KPL/FK Frame (FK) SPICE kernel file for Hera science operations frames =============================================================================== This frames kernel defines a number of frames used by the Hera science operations centre to perform mission analysis and attitude dependent science opportunity identification. These frames can be used stand-alone, i.e. referring directly to them and assuming they correspond to the Hera spacecraft reference frame, or in combination with the Hera spacecraft frames. The latter will allow the user to use the existing alignments and instrument frame definitions to perform instrument specific mission analysis and attitude dependent science opportunity identification. Please refer to the section ``Using these frames'' for further details. Version and Date ------------------------------------------------------------------------------- Version 0.0 -- May 22, 2016 -- Marc Costa Sitja, ESAC/ESA Initial version. References ------------------------------------------------------------------------------- [1] "Frames Required Reading" [2] "Kernel Pool Required Reading" Contact Information ------------------------------------------------------------------------------- If you have any questions regarding this file contact SPICE support at ESAC: Marc Costa Sitja (+34) 91-8131-457 mcosta@sciops.esa.int, esa_spice@sciops.esa.int 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 Hera Science Operations frame names and NAIF ID Codes ------------------------------------------------------------------------------- The following frame is defined in this kernel file: SPICE Frame Name Long-name ------------------------ --------------------------------------------- HERA_DIDYMOS_NPO Hera Didymos Nadir power-optimized pointing These frame has the following centers, frame class and NAIF ID: SPICE Frame Name Center Class NAIF ID ------------------------ --------------------- ------- --------- HERA_DIDYMOS_NPO HERA DYNAMIC -667010 The keywords implementing that frame definitions is located in the "TGO Science Operations Frame Definitions" section. General Notes About This File ------------------------------------------------------------------------------- About Required Data: -------------------- All the dynamic frames defined in this file require at least one of the following kernel types to be loaded prior to their evaluation, normally during program initialization: - Planetary and Satellite ephemeris data (SPK), i.e. de432, de405, etc; - Spacecraft ephemeris data (SPK); Note that loading different kernels will lead to different orientations of the same frame at a given epoch, providing different results from each other, in terms of state vectors referred to these frames. Using these frames ------------------ These frames have been implemented to define the different pointing profiles for the Hera spacecraft. These pointing profiles can be used in two different ways: [1] ``As is'' for analysis of offsets between the spacecraft attitude defined in the corresponding CK and a given pointing profile. Loading this kernel in combination with any Hera CK will allow the user to perform this comparison between the HERA_SPACECRAFT frame and any of the different frames defined within this kernel. [2] In combination with the Hera Frames kernel, to define a default pointing profile for the whole duration of the mission together with the spacecraft and instrument frames defined in the Hera FK. In this way, instrument-specific mission analysis activities, for which a particular pointing profile and knowledge of the instruments is required, can be conducted without the need for a spacecraft CK. In order to define such default pointing profile, the latest Hera frames kernel and this file shall be loaded before the selected ``Hera spacecraft frame overwrite'' frame kernel. As an example, imagine that the desired default pointing profile is "Nadir power optimized with respect to Didymos", then the furnish (metakernel) file should contain the following sequence of frames kernels, in the following order: ... $DATA/fk/hera_v00.tf $DATA/fk/hera_ops_v00.tf $DATA/fk/hera_sc_didymos_npo_v00.tf ... (*) the example presents version 0.0 of the Hera frames and Hera Science Operations frames kernels. Newer versions of these files will produce the same results. By loading the ``hera_sc_didymos_npo_vNN.tf'' frames kernel last, the spacecraft frame HERA_SPACECRAFT, which is defined as a CK-based frame in the ``Hera frames kernel'', will be overwritten as a type-4 fixed offset frame, mapping the HERA_SPACECRAFT frame to the HERA_DIDYMOS_NPO frame defined in the ``Hera Science Operations Frames Kernel'' (this) file. Hera Science Operations Frame Definitions ------------------------------------------------------------------------------- This section contains the definition of the Hera science operations frames. Hera Mars Nadir power-optimized pointing frame (HERA_DIDYMOS_NPO) ------------------------------------------------------------------------ Definition: ----------- The Hera Didymos Nadir power-optimized pointing frame is defined as follows (from [3]): - -Y axis is the primary vector and points from Hera to the center of Didymos (Nadir direction); - -X axis is the secondary vector and is the orthogonal component to the -Y axis of the Sun position relative to Hera; - +Z axis completes the right-handed system; - the original of this frame is the spacecraft's center of mass. All vectors are geometric: no corrections are used. Required Data: -------------- This frame is defined as a two-vector frame. Both the primary and the secondary vector are defined as an 'observer-target position' vectors, therefore, the ephemeris data required to compute both the Hera-Didymos position and the Hera-Sun position in J2000 frame have to be loaded before using this frame. Remarks: -------- Since the primary and secondary vectors of this frame are defined based on the Hera-Didymos position and Hera-Sun position vectors, the usage of different ephemerides to compute these vectors may lead to different frame orientation at given time. \begindata FRAME_HERA_DIDYMOS_NPO = -667010 FRAME_-667010_NAME = 'HERA_DIDYMOS_NPO' FRAME_-667010_CLASS = 5 FRAME_-667010_CLASS_ID = -667010 FRAME_-667010_CENTER = -667 FRAME_-667010_RELATIVE = 'J2000' FRAME_-667010_DEF_STYLE = 'PARAMETERIZED' FRAME_-667010_FAMILY = 'TWO-VECTOR' FRAME_-667010_PRI_AXIS = 'Z' FRAME_-667010_PRI_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_-667010_PRI_OBSERVER = 'HERA' FRAME_-667010_PRI_TARGET = 'DIDYMOS' FRAME_-667010_PRI_ABCORR = 'NONE' FRAME_-667010_SEC_AXIS = 'X' FRAME_-667010_SEC_VECTOR_DEF = 'OBSERVER_TARGET_POSITION' FRAME_-667010_SEC_OBSERVER = 'HERA' FRAME_-667010_SEC_TARGET = 'SUN' FRAME_-667010_SEC_ABCORR = 'NONE' FRAME_-667010_SEC_FRAME = 'J2000' \begintext End of FK file.