Fundamental Technologies

Galileo Spacecraft Pages

Appendix B. SEDR Files (continued)

1. General Description

Content Overview and Scope

This Software Interface Specification (SIS) provides the structure, content and format information for the F&P SEDR File required by the Galileo F&P PIs and the German Space Operations Center.

This section covers the detailed format of the F&P SEDR that will be generated by GSOC to accompany their distribution of EDR data during the interplanetary cruise phase of the mission and the F&P SEDR that will be generated by the JPL Galileo DMT to provide supplementary data during the Jupiter orbital operations mission phase. The GSOC format will contain only interplanetary parameters while the JPL format will contain both the interplanetary parameters (same as the GSOC format) plus geometries of Jupiter and the Galilean satellites.

Subsystem Siting

Interface Location, Medium. The F&P SEDR data shall be written as the second file on each EDR magnetic tape that is generated at GSOC. The SEDR data shall correspond to the EDR data contained on the first file of the tape and shall be continuous from tape to tape.

A F&P SEDR File shall be maintained as a database file on a JPL resident computer system. The current baseline is to transfer the SEDR data to users via magnetic tape. Eventually, the hope is (and plans are being made) that the database be made available for electronic query and access via data lines from both local and remote sites.

Data Source, Destinations, and Transfer Method. The F&P SEDR during interplanetary cruise shall be generated by GSOC operations personnel using orbiter state vectors and the Planetary Ephemeris File, SIS 210-05 (not available on this website), provided per agreements with the JPL Galileo Navigation Team. These input data shall be transferred from JPL in Pasadena, California, USA to GSOC near Munich, FRG via TWX (state vectors) and mail (ephemeris).

During planetary operations, the F&P SEDR shall be generated by the Galileo DMT at JPL using the Orbiter/Probe Ephemeris File (P-File) (not available on this website), SIS 210-16A&B, the Planetary Ephemeris File (not available on this website), SIS 210-05, the Satellite Ephemeris File (not available on this website), SIS 210-07 and the Navigation Constants File, SIS 210-25A&B (not available on this website) received via team interface agreements between DMT and the Navigation Team. In addition, the Navigation Team shall provide the runstream that generates the TWIST Save File, SIS 210-14 (not available on this website), to the DMT. The input ephemerides shall be provided to the DMT as computer files via file release forms which indicate the appropriate attributes of the interface file(s). The runstream shall be provided in card deck form. The Navigation Team shall be responsible for maintaining the runstream while the DMT shall be responsible for updating the runstream during SEDR production operations.

Generation Method and Frequency. During the interplanetary cruise science operations, GSOC operations personnel shall execute GSOC Data Management System (DMS) software to process the navigation state vectors and ephemerides to derive the required output SEDR parameters. GSOC EDR/SEDRs will be generated over two week periods containing EDR data for all telemetry data collected during the period and SEDR data covering from the end of the previous two week period and extending through to the end of the current two week period.

For Jupiter orbital operations, the JPL DMS SEDRGEN program shall access a TWIST Save File (SIS 210-14 - not available on this website) which contains the required output SEDR parameters previously derived by the Navigation System software TWIST. SEDRGEN shall extract and reformat as required the Save File parameters to build the F&P SEDR structure and format.

SEDRGEN shall be executed to generate a predict F&P SEDR (PSEDR) as soon as the ephemerides that are used to generate final uplink products become available for use. This shall be, typically, several days prior to the actual execution of the corresponding sequence load onboard the Galileo orbiter. After the onboard execution by the orbiter, the DMT shall analyze the PSEDR to determine if the predict data meets science pointing and orientation knowledge requirements. Data which meets these requirements shall be converted to final data and those that fail shall be replaced by final SEDR data derived from ephemerides generated from actual tracking data. The general assumption is that the majority of the orbital cruise data shall be converted to final data, while, the encounter time periods shall be replaced with final SEDR data. With this philosophy in mind, PSEDRs shall be generated once per orbiter sequence several days prior to the uplink of that sequence and final SEDRs shall be generated only for encounter sequences several weeks after the execution of those sequences onboard the orbiter (when the final ephemerides become available).

Pertinent Relationships with Other Interfaces. The F&P SEDR is intended to be used in conjunction with the F&P QEDRs and EDRs (part of SIS 224-04 - not available on this website) to provide ancillary information which defines the prevailing conditions that existed when the science data (contained on the EDRs) were gathered.

Labeling and Identification (Internal/External). The F&P SEDR shall be written in the Standard Formatted Data Unit (SFDU) format. The SFDU provides for label information to be included in header portion of each SEDR logical record. Tables and provide the format and content of the F&P SEDR SFDU headers.

When the F&P SEDR is written to magnetic tape as the medium for transfer of these data from either GSOC or JPL to the PIs, an external label shall be affixed to both the reel and the strap. These labels shall contain the SEDR tape number comprised of a three letter designation followed by a seven digit SEDR identification code. The three letter designation shall identify the experiment for which the SEDR applies, while, the seven digit code identifies the mission phase or orbit number, the SEDR type and revision or remake number. The tape number shall appear as follows:

X X X   A B B B C D D


X X Xis the three letter designation of each experiment.
  DMS - JPL Master File Archive
  DDS - Dust Detector Subsystem
  EPD - Energetic Particles Detector
  HIC - Heavy Ion Counter
  MAG - Magnetometer
  PLS - Plasma Subsystem
  PWS - Plasma Wave Subsystem
A is one digit to identify the experiment.
  0 - JPL Master File Archive
  1 - DDS
  2 - EPD
  3 - HIC
  4 - MAG
  5 - PLS
  6 - PWS
B B B is the orbit number.
  000 - Interplanetary Cruise (GSOC until JOI - 60d, JPL from
           JOI - 60d to JOI)
  nnn - Orbit Number (JPL)
C is the SEDR version code.
  0 - Predict SEDR (PSEDR)
  1 - Final SEDR (original)
  2 - Final SEDR revision 1
  . . . . .
  . . . . .
  . . . . .

  8 - Final SEDR revision 7
  9 - Final SEDR (special request by a PI)
D D is the sequence number. This code begins at 01 at the beginning of each orbit number (or Interplanetary Cruise phase) and increases by one for each successive SEDR tape.

Example: MAG 3003001

This SEDR tape number would indicate that the tape has been written for the Magnetometer experiment (MAG 3), the file is effective during the third orbit of Jupiter (003), the SEDR version is a predict SEDR (0) and the tape is the first for that orbit number (01). This tape would contain predict SEDR data for the first part of the third orbit of Jupiter.

Next: 2. Interface Characteristics

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Updated 9/13/04, T. Hunt-Ward