General information about SPICE SP-kernels ========================================== The purpose of the SP-kernel -- which stands for S(pacecraft) and P(lanet) Kernel -- is to allow ephemerides for any collection of solar system bodies, spacecraft or any other objects in 3D space to be combined under a common file format, and accessed by a common set of subroutines. SPK can be accessed by subroutines that are part of the SPICE library, the major component of the SPICE Toolkit. These subroutines can be integrated into user application programs. For information on the SPICE Toolkit and/or how to obtain it, please consult SPICE_INST.CAT and SOFT.CAT. To use SP-kernels, a Leapseconds (LSK) is also required. To use SP-Kernels containing positions given relative to the non-inertial and project-defined frames, one or more of Frame Definitions Kernel (FK), Planetary Constants Kernel (PcK), and C-Kernel (CK) files may also be required. Refer to the SPK.REQ document provided with the Toolkit to get more information on how to access SP-kernel data. Venus Express SPK Files ======================= This file describes the contents of the DATA/SPK directory of the Venus Express SPICE data set. Sources of kernels and naming convention: ---------------------------------------- - Kernels that are produced from the ESOC Flight Dynamics orbit products. These kernels are generated by an automated system located at ESAC, and operated by the ESAC SPICE Service. The naming convention for these kernels is the same used in the Ephemeris products used to create them; their file name start by OR. - Kernels that store information about Solar System bodies, ground stations, etc. They are produced by NAIF/JPL, and keep their original name, but in capitals, to be PDS compliant. The contents and time span covered by any SPK file may be easily determined using the 'brief' utility program available in all copies of the SPICE Toolkit. Examples of usage: %brief %brief <*.bsp> %brief Descriptive information about how/why/when an SPK file was created is usually available in the 'comment area' of the file. This may be viewed using the 'commnt' utility program available in all copies of the SPICE Toolkit. Use the '-r' option to read the comments. Example: %commnt -r All binary SPK files (*.BSP) contained in this directory are little-endian (LTL-IEEE) binary files. Venus Express SPK-Kernels Contained in this Data Set ==================================================== The following SPK-kernels are provided in this data set: DE405.BSP This file contains ephemeris data for the main Solar System bodies (planets barycenters, Mercury, Venus, Moon, Earth, Mars and Sun). It covers from Jan. 1950 to Jan. 2050. EARTHSTNS_FX_yymmdd.BSP Contains ephemeris data for NASA DSN stations relative to the terrestrial reference frame ITR93. In the interest of flexibility, in this file the reference frame is labelled with the alias 'EARTH_FIXED'. Any application using this file must map the alias 'EARTH_FIXED' to either 'ITR93' or 'IAU_EARTH'. This file was released on yy-mm-dd. EARTHSTNS_ITRF93_yymmdd.BSP Contains ephemeris data for NASA DSN stations relative to the terrestrial reference frame label 'ITR93'. This file was released on yy-mm-dd. ESTRACK_Vvv.BSP Contains locations of ESA tracking stations. In the interest of flexibility, in this file the reference frame is labeled with the alias 'EARTH_FIXED'. Any application using this file must map the alias 'EARTH_FIXED' to either 'ITR93' or 'IAU_EARTH'. OUTERPLANETS_Vvvvv.BSP Ephemeris information (predicted) for the outer planets of the solar system: Jupiter, Saturn, Uranus and Neptune. It is meant to complement DE405.BSP, which contains information for their barycenters, but not the bodies themselves. VEX_STRUCT_Vvv.BSP This file contains the location of various Venus-Express instruments and structures. ORVM_T19___________xxxxx.BSP SPICE kernel containing the latest VEX predicted and reconstructed ephemeris for both cruise and after orbit insertion and until End of Mission. This ephemeris corresponds to the final ESOC orbit file named: VOEM_150721OAS_PREDICT__0001.CR.gz.txt This is the file that should be used for data analysis after the End of Mission. Note that several versions of the same kernel can be provided. In that case, the file with the highest version number is the most up to date, and the one that should be used. Note: Files EARTHSTNS_FX_yymmdd.BSP and EARTHSTNS_ITRF93_yymmdd.BSP contain the same data. These files only differ in that the second one use the reference frame label 'ITR93' instead of 'EARTH_FIXED'. 'EARTH_FIXED' alias must be map to either 'ITR93' or 'IAU_EARTH' before using the file. For high accuracy work, EARTHSTNS_ITRF93_yymmdd.BSP is recommended (on the basis of ease of use). Kernel File Details =================== The most detailed description of the data in each SPK file is provided in metadata included inside the comment area of the file. This information can be viewed using utility programs 'commnt' and 'spacit' included in the SPICE Toolkit. At least a basic knowledge of the SPICE system is needed in order to use these kernels. The SPICE Toolkit provides versions in Fortran (SPICELIB), C (CSPICE), IDL (Icy), Matlab (Mice), and Java (JNISpice) and the user can choose any one that suits him/her. The SPICE routine FURNSH can be used to load a kernel file into a SPICE-based application to make kernel data usable with SPICE APIs. In the case when two or more binary SPK files contain data overlapping in time for a given object the file loaded last takes precedence. Please note that SPKs that contain 'T19' in their filename indicate that they are Type 19 SPKs as opposed to type 18. T19 SPKs contain the same data as their non-T19 counterparts but they have precedence due to computational efficiency (although they require Toolkit version N0065 or higher).