KPL/IK DART DRACO Instrument Kernel ============================================================================== This instrument kernel (I-kernel; IK) contains references to the mounting alignment, internal and FOV geometry for the Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO) instrument. Version and Date ------------------------------------------------------------------------ Version 003 -- October 05, 2022 -- Hari Nair, JHU/APL Updated IFOV and focal length. Version 002 -- September 20, 2021 -- Marc Costa Sitja, NAIF/JPL Version renamed and general clean-up. Added apparent FOV definitions and FOV definitions. Corrected detector array size and FOV Angular size for windowed FOV. Version 001 -- July 17, 2021 -- Hari Nair, JHU/APL Renamed version. Includes the following updates by Hari Nair from previous versions: Version 0.3 -- Jan. 20, 2021: Fix error in instrument frame description. Bottom left is (1,1), upper right is (2560,2160). Boresight direction -Z points into the page. Version 0.2 -- Oct. 9 2020: Revise instrument frame description. Top left is (1,1), bottom right is (2560,2160). Boresight direction is -Z in instrument frame. Version 0.1 -- Nov. 18, 2019: Initial release. References ------------------------------------------------------------------------ 1. "Kernel Pool Required Reading" 2. DART Spacecraft Frames Definition Kernel 3. Fletcher et al. (2018), "Design of the Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO) on the double asteroid redirection test (DART)", Proc. SPIE 10698, Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave, 106981X (6 July 2018); doi: 10.1117/12.2310136 Contact Information ------------------------------------------------------------------------ Hari Nair, JHU/APL, Hari.Nair@jhuapl.edu Carolyn Ernst, JHU/APL, Carolyn.Ernst@jhuapl.edu Marc Costa Sitja, NAIF/JPL, Marc.Costa.Sitja@jpl.nasa.gov 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 ( 'kernel_name; ) -- FORTRAN furnsh_c ( "kernel_name" ); -- C cspice_furnsh, kernel_name -- IDL cspice_furnsh( '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 I-kernel start with the characters 'INS' followed by the NAIF DART spacecraft ID number (-135) and then followed by the NAIF three digit code for the instrument (DRACO = 100). The remainder of the name is an underscore character followed by the unique name of the data item. For example, the DRACO boresight direction in the DART_DRACO frame (see [2]) is specified by: INS-135100_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 [3]: As the only instrument aboard DART, the Didymos Reconnaissance and Asteroid Camera for OpNav (DRACO) serves two purposes. First, DRACO provides images to the Small-body Maneuvering Autonomous Real-Time Navigation (SMARTNav) algorithm, allowing the spacecraft to precisely locate and impact the target. In its final moments, DRACO will also characterize the impact site by providing high resolution, scientific imagery of the surface. Derived from the Long Range Reconnaissance Imager (LORRI) on New Horizons, the telescope is a 208 mm aperture, f/12.6, catadioptric Ritchey-Chretien, with a 0.29 degree field of view. A lightweight opto-mechanical structure, with low CTE mirror substrates and a composite baffle tube, maintains telescope focus in the low temperature environment of deep space. At the focal plane is a 2560 by 2160 pixel, panchromatic, front-side illuminated complementary metal oxide semiconductor (CMOS) image sensor, with digital output, global shutter, and low read noise. Mounting Alignment ------------------------------------------------------------------------------ Refer to the latest version of the DART Frames Definition Kernel (FK) [2] for the DRACO reference frame definitions and mounting alignment information. Apparent FOV Layout ------------------------------------------------------------------------------ This section provides a diagram illustrating the DRACO apparent FOV layouts; the windowed FOV (1x1) and the binned FOV (2x2) in the corresponding reference frames. Pixel (1,1) is in the lower left corner of the image, and pixel (2048, 2048) or (1024,1024) is in the top right corner. +X, +Y, +Z axes are defined in the DART Frames Definition Kernel (FK) [2]. | 0.290 deg | Boresight (-Z axis) |<----------------->| is out of the page | | --- +-------------------(2048,2048) pixel (1x1) ^ | (1024,1024) pixel (2x2) | | | | 0.290 deg | +Zdraco | | | x-------------> +Xdraco | | | | | | | | v (2x2) | | | --- (1,1)-------|---------+ Pixel | | v +Ydraco Optical Parameters --------------------------------------------------------------- Basic optical parameters: From Table 2 of [3]: ----------------------------- ------------- parameter value ----------------------------- ------------- Aperture 208.28 mm F/number 12.60 Wavelength range 400 - 1000 nm ----------------------------- ------------- These values are given in the keywords below in the same units as the table above. \begindata INS-135100_APERTURE_DIAMETER = ( 208.28 ) INS-135100_FOCAL_LENGTH = ( 2628.3343 ) INS-135100_WAVELENGTH_RANGE = ( 400, 1000 ) INS-135100_F/NUMBER = ( 12.60 ) INS-135101_APERTURE_DIAMETER = ( 208.28 ) INS-135101_FOCAL_LENGTH = ( 2628.3343 ) INS-135101_WAVELENGTH_RANGE = ( 400, 1000 ) INS-135101_F/NUMBER = ( 12.60 ) INS-135102_APERTURE_DIAMETER = ( 208.28 ) INS-135102_FOCAL_LENGTH = ( 2628.3343 ) INS-135102_WAVELENGTH_RANGE = ( 400, 1000 ) INS-135102_F/NUMBER = ( 12.60 ) \begintext Field of View Parameters --------------------------------------------------------------- |<--------------------------------------------------->| (2560,2160) _____________________________________________________ / ___ | | ^ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | +Y | | | | | | L ^ | | | i + | | | n + | | | e + | | | s + |_____________________________________________________| _V_ / (1,1) + + + + > +X Samples The native resolution of the CMOS image sensor is 2560x2160 pixels, windowed to 2048x2048 pixels. The image may be 2x2 binned or windowed to 1024x1024 pixels. The table below shows the FOV parameters for both unbinned and binned imaging modes. ------------------------------ ----------- ----------- parameter windowed binned (1x1) (2x2) ------------------------------ ----------- ----------- Detector Array Size 2048x2048 1024x1024 Pixel Size, micron 6.5 13 FOV Angular Size, degrees 0.29x0.29 0.29x0.29 IFOV, microradian/pixel 2.473 4.946 ------------------------------ ----------- ----------- which translates to the following keyword and value pairs: \begindata INS-135101_PIXEL_SAMPLES = ( 2048 ) INS-135101_PIXEL_LINES = ( 2048 ) INS-135101_DETECTOR_CENTER = ( 1024, 1024 ) INS-135101_PIXEL_SIZE = ( 6.5 ) INS-135101_IFOV = ( 2.473 ) INS-135102_PIXEL_SAMPLES = ( 1024 ) INS-135102_PIXEL_LINES = ( 1024 ) INS-135102_DETECTOR_CENTER = ( 511.5, 511.5 ) INS-135102_PIXEL_SIZE = ( 13 ) INS-135102_IFOV = ( 4.946 ) \begintext FOV Definitions ------------------------------------------------------------------------------ This section contains definitions for the DRACO 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 DRACO FOVs with respect to the corresponding frames to be a rectangle with the corners defined by the first and last pixels of the first and last lines of the CCD and the boresight along the -Z axis. This FOV definition uses the FOV_ANGULAR_SIZE values from the ``Optical Parameters'' section above converted to degrees. DRACO windowed (1x1) \begindata INS-135101_NAME = 'DART_DRACO_1X1' INS-135101_FOV_FRAME = 'DART_DRACO' INS-135101_FOV_SHAPE = 'RECTANGLE' INS-135101_BORESIGHT = ( 0.0, 0.0, -1.0 ) INS-135101_FOV_CLASS_SPEC = 'ANGLES' INS-135101_FOV_REF_VECTOR = ( 1.0, 0.0, 0.0 ) INS-135101_FOV_REF_ANGLE = ( 0.14509308 ) INS-135101_FOV_CROSS_ANGLE = ( 0.14509308 ) INS-135101_FOV_ANGLE_UNITS = 'DEGREES' \begintext DRACO binned (2x2) \begindata INS-135102_NAME = 'DART_DRACO_2X2' INS-135102_FOV_FRAME = 'DART_DRACO' INS-135102_FOV_SHAPE = 'RECTANGLE' INS-135102_BORESIGHT = ( 0.0, 0.0, -1.0 ) INS-135102_FOV_CLASS_SPEC = 'ANGLES' INS-135102_FOV_REF_VECTOR = ( 1.0, 0.0, 0.0 ) INS-135102_FOV_REF_ANGLE = ( 0.14509308 ) INS-135102_FOV_CROSS_ANGLE = ( 0.14509308 ) INS-135102_FOV_ANGLE_UNITS = 'DEGREES' \begintext End of IK file.