============================================================================= MEX CK Files ============================================================================= Last update: 22 NOV 2005 This "aareadme.txt" file describes the contents of the KERNELS/CK directory of the MEX SPICE data server. It also provides the file naming conventions used for the MEX CK files, and it provides identification of the most current version of each kind of CK file. Four kinds of CK files exist in this subdirectory: predicted and reconstructed spacecraft orientation CKs, ``planning'' spacecraft CKs, and ASPERA scanner orientation CKs. Predicted spacecraft orientation CK files are produced by an automated system located at ESTEC, operated by the MEX Project Science Team (PST). We have chosen to use the ESOC naming convention for these predicted CK files, which are converted from ESOC's DDID Attitude files using the Auxiliary Data Conversion System (ADCS). Although this convention doesn't seem very descriptive and holds some redundant information, it was decided to use the same name style for the sake of consistency. Also, data handling performed by the PST automated system will be easier and faster. ``Planning'' CK files are also produced using ADCS. These files contain the spacecraft orientation requested by the MEX 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. These data, originally in ESOC's DDID format, are converted to CK files using ADCS. Then the new CK files are appended to the existing ``Reconstituted Data kernel file''. The comment area of this kernel is updated every time new data are appended. This process is executed manually. The MEX ASPERA-3 CK has been produced by the ASPERA Team and released to the Mars Express Project Science Team (PST). This file contains the ASPERA scanner orientation data and it will be updated on a monthly basis whenever the scanner begins its operation. 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). [Ref 3b] Contact Jorge Diaz del Rio (jdiaz@rssd.esa.int) or Joe Zender (Joe.Zender@esa.int) if you have any questions. ============================================================================= References ============================================================================= 1. Data Delivery Interface Document (DDID) Appendix H - FD products Issue 3.0 (MEX-ESC-IF-5003) 2. CK Required Reading. NAIF Document No. 174.08 3. Selected SPICE Tutorials from the NAIF server: ftp://naif.jpl.nasa.gov/pub/naif/toolkit_docs/Tutorials/office/individual_docs a) CK Tutorial 15_ck.ppt b) Porting Kernels Tutorial 09_porting_kernels.ppt 4. NAIF IDs Required Reading. NAIF Document No. 219.12 5. Mars Express Frames Definition Kernel (FK), latest version. ============================================================================= Mars Express CK Directory Structure ============================================================================= aareadme.txt Text file describing the directory structure, the naming conventions for the CKs, and the current version(s) of each CK type. former_versions Subdirectory that contains obsolete versions of the CK files that have been updated in the Current CK Kernels Set. ============================================================================= MEX Predicted S/C CK Naming Convention ffff_yYYMMDDhhmmss_xxxxx.ee ============================================================================= token description ------------ -------------------------------------------------- ffff Source Product Type Identifier: ATNM -- Predicted S/C attitude y Data Type Identifier P -- Predicted data YYMMDDhhmmss Coverage start time of the data contained in the ATNM file. xxxxx version number ee NAIF File Name Extension -- "BC" (binary C kernel) ============================================================================= MEX Reconstructed S/C CK Naming Convention ffff_RECONSTITUTED_xxxxx.ee ============================================================================= token description ------------ -------------------------------------------------- ffff Source Product Type Identifier: ATNM -- Reconstructed S/C attitude xxxxx file version number ee NAIF File Name Extension -- "BC" (binary C kernel) ============================================================================= MEX "Planning CK" Naming Convention ffff_PTRvvvvv_YYMMDD_xxx.ee ============================================================================= token description ------------ -------------------------------------------------- ffff Source Product Type Identifier: ATNM -- Predicted S/C attitude vvvvv PTR version number YYMMDD Coverage start time of the data contained in the ATNM file. xxx file version number ee NAIF File Name Extension -- "BC" (binary C kernel) ============================================================================= MEX ASPERA-3 CK Naming Convention MEX_ASPERA_SAF_yymmdd_xx.BC ============================================================================= token description ------------ -------------------------------------------------- yymmdd Coverage start time of the data contained in the file. xxx file version number. ============================================================================= Current CK Kernels Set ============================================================================= Name Comments -------------------------------- ------------------------------------- ATNM_PYYMMDDhhmmss_xxxxx.BC Contains Mars Express predicted attitude information covering the time span starting at the date YYMMDDhhmmss. This attitude information corresponds to the ESOC attitude file named: ATNM_FDLMMA_DAPYYMMDDhhmmss_xxxxx.MEX where xxxxx designates the version number. ATNM_PTRvvvvv_YYMMDD_xxx.BC Contains Mars Express predicted attitude information covering the time span starting at the date YYMMDD. This attitude information corresponds to the PTR file version vvvvv delivered from POS 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". ATNM_RECONSTITUTED_xxxxx.BC Contains Mars 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. MEX_ASPERA_SAF_yymmdd_xx.BC Contains the Mars Express ASPERA-3 Sensor Assembly Frame (SAF) orientation data relative to the ASPERA-3 Unit Reference Frame. These data describe the rotation of the ASPERA-3 scanner. The file covers the time span starting at the date yymmdd. For further information about the definition of these frames, please refer to [5].