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MEX CK Files
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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 <ck_file_name> <sclk_file_name> <lsk_file_name>
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 <ck_file_name>
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 Jose Luis Vazquez (jlvazquez@sciops.esa.int) or Joe Zender
(Joe.Zender@esa.int) if you have any questions.
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References
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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.
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Mars Express CK Directory Structure
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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.
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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)
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MEX Reconstructed S/C CK Naming Convention ffff_RECONSTITUTED_xxxxx.ee
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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)
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MEX "Planning CK" Naming Convention ffff_PTRvvvvv_YYMMDD_xxx.ee
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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)
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MEX ASPERA-3 CK Naming Convention MEX_ASPERA_SAF_yymmdd_xx.BC
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token description
------------ --------------------------------------------------
yymmdd Coverage start time of the data contained in the
file.
xxx file version number.
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Current CK Kernels Set
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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].