KPL/FK Huygens Probe Frame Definitions Kernel ============================================================================== This frame kernel contains the Huygens Probe frame definitions. Version 0.0 -- Jul 30, 2018 -- Alfredo Escalante (ESAC/ESA) -- Initial Release. References ---------------------------------------------------------- 1. ``C-kernel Required Reading'' 2. ``Kernel Pool Required Reading'' 3. ``Frames Required Reading'' 4. Huygens User Manual. Aerospatiale Espace and Defense. Contact Information ---------------------------------------------------------- Direct questions, comments, or concerns about the contents of this kernel to: 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. The SPICELIB routine FURNSH loads a kernel file 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 ) This file was created and may be updated with a text editor or word processor. Huygens Frames ---------------------------------------------------------- The following Huygens frames are defined in this kernel file: Frame Name Relative To Type NAIF ID ======================= =================== ======= ======= Spacecraft Frame: ----------- HUYGENS_PROBE J2000 FIXED -150000 Science Instrument frames: -------------------------- HUYGENS_DISR HUYGENS_PROBE CK -150100 Huygens Frames Hierarchy ---------------------------------------------------------- Notes: This diagram is subject to major revisions as this kernel evolves to suit the needs of each instrument. The diagram below shows the Huygens frames hierarchy: 'IAU_TITAN' (TITAN BODY FIXED) | |<--- pck | 'J2000' INERTIAL | |<--- ck | 'HUYGENS_DISR' | |<--- fixed | 'HUYGENS_PROBE' Spacecraft Configuration Description ---------------------------------------------------------- The Probe can be schematically described as a kernel surrounded by a shell, the kernel carrying all the experiments and service units operating during the decent while the shell protects it during the Cruise, Coast and Entry phases and is then jettisoned at the beginning of the Descent. The kernel is mainly constituted by two platforms supporting the Experiments and the equipment units assembled by light secondary structures. The jettisonable shell is constituted by a spherical-conical front shield and a back cover to complete the thermal protection during atmospheric entry. This jettison is aerodinamically operated by a Main Parachute large enough to pull the kernel rearwards from the Front Shield. This Main Parachute itself is extracted, along with the Back Cover, by the Pilot Chute which deployment is triggered by an acceleration threshold and extracted by a Pilot chute Deployment device (PDD). The threshold is detected by the Command and Data Management Subsystem (CDMS) accelerometers, then the Main Chute is jettisoned and a smaller Stabilizer Chute is deployed which allows the required Descent time. Swivels ensure decoupling of the Probe from possible parachute rotations. Probe controlled spin is provided by a series of aerodynamic winglets. Spacecraft Frame ---------------------------------------------------------- This scheme shows in a simplified way the body fixed reference frame as defined in [4], for more detailed description of the layout of the probe in descent configuration, refer to section 2.2 "Probe systems description", in [4] Huygens Probe +X ^ | | ---------------------------------- / \ / \ / \ --------------------|-------------------- | | | ---------------------x--------------------- ----> +Y \_ _/ \_ \ \ \ | | | / / /__/ \_______________________________/ +Z ^ | ___|___ ______|_______|______ ___/ | DISR | \___ / |_______| \ __/ \__ / \ / ^ \ | | | | | | | o-----> | ---> +Y | | | | | | | | \ / \__ __/ \ / \___ ___/ \_____________________/ From [4]: ``The spacecraft reference frame is a structural reference frame, defined when the probe has ejected the front and back shields and is in descent configuration as described in [4]. The origin of the reference frame axis is located on the bottom face of the experiment platform. The +X axis is coincident with the axis of revolution of the probe cover. The +Z axis is parallel to the line joining the origin of the reference frame with the DISR instrument center. The +Y axis completes the orthonormal reference frame. '' Spacecraft attitude with respect to an inertial frame is provided by a C kernel (see [1] for more information). \begindata FRAME_HUYGENS_PROBE = -150000 FRAME_-150000_NAME = 'HUYGENS_PROBE' FRAME_-150000_CLASS = 4 FRAME_-150000_CLASS_ID = -150000 FRAME_-150000_CENTER = -150 TKFRAME_-150000_SPEC = 'ANGLES' TKFRAME_-150000_RELATIVE = 'HUYGENS_DISR' TKFRAME_-150000_ANGLES = ( 0.0, 0.0, 0.0 ) TKFRAME_-150000_AXES = ( 1, 2, 3 ) TKFRAME_-150000_UNITS = 'DEGREES' \begintext DISR: Descent Imager/Spectral Radiometer Frame ------------------------------------------------------------------------------- \begindata FRAME_HUYGENS_DISR = -150100 FRAME_-150100_NAME = 'HUYGENS_DISR' FRAME_-150100_CLASS = 3 FRAME_-150100_CLASS_ID = -150100 FRAME_-150100_CENTER = -150 CK_-150100_SCLK = -150 CK_-150100_SPK = -150 \begintext HUYGENS NAIF ID Codes -- Definition Section ======================================================================== This section contains name to NAIF ID mappings for the Huygens Probe. Once the contents of this file is loaded into the KERNEL POOL, these mappings become available within SPICE, making it possible to use names instead of ID code in the high level SPICE routine calls. Spacecraft and its structures: ------------------------------ HUYGENS -150 CASSINI PROBE -150 CASP -150 HUYGENS_PROBE -150000 HUYGENS_SPACECRAFT -150000 HUYGENS_BUS -150000 HUYGENS_INSTRUMENT_PLATFORM -150000 HUYGENS_PLATFORM -150000 Science Instruments: -------------------- HUYGENS_DISR -150100 HUYGENS_DISR_SLI -150101 HUYGENS_DISR_MRI -150102 HUYGENS_DISR_HRI -150103 The mappings summarized in this table are implemented by the keywords below. \begindata NAIF_BODY_NAME += ( 'HUYGENS' ) NAIF_BODY_CODE += ( -150 ) NAIF_BODY_NAME += ( 'CASSINI PROBE' ) NAIF_BODY_CODE += ( -150 ) NAIF_BODY_NAME += ( 'CASP' ) NAIF_BODY_CODE += ( -150 ) NAIF_BODY_NAME += ( 'HUYGENS_PROBE' ) NAIF_BODY_CODE += ( -150000 ) NAIF_BODY_NAME += ( 'HUYGENS_SPACECRAFT' ) NAIF_BODY_CODE += ( -150000 ) NAIF_BODY_NAME += ( 'HUYGENS_BUS' ) NAIF_BODY_CODE += ( -150000 ) NAIF_BODY_NAME += ( 'HUYGENS_INSTRUMENT_PLATFORM' ) NAIF_BODY_CODE += ( -150000 ) NAIF_BODY_NAME += ( 'HUYGENS_PLATFORM' ) NAIF_BODY_CODE += ( -150000 ) NAIF_BODY_NAME += ( 'HUYGENS_DISR' ) NAIF_BODY_CODE += ( -150100 ) NAIF_BODY_NAME += ( 'HUYGENS_DISR_SLI' ) NAIF_BODY_CODE += ( -150101 ) NAIF_BODY_NAME += ( 'HUYGENS_DISR_MRI' ) NAIF_BODY_CODE += ( -150102 ) NAIF_BODY_NAME += ( 'HUYGENS_DISR_HRI' ) NAIF_BODY_CODE += ( -150103 ) \begintext Definition of the nadir frame ----------------------------- All vectors are geometric: no aberration corrections are used. The +X axis points from the center of Titan to the Spacecraft. The component of Titan's north pole direction orthogonal to to X is aligned with the +Z axis; the +Z axis points North. The +Y axis is the cross product of the +Z axis and the -X axis; the +Y axis points West. Frame specification data ------------------------ \begindata FRAME_HUYGENS_NADIR = 1400150 FRAME_1400150_NAME = 'HUYGENS_NADIR' FRAME_1400150_CLASS = 5 FRAME_1400150_CLASS_ID = 1400150 FRAME_1400150_CENTER = -150 FRAME_1400150_RELATIVE = 'J2000' FRAME_1400150_DEF_STYLE = 'PARAMETERIZED' FRAME_1400150_FAMILY = 'TWO-VECTOR' FRAME_1400150_PRI_AXIS = '-X' FRAME_1400150_PRI_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_1400150_PRI_OBSERVER = -150 FRAME_1400150_PRI_TARGET = 'TITAN' FRAME_1400150_PRI_ABCORR = 'NONE' FRAME_1400150_SEC_AXIS = 'Y' FRAME_1400150_SEC_VECTOR_DEF = 'CONSTANT' FRAME_1400150_SEC_SPEC = 'RECTANGULAR' FRAME_1400150_SEC_VECTOR = ( 0, 0, 1 ) FRAME_1400150_SEC_FRAME = 'IAU_TITAN' FRAME_1400150_SEC_ABCORR = 'NONE' \begintext