MEX CK SPICE Kernels
====================
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.
The CK in this subdirectory provide information on:
- predicted, measured 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 generated with the commanded
attitude. These files also contain a long Earth pointing block (of
around 24 hours) that reflects the attitude the S/C would fly without
a command update. Theses files are produced by a 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 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. These files also contain a long
Earth pointing block (of around 24 hours) that reflects the attitude the
S/C would fly without a command update. 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 MEASURED
data. These files contain the attitude obtained from the quaterions
extracted from the housekeeping telemetry data. In some occasions the
measured quaternions may be of reduced quality. For example if the number
of stars tracked by the star tracker is not sufficient and the attitude is
controlled only based on gyro-information for a period of time, the
on-board estimated quaternions can drift. In such cases the available
information would have to be analysed specifically.
* The fourth kind of spacecraft orientation CK files contain RECONSTRUCTED
data. There should be only one kernel of this type, 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 <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).
For information on the content of this folder or information in general on
SPICE for MEX, contact
ESA SPICE Team spice@sciops.esa.int
, or
Alfredo Escalante Lopez aescalante@sciops.esa.int
References
==========
1. Data Delivery Interface Document (DDID), Appendix H - FD products
Issue 3.0 (MEX-ESC-IF-5003)
2. CK Required Reading (NAIF Document).
3. NAIF IDs Required Reading (NAIF Document).
4. Mars Express Frames Definition Kernel (FK), latest version.
All the NAIF Documents are available at the NAIF web:
http://naif.jpl.nasa.gov
Mars 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.
ATNM_PYYMMDDhhmmss_xxxxx.BC SPICE Kernel (CK) that contains Mars
Express predicted attitude as commanded
information and an extension of Earth
pointing covering the time span starting
at the date YY-MM-DD hh:mm:ss. This
attitude information corresponds to
the ESOC attitude file named:
ATNM_FDLMMA_DAPYYMMDDhhmmss_xxxxx.MEX
where xxxxx designates the version number.
ATNM_T6_PYYMMDDhhmmss_xxxxx.BC SPICE Kernel (CK) that contains Mars
Express predicted attitude as commanded
information starting at the date
YYMMDDhhmmss. This product is a Type 6 CK
kernel and requires at least the SPICE
Toolkit N0065 to be used. This attitude
information corresponds to the ESOC
attitude file named:
ATNM_FDLMMA_DAPYYMMDDhhmmss_xxxxx.MEX
where xxxxx designates the version number.
ATNM_SGS_PYYMMDDhhmmss_xxxxx.BC
SPICE Kernel (CK) that contains Mars
Express spacecraft predicted attitude
information and an extension of Earth
pointing covering the time span starting
at the date YY-MM-DD. This product is a
Type 6 CK kernel and requires at least
the SPICE Toolkit N0065 to be used. 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 SPICE Kernel (CK) that contains Mars
Express predicted attitude information
and an extension of Earth pointing covering
the covering the time span starting at the
date YY-MM-DD. 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_MEASURED_YYYY_Vvv.BC SPICE Kernel (CK) that contains Mars Express
measured attitude, provided by the onboard
AOCS system. The coverage is for the year
indicated by YYYY.
ATNM_RECONSTITUTED_xxxxx.BC SPICE kernel (CK) that 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 SPICE kernel (CK) that 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 YY-MM-DD.
MEX_PFS_ZERO_Vvv.BC SPICE kernel (CK) that contains the Mars
Express PFS Scanner position. These data
provide a zero rotation of the PFS scanner
for the entire mission duration.
MEX_SA_YYYY_Vvvvv.BC SPICE kernel (CK) that contains orientation
for the Mars Express Solar Arrays, for the
year YYYY. Vvvvv is the version number.
-------------------
This file was last modified on March 22th, 2021. (R. Valles)
End of aareadme file.