrometer (NIRS3) instrument. Version and Date ------------------------------------------------------------------------------ Version 0.3 -- Feb. 18, 2025 -- Shin-ya Murakami, ISAS, JAXA - Updated the "Instrument Optical Parameters" section. Version 0.3b -- Sep. 6, 2024 -- Shin-ya Murakami, ISAS, JAXA - Updated descriptions in the "Instrument Optical Parameters" section and the "Instrument FOV Definition(s)" section. - Added some keywords to the "Instrument Optical Parameters" section. Version 0.3a -- Feb. 10, 2023 -- Shin-ya Murakami, ISAS, JAXA - Applied cosmetic changes. - Update descriptions. Version 0.2 -- Feb. 20, 2020 -- Yukio Yamamoto, ISAS, JAXA - Updated major version for public release. Version 0.1a -- Aug. 05, 2019 -- Shin-ya Murakami, ISAS, JAXA - Applied cosmetic changes. - Filled some blanks. Version 0.1 -- Mar. 08, 2017 -- Kohei KITAZATO, Univ. of Aizu - Fixed NIRS3 alignment as a result of the NIRS3 experiment. Version 0.0 -- Jan. 12, 2017 -- Hayabusa2 DAC Team - Initial version. Reference ------------------------------------------------------------------------------ 1. Kernel Pool Required Reading 2. GETFOV, getfoc_c, cspice_getfov headers 3. Hayabusa2 FK file, latest version 4. Iwata et al., 2017, NIRS3: The Near Infrared Spectrometer on Hayabusa2, Space Sci. Rev., 208:317-337, https://doi.org/10.1007/s11214-017-0341-0 5. Kitazato et al., 2021, Software Interface Specification for the Hayabusa2 NIRS3 Products, urn:jaxa:darts:hyb2_nirs3:document:nirs3_dpsis Contact Information ------------------------------------------------------------------------------ Kohei KITAZATO, Univ. of Aizu, kitazato@u-aizu.ac.jp Implementation Notes ------------------------------------------------------------------------------ This file is used by the SPICE system as follows: programs that make use of this kernel must ``load'' the kernel, normally during program initialization. The SPICE routine FURNSH loads a kernel file into the pool as shown below. CALL FURNSH ( 'frame_kernel_name; ) -- FORTRAN furnsh_c ( "frame_kernel_name" ); -- C cspice_furnsh, frame_kernel_name -- IDL cspice_furnsh( 'frame_kernel_name' ) -- MATLAB Once the file has been loaded, the SPICE routine GETFOV (getfov_c in C, cspice_getfov in IDL and MATLAB) can be used to retrieve FOV parameters for a given instrument or structure. This file was created and may be updated with a text editor or word processor. Naming Conventions ------------------------------------------------------------------------------ All names referencing values in this IK file start with the characters `INS' followed by the NAIF Hayabusa2 ID number (-37) followed by a NAIF three digit ID code for one of NIRS3: HAYABUSA2_NIRS3-S -37300 The remainder of the keyword name is an underscore character followed by the unique name of the data item. For example, the boresight direction of HAYABUSA2_NISR3-S is specified by: INS-37300_BORESIGHT The upper bound on the length of the name of any data item 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. Instrument Description ------------------------------------------------------------------------------ From [4]: NIRS3: The Near Infrared Spectrometer is installed on the Hayabusa2 spacecraft to observe the target C-type asteroid 162173 Ryugu at near infrared wavelengths of 1.8 to 3.2 um. It aims to obtain reflectance spectra in order to detect absorption bands of hydrated and hydroxide minerals in the 3 um-band. We adopted a linear-image sensor with indium arsenide (InAs) photo diodes and a cooling system with a passive radiator to achieve an optics temperature of 188 K (-85 degrees Celsius), which enables to retaining sufficient sensitivity and noise level in the 3 um wavelength region. We conducted ground performance tests for the NIRS3 flight model (FM) to confirm its baseline specifications. The results imply that the properties such as the signal-to-noise ratio (SNR) conform to scientific requirements to determine the degree of aqueous alteration, such as CM or CI chondrite, and the stage of thermal metamorphism on the asteroid surface. Mounting Alignment ------------------------------------------------------------------------------- Refer to the latest version of the Hayabusa2 Frames Definition Kernel (FK) [3] for the instrument reference frame definitions and mounting alignment information. Apparent FOV Layout ------------------------------------------------------------------------------ This diagram illustrates the Hayabusa2 NIRS3 apparent FOV layout in the HAYABUSA2_NIRS3-S reference frame. The FOV size of the spectrometer unit of the NIRS3 (NIRS3-S) is 0.1 degrees x 0.11 degrees. ^ Y | | | --- *----|----+ ^ | | | | 0.11 deg | x-------> X V | | --- +---------+ | | 0.1 deg | |<------->| | | Boresight (-Z axis) is into the page For the alignment of the HAYABUSA2_NIRS3-S frame with respect to the HAYABUSA2_SC_BUS_PRIME frame and with respect to each other, please refer to [3]. Instrument Detector/Sensor Parameters ------------------------------------------------------------------------------- The NIRS3 detector parameters are tabulated below, taken from [4]. ----------------------------------------------------------------- parameter value ----------------------------------------------------------------- Pixel size 50 um x 100 um Detector Array Size 128 ----------------------------------------------------------------- \begindata INS-37300_PIXEL_SIZE = ( 50, 100 ) INS-37300_PIXEL_SAMPLES = ( 128 ) INS-37300_PIXEL_LINES = ( 1 ) \begintext Instrument Optical Parameters ------------------------------------------------------------------------------- The following nominal NIRS3 first order optical parameters are provided in [5]. ----------------------------------------------------------------- parameter value ----------------------------------------------------------------- f/ratio f/1.0 Aperture diameter 30 mm Slit size 50 um x 55 um (*) Effective spectral range 1.8 - 3.2 um Spectral sampling 18 nm / channel (in average) ----------------------------------------------------------------- (*) According to [4], the slit size is 55 um x 55 um which is different with the size in [5]. The size 55 um x 55 um is the design value and the actual (measured) value is 50 um x 55 um. In [5], the slit size is written as 50 um x 50 um in the SIS version 1.0, but the value is mistakenly rounded. IFOV is computed as 0.1 degree in radians, i.e., about 0.0017 radians. \begindata INS-37300_FOCAL_LENGTH = ( 30.0 ) INS-37100_F/RATIO = ( 1.0 ) INS-37100_IFOV = ( 0.0017 ) \begintext Instrument FOV Definition(s) ------------------------------------------------------------------------------- FOV is 0.1 deg x 0.11 deg which is determined by slit size, 50 um x 55 um. This section defines the following FOV(s): ID SHAPE FRAME ------- --------- ----------------- -37300 RECTANGLE HAYABUSA2_NIRS3-S The boresight vector is along the -Z direction and magnitude is set to approximate value of focal length, 30 mm, which is calculated from the f/ratio and the aperture diameter. \begindata INS-37300_FOV_FRAME = 'HAYABUSA2_NIRS3-S' INS-37300_FOV_SHAPE = 'RECTANGLE' INS-37300_BORESIGHT = ( 0.0 0.0 -30.0 ) INS-37300_FOV_CLASS_SPEC = 'ANGLES' INS-37300_FOV_REF_VECTOR = ( 1.0 0.0 0.0 ) INS-37300_FOV_REF_ANGLE = ( 0.050 ) INS-37300_FOV_CROSS_ANGLE = ( 0.055 ) INS-37300_FOV_ANGLE_UNITS = 'DEGREES' \begintext End of the IK file.