VEX CK SPICE Kernels ==================== This "aareadme.txt" file describes the contents of the kernels/ck directory of the VEX SPICE data server. It also provides the file naming conventions used for the VEX CK files. The CK in this subdirectory provide information on: - predicted and reconstructed spacecraft orientation CKs, - "planning" spacecraft CKs, - orientation CKs for instruments with moving parts. - orientation for the Solar Arrays. Each kernel file provides information of only one of the types above. * Predicted spacecraft orientation CK files are produced by an automated system located at ESAC, operated by the ESA SPICE Team. * "Planning" CK files are also produced using ADCS. These files contain the spacecraft orientation requested by the VEX Project Science Team through the Pointing Timeline Request (PTR) files. Each of these files is produced at the end of a medium term planning cycle. They should only be used in support of the planning activity and NEVER for data analysis since the pointing may change before being implemented on the spacecraft during the short term planning activities. * The third kind of spacecraft orientation CK files contain RECONSTRUCTED data. There shall be only one kernel of this type (if any), with the orientation of the spacecraft for all the time periods for which the predicted attitude was not accurate enough; for these periods, a recostruction of the attitude was requested to ESOC, and stored in this kernel. * The instrument CKs are generated by the instrument teams, and contain orientation of the moving parts for each instrument. * The CKs for the Solar Arrays contain information about their orientation, with respect to the spacecraft reference frame. The contents and time span covered by any CK file may be easily determined using the "ckbrief" utility program available in all copies of the SPICE Toolkit. Examples of usage: %ckbrief This utility requires a SPICE sclk file and an lsk file in addition to the CK file; use the latest versions of these files. Descriptive information about how/why/when an CK 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 CK files (*.BC) contained in this directory are unix binary files. These may be used as is (without format conversion) in a non-unix environment when using any recent version of the SPICE Toolkit (Version N0052 or later). For information on the content of this folder or information in general on SPICE for VEX, contact ESA SPICE Team, esa_spice@sciops.esa.int , or Jose Luis VAzquez, jlvazquez@sciops.esa.int References ========== 1. Data Delivery Interface Document (DDID), Appendix H - FD products Issue 3.0 (VEX-ESC-IF-5003) 2. CK Required Reading (NAIF Document). 3. NAIF IDs Required Reading (NAIF Document). 4. Venus Express Frames Definition Kernel (FK), latest version. All the NAIF Documents are available at the NAIF web: http://naif.jpl.nasa.gov Venus Express CK Directory Structure ==================================== aareadme.txt This file. former_versions Subdirectory that contains obsolete versions of the CK files that have been updated in the Current CK Kernels Set. ATNV_PYYMMDDhhmmss_xxxxx.BC Contains Venus Express predicted attitude information covering the time span starting at the date YYMMDDhhmmss. This attitude information corresponds to the ESOC attitude file named: ATNV_FDLMMA_DAPYYMMDDhhmmss_xxxxx.VEX where xxxxx designates the version number. ATPV_Pvvvvv_YYMMDD_xxxxx.BC Contains Venus Express medium term planning predicted attitude information covering the time span starting at the date YYMMDD. This attitude information corresponds to the ESOC attitude file named: ATPV_FDLVMA_DAPvvvvv_YYMMDD_xxxxx.VEX where xxxxx designates the version number. This attitude information corresponds to the PTR file version vvvvv delivered from VSOC to ESOC and it is intended for the Teams to check the pointings. The final attitude file is fixed after iterating the PTR and it may differ from this "planning C-Kernel." (*) ATPV_PxNyHz_YYMMDD_xxxxx.BC Planning attitude kernels used during quadrature. These files correspond to the ESOC files ATPV_FDRVMA_DAPxNyHz_YYMMDD_xxxxx.VEX x - ecliptic flag y - north flag z - HGA flag xxxxx - version of the file ATPV_PExHG1_YYMMDD_xxxxx.BC Same as above, but with an older naming scheme ATNV_RECONSTITUTED_xxxxx.BC Contains Venus Express RECONSTITUTED attitude information. This attitude information corresponds to all reconstituted attitude files delivered from ESOC to PST. This file is updated every time new reconstituted data are available. The file contains gaps between data segments. Extensive documentation specifying valid interpolation intervals (periods with no data gaps) is provided in the comment area. Please refer to text above for information about using the COMMNT utility. ATNV_MEASURED_Vvv.BC Contains Venus Express MEASURED attitude, provided by the onboard AOCS system. The coverage is not coninuous; instead, periods with measured attitude are added to this kernel as requested by the Teams. VEX_BOOM_vxx.BC This file contains orientation of the Venus Express Magnetometer's Boom frame ('VEX_MAG_MAGB' frame) relative to the Magnetometer's Boom hinge frame ('VEX_MAG_MAGB-H' frame). VEX_SA_YYYYVvvvv.BC Contains orientation for the Solar Arrays, for the year YYYY. vvvv is the version number, and it is increased when new data is added to the file. ------------------- This file was last modified on March 17th, 2009. (J. Vazquez)