============================================================================= SMART-1 Orbit Number Files ============================================================================= Last update: 29 OCT 2007 This "aareadme.txt" file describes the contents of the KERNELS/ORBNUM directory of the SMART-1 SPICE data server. It also provides the file naming conventions used for the SMART-1 Orbit Number files, and it provides identification of the most current version of each kind of ORBNUM file. These are created from the SPK files converted from the ESOC DDID Orbit Files. Orbit Number files (*.ORB) contained in this directory are unix text files. These may be used in a non-compatible text environment by using the ASCII mode of FTP to port the files. [Ref 2a] Contact Jose Luis Vazquez (jlvazquez@sciops.esa.int) or Jorge Diaz del Rio (jdiaz@sciops.esa.int) if you have any questions regarding this file. ============================================================================= References ============================================================================= 1. Data Delivery Interface Document (DDID) Appendix H - FD products Issue 3.0 (S1-ESC-IF-5003) 2. Selected SPICE Tutorials from the NAIF server: ftp://naif.jpl.nasa.gov/pub/naif/toolkit_docs/Tutorials/office/individual_docs a) Porting Kernels Tutorial 09_porting_kernels.ppt b) Derived Quantities Tutorial 21_derived_quant.ppt 3. ESA Generic Frame Definitions Kernel (FK), latest version. ============================================================================= Important Note Regarding Orbit Number Files ============================================================================= The official SMART-1 orbit number files are produced by NAIF's ORBNUM utility program for both the Earth escape and the lunar phases (ORES and ORMS identifiers). In both cases, the same set of derived quantities is provided, although the reference frames used in each case are different, and so is the orbit numbering scheme that define the orbit boundaries and pericenter numbers. ----------------------------------------------------------------------------- About the Inertial Frames used in the Orbit Number Files ----------------------------------------------------------------------------- In the Earth escape phase orbit number file (ORES), the J2000 inertial frame is used to compute the orbital elements and the IAU_EARTH body-fixed frame for sub-solar lon/lat and sub-spacecraft lon/lat/alt. In the lunar phase orbit number file (ORMS), the Moon Mean Equator of date J2000 (LME2000) inertial frame is used to compute the orbital elements, and the IAU_MOON body-fixed frame for sub-solar lon/lat and sub-spacecraft lon/lat/alt. The LME2000 inertial frame is defined as follows: * Z-axis towards the Moon north pole of epoch 2000; * X-axis towards the descending node of Earth's equator of epoch 2000 with respect to Moon's equator of epoch 2000; * Y-axis completes the right-handed system; * the origin of the frame is the Moon's center of mass. Epoch 2000 refers to 2000-01-01T12:00:00 (TDB). For further information about this frame please refer to ESA generic Frame Definitions Kernel [Ref. 3]. ----------------------------------------------------------------------------- About the Orbit Numbering Scheme used in the Orbit Number Files ----------------------------------------------------------------------------- In the Earth escape phase orbit number file (ORES), each of the records contains the time of THAT orbit's pericenter and the time of the NEXT orbit's apocenter. For example, the line for orbit ``3'' provides UTC and SCLK of orbit ``3'' pericenter and UTC of orbit ``4'' apocenter. Since the project accepted orbit numbering scheme for the Earth escape phase dictates the orbit number change to occur at apocenter, the time boundaries for a given orbit can be determined by taking the apocenter time from the PREVIOUS orbit record and the apocenter time from THIS orbit record. Orbit number 1 for the Earth escape phase corresponds to the first orbit after Launch. In the Lunar phase orbit number file (ORMS), each of the records contains the time of PREVIOUS orbit's pericenter and the time of THIS orbit apocenter. For example, the line for orbit ``3'' provides UTC and SCLK of orbit ``2'' pericenter (*) and UTC of orbit ``3'' apocenter. Since the project accepted orbit numbering scheme for the Lunar phase dictates that orbit number change to occur at apocenter, and it starts counting from Moon Capture(*), the time boundaries for a given orbit can be determined by taking the apocenter time from THIS orbit record and the apocenter time from NEXT orbit record. Orbit number 1 for the Lunar phase corresponds to the first orbit after Moon Capture(*). All derived quantities provided on each record -- sub-solar lon/lat, sub-spacecraft lon/lat/alt, and orbital elements -- are computed for the time of pericenter. (*) NOTE that Moon Capture was considered to be after the first perilune passage (that is considered pericenter number 1) and therefore there is a mismatch between pericenter numbering and orbit numbering, being N+1 the pericenter number for orbit number N. For example, the line for orbit ``3'' provides UTC and SCLK of orbit ``2'' pericenter, despite being numbered pericenter ``3''. ----------------------------------------------------------------------------- Example ----------------------------------------------------------------------------- This is an example of SMART-1 Earth escape phase orbit number file (spacing was altered to fit the page): No Event UTC PERI Event SCLK PERI OP-Event UTC APO ... == ==================== ================== ==================== ... 1 2003 SEP 28 10:12:33 1/0000036974.26621 2003 SEP 28 15:33:06 ... 2 2003 SEP 28 20:53:40 1/0000075441.18435 2003 SEP 29 02:14:13 ... 3 2003 SEP 29 07:34:46 2/0000030087.21830 2003 SEP 29 12:55:19 ... 4 2003 SEP 29 18:15:53 2/0000068553.57508 2003 SEP 29 23:36:26 ... ... Given this example one can determine that: -- orbit 3 pericenter time is ``2003 SEP 29 07:34:46'' -- orbit 3 time boundaries are from ``2003 SEP 29 02:14:13'' to ``2003 SEP 29 12:55:19'' This is an example of SMART-1 Lunar phase orbit number file (spacing was altered to fit the page): No Event UTC PERI Event SCLK PERI OP-Event UTC APO ... == ==================== ================== ==================== ... 1 2004 NOV 15 17:47:39 8/0022825575.11367 2004 NOV 17 14:18:26 ... 2 2004 NOV 19 11:01:02 8/0023146778.35319 2004 NOV 21 00:34:09 ... 3 2004 NOV 22 14:29:38 8/0023418494.56383 2004 NOV 24 00:08:09 ... 4 2004 NOV 25 11:36:12 8/0023667287.61036 2004 NOV 26 16:31:27 ... ... Given this example one can determine that: -- orbit 3 pericenter time is ``2004 NOV 25 11:36:12'' -- orbit 3 time boundaries are from ``2004 NOV 24 00:08:09'' to ``2004 NOV 26 16:31:27'' -- pericenter 4 corresponds to orbit 3 pericenter and its time is ``2004 NOV 25 11:36:12'' ============================================================================= SMART-1 Orbit Number Directory Structure ============================================================================= aareadme.txt Text file describing the directory structure, the naming conventions for the ORBNUMs, and the current version(s) of each file. former_versions Subdirectory that contains obsolete versions of the ORBNUM files that have been updated in the Current ORBNUM File Set. ============================================================================= SMART-1 Orbit Number Naming Covention ffff_______________vvvvv.ORB xxxx_MERGED_vvvvv.ORB ============================================================================= token description ------------ -------------------------------------------------- ffff Source Product Type Identifier: ORES -- S/C Orbit, Earth escape, Earth centric. xxxx Source Product Type Identifier: ORMS -- S/C Orbit, Moon phase, Moon centric. vvvvv version number NOTE: The naming convetions descrived here represent the official naming scheme used throughtout the SMART-1 Mission. Due to the production of a new SMART-1 SCLK after the end of the mission, the latest ORBNUM files have been reprocessed. To keep the ORBNUM file and corresponding SPK versioning consistent, the token 'REPROCESSED' has been added to the file names: ORES___REPROCESSED_00125.ORB ORMS_MERGED_REPROCESSED_00233.ORB ============================================================================= Current Orbit Number File Set ============================================================================= Name Comments ------------------------------ ------------------------------------------- ORES___REPROCESSED_00125.ORB Contains SMART-1 orbit pericenter and apocenter times, orbital elements, and additional geometry parameters computed from the SPK file named: ORES_______________00125.BSP This file contains data related to the Earth escape phase. This file has been reprocessed using the latest SMART-1 SCLK file available, SMART1_070227_STEP.TSC, produced after the original file was released. The SCLK used to process the original file was SMART1_051207_FAKE.TSC. ORMS_MERGED_REPROCESSED_00233.ORB Contains SMART-1 orbit pericenter and apocenter times, orbital elements, and additional geometry parameters computed from the latest set of ORMS SPK files available on the FTP server: ORMS__041111020517_00206.BSP ORMS_______________00233.BSP This file contains data related to the Lunar phase (for both Nominal and Extended Mission phases). This file has been reprocessed using the latest SMART-1 SCLK file available, SMART1_070227_STEP.TSC, produced after the original file was released. The SCLK used to process the original file was SMART1_051207_FAKE.TSC.